Imported from /home/lorry/working-area/delta_mozilla_mozjs17/mozjs17.0.0.tar.gz.HEADmozjs17.0.0master

58 files changed, 13171 insertions, 0 deletions

diff --git a/mfbt/Assertions.h b/mfbt/Assertions.h
new file mode 100644
index 0000000..407fb24
--- /dev/null
+++ b/mfbt/Assertions.h
@@ -0,0 +1,376 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+/* Implementations of runtime and static assertion macros for C and C++. */
+
+#ifndef mozilla_Assertions_h_
+#define mozilla_Assertions_h_
+
+#include "mozilla/Attributes.h"
+
+#include <stddef.h>
+#include <stdio.h>
+#include <stdlib.h>
+#ifdef WIN32
+   /*
+    * TerminateProcess and GetCurrentProcess are defined in <winbase.h>, which
+    * further depends on <windef.h>.  We hardcode these few definitions manually
+    * because those headers clutter the global namespace with a significant
+    * number of undesired macros and symbols.
+    */
+#  ifdef __cplusplus
+   extern "C" {
+#  endif
+   __declspec(dllimport) int __stdcall
+   TerminateProcess(void* hProcess, unsigned int uExitCode);
+   __declspec(dllimport) void* __stdcall GetCurrentProcess(void);
+#  ifdef __cplusplus
+   }
+#  endif
+#else
+#  include <signal.h>
+#endif
+#ifdef ANDROID
+#  include <android/log.h>
+#endif
+
+/*
+ * MOZ_STATIC_ASSERT may be used to assert a condition *at compile time*.  This
+ * can be useful when you make certain assumptions about what must hold for
+ * optimal, or even correct, behavior.  For example, you might assert that the
+ * size of a struct is a multiple of the target architecture's word size:
+ *
+ *   struct S { ... };
+ *   MOZ_STATIC_ASSERT(sizeof(S) % sizeof(size_t) == 0,
+ *                     "S should be a multiple of word size for efficiency");
+ *
+ * This macro can be used in any location where both an extern declaration and a
+ * typedef could be used.
+ *
+ * Be aware of the gcc 4.2 concerns noted further down when writing patches that
+ * use this macro, particularly if a patch only bounces on OS X.
+ */
+#ifdef __cplusplus
+#  if defined(__clang__)
+#    ifndef __has_extension
+#      define __has_extension __has_feature /* compatibility, for older versions of clang */
+#    endif
+#    if __has_extension(cxx_static_assert)
+#      define MOZ_STATIC_ASSERT(cond, reason)    static_assert((cond), reason)
+#    endif
+#  elif defined(__GNUC__)
+#    if (defined(__GXX_EXPERIMENTAL_CXX0X__) || __cplusplus >= 201103L) && \
+        (__GNUC__ > 4 || (__GNUC__ == 4 && __GNUC_MINOR__ >= 3))
+#      define MOZ_STATIC_ASSERT(cond, reason)    static_assert((cond), reason)
+#    endif
+#  elif defined(_MSC_VER)
+#    if _MSC_VER >= 1600 /* MSVC 10 */
+#      define MOZ_STATIC_ASSERT(cond, reason)    static_assert((cond), reason)
+#    endif
+#  elif defined(__HP_aCC)
+#    if __HP_aCC >= 62500 && defined(_HP_CXX0x_SOURCE)
+#      define MOZ_STATIC_ASSERT(cond, reason)    static_assert((cond), reason)
+#    endif
+#  endif
+#endif
+#ifndef MOZ_STATIC_ASSERT
+#  define MOZ_STATIC_ASSERT_GLUE1(x, y)          x##y
+#  define MOZ_STATIC_ASSERT_GLUE(x, y)           MOZ_STATIC_ASSERT_GLUE1(x, y)
+#  if defined(__SUNPRO_CC)
+     /*
+      * The Sun Studio C++ compiler is buggy when declaring, inside a function,
+      * another extern'd function with an array argument whose length contains a
+      * sizeof, triggering the error message "sizeof expression not accepted as
+      * size of array parameter".  This bug (6688515, not public yet) would hit
+      * defining moz_static_assert as a function, so we always define an extern
+      * array for Sun Studio.
+      *
+      * We include the line number in the symbol name in a best-effort attempt
+      * to avoid conflicts (see below).
+      */
+#    define MOZ_STATIC_ASSERT(cond, reason) \
+       extern char MOZ_STATIC_ASSERT_GLUE(moz_static_assert, __LINE__)[(cond) ? 1 : -1]
+#  elif defined(__COUNTER__)
+     /*
+      * If there was no preferred alternative, use a compiler-agnostic version.
+      *
+      * Note that the non-__COUNTER__ version has a bug in C++: it can't be used
+      * in both |extern "C"| and normal C++ in the same translation unit.  (Alas
+      * |extern "C"| isn't allowed in a function.)  The only affected compiler
+      * we really care about is gcc 4.2.  For that compiler and others like it,
+      * we include the line number in the function name to do the best we can to
+      * avoid conflicts.  These should be rare: a conflict would require use of
+      * MOZ_STATIC_ASSERT on the same line in separate files in the same
+      * translation unit, *and* the uses would have to be in code with
+      * different linkage, *and* the first observed use must be in C++-linkage
+      * code.
+      */
+#    define MOZ_STATIC_ASSERT(cond, reason) \
+       typedef int MOZ_STATIC_ASSERT_GLUE(moz_static_assert, __COUNTER__)[(cond) ? 1 : -1]
+#  else
+#    define MOZ_STATIC_ASSERT(cond, reason) \
+       extern void MOZ_STATIC_ASSERT_GLUE(moz_static_assert, __LINE__)(int arg[(cond) ? 1 : -1])
+#  endif
+#endif
+
+#define MOZ_STATIC_ASSERT_IF(cond, expr, reason)  MOZ_STATIC_ASSERT(!(cond) || (expr), reason)
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+/*
+ * MOZ_CRASH crashes the program, plain and simple, in a Breakpad-compatible
+ * way, in both debug and release builds.
+ *
+ * MOZ_CRASH is a good solution for "handling" failure cases when you're
+ * unwilling or unable to handle them more cleanly -- for OOM, for likely memory
+ * corruption, and so on.  It's also a good solution if you need safe behavior
+ * in release builds as well as debug builds.  But if the failure is one that
+ * should be debugged and fixed, MOZ_ASSERT is generally preferable.
+ */
+#if defined(_MSC_VER)
+   /*
+    * On MSVC use the __debugbreak compiler intrinsic, which produces an inline
+    * (not nested in a system function) breakpoint.  This distinctively invokes
+    * Breakpad without requiring system library symbols on all stack-processing
+    * machines, as a nested breakpoint would require.  We use TerminateProcess
+    * with the exit code aborting would generate because we don't want to invoke
+    * atexit handlers, destructors, library unload handlers, and so on when our
+    * process might be in a compromised state.  We don't use abort() because
+    * it'd cause Windows to annoyingly pop up the process error dialog multiple
+    * times.  See bug 345118 and bug 426163.
+    *
+    * (Technically these are Windows requirements, not MSVC requirements.  But
+    * practically you need MSVC for debugging, and we only ship builds created
+    * by MSVC, so doing it this way reduces complexity.)
+    */
+#  ifdef __cplusplus
+#    define MOZ_CRASH() \
+       do { \
+         __debugbreak(); \
+         *((volatile int*) NULL) = 123; \
+         ::TerminateProcess(::GetCurrentProcess(), 3); \
+       } while (0)
+#  else
+#    define MOZ_CRASH() \
+       do { \
+         __debugbreak(); \
+         *((volatile int*) NULL) = 123; \
+         TerminateProcess(GetCurrentProcess(), 3); \
+       } while (0)
+#  endif
+#else
+#  ifdef __cplusplus
+#    define MOZ_CRASH() \
+       do { \
+         *((volatile int*) NULL) = 123; \
+         ::abort(); \
+       } while (0)
+#  else
+#    define MOZ_CRASH() \
+       do { \
+         *((volatile int*) NULL) = 123; \
+         abort(); \
+       } while (0)
+#  endif
+#endif
+
+/*
+ * Prints |s| as an assertion failure (using file and ln as the location of the
+ * assertion) to the standard debug-output channel.
+ *
+ * Usually you should use MOZ_ASSERT instead of this method.  This method is
+ * primarily for internal use in this header, and only secondarily for use in
+ * implementing release-build assertions.
+ */
+static MOZ_ALWAYS_INLINE void
+MOZ_ReportAssertionFailure(const char* s, const char* file, int ln)
+{
+#ifdef ANDROID
+  __android_log_print(ANDROID_LOG_FATAL, "MOZ_Assert",
+                      "Assertion failure: %s, at %s:%d\n", s, file, ln);
+#else
+  fprintf(stderr, "Assertion failure: %s, at %s:%d\n", s, file, ln);
+  fflush(stderr);
+#endif
+}
+
+#ifdef __cplusplus
+} /* extern "C" */
+#endif
+
+/*
+ * MOZ_ASSERT(expr [, explanation-string]) asserts that |expr| must be truthy in
+ * debug builds.  If it is, execution continues.  Otherwise, an error message
+ * including the expression and the explanation-string (if provided) is printed,
+ * an attempt is made to invoke any existing debugger, and execution halts.
+ * MOZ_ASSERT is fatal: no recovery is possible.  Do not assert a condition
+ * which can correctly be falsy.
+ *
+ * The optional explanation-string, if provided, must be a string literal
+ * explaining the assertion.  It is intended for use with assertions whose
+ * correctness or rationale is non-obvious, and for assertions where the "real"
+ * condition being tested is best described prosaically.  Don't provide an
+ * explanation if it's not actually helpful.
+ *
+ *   // No explanation needed: pointer arguments often must not be NULL.
+ *   MOZ_ASSERT(arg);
+ *
+ *   // An explanation can be helpful to explain exactly how we know an
+ *   // assertion is valid.
+ *   MOZ_ASSERT(state == WAITING_FOR_RESPONSE,
+ *              "given that <thingA> and <thingB>, we must have...");
+ *
+ *   // Or it might disambiguate multiple identical (save for their location)
+ *   // assertions of the same expression.
+ *   MOZ_ASSERT(getSlot(PRIMITIVE_THIS_SLOT).isUndefined(),
+ *              "we already set [[PrimitiveThis]] for this Boolean object");
+ *   MOZ_ASSERT(getSlot(PRIMITIVE_THIS_SLOT).isUndefined(),
+ *              "we already set [[PrimitiveThis]] for this String object");
+ *
+ * MOZ_ASSERT has no effect in non-debug builds.  It is designed to catch bugs
+ * *only* during debugging, not "in the field".
+ */
+#ifdef DEBUG
+   /* First the single-argument form. */
+#  define MOZ_ASSERT_HELPER1(expr) \
+     do { \
+       if (!(expr)) { \
+         MOZ_ReportAssertionFailure(#expr, __FILE__, __LINE__); \
+         MOZ_CRASH(); \
+       } \
+     } while (0)
+   /* Now the two-argument form. */
+#  define MOZ_ASSERT_HELPER2(expr, explain) \
+     do { \
+       if (!(expr)) { \
+         MOZ_ReportAssertionFailure(#expr " (" explain ")", __FILE__, __LINE__); \
+         MOZ_CRASH(); \
+       } \
+     } while (0)
+   /* And now, helper macrology up the wazoo. */
+   /*
+    * Count the number of arguments passed to MOZ_ASSERT, very carefully
+    * tiptoeing around an MSVC bug where it improperly expands __VA_ARGS__ as a
+    * single token in argument lists.  See these URLs for details:
+    *
+    *   http://connect.microsoft.com/VisualStudio/feedback/details/380090/variadic-macro-replacement
+    *   http://cplusplus.co.il/2010/07/17/variadic-macro-to-count-number-of-arguments/#comment-644
+    */
+#  define MOZ_COUNT_ASSERT_ARGS_IMPL2(_1, _2, count, ...) \
+     count
+#  define MOZ_COUNT_ASSERT_ARGS_IMPL(args) \
+	 MOZ_COUNT_ASSERT_ARGS_IMPL2 args
+#  define MOZ_COUNT_ASSERT_ARGS(...) \
+     MOZ_COUNT_ASSERT_ARGS_IMPL((__VA_ARGS__, 2, 1, 0))
+   /* Pick the right helper macro to invoke. */
+#  define MOZ_ASSERT_CHOOSE_HELPER2(count) MOZ_ASSERT_HELPER##count
+#  define MOZ_ASSERT_CHOOSE_HELPER1(count) MOZ_ASSERT_CHOOSE_HELPER2(count)
+#  define MOZ_ASSERT_CHOOSE_HELPER(count) MOZ_ASSERT_CHOOSE_HELPER1(count)
+   /* The actual macro. */
+#  define MOZ_ASSERT_GLUE(x, y) x y
+#  define MOZ_ASSERT(...) \
+     MOZ_ASSERT_GLUE(MOZ_ASSERT_CHOOSE_HELPER(MOZ_COUNT_ASSERT_ARGS(__VA_ARGS__)), \
+                     (__VA_ARGS__))
+#else
+#  define MOZ_ASSERT(...) do { } while(0)
+#endif /* DEBUG */
+
+/*
+ * MOZ_ASSERT_IF(cond1, cond2) is equivalent to MOZ_ASSERT(cond2) if cond1 is
+ * true.
+ *
+ *   MOZ_ASSERT_IF(isPrime(num), num == 2 || isOdd(num));
+ *
+ * As with MOZ_ASSERT, MOZ_ASSERT_IF has effect only in debug builds.  It is
+ * designed to catch bugs during debugging, not "in the field".
+ */
+#ifdef DEBUG
+#  define MOZ_ASSERT_IF(cond, expr) \
+     do { \
+       if (cond) \
+         MOZ_ASSERT(expr); \
+     } while (0)
+#else
+#  define MOZ_ASSERT_IF(cond, expr)  do { } while (0)
+#endif
+
+/*
+ * MOZ_NOT_REACHED_MARKER() expands to an expression which states that it is
+ * undefined behavior for execution to reach this point.  No guarantees are made
+ * about what will happen if this is reached at runtime.  Most code should
+ * probably use the higher level MOZ_NOT_REACHED, which uses this when
+ * appropriate.
+ */
+#if defined(__clang__)
+#  define MOZ_NOT_REACHED_MARKER() __builtin_unreachable()
+#elif defined(__GNUC__)
+   /*
+    * __builtin_unreachable() was implemented in gcc 4.5.  If we don't have
+    * that, call a noreturn function; abort() will do nicely.  Qualify the call
+    * in C++ in case there's another abort() visible in local scope.
+    */
+#  if __GNUC__ > 4 || (__GNUC__ == 4 && __GNUC_MINOR__ >= 5)
+#    define MOZ_NOT_REACHED_MARKER() __builtin_unreachable()
+#  else
+#    ifdef __cplusplus
+#      define MOZ_NOT_REACHED_MARKER() ::abort()
+#    else
+#      define MOZ_NOT_REACHED_MARKER() abort()
+#    endif
+#  endif
+#elif defined(_MSC_VER)
+#  define MOZ_NOT_REACHED_MARKER() __assume(0)
+#else
+#  ifdef __cplusplus
+#    define MOZ_NOT_REACHED_MARKER() ::abort()
+#  else
+#    define MOZ_NOT_REACHED_MARKER() abort()
+#  endif
+#endif
+
+/*
+ * MOZ_NOT_REACHED(reason) indicates that the given point can't be reached
+ * during execution: simply reaching that point in execution is a bug.  It takes
+ * as an argument an error message indicating the reason why that point should
+ * not have been reachable.
+ *
+ *   // ...in a language parser...
+ *   void handle(BooleanLiteralNode node)
+ *   {
+ *     if (node.isTrue())
+ *       handleTrueLiteral();
+ *     else if (node.isFalse())
+ *       handleFalseLiteral();
+ *     else
+ *       MOZ_NOT_REACHED("boolean literal that's not true or false?");
+ *   }
+ */
+#if defined(DEBUG)
+#  define MOZ_NOT_REACHED(reason) \
+     do { \
+       MOZ_ASSERT(false, reason); \
+       MOZ_NOT_REACHED_MARKER(); \
+     } while (0)
+#else
+#  define MOZ_NOT_REACHED(reason)  MOZ_NOT_REACHED_MARKER()
+#endif
+
+/*
+ * MOZ_ALWAYS_TRUE(expr) and MOZ_ALWAYS_FALSE(expr) always evaluate the provided
+ * expression, in debug builds and in release builds both.  Then, in debug
+ * builds only, the value of the expression is asserted either true or false
+ * using MOZ_ASSERT.
+ */
+#ifdef DEBUG
+#  define MOZ_ALWAYS_TRUE(expr)      MOZ_ASSERT((expr))
+#  define MOZ_ALWAYS_FALSE(expr)     MOZ_ASSERT(!(expr))
+#else
+#  define MOZ_ALWAYS_TRUE(expr)      ((void)(expr))
+#  define MOZ_ALWAYS_FALSE(expr)     ((void)(expr))
+#endif
+
+#endif /* mozilla_Assertions_h_ */
diff --git a/mfbt/Attributes.h b/mfbt/Attributes.h
new file mode 100644
index 0000000..8c5d49f
--- /dev/null
+++ b/mfbt/Attributes.h
@@ -0,0 +1,498 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+/* Implementations of various class and method modifier attributes. */
+
+#ifndef mozilla_Attributes_h_
+#define mozilla_Attributes_h_
+
+/*
+ * This header does not include any other headers so that it can be included by
+ * code that is (only currently) mfbt-incompatible.
+ */
+
+/* Suppress any warnings about c++0x extensions. */
+#if defined(__clang__)
+# pragma clang diagnostic ignored "-Wc++0x-extensions"
+#endif
+
+/*
+ * MOZ_INLINE is a macro which expands to tell the compiler that the method
+ * decorated with it should be inlined.  This macro is usable from C and C++
+ * code, even though C89 does not support the |inline| keyword.  The compiler
+ * may ignore this directive if it chooses.
+ */
+#if defined(__cplusplus)
+#  define MOZ_INLINE            inline
+#elif defined(_MSC_VER)
+#  define MOZ_INLINE            __inline
+#elif defined(__GNUC__)
+#  define MOZ_INLINE            __inline__
+#else
+#  define MOZ_INLINE            inline
+#endif
+
+/*
+ * MOZ_ALWAYS_INLINE is a macro which expands to tell the compiler that the
+ * method decorated with it must be inlined, even if the compiler thinks
+ * otherwise.  This is only a (much) stronger version of the MOZ_INLINE hint:
+ * compilers are not guaranteed to respect it (although they're much more likely
+ * to do so).
+ */
+#if defined(DEBUG)
+#  define MOZ_ALWAYS_INLINE     MOZ_INLINE
+#elif defined(_MSC_VER)
+#  define MOZ_ALWAYS_INLINE     __forceinline
+#elif defined(__GNUC__)
+#  define MOZ_ALWAYS_INLINE     __attribute__((always_inline)) MOZ_INLINE
+#else
+#  define MOZ_ALWAYS_INLINE     MOZ_INLINE
+#endif
+
+/*
+ * g++ requires -std=c++0x or -std=gnu++0x to support C++11 functionality
+ * without warnings (functionality used by the macros below).  These modes are
+ * detectable by checking whether __GXX_EXPERIMENTAL_CXX0X__ is defined or, more
+ * standardly, by checking whether __cplusplus has a C++11 or greater value.
+ * Current versions of g++ do not correctly set __cplusplus, so we check both
+ * for forward compatibility.
+ */
+#if defined(__clang__)
+   /*
+    * Per Clang documentation, "Note that marketing version numbers should not
+    * be used to check for language features, as different vendors use different
+    * numbering schemes. Instead, use the feature checking macros."
+    */
+#  ifndef __has_extension
+#    define __has_extension __has_feature /* compatibility, for older versions of clang */
+#  endif
+#  if __has_extension(cxx_deleted_functions)
+#    define MOZ_HAVE_CXX11_DELETE
+#  endif
+#  if __has_extension(cxx_override_control)
+#    define MOZ_HAVE_CXX11_OVERRIDE
+#    define MOZ_HAVE_CXX11_FINAL         final
+#  endif
+#  if __has_extension(cxx_strong_enums)
+#    define MOZ_HAVE_CXX11_ENUM_TYPE
+#    define MOZ_HAVE_CXX11_STRONG_ENUMS
+#  endif
+#  if __has_attribute(noinline)
+#    define MOZ_HAVE_NEVER_INLINE        __attribute__((noinline))
+#  endif
+#  if __has_attribute(noreturn)
+#    define MOZ_HAVE_NORETURN            __attribute__((noreturn))
+#  endif
+#elif defined(__GNUC__)
+#  if defined(__GXX_EXPERIMENTAL_CXX0X__) || __cplusplus >= 201103L
+#    if __GNUC__ > 4
+#      define MOZ_HAVE_CXX11_DELETE
+#      define MOZ_HAVE_CXX11_OVERRIDE
+#      define MOZ_HAVE_CXX11_FINAL       final
+#    elif __GNUC__ == 4
+#      if __GNUC_MINOR__ >= 7
+#        define MOZ_HAVE_CXX11_OVERRIDE
+#        define MOZ_HAVE_CXX11_FINAL     final
+#      endif
+#      if __GNUC_MINOR__ >= 4
+#        define MOZ_HAVE_CXX11_DELETE
+#        define MOZ_HAVE_CXX11_ENUM_TYPE
+#        define MOZ_HAVE_CXX11_STRONG_ENUMS
+#      endif
+#    endif
+#  else
+     /* __final is a non-C++11 GCC synonym for 'final', per GCC r176655. */
+#    if __GNUC__ > 4
+#      define MOZ_HAVE_CXX11_FINAL       __final
+#    elif __GNUC__ == 4
+#      if __GNUC_MINOR__ >= 7
+#        define MOZ_HAVE_CXX11_FINAL     __final
+#      endif
+#    endif
+#  endif
+#  define MOZ_HAVE_NEVER_INLINE          __attribute__((noinline))
+#  define MOZ_HAVE_NORETURN              __attribute__((noreturn))
+#elif defined(_MSC_VER)
+#  if _MSC_VER >= 1400
+#    define MOZ_HAVE_CXX11_OVERRIDE
+     /* MSVC currently spells "final" as "sealed". */
+#    define MOZ_HAVE_CXX11_FINAL         sealed
+#    define MOZ_HAVE_CXX11_ENUM_TYPE
+#  endif
+#  if _MSC_VER >= 1700
+#    define MOZ_HAVE_CXX11_STRONG_ENUMS
+#  endif
+#  define MOZ_HAVE_NEVER_INLINE          __declspec(noinline)
+#  define MOZ_HAVE_NORETURN              __declspec(noreturn)
+#endif
+
+/*
+ * MOZ_NEVER_INLINE is a macro which expands to tell the compiler that the
+ * method decorated with it must never be inlined, even if the compiler would
+ * otherwise choose to inline the method.  Compilers aren't absolutely
+ * guaranteed to support this, but most do.
+ */
+#if defined(MOZ_HAVE_NEVER_INLINE)
+#  define MOZ_NEVER_INLINE      MOZ_HAVE_NEVER_INLINE
+#else
+#  define MOZ_NEVER_INLINE      /* no support */
+#endif
+
+/*
+ * MOZ_NORETURN, specified at the start of a function declaration, indicates
+ * that the given function does not return.  (The function definition does not
+ * need to be annotated.)
+ *
+ *   MOZ_NORETURN void abort(const char* msg);
+ *
+ * This modifier permits the compiler to optimize code assuming a call to such a
+ * function will never return.  It also enables the compiler to avoid spurious
+ * warnings about not initializing variables, or about any other seemingly-dodgy
+ * operations performed after the function returns.
+ *
+ * This modifier does not affect the corresponding function's linking behavior.
+ */
+#if defined(MOZ_HAVE_NORETURN)
+#  define MOZ_NORETURN          MOZ_HAVE_NORETURN
+#else
+#  define MOZ_NORETURN          /* no support */
+#endif
+
+/*
+ * MOZ_ASAN_BLACKLIST is a macro to tell AddressSanitizer (a compile-time
+ * instrumentation shipped with Clang) to not instrument the annotated function.
+ * Furthermore, it will prevent the compiler from inlining the function because
+ * inlining currently breaks the blacklisting mechanism of AddressSanitizer.
+ */
+#if defined(MOZ_ASAN)
+#  define MOZ_ASAN_BLACKLIST MOZ_NEVER_INLINE __attribute__((no_address_safety_analysis))
+# else
+#  define MOZ_ASAN_BLACKLIST
+#endif
+
+
+#ifdef __cplusplus
+
+/*
+ * MOZ_DELETE, specified immediately prior to the ';' terminating an undefined-
+ * method declaration, attempts to delete that method from the corresponding
+ * class.  An attempt to use the method will always produce an error *at compile
+ * time* (instead of sometimes as late as link time) when this macro can be
+ * implemented.  For example, you can use MOZ_DELETE to produce classes with no
+ * implicit copy constructor or assignment operator:
+ *
+ *   struct NonCopyable
+ *   {
+ *     private:
+ *       NonCopyable(const NonCopyable& other) MOZ_DELETE;
+ *       void operator=(const NonCopyable& other) MOZ_DELETE;
+ *   };
+ *
+ * If MOZ_DELETE can't be implemented for the current compiler, use of the
+ * annotated method will still cause an error, but the error might occur at link
+ * time in some cases rather than at compile time.
+ *
+ * MOZ_DELETE relies on C++11 functionality not universally implemented.  As a
+ * backstop, method declarations using MOZ_DELETE should be private.
+ */
+#if defined(MOZ_HAVE_CXX11_DELETE)
+#  define MOZ_DELETE            = delete
+#else
+#  define MOZ_DELETE            /* no support */
+#endif
+
+/*
+ * MOZ_OVERRIDE explicitly indicates that a virtual member function in a class
+ * overrides a member function of a base class, rather than potentially being a
+ * new member function.  MOZ_OVERRIDE should be placed immediately before the
+ * ';' terminating the member function's declaration, or before '= 0;' if the
+ * member function is pure.  If the member function is defined in the class
+ * definition, it should appear before the opening brace of the function body.
+ *
+ *   class Base
+ *   {
+ *     public:
+ *       virtual void f() = 0;
+ *   };
+ *   class Derived1 : public Base
+ *   {
+ *     public:
+ *       virtual void f() MOZ_OVERRIDE;
+ *   };
+ *   class Derived2 : public Base
+ *   {
+ *     public:
+ *       virtual void f() MOZ_OVERRIDE = 0;
+ *   };
+ *   class Derived3 : public Base
+ *   {
+ *     public:
+ *       virtual void f() MOZ_OVERRIDE { }
+ *   };
+ *
+ * In compilers supporting C++11 override controls, MOZ_OVERRIDE *requires* that
+ * the function marked with it override a member function of a base class: it
+ * is a compile error if it does not.  Otherwise MOZ_OVERRIDE does not affect
+ * semantics and merely documents the override relationship to the reader (but
+ * of course must still be used correctly to not break C++11 compilers).
+ */
+#if defined(MOZ_HAVE_CXX11_OVERRIDE)
+#  define MOZ_OVERRIDE          override
+#else
+#  define MOZ_OVERRIDE          /* no support */
+#endif
+
+/*
+ * MOZ_FINAL indicates that some functionality cannot be overridden through
+ * inheritance.  It can be used to annotate either classes/structs or virtual
+ * member functions.
+ *
+ * To annotate a class/struct with MOZ_FINAL, place MOZ_FINAL immediately after
+ * the name of the class, before the list of classes from which it derives (if
+ * any) and before its opening brace.  MOZ_FINAL must not be used to annotate
+ * unnamed classes or structs.  (With some compilers, and with C++11 proper, the
+ * underlying expansion is ambiguous with specifying a class name.)
+ *
+ *   class Base MOZ_FINAL
+ *   {
+ *     public:
+ *       Base();
+ *       ~Base();
+ *       virtual void f() { }
+ *   };
+ *   // This will be an error in some compilers:
+ *   class Derived : public Base
+ *   {
+ *     public:
+ *       ~Derived() { }
+ *   };
+ *
+ * One particularly common reason to specify MOZ_FINAL upon a class is to tell
+ * the compiler that it's not dangerous for it to have a non-virtual destructor
+ * yet have one or more virtual functions, silencing the warning it might emit
+ * in this case.  Suppose Base above weren't annotated with MOZ_FINAL.  Because
+ * ~Base() is non-virtual, an attempt to delete a Derived* through a Base*
+ * wouldn't call ~Derived(), so any cleanup ~Derived() might do wouldn't happen.
+ * (Formally C++ says behavior is undefined, but compilers will likely just call
+ * ~Base() and not ~Derived().)  Specifying MOZ_FINAL tells the compiler that
+ * it's safe for the destructor to be non-virtual.
+ *
+ * In compilers implementing final controls, it is an error to inherit from a
+ * class annotated with MOZ_FINAL.  In other compilers it serves only as
+ * documentation.
+ *
+ * To annotate a virtual member function with MOZ_FINAL, place MOZ_FINAL
+ * immediately before the ';' terminating the member function's declaration, or
+ * before '= 0;' if the member function is pure.  If the member function is
+ * defined in the class definition, it should appear before the opening brace of
+ * the function body.  (This placement is identical to that for MOZ_OVERRIDE.
+ * If both are used, they should appear in the order 'MOZ_FINAL MOZ_OVERRIDE'
+ * for consistency.)
+ *
+ *   class Base
+ *   {
+ *     public:
+ *       virtual void f() MOZ_FINAL;
+ *   };
+ *   class Derived
+ *   {
+ *     public:
+ *       // This will be an error in some compilers:
+ *       virtual void f();
+ *   };
+ *
+ * In compilers implementing final controls, it is an error for a derived class
+ * to override a method annotated with MOZ_FINAL.  In other compilers it serves
+ * only as documentation.
+ */
+#if defined(MOZ_HAVE_CXX11_FINAL)
+#  define MOZ_FINAL             MOZ_HAVE_CXX11_FINAL
+#else
+#  define MOZ_FINAL             /* no support */
+#endif
+
+/**
+ * MOZ_ENUM_TYPE specifies the underlying numeric type for an enum.  It's
+ * specified by placing MOZ_ENUM_TYPE(type) immediately after the enum name in
+ * its declaration, and before the opening curly brace, like
+ *
+ *   enum MyEnum MOZ_ENUM_TYPE(uint16_t)
+ *   {
+ *     A,
+ *     B = 7,
+ *     C
+ *   };
+ *
+ * In supporting compilers, the macro will expand to ": uint16_t".  The
+ * compiler will allocate exactly two bytes for MyEnum, and will require all
+ * enumerators to have values between 0 and 65535.  (Thus specifying "B =
+ * 100000" instead of "B = 7" would fail to compile.)  In old compilers, the
+ * macro expands to the empty string, and the underlying type is generally
+ * undefined.
+ */
+#ifdef MOZ_HAVE_CXX11_ENUM_TYPE
+#  define MOZ_ENUM_TYPE(type)   : type
+#else
+#  define MOZ_ENUM_TYPE(type)   /* no support */
+#endif
+
+/**
+ * MOZ_BEGIN_ENUM_CLASS and MOZ_END_ENUM_CLASS provide access to the
+ * strongly-typed enumeration feature of C++11 ("enum class").  If supported
+ * by the compiler, an enum defined using these macros will not be implicitly
+ * converted to any other type, and its enumerators will be scoped using the
+ * enumeration name.  Place MOZ_BEGIN_ENUM_CLASS(EnumName, type) in place of
+ * "enum EnumName {", and MOZ_END_ENUM_CLASS(EnumName) in place of the closing
+ * "};".  For example,
+ *
+ *   MOZ_BEGIN_ENUM_CLASS(Enum, int32_t)
+ *     A, B = 6
+ *   MOZ_END_ENUM_CLASS(Enum)
+ *
+ * This will make "Enum::A" and "Enum::B" appear in the global scope, but "A"
+ * and "B" will not.  In compilers that support C++11 strongly-typed
+ * enumerations, implicit conversions of Enum values to numeric types will
+ * fail.  In other compilers, Enum itself will actually be defined as a class,
+ * and some implicit conversions will fail while others will succeed.
+ *
+ * The type argument specifies the underlying type for the enum where
+ * supported, as with MOZ_ENUM_TYPE().  For simplicity, it is currently
+ * mandatory.  As with MOZ_ENUM_TYPE(), it will do nothing on compilers that do
+ * not support it.
+ */
+#if defined(MOZ_HAVE_CXX11_STRONG_ENUMS)
+  /* All compilers that support strong enums also support an explicit
+   * underlying type, so no extra check is needed */
+#  define MOZ_BEGIN_ENUM_CLASS(Name, type) enum class Name : type {
+#  define MOZ_END_ENUM_CLASS(Name)         };
+#else
+   /**
+    * We need Name to both name a type, and scope the provided enumerator
+    * names.  Namespaces and classes both provide scoping, but namespaces
+    * aren't types, so we need to use a class that wraps the enum values.  We
+    * have an implicit conversion from the inner enum type to the class, so
+    * statements like
+    *
+    *   Enum x = Enum::A;
+    *
+    * will still work.  We need to define an implicit conversion from the class
+    * to the inner enum as well, so that (for instance) switch statements will
+    * work.  This means that the class can be implicitly converted to a numeric
+    * value as well via the enum type, since C++ allows an implicit
+    * user-defined conversion followed by a standard conversion to still be
+    * implicit.
+    *
+    * We have an explicit constructor from int defined, so that casts like
+    * (Enum)7 will still work.  We also have a zero-argument constructor with
+    * no arguments, so declaration without initialization (like "Enum foo;")
+    * will work.
+    *
+    * Additionally, we'll delete as many operators as possible for the inner
+    * enum type, so statements like this will still fail:
+    *
+    *   f(5 + Enum::B); // deleted operator+
+    *
+    * But we can't prevent things like this, because C++ doesn't allow
+    * overriding conversions or assignment operators for enums:
+    *
+    *   int x = Enum::A;
+    *   int f()
+    *   {
+    *     return Enum::A;
+    *   }
+    */
+#  define MOZ_BEGIN_ENUM_CLASS(Name, type) \
+     class Name \
+     { \
+       public: \
+         enum Enum MOZ_ENUM_TYPE(type) \
+         {
+#  define MOZ_END_ENUM_CLASS(Name) \
+         }; \
+         Name() {} \
+         Name(Enum aEnum) : mEnum(aEnum) {} \
+         explicit Name(int num) : mEnum((Enum)num) {} \
+         operator Enum() const { return mEnum; } \
+       private: \
+         Enum mEnum; \
+     }; \
+     inline int operator+(const int&, const Name::Enum&) MOZ_DELETE; \
+     inline int operator+(const Name::Enum&, const int&) MOZ_DELETE; \
+     inline int operator-(const int&, const Name::Enum&) MOZ_DELETE; \
+     inline int operator-(const Name::Enum&, const int&) MOZ_DELETE; \
+     inline int operator*(const int&, const Name::Enum&) MOZ_DELETE; \
+     inline int operator*(const Name::Enum&, const int&) MOZ_DELETE; \
+     inline int operator/(const int&, const Name::Enum&) MOZ_DELETE; \
+     inline int operator/(const Name::Enum&, const int&) MOZ_DELETE; \
+     inline int operator%(const int&, const Name::Enum&) MOZ_DELETE; \
+     inline int operator%(const Name::Enum&, const int&) MOZ_DELETE; \
+     inline int operator+(const Name::Enum&) MOZ_DELETE; \
+     inline int operator-(const Name::Enum&) MOZ_DELETE; \
+     inline int& operator++(Name::Enum&) MOZ_DELETE; \
+     inline int operator++(Name::Enum&, int) MOZ_DELETE; \
+     inline int& operator--(Name::Enum&) MOZ_DELETE; \
+     inline int operator--(Name::Enum&, int) MOZ_DELETE; \
+     inline bool operator==(const int&, const Name::Enum&) MOZ_DELETE; \
+     inline bool operator==(const Name::Enum&, const int&) MOZ_DELETE; \
+     inline bool operator!=(const int&, const Name::Enum&) MOZ_DELETE; \
+     inline bool operator!=(const Name::Enum&, const int&) MOZ_DELETE; \
+     inline bool operator>(const int&, const Name::Enum&) MOZ_DELETE; \
+     inline bool operator>(const Name::Enum&, const int&) MOZ_DELETE; \
+     inline bool operator<(const int&, const Name::Enum&) MOZ_DELETE; \
+     inline bool operator<(const Name::Enum&, const int&) MOZ_DELETE; \
+     inline bool operator>=(const int&, const Name::Enum&) MOZ_DELETE; \
+     inline bool operator>=(const Name::Enum&, const int&) MOZ_DELETE; \
+     inline bool operator<=(const int&, const Name::Enum&) MOZ_DELETE; \
+     inline bool operator<=(const Name::Enum&, const int&) MOZ_DELETE; \
+     inline bool operator!(const Name::Enum&) MOZ_DELETE; \
+     inline bool operator&&(const bool&, const Name::Enum&) MOZ_DELETE; \
+     inline bool operator&&(const Name::Enum&, const bool&) MOZ_DELETE; \
+     inline bool operator||(const bool&, const Name::Enum&) MOZ_DELETE; \
+     inline bool operator||(const Name::Enum&, const bool&) MOZ_DELETE; \
+     inline int operator~(const Name::Enum&) MOZ_DELETE; \
+     inline int operator&(const int&, const Name::Enum&) MOZ_DELETE; \
+     inline int operator&(const Name::Enum&, const int&) MOZ_DELETE; \
+     inline int operator|(const int&, const Name::Enum&) MOZ_DELETE; \
+     inline int operator|(const Name::Enum&, const int&) MOZ_DELETE; \
+     inline int operator^(const int&, const Name::Enum&) MOZ_DELETE; \
+     inline int operator^(const Name::Enum&, const int&) MOZ_DELETE; \
+     inline int operator<<(const int&, const Name::Enum&) MOZ_DELETE; \
+     inline int operator<<(const Name::Enum&, const int&) MOZ_DELETE; \
+     inline int operator>>(const int&, const Name::Enum&) MOZ_DELETE; \
+     inline int operator>>(const Name::Enum&, const int&) MOZ_DELETE; \
+     inline int& operator+=(int&, const Name::Enum&) MOZ_DELETE; \
+     inline int& operator-=(int&, const Name::Enum&) MOZ_DELETE; \
+     inline int& operator*=(int&, const Name::Enum&) MOZ_DELETE; \
+     inline int& operator/=(int&, const Name::Enum&) MOZ_DELETE; \
+     inline int& operator%=(int&, const Name::Enum&) MOZ_DELETE; \
+     inline int& operator&=(int&, const Name::Enum&) MOZ_DELETE; \
+     inline int& operator|=(int&, const Name::Enum&) MOZ_DELETE; \
+     inline int& operator^=(int&, const Name::Enum&) MOZ_DELETE; \
+     inline int& operator<<=(int&, const Name::Enum&) MOZ_DELETE; \
+     inline int& operator>>=(int&, const Name::Enum&) MOZ_DELETE;
+#endif
+
+/**
+ * MOZ_WARN_UNUSED_RESULT tells the compiler to emit a warning if a function's
+ * return value is not used by the caller.
+ *
+ * Place this attribute at the very beginning of a function definition. For
+ * example, write
+ *
+ *   MOZ_WARN_UNUSED_RESULT int foo();
+ *
+ * or
+ *
+ *   MOZ_WARN_UNUSED_RESULT int foo() { return 42; }
+ */
+#if defined(__GNUC__) || defined(__clang__)
+#  define MOZ_WARN_UNUSED_RESULT __attribute__ ((warn_unused_result))
+#else
+#  define MOZ_WARN_UNUSED_RESULT
+#endif
+
+#endif /* __cplusplus */
+
+#endif  /* mozilla_Attributes_h_ */
diff --git a/mfbt/BloomFilter.h b/mfbt/BloomFilter.h
new file mode 100644
index 0000000..9effa17
--- /dev/null
+++ b/mfbt/BloomFilter.h
@@ -0,0 +1,233 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this file,
+ * You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+/*
+ * A counting Bloom filter implementation.  This allows consumers to
+ * do fast probabilistic "is item X in set Y?" testing which will
+ * never answer "no" when the correct answer is "yes" (but might
+ * incorrectly answer "yes" when the correct answer is "no").
+ */
+
+#ifndef mozilla_BloomFilter_h_
+#define mozilla_BloomFilter_h_
+
+#include "mozilla/Likely.h"
+#include "mozilla/StandardInteger.h"
+#include "mozilla/Util.h"
+
+#include <string.h>
+
+namespace mozilla {
+
+/*
+ * This class implements a counting Bloom filter as described at
+ * <http://en.wikipedia.org/wiki/Bloom_filter#Counting_filters>, with
+ * 8-bit counters.  This allows quick probabilistic answers to the
+ * question "is object X in set Y?" where the contents of Y might not
+ * be time-invariant.  The probabilistic nature of the test means that
+ * sometimes the answer will be "yes" when it should be "no".  If the
+ * answer is "no", then X is guaranteed not to be in Y.
+ *
+ * The filter is parametrized on KeySize, which is the size of the key
+ * generated by each of hash functions used by the filter, in bits,
+ * and the type of object T being added and removed.  T must implement
+ * a |uint32_t hash() const| method which returns a uint32_t hash key
+ * that will be used to generate the two separate hash functions for
+ * the Bloom filter.  This hash key MUST be well-distributed for good
+ * results!  KeySize is not allowed to be larger than 16.
+ *
+ * The filter uses exactly 2**KeySize bytes of memory.  From now on we
+ * will refer to the memory used by the filter as M.
+ *
+ * The expected rate of incorrect "yes" answers depends on M and on
+ * the number N of objects in set Y.  As long as N is small compared
+ * to M, the rate of such answers is expected to be approximately
+ * 4*(N/M)**2 for this filter.  In practice, if Y has a few hundred
+ * elements then using a KeySize of 12 gives a reasonably low
+ * incorrect answer rate.  A KeySize of 12 has the additional benefit
+ * of using exactly one page for the filter in typical hardware
+ * configurations.
+ */
+
+template<unsigned KeySize, class T>
+class BloomFilter
+{
+    /*
+     * A counting Bloom filter with 8-bit counters.  For now we assume
+     * that having two hash functions is enough, but we may revisit that
+     * decision later.
+     *
+     * The filter uses an array with 2**KeySize entries.
+     *
+     * Assuming a well-distributed hash function, a Bloom filter with
+     * array size M containing N elements and
+     * using k hash function has expected false positive rate exactly
+     *
+     * $  (1 - (1 - 1/M)^{kN})^k  $
+     *
+     * because each array slot has a
+     *
+     * $  (1 - 1/M)^{kN}  $
+     *
+     * chance of being 0, and the expected false positive rate is the
+     * probability that all of the k hash functions will hit a nonzero
+     * slot.
+     *
+     * For reasonable assumptions (M large, kN large, which should both
+     * hold if we're worried about false positives) about M and kN this
+     * becomes approximately
+     *
+     * $$  (1 - \exp(-kN/M))^k   $$
+     *
+     * For our special case of k == 2, that's $(1 - \exp(-2N/M))^2$,
+     * or in other words
+     *
+     * $$    N/M = -0.5 * \ln(1 - \sqrt(r))   $$
+     *
+     * where r is the false positive rate.  This can be used to compute
+     * the desired KeySize for a given load N and false positive rate r.
+     *
+     * If N/M is assumed small, then the false positive rate can
+     * further be approximated as 4*N^2/M^2.  So increasing KeySize by
+     * 1, which doubles M, reduces the false positive rate by about a
+     * factor of 4, and a false positive rate of 1% corresponds to
+     * about M/N == 20.
+     *
+     * What this means in practice is that for a few hundred keys using a
+     * KeySize of 12 gives false positive rates on the order of 0.25-4%.
+     *
+     * Similarly, using a KeySize of 10 would lead to a 4% false
+     * positive rate for N == 100 and to quite bad false positive
+     * rates for larger N.
+     */
+  public:
+    BloomFilter() {
+        MOZ_STATIC_ASSERT(KeySize <= keyShift, "KeySize too big");
+
+        // Should we have a custom operator new using calloc instead and
+        // require that we're allocated via the operator?
+        clear();
+    }
+
+    /*
+     * Clear the filter.  This should be done before reusing it, because
+     * just removing all items doesn't clear counters that hit the upper
+     * bound.
+     */
+    void clear();
+
+    /*
+     * Add an item to the filter.
+     */
+    void add(const T* t);
+
+    /*
+     * Remove an item from the filter.
+     */
+    void remove(const T* t);
+
+    /*
+     * Check whether the filter might contain an item.  This can
+     * sometimes return true even if the item is not in the filter,
+     * but will never return false for items that are actually in the
+     * filter.
+     */
+    bool mightContain(const T* t) const;
+
+    /*
+     * Methods for add/remove/contain when we already have a hash computed
+     */
+    void add(uint32_t hash);
+    void remove(uint32_t hash);
+    bool mightContain(uint32_t hash) const;
+
+  private:
+    static const size_t arraySize = (1 << KeySize);
+    static const uint32_t keyMask = (1 << KeySize) - 1;
+    static const uint32_t keyShift = 16;
+
+    static uint32_t hash1(uint32_t hash) { return hash & keyMask; }
+    static uint32_t hash2(uint32_t hash) { return (hash >> keyShift) & keyMask; }
+
+    uint8_t& firstSlot(uint32_t hash) { return counters[hash1(hash)]; }
+    uint8_t& secondSlot(uint32_t hash) { return counters[hash2(hash)]; }
+    const uint8_t& firstSlot(uint32_t hash) const { return counters[hash1(hash)]; }
+    const uint8_t& secondSlot(uint32_t hash) const { return counters[hash2(hash)]; }
+
+    static bool full(const uint8_t& slot) { return slot == UINT8_MAX; }
+
+    uint8_t counters[arraySize];
+};
+
+template<unsigned KeySize, class T>
+inline void
+BloomFilter<KeySize, T>::clear()
+{
+  memset(counters, 0, arraySize);
+}
+
+template<unsigned KeySize, class T>
+inline void
+BloomFilter<KeySize, T>::add(uint32_t hash)
+{
+  uint8_t& slot1 = firstSlot(hash);
+  if (MOZ_LIKELY(!full(slot1)))
+    ++slot1;
+
+  uint8_t& slot2 = secondSlot(hash);
+  if (MOZ_LIKELY(!full(slot2)))
+    ++slot2;
+}
+
+template<unsigned KeySize, class T>
+MOZ_ALWAYS_INLINE void
+BloomFilter<KeySize, T>::add(const T* t)
+{
+  uint32_t hash = t->hash();
+  return add(hash);
+}
+
+template<unsigned KeySize, class T>
+inline void
+BloomFilter<KeySize, T>::remove(uint32_t hash)
+{
+  // If the slots are full, we don't know whether we bumped them to be
+  // there when we added or not, so just leave them full.
+  uint8_t& slot1 = firstSlot(hash);
+  if (MOZ_LIKELY(!full(slot1)))
+    --slot1;
+
+  uint8_t& slot2 = secondSlot(hash);
+  if (MOZ_LIKELY(!full(slot2)))
+    --slot2;
+}
+
+template<unsigned KeySize, class T>
+MOZ_ALWAYS_INLINE void
+BloomFilter<KeySize, T>::remove(const T* t)
+{
+  uint32_t hash = t->hash();
+  remove(hash);
+}
+
+template<unsigned KeySize, class T>
+MOZ_ALWAYS_INLINE bool
+BloomFilter<KeySize, T>::mightContain(uint32_t hash) const
+{
+  // Check that all the slots for this hash contain something
+  return firstSlot(hash) && secondSlot(hash);
+}
+
+template<unsigned KeySize, class T>
+MOZ_ALWAYS_INLINE bool
+BloomFilter<KeySize, T>::mightContain(const T* t) const
+{
+  uint32_t hash = t->hash();
+  return mightContain(hash);
+}
+
+} // namespace mozilla
+
+#endif /* mozilla_BloomFilter_h_ */
diff --git a/mfbt/CheckedInt.h b/mfbt/CheckedInt.h
new file mode 100644
index 0000000..790fc6e
--- /dev/null
+++ b/mfbt/CheckedInt.h
@@ -0,0 +1,809 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this file,
+ * You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+/* Provides checked integers, detecting integer overflow and divide-by-0. */
+
+#ifndef mozilla_CheckedInt_h_
+#define mozilla_CheckedInt_h_
+
+/*
+ * Build options. Comment out these #defines to disable the corresponding
+ * optional feature. Disabling features may be useful for code using
+ * CheckedInt outside of Mozilla (e.g. WebKit)
+ */
+
+// Enable usage of MOZ_STATIC_ASSERT to check for unsupported types.
+// If disabled, static asserts are replaced by regular assert().
+#define MOZ_CHECKEDINT_ENABLE_MOZ_ASSERTS
+
+/*
+ * End of build options
+ */
+
+
+#ifdef MOZ_CHECKEDINT_ENABLE_MOZ_ASSERTS
+#  include "mozilla/Assertions.h"
+#else
+#  ifndef MOZ_STATIC_ASSERT
+#    include <cassert>
+#    define MOZ_STATIC_ASSERT(cond, reason) assert((cond) && reason)
+#    define MOZ_ASSERT(cond, reason) assert((cond) && reason)
+#  endif
+#endif
+
+#include "mozilla/StandardInteger.h"
+
+#include <climits>
+#include <cstddef>
+
+namespace mozilla {
+
+namespace detail {
+
+/*
+ * Step 1: manually record supported types
+ *
+ * What's nontrivial here is that there are different families of integer
+ * types: basic integer types and stdint types. It is merrily undefined which
+ * types from one family may be just typedefs for a type from another family.
+ *
+ * For example, on GCC 4.6, aside from the basic integer types, the only other
+ * type that isn't just a typedef for some of them, is int8_t.
+ */
+
+struct UnsupportedType {};
+
+template<typename IntegerType>
+struct IsSupportedPass2
+{
+    static const bool value = false;
+};
+
+template<typename IntegerType>
+struct IsSupported
+{
+    static const bool value = IsSupportedPass2<IntegerType>::value;
+};
+
+template<>
+struct IsSupported<int8_t>
+{ static const bool value = true; };
+
+template<>
+struct IsSupported<uint8_t>
+{ static const bool value = true; };
+
+template<>
+struct IsSupported<int16_t>
+{ static const bool value = true; };
+
+template<>
+struct IsSupported<uint16_t>
+{ static const bool value = true; };
+
+template<>
+struct IsSupported<int32_t>
+{ static const bool value = true; };
+
+template<>
+struct IsSupported<uint32_t>
+{ static const bool value = true; };
+
+template<>
+struct IsSupported<int64_t>
+{ static const bool value = true; };
+
+template<>
+struct IsSupported<uint64_t>
+{ static const bool value = true; };
+
+
+template<>
+struct IsSupportedPass2<char>
+{ static const bool value = true; };
+
+template<>
+struct IsSupportedPass2<unsigned char>
+{ static const bool value = true; };
+
+template<>
+struct IsSupportedPass2<short>
+{ static const bool value = true; };
+
+template<>
+struct IsSupportedPass2<unsigned short>
+{ static const bool value = true; };
+
+template<>
+struct IsSupportedPass2<int>
+{ static const bool value = true; };
+
+template<>
+struct IsSupportedPass2<unsigned int>
+{ static const bool value = true; };
+
+template<>
+struct IsSupportedPass2<long>
+{ static const bool value = true; };
+
+template<>
+struct IsSupportedPass2<unsigned long>
+{ static const bool value = true; };
+
+
+/*
+ * Step 2: some integer-traits kind of stuff.
+ */
+
+template<size_t Size, bool Signedness>
+struct StdintTypeForSizeAndSignedness
+{};
+
+template<>
+struct StdintTypeForSizeAndSignedness<1, true>
+{ typedef int8_t   Type; };
+
+template<>
+struct StdintTypeForSizeAndSignedness<1, false>
+{ typedef uint8_t  Type; };
+
+template<>
+struct StdintTypeForSizeAndSignedness<2, true>
+{ typedef int16_t  Type; };
+
+template<>
+struct StdintTypeForSizeAndSignedness<2, false>
+{ typedef uint16_t Type; };
+
+template<>
+struct StdintTypeForSizeAndSignedness<4, true>
+{ typedef int32_t  Type; };
+
+template<>
+struct StdintTypeForSizeAndSignedness<4, false>
+{ typedef uint32_t Type; };
+
+template<>
+struct StdintTypeForSizeAndSignedness<8, true>
+{ typedef int64_t  Type; };
+
+template<>
+struct StdintTypeForSizeAndSignedness<8, false>
+{ typedef uint64_t Type; };
+
+template<typename IntegerType>
+struct UnsignedType
+{
+    typedef typename StdintTypeForSizeAndSignedness<sizeof(IntegerType),
+                                                    false>::Type Type;
+};
+
+template<typename IntegerType>
+struct IsSigned
+{
+    static const bool value = IntegerType(-1) <= IntegerType(0);
+};
+
+template<typename IntegerType, size_t Size = sizeof(IntegerType)>
+struct TwiceBiggerType
+{
+    typedef typename StdintTypeForSizeAndSignedness<
+                       sizeof(IntegerType) * 2,
+                       IsSigned<IntegerType>::value
+                     >::Type Type;
+};
+
+template<typename IntegerType>
+struct TwiceBiggerType<IntegerType, 8>
+{
+    typedef UnsupportedType Type;
+};
+
+template<typename IntegerType>
+struct PositionOfSignBit
+{
+    static const size_t value = CHAR_BIT * sizeof(IntegerType) - 1;
+};
+
+template<typename IntegerType>
+struct MinValue
+{
+  private:
+    typedef typename UnsignedType<IntegerType>::Type UnsignedIntegerType;
+    static const size_t PosOfSignBit = PositionOfSignBit<IntegerType>::value;
+
+  public:
+    // Bitwise ops may return a larger type, that's why we cast explicitly.
+    // In C++, left bit shifts on signed values is undefined by the standard
+    // unless the shifted value is representable.
+    // Notice that signed-to-unsigned conversions are always well-defined in
+    // the standard as the value congruent to 2**n, as expected. By contrast,
+    // unsigned-to-signed is only well-defined if the value is representable.
+    static const IntegerType value =
+        IsSigned<IntegerType>::value
+        ? IntegerType(UnsignedIntegerType(1) << PosOfSignBit)
+        : IntegerType(0);
+};
+
+template<typename IntegerType>
+struct MaxValue
+{
+    // Tricksy, but covered by the unit test.
+    // Relies heavily on the type of MinValue<IntegerType>::value
+    // being IntegerType.
+    static const IntegerType value = ~MinValue<IntegerType>::value;
+};
+
+/*
+ * Step 3: Implement the actual validity checks.
+ *
+ * Ideas taken from IntegerLib, code different.
+ */
+
+template<typename T>
+inline bool
+HasSignBit(T x)
+{
+  // In C++, right bit shifts on negative values is undefined by the standard.
+  // Notice that signed-to-unsigned conversions are always well-defined in the
+  // standard, as the value congruent modulo 2**n as expected. By contrast,
+  // unsigned-to-signed is only well-defined if the value is representable.
+  return bool(typename UnsignedType<T>::Type(x)
+                >> PositionOfSignBit<T>::value);
+}
+
+// Bitwise ops may return a larger type, so it's good to use this inline
+// helper guaranteeing that the result is really of type T.
+template<typename T>
+inline T
+BinaryComplement(T x)
+{
+  return ~x;
+}
+
+template<typename T,
+         typename U,
+         bool IsTSigned = IsSigned<T>::value,
+         bool IsUSigned = IsSigned<U>::value>
+struct DoesRangeContainRange
+{
+};
+
+template<typename T, typename U, bool Signedness>
+struct DoesRangeContainRange<T, U, Signedness, Signedness>
+{
+    static const bool value = sizeof(T) >= sizeof(U);
+};
+
+template<typename T, typename U>
+struct DoesRangeContainRange<T, U, true, false>
+{
+    static const bool value = sizeof(T) > sizeof(U);
+};
+
+template<typename T, typename U>
+struct DoesRangeContainRange<T, U, false, true>
+{
+    static const bool value = false;
+};
+
+template<typename T,
+         typename U,
+         bool IsTSigned = IsSigned<T>::value,
+         bool IsUSigned = IsSigned<U>::value,
+         bool DoesTRangeContainURange = DoesRangeContainRange<T, U>::value>
+struct IsInRangeImpl {};
+
+template<typename T, typename U, bool IsTSigned, bool IsUSigned>
+struct IsInRangeImpl<T, U, IsTSigned, IsUSigned, true>
+{
+    static bool run(U)
+    {
+       return true;
+    }
+};
+
+template<typename T, typename U>
+struct IsInRangeImpl<T, U, true, true, false>
+{
+    static bool run(U x)
+    {
+      return x <= MaxValue<T>::value && x >= MinValue<T>::value;
+    }
+};
+
+template<typename T, typename U>
+struct IsInRangeImpl<T, U, false, false, false>
+{
+    static bool run(U x)
+    {
+      return x <= MaxValue<T>::value;
+    }
+};
+
+template<typename T, typename U>
+struct IsInRangeImpl<T, U, true, false, false>
+{
+    static bool run(U x)
+    {
+      return sizeof(T) > sizeof(U) || x <= U(MaxValue<T>::value);
+    }
+};
+
+template<typename T, typename U>
+struct IsInRangeImpl<T, U, false, true, false>
+{
+    static bool run(U x)
+    {
+      return sizeof(T) >= sizeof(U)
+             ? x >= 0
+             : x >= 0 && x <= U(MaxValue<T>::value);
+    }
+};
+
+template<typename T, typename U>
+inline bool
+IsInRange(U x)
+{
+  return IsInRangeImpl<T, U>::run(x);
+}
+
+template<typename T>
+inline bool
+IsAddValid(T x, T y)
+{
+  // Addition is valid if the sign of x+y is equal to either that of x or that
+  // of y. Since the value of x+y is undefined if we have a signed type, we
+  // compute it using the unsigned type of the same size.
+  // Beware! These bitwise operations can return a larger integer type,
+  // if T was a small type like int8_t, so we explicitly cast to T.
+
+  typename UnsignedType<T>::Type ux = x;
+  typename UnsignedType<T>::Type uy = y;
+  typename UnsignedType<T>::Type result = ux + uy;
+  return IsSigned<T>::value
+         ? HasSignBit(BinaryComplement(T((result ^ x) & (result ^ y))))
+         : BinaryComplement(x) >= y;
+}
+
+template<typename T>
+inline bool
+IsSubValid(T x, T y)
+{
+  // Subtraction is valid if either x and y have same sign, or x-y and x have
+  // same sign. Since the value of x-y is undefined if we have a signed type,
+  // we compute it using the unsigned type of the same size.
+  typename UnsignedType<T>::Type ux = x;
+  typename UnsignedType<T>::Type uy = y;
+  typename UnsignedType<T>::Type result = ux - uy;
+
+  return IsSigned<T>::value
+         ? HasSignBit(BinaryComplement(T((result ^ x) & (x ^ y))))
+         : x >= y;
+}
+
+template<typename T,
+         bool IsSigned = IsSigned<T>::value,
+         bool TwiceBiggerTypeIsSupported =
+           IsSupported<typename TwiceBiggerType<T>::Type>::value>
+struct IsMulValidImpl {};
+
+template<typename T, bool IsSigned>
+struct IsMulValidImpl<T, IsSigned, true>
+{
+    static bool run(T x, T y)
+    {
+      typedef typename TwiceBiggerType<T>::Type TwiceBiggerType;
+      TwiceBiggerType product = TwiceBiggerType(x) * TwiceBiggerType(y);
+      return IsInRange<T>(product);
+    }
+};
+
+template<typename T>
+struct IsMulValidImpl<T, true, false>
+{
+    static bool run(T x, T y)
+    {
+      const T max = MaxValue<T>::value;
+      const T min = MinValue<T>::value;
+
+      if (x == 0 || y == 0)
+        return true;
+
+      if (x > 0) {
+        return y > 0
+               ? x <= max / y
+               : y >= min / x;
+      }
+
+      // If we reach this point, we know that x < 0.
+      return y > 0
+             ? x >= min / y
+             : y >= max / x;
+    }
+};
+
+template<typename T>
+struct IsMulValidImpl<T, false, false>
+{
+    static bool run(T x, T y)
+    {
+      return y == 0 ||  x <= MaxValue<T>::value / y;
+    }
+};
+
+template<typename T>
+inline bool
+IsMulValid(T x, T y)
+{
+  return IsMulValidImpl<T>::run(x, y);
+}
+
+template<typename T>
+inline bool
+IsDivValid(T x, T y)
+{
+  // Keep in mind that in the signed case, min/-1 is invalid because abs(min)>max.
+  return y != 0 &&
+         !(IsSigned<T>::value && x == MinValue<T>::value && y == T(-1));
+}
+
+// This is just to shut up msvc warnings about negating unsigned ints.
+template<typename T, bool IsSigned = IsSigned<T>::value>
+struct OppositeIfSignedImpl
+{
+    static T run(T x) { return -x; }
+};
+template<typename T>
+struct OppositeIfSignedImpl<T, false>
+{
+    static T run(T x) { return x; }
+};
+template<typename T>
+inline T
+OppositeIfSigned(T x)
+{
+  return OppositeIfSignedImpl<T>::run(x);
+}
+
+} // namespace detail
+
+
+/*
+ * Step 4: Now define the CheckedInt class.
+ */
+
+/**
+ * @class CheckedInt
+ * @brief Integer wrapper class checking for integer overflow and other errors
+ * @param T the integer type to wrap. Can be any type among the following:
+ *            - any basic integer type such as |int|
+ *            - any stdint type such as |int8_t|
+ *
+ * This class implements guarded integer arithmetic. Do a computation, check
+ * that isValid() returns true, you then have a guarantee that no problem, such
+ * as integer overflow, happened during this computation, and you can call
+ * value() to get the plain integer value.
+ *
+ * The arithmetic operators in this class are guaranteed not to raise a signal
+ * (e.g. in case of a division by zero).
+ *
+ * For example, suppose that you want to implement a function that computes
+ * (x+y)/z, that doesn't crash if z==0, and that reports on error (divide by
+ * zero or integer overflow). You could code it as follows:
+   @code
+   bool computeXPlusYOverZ(int x, int y, int z, int *result)
+   {
+       CheckedInt<int> checkedResult = (CheckedInt<int>(x) + y) / z;
+       if (checkedResult.isValid()) {
+           *result = checkedResult.value();
+           return true;
+       } else {
+           return false;
+       }
+   }
+   @endcode
+ *
+ * Implicit conversion from plain integers to checked integers is allowed. The
+ * plain integer is checked to be in range before being casted to the
+ * destination type. This means that the following lines all compile, and the
+ * resulting CheckedInts are correctly detected as valid or invalid:
+ * @code
+   // 1 is of type int, is found to be in range for uint8_t, x is valid
+   CheckedInt<uint8_t> x(1);
+   // -1 is of type int, is found not to be in range for uint8_t, x is invalid
+   CheckedInt<uint8_t> x(-1);
+   // -1 is of type int, is found to be in range for int8_t, x is valid
+   CheckedInt<int8_t> x(-1);
+   // 1000 is of type int16_t, is found not to be in range for int8_t,
+   // x is invalid
+   CheckedInt<int8_t> x(int16_t(1000)); 
+   // 3123456789 is of type uint32_t, is found not to be in range for int32_t,
+   // x is invalid
+   CheckedInt<int32_t> x(uint32_t(3123456789));
+ * @endcode
+ * Implicit conversion from
+ * checked integers to plain integers is not allowed. As shown in the
+ * above example, to get the value of a checked integer as a normal integer,
+ * call value().
+ *
+ * Arithmetic operations between checked and plain integers is allowed; the
+ * result type is the type of the checked integer.
+ *
+ * Checked integers of different types cannot be used in the same arithmetic
+ * expression.
+ *
+ * There are convenience typedefs for all stdint types, of the following form
+ * (these are just 2 examples):
+   @code
+   typedef CheckedInt<int32_t> CheckedInt32;
+   typedef CheckedInt<uint16_t> CheckedUint16;
+   @endcode
+ */
+template<typename T>
+class CheckedInt
+{
+  protected:
+    T mValue;
+    bool mIsValid;
+
+    template<typename U>
+    CheckedInt(U value, bool isValid) : mValue(value), mIsValid(isValid)
+    {
+      MOZ_STATIC_ASSERT(detail::IsSupported<T>::value,
+                        "This type is not supported by CheckedInt");
+    }
+
+  public:
+    /**
+     * Constructs a checked integer with given @a value. The checked integer is
+     * initialized as valid or invalid depending on whether the @a value
+     * is in range.
+     *
+     * This constructor is not explicit. Instead, the type of its argument is a
+     * separate template parameter, ensuring that no conversion is performed
+     * before this constructor is actually called. As explained in the above
+     * documentation for class CheckedInt, this constructor checks that its
+     * argument is valid.
+     */
+    template<typename U>
+    CheckedInt(U value)
+      : mValue(T(value)),
+        mIsValid(detail::IsInRange<T>(value))
+    {
+      MOZ_STATIC_ASSERT(detail::IsSupported<T>::value,
+                        "This type is not supported by CheckedInt");
+    }
+
+    /** Constructs a valid checked integer with initial value 0 */
+    CheckedInt() : mValue(0), mIsValid(true)
+    {
+      MOZ_STATIC_ASSERT(detail::IsSupported<T>::value,
+                        "This type is not supported by CheckedInt");
+    }
+
+    /** @returns the actual value */
+    T value() const
+    {
+      MOZ_ASSERT(mIsValid, "Invalid checked integer (division by zero or integer overflow)");
+      return mValue;
+    }
+
+    /**
+     * @returns true if the checked integer is valid, i.e. is not the result
+     * of an invalid operation or of an operation involving an invalid checked
+     * integer
+     */
+    bool isValid() const
+    {
+      return mIsValid;
+    }
+
+    template<typename U>
+    friend CheckedInt<U> operator +(const CheckedInt<U>& lhs,
+                                    const CheckedInt<U>& rhs);
+    template<typename U>
+    CheckedInt& operator +=(U rhs);
+    template<typename U>
+    friend CheckedInt<U> operator -(const CheckedInt<U>& lhs,
+                                    const CheckedInt<U> &rhs);
+    template<typename U>
+    CheckedInt& operator -=(U rhs);
+    template<typename U>
+    friend CheckedInt<U> operator *(const CheckedInt<U>& lhs,
+                                    const CheckedInt<U> &rhs);
+    template<typename U>
+    CheckedInt& operator *=(U rhs);
+    template<typename U>
+    friend CheckedInt<U> operator /(const CheckedInt<U>& lhs,
+                                    const CheckedInt<U> &rhs);
+    template<typename U>
+    CheckedInt& operator /=(U rhs);
+
+    CheckedInt operator -() const
+    {
+      // Circumvent msvc warning about - applied to unsigned int.
+      // if we're unsigned, the only valid case anyway is 0
+      // in which case - is a no-op.
+      T result = detail::OppositeIfSigned(mValue);
+      /* Help the compiler perform RVO (return value optimization). */
+      return CheckedInt(result,
+                        mIsValid && detail::IsSubValid(T(0),
+                                                       mValue));
+    }
+
+    /**
+     * @returns true if the left and right hand sides are valid
+     * and have the same value.
+     *
+     * Note that these semantics are the reason why we don't offer
+     * a operator!=. Indeed, we'd want to have a!=b be equivalent to !(a==b)
+     * but that would mean that whenever a or b is invalid, a!=b
+     * is always true, which would be very confusing.
+     *
+     * For similar reasons, operators <, >, <=, >= would be very tricky to
+     * specify, so we just avoid offering them.
+     *
+     * Notice that these == semantics are made more reasonable by these facts:
+     *  1. a==b implies equality at the raw data level
+     *     (the converse is false, as a==b is never true among invalids)
+     *  2. This is similar to the behavior of IEEE floats, where a==b
+     *     means that a and b have the same value *and* neither is NaN.
+     */
+    bool operator ==(const CheckedInt& other) const
+    {
+      return mIsValid && other.mIsValid && mValue == other.mValue;
+    }
+
+    /** prefix ++ */
+    CheckedInt& operator++()
+    {
+      *this += 1;
+      return *this;
+    }
+
+    /** postfix ++ */
+    CheckedInt operator++(int)
+    {
+      CheckedInt tmp = *this;
+      *this += 1;
+      return tmp;
+    }
+
+    /** prefix -- */
+    CheckedInt& operator--()
+    {
+      *this -= 1;
+      return *this;
+    }
+
+    /** postfix -- */
+    CheckedInt operator--(int)
+    {
+      CheckedInt tmp = *this;
+      *this -= 1;
+      return tmp;
+    }
+
+  private:
+    /**
+     * The !=, <, <=, >, >= operators are disabled:
+     * see the comment on operator==.
+     */
+    template<typename U>
+    bool operator !=(U other) const MOZ_DELETE;
+    template<typename U>
+    bool operator <(U other) const MOZ_DELETE;
+    template<typename U>
+    bool operator <=(U other) const MOZ_DELETE;
+    template<typename U>
+    bool operator >(U other) const MOZ_DELETE;
+    template<typename U>
+    bool operator >=(U other) const MOZ_DELETE;
+};
+
+#define MOZ_CHECKEDINT_BASIC_BINARY_OPERATOR(NAME, OP)                \
+template<typename T>                                                  \
+inline CheckedInt<T> operator OP(const CheckedInt<T> &lhs,            \
+                                 const CheckedInt<T> &rhs)            \
+{                                                                     \
+  if (!detail::Is##NAME##Valid(lhs.mValue, rhs.mValue))               \
+    return CheckedInt<T>(0, false);                                   \
+                                                                      \
+  return CheckedInt<T>(lhs.mValue OP rhs.mValue,                      \
+                       lhs.mIsValid && rhs.mIsValid);                 \
+}
+
+MOZ_CHECKEDINT_BASIC_BINARY_OPERATOR(Add, +)
+MOZ_CHECKEDINT_BASIC_BINARY_OPERATOR(Sub, -)
+MOZ_CHECKEDINT_BASIC_BINARY_OPERATOR(Mul, *)
+MOZ_CHECKEDINT_BASIC_BINARY_OPERATOR(Div, /)
+
+#undef MOZ_CHECKEDINT_BASIC_BINARY_OPERATOR
+
+// Implement castToCheckedInt<T>(x), making sure that
+//  - it allows x to be either a CheckedInt<T> or any integer type
+//    that can be casted to T
+//  - if x is already a CheckedInt<T>, we just return a reference to it,
+//    instead of copying it (optimization)
+
+namespace detail {
+
+template<typename T, typename U>
+struct CastToCheckedIntImpl
+{
+    typedef CheckedInt<T> ReturnType;
+    static CheckedInt<T> run(U u) { return u; }
+};
+
+template<typename T>
+struct CastToCheckedIntImpl<T, CheckedInt<T> >
+{
+    typedef const CheckedInt<T>& ReturnType;
+    static const CheckedInt<T>& run(const CheckedInt<T>& u) { return u; }
+};
+
+} // namespace detail
+
+template<typename T, typename U>
+inline typename detail::CastToCheckedIntImpl<T, U>::ReturnType
+castToCheckedInt(U u)
+{
+  return detail::CastToCheckedIntImpl<T, U>::run(u);
+}
+
+#define MOZ_CHECKEDINT_CONVENIENCE_BINARY_OPERATORS(OP, COMPOUND_OP)  \
+template<typename T>                                              \
+template<typename U>                                              \
+CheckedInt<T>& CheckedInt<T>::operator COMPOUND_OP(U rhs)         \
+{                                                                 \
+  *this = *this OP castToCheckedInt<T>(rhs);                      \
+  return *this;                                                   \
+}                                                                 \
+template<typename T, typename U>                                  \
+inline CheckedInt<T> operator OP(const CheckedInt<T> &lhs, U rhs) \
+{                                                                 \
+  return lhs OP castToCheckedInt<T>(rhs);                         \
+}                                                                 \
+template<typename T, typename U>                                  \
+inline CheckedInt<T> operator OP(U lhs, const CheckedInt<T> &rhs) \
+{                                                                 \
+  return castToCheckedInt<T>(lhs) OP rhs;                         \
+}
+
+MOZ_CHECKEDINT_CONVENIENCE_BINARY_OPERATORS(+, +=)
+MOZ_CHECKEDINT_CONVENIENCE_BINARY_OPERATORS(*, *=)
+MOZ_CHECKEDINT_CONVENIENCE_BINARY_OPERATORS(-, -=)
+MOZ_CHECKEDINT_CONVENIENCE_BINARY_OPERATORS(/, /=)
+
+#undef MOZ_CHECKEDINT_CONVENIENCE_BINARY_OPERATORS
+
+template<typename T, typename U>
+inline bool
+operator ==(const CheckedInt<T> &lhs, U rhs)
+{
+  return lhs == castToCheckedInt<T>(rhs);
+}
+
+template<typename T, typename U>
+inline bool
+operator ==(U  lhs, const CheckedInt<T> &rhs)
+{
+  return castToCheckedInt<T>(lhs) == rhs;
+}
+
+// Convenience typedefs.
+typedef CheckedInt<int8_t>   CheckedInt8;
+typedef CheckedInt<uint8_t>  CheckedUint8;
+typedef CheckedInt<int16_t>  CheckedInt16;
+typedef CheckedInt<uint16_t> CheckedUint16;
+typedef CheckedInt<int32_t>  CheckedInt32;
+typedef CheckedInt<uint32_t> CheckedUint32;
+typedef CheckedInt<int64_t>  CheckedInt64;
+typedef CheckedInt<uint64_t> CheckedUint64;
+
+} // namespace mozilla
+
+#endif /* mozilla_CheckedInt_h_ */
diff --git a/mfbt/Constants.h b/mfbt/Constants.h
new file mode 100644
index 0000000..904b301
--- /dev/null
+++ b/mfbt/Constants.h
@@ -0,0 +1,15 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+/* mfbt math constants. */
+
+#ifndef mozilla_Constants_h_
+#define mozilla_Constants_h_
+
+#ifndef M_PI
+#  define M_PI 3.14159265358979323846
+#endif
+
+#endif  /* mozilla_Constants_h_ */
diff --git a/mfbt/FloatingPoint.h b/mfbt/FloatingPoint.h
new file mode 100644
index 0000000..cb1394e
--- /dev/null
+++ b/mfbt/FloatingPoint.h
@@ -0,0 +1,244 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this file,
+ * You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+/* Various predicates and operations on IEEE-754 floating point types. */
+
+#ifndef mozilla_FloatingPoint_h_
+#define mozilla_FloatingPoint_h_
+
+#include "mozilla/Assertions.h"
+#include "mozilla/Attributes.h"
+#include "mozilla/StandardInteger.h"
+
+/*
+ * It's reasonable to ask why we have this header at all.  Don't isnan,
+ * copysign, the built-in comparison operators, and the like solve these
+ * problems?  Unfortunately, they don't.  We've found that various compilers
+ * (MSVC, MSVC when compiling with PGO, and GCC on OS X, at least) miscompile
+ * the standard methods in various situations, so we can't use them.  Some of
+ * these compilers even have problems compiling seemingly reasonable bitwise
+ * algorithms!  But with some care we've found algorithms that seem to not
+ * trigger those compiler bugs.
+ *
+ * For the aforementioned reasons, be very wary of making changes to any of
+ * these algorithms.  If you must make changes, keep a careful eye out for
+ * compiler bustage, particularly PGO-specific bustage.
+ *
+ * Some users require that this file be C-compatible.  Unfortunately, this means
+ * no mozilla namespace to contain everything, no detail namespace clarifying
+ * MozDoublePun to be an internal data structure, and so on.
+ */
+
+/*
+ * These implementations all assume |double| is a 64-bit double format number
+ * type, compatible with the IEEE-754 standard.  C/C++ don't require this to be
+ * the case.  But we required this in implementations of these algorithms that
+ * preceded this header, so we shouldn't break anything if we continue doing so.
+ */
+MOZ_STATIC_ASSERT(sizeof(double) == sizeof(uint64_t), "double must be 64 bits");
+
+/*
+ * Constant expressions in C can't refer to consts, unfortunately, so #define
+ * these rather than use |const uint64_t|.
+ */
+#define MOZ_DOUBLE_SIGN_BIT          0x8000000000000000ULL
+#define MOZ_DOUBLE_EXPONENT_BITS     0x7ff0000000000000ULL
+#define MOZ_DOUBLE_SIGNIFICAND_BITS  0x000fffffffffffffULL
+
+#define MOZ_DOUBLE_EXPONENT_BIAS   1023
+#define MOZ_DOUBLE_EXPONENT_SHIFT  52
+
+MOZ_STATIC_ASSERT((MOZ_DOUBLE_SIGN_BIT & MOZ_DOUBLE_EXPONENT_BITS) == 0,
+                  "sign bit doesn't overlap exponent bits");
+MOZ_STATIC_ASSERT((MOZ_DOUBLE_SIGN_BIT & MOZ_DOUBLE_SIGNIFICAND_BITS) == 0,
+                  "sign bit doesn't overlap significand bits");
+MOZ_STATIC_ASSERT((MOZ_DOUBLE_EXPONENT_BITS & MOZ_DOUBLE_SIGNIFICAND_BITS) == 0,
+                  "exponent bits don't overlap significand bits");
+
+MOZ_STATIC_ASSERT((MOZ_DOUBLE_SIGN_BIT | MOZ_DOUBLE_EXPONENT_BITS | MOZ_DOUBLE_SIGNIFICAND_BITS)
+                  == ~(uint64_t)0,
+                  "all bits accounted for");
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+/*
+ * This union is NOT a public data structure, and it is not to be used outside
+ * this file!
+ */
+union MozDoublePun {
+    /*
+     * Every way to pun the bits of a double introduces an additional layer of
+     * complexity, across a multitude of platforms, architectures, and ABIs.
+     * Use *only* uint64_t to reduce complexity.  Don't add new punning here
+     * without discussion!
+     */
+    uint64_t u;
+    double d;
+};
+
+/** Determines whether a double is NaN. */
+static MOZ_ALWAYS_INLINE int
+MOZ_DOUBLE_IS_NaN(double d)
+{
+  union MozDoublePun pun;
+  pun.d = d;
+
+  /*
+   * A double is NaN if all exponent bits are 1 and the significand contains at
+   * least one non-zero bit.
+   */
+  return (pun.u & MOZ_DOUBLE_EXPONENT_BITS) == MOZ_DOUBLE_EXPONENT_BITS &&
+         (pun.u & MOZ_DOUBLE_SIGNIFICAND_BITS) != 0;
+}
+
+/** Determines whether a double is +Infinity or -Infinity. */
+static MOZ_ALWAYS_INLINE int
+MOZ_DOUBLE_IS_INFINITE(double d)
+{
+  union MozDoublePun pun;
+  pun.d = d;
+
+  /* Infinities have all exponent bits set to 1 and an all-0 significand. */
+  return (pun.u & ~MOZ_DOUBLE_SIGN_BIT) == MOZ_DOUBLE_EXPONENT_BITS;
+}
+
+/** Determines whether a double is not NaN or infinite. */
+static MOZ_ALWAYS_INLINE int
+MOZ_DOUBLE_IS_FINITE(double d)
+{
+  union MozDoublePun pun;
+  pun.d = d;
+
+  /*
+   * NaN and Infinities are the only non-finite doubles, and both have all
+   * exponent bits set to 1.
+   */
+  return (pun.u & MOZ_DOUBLE_EXPONENT_BITS) != MOZ_DOUBLE_EXPONENT_BITS;
+}
+
+/**
+ * Determines whether a double is negative.  It is an error to call this method
+ * on a double which is NaN.
+ */
+static MOZ_ALWAYS_INLINE int
+MOZ_DOUBLE_IS_NEGATIVE(double d)
+{
+  union MozDoublePun pun;
+  pun.d = d;
+
+  MOZ_ASSERT(!MOZ_DOUBLE_IS_NaN(d), "NaN does not have a sign");
+
+  /* The sign bit is set if the double is negative. */
+  return (pun.u & MOZ_DOUBLE_SIGN_BIT) != 0;
+}
+
+/** Determines whether a double represents -0. */
+static MOZ_ALWAYS_INLINE int
+MOZ_DOUBLE_IS_NEGATIVE_ZERO(double d)
+{
+  union MozDoublePun pun;
+  pun.d = d;
+
+  /* Only the sign bit is set if the double is -0. */
+  return pun.u == MOZ_DOUBLE_SIGN_BIT;
+}
+
+/** Returns the exponent portion of the double. */
+static MOZ_ALWAYS_INLINE int_fast16_t
+MOZ_DOUBLE_EXPONENT(double d)
+{
+  union MozDoublePun pun;
+  pun.d = d;
+
+  /*
+   * The exponent component of a double is an unsigned number, biased from its
+   * actual value.  Subtract the bias to retrieve the actual exponent.
+   */
+  return (int_fast16_t)((pun.u & MOZ_DOUBLE_EXPONENT_BITS) >> MOZ_DOUBLE_EXPONENT_SHIFT) -
+                        MOZ_DOUBLE_EXPONENT_BIAS;
+}
+
+/** Returns +Infinity. */
+static MOZ_ALWAYS_INLINE double
+MOZ_DOUBLE_POSITIVE_INFINITY()
+{
+  union MozDoublePun pun;
+
+  /*
+   * Positive infinity has all exponent bits set, sign bit set to 0, and no
+   * significand.
+   */
+  pun.u = MOZ_DOUBLE_EXPONENT_BITS;
+  return pun.d;
+}
+
+/** Returns -Infinity. */
+static MOZ_ALWAYS_INLINE double
+MOZ_DOUBLE_NEGATIVE_INFINITY()
+{
+  union MozDoublePun pun;
+
+  /*
+   * Negative infinity has all exponent bits set, sign bit set to 1, and no
+   * significand.
+   */
+  pun.u = MOZ_DOUBLE_SIGN_BIT | MOZ_DOUBLE_EXPONENT_BITS;
+  return pun.d;
+}
+
+/** Constructs a NaN value with the specified sign bit and significand bits. */
+static MOZ_ALWAYS_INLINE double
+MOZ_DOUBLE_SPECIFIC_NaN(int signbit, uint64_t significand)
+{
+  union MozDoublePun pun;
+
+  MOZ_ASSERT(signbit == 0 || signbit == 1);
+  MOZ_ASSERT((significand & ~MOZ_DOUBLE_SIGNIFICAND_BITS) == 0);
+  MOZ_ASSERT(significand & MOZ_DOUBLE_SIGNIFICAND_BITS);
+
+  pun.u = (signbit ? MOZ_DOUBLE_SIGN_BIT : 0) |
+          MOZ_DOUBLE_EXPONENT_BITS |
+          significand;
+  MOZ_ASSERT(MOZ_DOUBLE_IS_NaN(pun.d));
+  return pun.d;
+}
+
+/**
+ * Computes a NaN value.  Do not use this method if you depend upon a particular
+ * NaN value being returned.
+ */
+static MOZ_ALWAYS_INLINE double
+MOZ_DOUBLE_NaN()
+{
+  return MOZ_DOUBLE_SPECIFIC_NaN(0, 0xfffffffffffffULL);
+}
+
+/** Computes the smallest non-zero positive double value. */
+static MOZ_ALWAYS_INLINE double
+MOZ_DOUBLE_MIN_VALUE()
+{
+  union MozDoublePun pun;
+  pun.u = 1;
+  return pun.d;
+}
+
+static MOZ_ALWAYS_INLINE int
+MOZ_DOUBLE_IS_INT32(double d, int32_t* i)
+{
+  /*
+   * XXX Casting a double that doesn't truncate to int32_t, to int32_t, induces
+   *     undefined behavior.  We should definitely fix this (bug 744965), but as
+   *     apparently it "works" in practice, it's not a pressing concern now.
+   */
+  return !MOZ_DOUBLE_IS_NEGATIVE_ZERO(d) && d == (*i = (int32_t)d);
+}
+
+#ifdef __cplusplus
+} /* extern "C" */
+#endif
+
+#endif  /* mozilla_FloatingPoint_h_ */
diff --git a/mfbt/GuardObjects.h b/mfbt/GuardObjects.h
new file mode 100644
index 0000000..95aa37a
--- /dev/null
+++ b/mfbt/GuardObjects.h
@@ -0,0 +1,147 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+/* Implementation of macros to ensure correct use of RAII Auto* objects. */
+
+#ifndef mozilla_GuardObjects_h
+#define mozilla_GuardObjects_h
+
+#include "mozilla/Assertions.h"
+#include "mozilla/Types.h"
+
+#ifdef __cplusplus
+
+#ifdef DEBUG
+
+namespace mozilla {
+namespace detail {
+
+/*
+ * The following classes are designed to cause assertions to detect
+ * inadvertent use of guard objects as temporaries. In other words,
+ * when we have a guard object whose only purpose is its constructor and
+ * destructor (and is never otherwise referenced), the intended use
+ * might be:
+ *
+ *   AutoRestore savePainting(mIsPainting);
+ *
+ * but is is easy to accidentally write:
+ *
+ *   AutoRestore(mIsPainting);
+ *
+ * which compiles just fine, but runs the destructor well before the
+ * intended time.
+ *
+ * They work by adding (#ifdef DEBUG) an additional parameter to the
+ * guard object's constructor, with a default value, so that users of
+ * the guard object's API do not need to do anything. The default value
+ * of this parameter is a temporary object. C++ (ISO/IEC 14882:1998),
+ * section 12.2 [class.temporary], clauses 4 and 5 seem to assume a
+ * guarantee that temporaries are destroyed in the reverse of their
+ * construction order, but I actually can't find a statement that that
+ * is true in the general case (beyond the two specific cases mentioned
+ * there). However, it seems to be true.
+ *
+ * These classes are intended to be used only via the macros immediately
+ * below them:
+ *
+ *   MOZ_DECL_USE_GUARD_OBJECT_NOTIFIER declares (ifdef DEBUG) a member
+ *     variable, and should be put where a declaration of a private
+ *     member variable would be placed.
+ *   MOZ_GUARD_OBJECT_NOTIFIER_PARAM should be placed at the end of the
+ *     parameters to each constructor of the guard object; it declares
+ *     (ifdef DEBUG) an additional parameter. (But use the *_ONLY_PARAM
+ *     variant for constructors that take no other parameters.)
+ *   MOZ_GUARD_OBJECT_NOTIFIER_PARAM_IN_IMPL should likewise be used in
+ *     the implementation of such constructors when they are not inline.
+ *   MOZ_GUARD_OBJECT_NOTIFIER_PARAM_TO_PARENT should be used in
+ *     the implementation of such constructors to pass the parameter to
+ *     a base class that also uses these macros
+ *   MOZ_GUARD_OBJECT_NOTIFIER_INIT is a statement that belongs in each
+ *     constructor. It uses the parameter declared by
+ *     MOZ_GUARD_OBJECT_NOTIFIER_PARAM.
+ *
+ * For more details, and examples of using these macros, see
+ * https://developer.mozilla.org/en/Using_RAII_classes_in_Mozilla
+ */
+class MOZ_EXPORT_API(GuardObjectNotifier)
+{
+  private:
+    bool* statementDone;
+
+  public:
+    GuardObjectNotifier() : statementDone(NULL) { }
+
+    ~GuardObjectNotifier() {
+      *statementDone = true;
+    }
+
+    void setStatementDone(bool* statementIsDone) {
+      statementDone = statementIsDone;
+    }
+};
+
+class MOZ_EXPORT_API(GuardObjectNotificationReceiver)
+{
+  private:
+    bool statementDone;
+
+  public:
+    GuardObjectNotificationReceiver() : statementDone(false) { }
+
+    ~GuardObjectNotificationReceiver() {
+      /*
+       * Assert that the guard object was not used as a temporary.  (Note that
+       * this assert might also fire if init is not called because the guard
+       * object's implementation is not using the above macros correctly.)
+       */
+      MOZ_ASSERT(statementDone);
+    }
+
+    void init(const GuardObjectNotifier& constNotifier) {
+      /*
+       * constNotifier is passed as a const reference so that we can pass a
+       * temporary, but we really intend it as non-const.
+       */
+      GuardObjectNotifier& notifier = const_cast<GuardObjectNotifier&>(constNotifier);
+      notifier.setStatementDone(&statementDone);
+    }
+};
+
+} /* namespace detail */
+} /* namespace mozilla */
+
+#endif /* DEBUG */
+
+#ifdef DEBUG
+#  define MOZ_DECL_USE_GUARD_OBJECT_NOTIFIER \
+     mozilla::detail::GuardObjectNotificationReceiver _mCheckNotUsedAsTemporary;
+#  define MOZ_GUARD_OBJECT_NOTIFIER_PARAM \
+     , const mozilla::detail::GuardObjectNotifier& _notifier = \
+         mozilla::detail::GuardObjectNotifier()
+#  define MOZ_GUARD_OBJECT_NOTIFIER_ONLY_PARAM \
+     const mozilla::detail::GuardObjectNotifier& _notifier = \
+         mozilla::detail::GuardObjectNotifier()
+#  define MOZ_GUARD_OBJECT_NOTIFIER_PARAM_IN_IMPL \
+     , const mozilla::detail::GuardObjectNotifier& _notifier
+#  define MOZ_GUARD_OBJECT_NOTIFIER_PARAM_TO_PARENT \
+     , _notifier
+#  define MOZ_GUARD_OBJECT_NOTIFIER_ONLY_PARAM_TO_PARENT \
+       _notifier
+#  define MOZ_GUARD_OBJECT_NOTIFIER_INIT \
+     do { _mCheckNotUsedAsTemporary.init(_notifier); } while (0)
+#else
+#  define MOZ_DECL_USE_GUARD_OBJECT_NOTIFIER
+#  define MOZ_GUARD_OBJECT_NOTIFIER_PARAM
+#  define MOZ_GUARD_OBJECT_NOTIFIER_ONLY_PARAM
+#  define MOZ_GUARD_OBJECT_NOTIFIER_PARAM_IN_IMPL
+#  define MOZ_GUARD_OBJECT_NOTIFIER_ONLY_PARAM_TO_PARENT
+#  define MOZ_GUARD_OBJECT_NOTIFIER_PARAM_TO_PARENT
+#  define MOZ_GUARD_OBJECT_NOTIFIER_INIT do { } while (0)
+#endif
+
+#endif /* __cplusplus */
+
+#endif /* mozilla_GuardObjects_h */
diff --git a/mfbt/HashFunctions.cpp b/mfbt/HashFunctions.cpp
new file mode 100644
index 0000000..28d4c9f
--- /dev/null
+++ b/mfbt/HashFunctions.cpp
@@ -0,0 +1,38 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+/* Implementations of hash functions. */
+
+#include "mozilla/HashFunctions.h"
+#include "mozilla/Types.h"
+
+#include <string.h>
+
+namespace mozilla {
+
+MFBT_API(uint32_t)
+HashBytes(const void* bytes, size_t length)
+{
+  uint32_t hash = 0;
+  const char* b = reinterpret_cast<const char*>(bytes);
+
+  /* Walk word by word. */
+  size_t i = 0;
+  for (; i < length - (length % sizeof(size_t)); i += sizeof(size_t)) {
+    /* Do an explicitly unaligned load of the data. */
+    size_t data;
+    memcpy(&data, b + i, sizeof(size_t));
+
+    hash = AddToHash(hash, data, sizeof(data));
+  }
+
+  /* Get the remaining bytes. */
+  for (; i < length; i++)
+    hash = AddToHash(hash, b[i]);
+
+  return hash;
+}
+
+} /* namespace mozilla */
diff --git a/mfbt/HashFunctions.h b/mfbt/HashFunctions.h
new file mode 100644
index 0000000..badfc3c
--- /dev/null
+++ b/mfbt/HashFunctions.h
@@ -0,0 +1,359 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this file,
+ * You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+/* Utilities for hashing. */
+
+/*
+ * This file exports functions for hashing data down to a 32-bit value,
+ * including:
+ *
+ *  - HashString    Hash a char* or uint16_t/wchar_t* of known or unknown
+ *                  length.
+ *
+ *  - HashBytes     Hash a byte array of known length.
+ *
+ *  - HashGeneric   Hash one or more values.  Currently, we support uint32_t,
+ *                  types which can be implicitly cast to uint32_t, data
+ *                  pointers, and function pointers.
+ *
+ *  - AddToHash     Add one or more values to the given hash.  This supports the
+ *                  same list of types as HashGeneric.
+ *
+ *
+ * You can chain these functions together to hash complex objects.  For example:
+ *
+ *  class ComplexObject
+ *  {
+ *      char* str;
+ *      uint32_t uint1, uint2;
+ *      void (*callbackFn)();
+ *
+ *    public:
+ *      uint32_t hash() {
+ *        uint32_t hash = HashString(str);
+ *        hash = AddToHash(hash, uint1, uint2);
+ *        return AddToHash(hash, callbackFn);
+ *      }
+ *  };
+ *
+ * If you want to hash an nsAString or nsACString, use the HashString functions
+ * in nsHashKey.h.
+ */
+
+#ifndef mozilla_HashFunctions_h_
+#define mozilla_HashFunctions_h_
+
+#include "mozilla/Assertions.h"
+#include "mozilla/Attributes.h"
+#include "mozilla/StandardInteger.h"
+#include "mozilla/Types.h"
+
+#ifdef __cplusplus
+namespace mozilla {
+
+/**
+ * The golden ratio as a 32-bit fixed-point value.
+ */
+static const uint32_t GoldenRatioU32 = 0x9E3779B9U;
+
+inline uint32_t
+RotateBitsLeft32(uint32_t value, uint8_t bits)
+{
+  MOZ_ASSERT(bits < 32);
+  return (value << bits) | (value >> (32 - bits));
+}
+
+namespace detail {
+
+inline uint32_t
+AddU32ToHash(uint32_t hash, uint32_t value)
+{
+  /*
+   * This is the meat of all our hash routines.  This hash function is not
+   * particularly sophisticated, but it seems to work well for our mostly
+   * plain-text inputs.  Implementation notes follow.
+   *
+   * Our use of the golden ratio here is arbitrary; we could pick almost any
+   * number which:
+   *
+   *  * is odd (because otherwise, all our hash values will be even)
+   *
+   *  * has a reasonably-even mix of 1's and 0's (consider the extreme case
+   *    where we multiply by 0x3 or 0xeffffff -- this will not produce good
+   *    mixing across all bits of the hash).
+   *
+   * The rotation length of 5 is also arbitrary, although an odd number is again
+   * preferable so our hash explores the whole universe of possible rotations.
+   *
+   * Finally, we multiply by the golden ratio *after* xor'ing, not before.
+   * Otherwise, if |hash| is 0 (as it often is for the beginning of a message),
+   * the expression
+   *
+   *   (GoldenRatioU32 * RotateBitsLeft(hash, 5)) |xor| value
+   *
+   * evaluates to |value|.
+   *
+   * (Number-theoretic aside: Because any odd number |m| is relatively prime to
+   * our modulus (2^32), the list
+   *
+   *    [x * m (mod 2^32) for 0 <= x < 2^32]
+   *
+   * has no duplicate elements.  This means that multiplying by |m| does not
+   * cause us to skip any possible hash values.
+   *
+   * It's also nice if |m| has large-ish order mod 2^32 -- that is, if the
+   * smallest k such that m^k == 1 (mod 2^32) is large -- so we can safely
+   * multiply our hash value by |m| a few times without negating the
+   * multiplicative effect.  Our golden ratio constant has order 2^29, which is
+   * more than enough for our purposes.)
+   */
+  return GoldenRatioU32 * (RotateBitsLeft32(hash, 5) ^ value);
+}
+
+/**
+ * AddUintptrToHash takes sizeof(uintptr_t) as a template parameter.
+ */
+template<size_t PtrSize>
+inline uint32_t
+AddUintptrToHash(uint32_t hash, uintptr_t value);
+
+template<>
+inline uint32_t
+AddUintptrToHash<4>(uint32_t hash, uintptr_t value)
+{
+  return AddU32ToHash(hash, static_cast<uint32_t>(value));
+}
+
+template<>
+inline uint32_t
+AddUintptrToHash<8>(uint32_t hash, uintptr_t value)
+{
+  /*
+   * The static cast to uint64_t below is necessary because this function
+   * sometimes gets compiled on 32-bit platforms (yes, even though it's a
+   * template and we never call this particular override in a 32-bit build).  If
+   * we do value >> 32 on a 32-bit machine, we're shifting a 32-bit uintptr_t
+   * right 32 bits, and the compiler throws an error.
+   */
+  uint32_t v1 = static_cast<uint32_t>(value);
+  uint32_t v2 = static_cast<uint32_t>(static_cast<uint64_t>(value) >> 32);
+  return AddU32ToHash(AddU32ToHash(hash, v1), v2);
+}
+
+} /* namespace detail */
+
+/**
+ * AddToHash takes a hash and some values and returns a new hash based on the
+ * inputs.
+ *
+ * Currently, we support hashing uint32_t's, values which we can implicitly
+ * convert to uint32_t, data pointers, and function pointers.
+ */
+template<typename A>
+MOZ_WARN_UNUSED_RESULT
+inline uint32_t
+AddToHash(uint32_t hash, A a)
+{
+  /*
+   * Try to convert |A| to uint32_t implicitly.  If this works, great.  If not,
+   * we'll error out.
+   */
+  return detail::AddU32ToHash(hash, a);
+}
+
+template<typename A>
+MOZ_WARN_UNUSED_RESULT
+inline uint32_t
+AddToHash(uint32_t hash, A* a)
+{
+  /*
+   * You might think this function should just take a void*.  But then we'd only
+   * catch data pointers and couldn't handle function pointers.
+   */
+
+  MOZ_STATIC_ASSERT(sizeof(a) == sizeof(uintptr_t),
+                    "Strange pointer!");
+
+  return detail::AddUintptrToHash<sizeof(uintptr_t)>(hash, uintptr_t(a));
+}
+
+template<>
+MOZ_WARN_UNUSED_RESULT
+inline uint32_t
+AddToHash(uint32_t hash, uintptr_t a)
+{
+  return detail::AddUintptrToHash<sizeof(uintptr_t)>(hash, a);
+}
+
+template<typename A, typename B>
+MOZ_WARN_UNUSED_RESULT
+uint32_t
+AddToHash(uint32_t hash, A a, B b)
+{
+  return AddToHash(AddToHash(hash, a), b);
+}
+
+template<typename A, typename B, typename C>
+MOZ_WARN_UNUSED_RESULT
+uint32_t
+AddToHash(uint32_t hash, A a, B b, C c)
+{
+  return AddToHash(AddToHash(hash, a, b), c);
+}
+
+template<typename A, typename B, typename C, typename D>
+MOZ_WARN_UNUSED_RESULT
+uint32_t
+AddToHash(uint32_t hash, A a, B b, C c, D d)
+{
+  return AddToHash(AddToHash(hash, a, b, c), d);
+}
+
+template<typename A, typename B, typename C, typename D, typename E>
+MOZ_WARN_UNUSED_RESULT
+uint32_t
+AddToHash(uint32_t hash, A a, B b, C c, D d, E e)
+{
+  return AddToHash(AddToHash(hash, a, b, c, d), e);
+}
+
+/**
+ * The HashGeneric class of functions let you hash one or more values.
+ *
+ * If you want to hash together two values x and y, calling HashGeneric(x, y) is
+ * much better than calling AddToHash(x, y), because AddToHash(x, y) assumes
+ * that x has already been hashed.
+ */
+template<typename A>
+MOZ_WARN_UNUSED_RESULT
+inline uint32_t
+HashGeneric(A a)
+{
+  return AddToHash(0, a);
+}
+
+template<typename A, typename B>
+MOZ_WARN_UNUSED_RESULT
+inline uint32_t
+HashGeneric(A a, B b)
+{
+  return AddToHash(0, a, b);
+}
+
+template<typename A, typename B, typename C>
+MOZ_WARN_UNUSED_RESULT
+inline uint32_t
+HashGeneric(A a, B b, C c)
+{
+  return AddToHash(0, a, b, c);
+}
+
+template<typename A, typename B, typename C, typename D>
+MOZ_WARN_UNUSED_RESULT
+inline uint32_t
+HashGeneric(A a, B b, C c, D d)
+{
+  return AddToHash(0, a, b, c, d);
+}
+
+template<typename A, typename B, typename C, typename D, typename E>
+MOZ_WARN_UNUSED_RESULT
+inline uint32_t
+HashGeneric(A a, B b, C c, D d, E e)
+{
+  return AddToHash(0, a, b, c, d, e);
+}
+
+namespace detail {
+
+template<typename T>
+uint32_t
+HashUntilZero(const T* str)
+{
+  uint32_t hash = 0;
+  for (T c; (c = *str); str++)
+    hash = AddToHash(hash, c);
+  return hash;
+}
+
+template<typename T>
+uint32_t
+HashKnownLength(const T* str, size_t length)
+{
+  uint32_t hash = 0;
+  for (size_t i = 0; i < length; i++)
+    hash = AddToHash(hash, str[i]);
+  return hash;
+}
+
+} /* namespace detail */
+
+/**
+ * The HashString overloads below do just what you'd expect.
+ *
+ * If you have the string's length, you might as well call the overload which
+ * includes the length.  It may be marginally faster.
+ */
+MOZ_WARN_UNUSED_RESULT
+inline uint32_t
+HashString(const char* str)
+{
+  return detail::HashUntilZero(str);
+}
+
+MOZ_WARN_UNUSED_RESULT
+inline uint32_t
+HashString(const char* str, size_t length)
+{
+  return detail::HashKnownLength(str, length);
+}
+
+MOZ_WARN_UNUSED_RESULT
+inline uint32_t
+HashString(const uint16_t* str)
+{
+  return detail::HashUntilZero(str);
+}
+
+MOZ_WARN_UNUSED_RESULT
+inline uint32_t
+HashString(const uint16_t* str, size_t length)
+{
+  return detail::HashKnownLength(str, length);
+}
+
+/*
+ * On Windows, wchar_t (PRUnichar) is not the same as uint16_t, even though it's
+ * the same width!
+ */
+#ifdef WIN32
+MOZ_WARN_UNUSED_RESULT
+inline uint32_t
+HashString(const wchar_t* str)
+{
+  return detail::HashUntilZero(str);
+}
+
+MOZ_WARN_UNUSED_RESULT
+inline uint32_t
+HashString(const wchar_t* str, size_t length)
+{
+  return detail::HashKnownLength(str, length);
+}
+#endif
+
+/**
+ * Hash some number of bytes.
+ *
+ * This hash walks word-by-word, rather than byte-by-byte, so you won't get the
+ * same result out of HashBytes as you would out of HashString.
+ */
+MOZ_WARN_UNUSED_RESULT
+extern MFBT_API(uint32_t)
+HashBytes(const void* bytes, size_t length);
+
+} /* namespace mozilla */
+#endif /* __cplusplus */
+#endif /* mozilla_HashFunctions_h_ */
diff --git a/mfbt/Likely.h b/mfbt/Likely.h
new file mode 100644
index 0000000..a217e60
--- /dev/null
+++ b/mfbt/Likely.h
@@ -0,0 +1,22 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this file,
+ * You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+/*
+ * MOZ_LIKELY and MOZ_UNLIKELY macros to hint to the compiler how a
+ * boolean predicate should be branch-predicted.
+ */
+
+#ifndef mozilla_Likely_h_
+#define mozilla_Likely_h_
+
+#if defined(__clang__) || (defined(__GNUC__) && (__GNUC__ > 2))
+#  define MOZ_LIKELY(x)   (__builtin_expect((x), 1))
+#  define MOZ_UNLIKELY(x) (__builtin_expect((x), 0))
+#else
+#  define MOZ_LIKELY(x)   (x)
+#  define MOZ_UNLIKELY(x) (x)
+#endif
+
+#endif /* mozilla_Likely_h_ */
diff --git a/mfbt/LinkedList.h b/mfbt/LinkedList.h
new file mode 100644
index 0000000..d7d3b23
--- /dev/null
+++ b/mfbt/LinkedList.h
@@ -0,0 +1,385 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+/* A type-safe doubly-linked list class. */
+
+/*
+ * The classes LinkedList<T> and LinkedListElement<T> together form a
+ * convenient, type-safe doubly-linked list implementation.
+ *
+ * The class T which will be inserted into the linked list must inherit from
+ * LinkedListElement<T>.  A given object may be in only one linked list at a
+ * time.
+ *
+ * For example, you might use LinkedList in a simple observer list class as
+ * follows.
+ *
+ *   class Observer : public LinkedListElement<Observer>
+ *   {
+ *     public:
+ *       void observe(char* topic) { ... }
+ *   };
+ *
+ *   class ObserverContainer
+ *   {
+ *     private:
+ *       LinkedList<Observer> list;
+ *
+ *     public:
+ *       void addObserver(Observer* observer) {
+ *         // Will assert if |observer| is part of another list.
+ *         list.insertBack(observer);
+ *       }
+ *
+ *       void removeObserver(Observer* observer) {
+ *         // Will assert if |observer| is not part of some list.
+ *         observer.remove();
+ *       }
+ *
+ *       void notifyObservers(char* topic) {
+ *         for (Observer* o = list.getFirst(); o != NULL; o = o->getNext())
+ *           o->Observe(topic);
+ *       }
+ *   };
+ *
+ */
+
+#ifndef mozilla_LinkedList_h_
+#define mozilla_LinkedList_h_
+
+#include "mozilla/Assertions.h"
+#include "mozilla/Attributes.h"
+
+#ifdef __cplusplus
+
+namespace mozilla {
+
+template<typename T>
+class LinkedList;
+
+template<typename T>
+class LinkedListElement
+{
+    /*
+     * It's convenient that we return NULL when getNext() or getPrevious() hits
+     * the end of the list, but doing so costs an extra word of storage in each
+     * linked list node (to keep track of whether |this| is the sentinel node)
+     * and a branch on this value in getNext/getPrevious.
+     *
+     * We could get rid of the extra word of storage by shoving the "is
+     * sentinel" bit into one of the pointers, although this would, of course,
+     * have performance implications of its own.
+     *
+     * But the goal here isn't to win an award for the fastest or slimmest
+     * linked list; rather, we want a *convenient* linked list.  So we won't
+     * waste time guessing which micro-optimization strategy is best.
+     *
+     *
+     * Speaking of unnecessary work, it's worth addressing here why we wrote
+     * mozilla::LinkedList in the first place, instead of using stl::list.
+     *
+     * The key difference between mozilla::LinkedList and stl::list is that
+     * mozilla::LinkedList stores the prev/next pointers in the object itself,
+     * while stl::list stores the prev/next pointers in a list element which
+     * itself points to the object being stored.
+     *
+     * mozilla::LinkedList's approach makes it harder to store an object in more
+     * than one list.  But the upside is that you can call next() / prev() /
+     * remove() directly on the object.  With stl::list, you'd need to store a
+     * pointer to its iterator in the object in order to accomplish this.  Not
+     * only would this waste space, but you'd have to remember to update that
+     * pointer every time you added or removed the object from a list.
+     *
+     * In-place, constant-time removal is a killer feature of doubly-linked
+     * lists, and supporting this painlessly was a key design criterion.
+     */
+
+  private:
+    LinkedListElement* next;
+    LinkedListElement* prev;
+    const bool isSentinel;
+
+  public:
+    LinkedListElement() : next(this), prev(this), isSentinel(false) { }
+
+    /*
+     * Get the next element in the list, or NULL if this is the last element in
+     * the list.
+     */
+    T* getNext() {
+      return next->asT();
+    }
+    const T* getNext() const {
+      return next->asT();
+    }
+
+    /*
+     * Get the previous element in the list, or NULL if this is the first element
+     * in the list.
+     */
+    T* getPrevious() {
+      return prev->asT();
+    }
+    const T* getPrevious() const {
+      return prev->asT();
+    }
+
+    /*
+     * Insert elem after this element in the list.  |this| must be part of a
+     * linked list when you call setNext(); otherwise, this method will assert.
+     */
+    void setNext(T* elem) {
+        MOZ_ASSERT(isInList());
+        setNextUnsafe(elem);
+    }
+
+    /*
+     * Insert elem before this element in the list.  |this| must be part of a
+     * linked list when you call setPrevious(); otherwise, this method will
+     * assert.
+     */
+    void setPrevious(T* elem) {
+      MOZ_ASSERT(isInList());
+      setPreviousUnsafe(elem);
+    }
+
+    /*
+     * Remove this element from the list which contains it.  If this element is
+     * not currently part of a linked list, this method asserts.
+     */
+    void remove() {
+      MOZ_ASSERT(isInList());
+
+      prev->next = next;
+      next->prev = prev;
+      next = this;
+      prev = this;
+    }
+
+    /*
+     * Return true if |this| part is of a linked list, and false otherwise.
+     */
+    bool isInList() const {
+      MOZ_ASSERT((next == this) == (prev == this));
+      return next != this;
+    }
+
+  private:
+    friend class LinkedList<T>;
+
+    enum NodeKind {
+      NODE_KIND_NORMAL,
+      NODE_KIND_SENTINEL
+    };
+
+    LinkedListElement(NodeKind nodeKind)
+      : next(this),
+        prev(this),
+        isSentinel(nodeKind == NODE_KIND_SENTINEL)
+    {
+    }
+
+    /*
+     * Return |this| cast to T* if we're a normal node, or return NULL if we're
+     * a sentinel node.
+     */
+    T* asT() {
+      if (isSentinel)
+        return NULL;
+
+      return static_cast<T*>(this);
+    }
+    const T* asT() const {
+      if (isSentinel)
+        return NULL;
+
+      return static_cast<const T*>(this);
+    }
+
+    /*
+     * Insert elem after this element, but don't check that this element is in
+     * the list.  This is called by LinkedList::insertFront().
+     */
+    void setNextUnsafe(T* elem) {
+      LinkedListElement *listElem = static_cast<LinkedListElement*>(elem);
+      MOZ_ASSERT(!listElem->isInList());
+
+      listElem->next = this->next;
+      listElem->prev = this;
+      this->next->prev = listElem;
+      this->next = listElem;
+    }
+
+    /*
+     * Insert elem before this element, but don't check that this element is in
+     * the list.  This is called by LinkedList::insertBack().
+     */
+    void setPreviousUnsafe(T* elem) {
+      LinkedListElement<T>* listElem = static_cast<LinkedListElement<T>*>(elem);
+      MOZ_ASSERT(!listElem->isInList());
+
+      listElem->next = this;
+      listElem->prev = this->prev;
+      this->prev->next = listElem;
+      this->prev = listElem;
+    }
+
+  private:
+    LinkedListElement& operator=(const LinkedList<T>& other) MOZ_DELETE;
+    LinkedListElement(const LinkedList<T>& other) MOZ_DELETE;
+};
+
+template<typename T>
+class LinkedList
+{
+  private:
+    LinkedListElement<T> sentinel;
+
+  public:
+    LinkedList() : sentinel(LinkedListElement<T>::NODE_KIND_SENTINEL) { }
+
+    /*
+     * Add elem to the front of the list.
+     */
+    void insertFront(T* elem) {
+      /* Bypass setNext()'s this->isInList() assertion. */
+      sentinel.setNextUnsafe(elem);
+    }
+
+    /*
+     * Add elem to the back of the list.
+     */
+    void insertBack(T* elem) {
+      sentinel.setPreviousUnsafe(elem);
+    }
+
+    /*
+     * Get the first element of the list, or NULL if the list is empty.
+     */
+    T* getFirst() {
+      return sentinel.getNext();
+    }
+    const T* getFirst() const {
+      return sentinel.getNext();
+    }
+
+    /*
+     * Get the last element of the list, or NULL if the list is empty.
+     */
+    T* getLast() {
+      return sentinel.getPrevious();
+    }
+    const T* getLast() const {
+      return sentinel.getPrevious();
+    }
+
+    /*
+     * Get and remove the first element of the list.  If the list is empty,
+     * return NULL.
+     */
+    T* popFirst() {
+      T* ret = sentinel.getNext();
+      if (ret)
+        static_cast<LinkedListElement<T>*>(ret)->remove();
+      return ret;
+    }
+
+    /*
+     * Get and remove the last element of the list.  If the list is empty,
+     * return NULL.
+     */
+    T* popLast() {
+      T* ret = sentinel.getPrevious();
+      if (ret)
+        static_cast<LinkedListElement<T>*>(ret)->remove();
+      return ret;
+    }
+
+    /*
+     * Return true if the list is empty, or false otherwise.
+     */
+    bool isEmpty() const {
+      return !sentinel.isInList();
+    }
+
+    /*
+     * Remove all the elements from the list.
+     *
+     * This runs in time linear to the list's length, because we have to mark
+     * each element as not in the list.
+     */
+    void clear() {
+      while (popFirst())
+        continue;
+    }
+
+    /*
+     * In a debug build, make sure that the list is sane (no cycles, consistent
+     * next/prev pointers, only one sentinel).  Has no effect in release builds.
+     */
+    void debugAssertIsSane() const {
+#ifdef DEBUG
+      const LinkedListElement<T>* slow;
+      const LinkedListElement<T>* fast1;
+      const LinkedListElement<T>* fast2;
+
+      /*
+       * Check for cycles in the forward singly-linked list using the
+       * tortoise/hare algorithm.
+       */
+      for (slow = sentinel.next,
+           fast1 = sentinel.next->next,
+           fast2 = sentinel.next->next->next;
+           slow != sentinel && fast1 != sentinel && fast2 != sentinel;
+           slow = slow->next, fast1 = fast2->next, fast2 = fast1->next)
+      {
+        MOZ_ASSERT(slow != fast1);
+        MOZ_ASSERT(slow != fast2);
+      }
+
+      /* Check for cycles in the backward singly-linked list. */
+      for (slow = sentinel.prev,
+           fast1 = sentinel.prev->prev,
+           fast2 = sentinel.prev->prev->prev;
+           slow != sentinel && fast1 != sentinel && fast2 != sentinel;
+           slow = slow->prev, fast1 = fast2->prev, fast2 = fast1->prev)
+      {
+        MOZ_ASSERT(slow != fast1);
+        MOZ_ASSERT(slow != fast2);
+      }
+
+      /*
+       * Check that |sentinel| is the only node in the list with
+       * isSentinel == true.
+       */
+      for (const LinkedListElement<T>* elem = sentinel.next;
+           elem != sentinel;
+           elem = elem->next)
+      {
+        MOZ_ASSERT(!elem->isSentinel);
+      }
+
+      /* Check that the next/prev pointers match up. */
+      const LinkedListElement<T>* prev = sentinel;
+      const LinkedListElement<T>* cur = sentinel.next;
+      do {
+          MOZ_ASSERT(cur->prev == prev);
+          MOZ_ASSERT(prev->next == cur);
+
+          prev = cur;
+          cur = cur->next;
+      } while (cur != sentinel);
+#endif /* ifdef DEBUG */
+    }
+
+  private:
+    LinkedList& operator=(const LinkedList<T>& other) MOZ_DELETE;
+    LinkedList(const LinkedList<T>& other) MOZ_DELETE;
+};
+
+} /* namespace mozilla */
+
+#endif /* ifdef __cplusplus */
+#endif /* ifdef mozilla_LinkedList_h_ */
diff --git a/mfbt/MSStdInt.h b/mfbt/MSStdInt.h
new file mode 100644
index 0000000..0447f2f
--- /dev/null
+++ b/mfbt/MSStdInt.h
@@ -0,0 +1,247 @@
+// ISO C9x  compliant stdint.h for Microsoft Visual Studio
+// Based on ISO/IEC 9899:TC2 Committee draft (May 6, 2005) WG14/N1124 
+// 
+//  Copyright (c) 2006-2008 Alexander Chemeris
+// 
+// Redistribution and use in source and binary forms, with or without
+// modification, are permitted provided that the following conditions are met:
+// 
+//   1. Redistributions of source code must retain the above copyright notice,
+//      this list of conditions and the following disclaimer.
+// 
+//   2. Redistributions in binary form must reproduce the above copyright
+//      notice, this list of conditions and the following disclaimer in the
+//      documentation and/or other materials provided with the distribution.
+// 
+//   3. The name of the author may be used to endorse or promote products
+//      derived from this software without specific prior written permission.
+// 
+// THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR IMPLIED
+// WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
+// MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO
+// EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
+// PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS;
+// OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, 
+// WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR
+// OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF
+// ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+// 
+///////////////////////////////////////////////////////////////////////////////
+
+#ifndef _MSC_VER // [
+#error "Use this header only with Microsoft Visual C++ compilers!"
+#endif // _MSC_VER ]
+
+#ifndef _MSC_STDINT_H_ // [
+#define _MSC_STDINT_H_
+
+#if _MSC_VER > 1000
+#pragma once
+#endif
+
+#include <limits.h>
+
+// For Visual Studio 6 in C++ mode and for many Visual Studio versions when
+// compiling for ARM we should wrap <wchar.h> include with 'extern "C++" {}'
+// or compiler give many errors like this:
+//   error C2733: second C linkage of overloaded function 'wmemchr' not allowed
+#ifdef __cplusplus
+extern "C" {
+#endif
+#  include <wchar.h>
+#ifdef __cplusplus
+}
+#endif
+
+// Define _W64 macros to mark types changing their size, like intptr_t.
+#ifndef _W64
+#  if !defined(__midl) && (defined(_X86_) || defined(_M_IX86)) && _MSC_VER >= 1300
+#     define _W64 __w64
+#  else
+#     define _W64
+#  endif
+#endif
+
+
+// 7.18.1 Integer types
+
+// 7.18.1.1 Exact-width integer types
+
+// Visual Studio 6 and Embedded Visual C++ 4 doesn't
+// realize that, e.g. char has the same size as __int8
+// so we give up on __intX for them.
+#if (_MSC_VER < 1300)
+   typedef signed char       int8_t;
+   typedef signed short      int16_t;
+   typedef signed int        int32_t;
+   typedef unsigned char     uint8_t;
+   typedef unsigned short    uint16_t;
+   typedef unsigned int      uint32_t;
+#else
+   typedef signed __int8     int8_t;
+   typedef signed __int16    int16_t;
+   typedef signed __int32    int32_t;
+   typedef unsigned __int8   uint8_t;
+   typedef unsigned __int16  uint16_t;
+   typedef unsigned __int32  uint32_t;
+#endif
+typedef signed __int64       int64_t;
+typedef unsigned __int64     uint64_t;
+
+
+// 7.18.1.2 Minimum-width integer types
+typedef int8_t    int_least8_t;
+typedef int16_t   int_least16_t;
+typedef int32_t   int_least32_t;
+typedef int64_t   int_least64_t;
+typedef uint8_t   uint_least8_t;
+typedef uint16_t  uint_least16_t;
+typedef uint32_t  uint_least32_t;
+typedef uint64_t  uint_least64_t;
+
+// 7.18.1.3 Fastest minimum-width integer types
+typedef int8_t    int_fast8_t;
+typedef int32_t   int_fast16_t;
+typedef int32_t   int_fast32_t;
+typedef int64_t   int_fast64_t;
+typedef uint8_t   uint_fast8_t;
+typedef uint32_t  uint_fast16_t;
+typedef uint32_t  uint_fast32_t;
+typedef uint64_t  uint_fast64_t;
+
+// 7.18.1.4 Integer types capable of holding object pointers
+#ifdef _WIN64 // [
+   typedef signed __int64    intptr_t;
+   typedef unsigned __int64  uintptr_t;
+#else // _WIN64 ][
+   typedef _W64 signed int   intptr_t;
+   typedef _W64 unsigned int uintptr_t;
+#endif // _WIN64 ]
+
+// 7.18.1.5 Greatest-width integer types
+typedef int64_t   intmax_t;
+typedef uint64_t  uintmax_t;
+
+
+// 7.18.2 Limits of specified-width integer types
+
+#if !defined(__cplusplus) || defined(__STDC_LIMIT_MACROS) // [   See footnote 220 at page 257 and footnote 221 at page 259
+
+// 7.18.2.1 Limits of exact-width integer types
+#define INT8_MIN     ((int8_t)_I8_MIN)
+#define INT8_MAX     _I8_MAX
+#define INT16_MIN    ((int16_t)_I16_MIN)
+#define INT16_MAX    _I16_MAX
+#define INT32_MIN    ((int32_t)_I32_MIN)
+#define INT32_MAX    _I32_MAX
+#define INT64_MIN    ((int64_t)_I64_MIN)
+#define INT64_MAX    _I64_MAX
+#define UINT8_MAX    _UI8_MAX
+#define UINT16_MAX   _UI16_MAX
+#define UINT32_MAX   _UI32_MAX
+#define UINT64_MAX   _UI64_MAX
+
+// 7.18.2.2 Limits of minimum-width integer types
+#define INT_LEAST8_MIN    INT8_MIN
+#define INT_LEAST8_MAX    INT8_MAX
+#define INT_LEAST16_MIN   INT16_MIN
+#define INT_LEAST16_MAX   INT16_MAX
+#define INT_LEAST32_MIN   INT32_MIN
+#define INT_LEAST32_MAX   INT32_MAX
+#define INT_LEAST64_MIN   INT64_MIN
+#define INT_LEAST64_MAX   INT64_MAX
+#define UINT_LEAST8_MAX   UINT8_MAX
+#define UINT_LEAST16_MAX  UINT16_MAX
+#define UINT_LEAST32_MAX  UINT32_MAX
+#define UINT_LEAST64_MAX  UINT64_MAX
+
+// 7.18.2.3 Limits of fastest minimum-width integer types
+#define INT_FAST8_MIN    INT8_MIN
+#define INT_FAST8_MAX    INT8_MAX
+#define INT_FAST16_MIN   INT16_MIN
+#define INT_FAST16_MAX   INT16_MAX
+#define INT_FAST32_MIN   INT32_MIN
+#define INT_FAST32_MAX   INT32_MAX
+#define INT_FAST64_MIN   INT64_MIN
+#define INT_FAST64_MAX   INT64_MAX
+#define UINT_FAST8_MAX   UINT8_MAX
+#define UINT_FAST16_MAX  UINT16_MAX
+#define UINT_FAST32_MAX  UINT32_MAX
+#define UINT_FAST64_MAX  UINT64_MAX
+
+// 7.18.2.4 Limits of integer types capable of holding object pointers
+#ifdef _WIN64 // [
+#  define INTPTR_MIN   INT64_MIN
+#  define INTPTR_MAX   INT64_MAX
+#  define UINTPTR_MAX  UINT64_MAX
+#else // _WIN64 ][
+#  define INTPTR_MIN   INT32_MIN
+#  define INTPTR_MAX   INT32_MAX
+#  define UINTPTR_MAX  UINT32_MAX
+#endif // _WIN64 ]
+
+// 7.18.2.5 Limits of greatest-width integer types
+#define INTMAX_MIN   INT64_MIN
+#define INTMAX_MAX   INT64_MAX
+#define UINTMAX_MAX  UINT64_MAX
+
+// 7.18.3 Limits of other integer types
+
+#ifdef _WIN64 // [
+#  define PTRDIFF_MIN  _I64_MIN
+#  define PTRDIFF_MAX  _I64_MAX
+#else  // _WIN64 ][
+#  define PTRDIFF_MIN  _I32_MIN
+#  define PTRDIFF_MAX  _I32_MAX
+#endif  // _WIN64 ]
+
+#define SIG_ATOMIC_MIN  INT_MIN
+#define SIG_ATOMIC_MAX  INT_MAX
+
+#ifndef SIZE_MAX // [
+#  ifdef _WIN64 // [
+#     define SIZE_MAX  _UI64_MAX
+#  else // _WIN64 ][
+#     define SIZE_MAX  _UI32_MAX
+#  endif // _WIN64 ]
+#endif // SIZE_MAX ]
+
+// WCHAR_MIN and WCHAR_MAX are also defined in <wchar.h>
+#ifndef WCHAR_MIN // [
+#  define WCHAR_MIN  0
+#endif  // WCHAR_MIN ]
+#ifndef WCHAR_MAX // [
+#  define WCHAR_MAX  _UI16_MAX
+#endif  // WCHAR_MAX ]
+
+#define WINT_MIN  0
+#define WINT_MAX  _UI16_MAX
+
+#endif // __STDC_LIMIT_MACROS ]
+
+
+// 7.18.4 Limits of other integer types
+
+#if !defined(__cplusplus) || defined(__STDC_CONSTANT_MACROS) // [   See footnote 224 at page 260
+
+// 7.18.4.1 Macros for minimum-width integer constants
+
+#define INT8_C(val)  val##i8
+#define INT16_C(val) val##i16
+#define INT32_C(val) val##i32
+#define INT64_C(val) val##i64
+
+#define UINT8_C(val)  val##ui8
+#define UINT16_C(val) val##ui16
+#define UINT32_C(val) val##ui32
+#define UINT64_C(val) val##ui64
+
+// 7.18.4.2 Macros for greatest-width integer constants
+#define INTMAX_C   INT64_C
+#define UINTMAX_C  UINT64_C
+
+#endif // __STDC_CONSTANT_MACROS ]
+
+
+#endif // _MSC_STDINT_H_ ]
diff --git a/mfbt/Makefile.in b/mfbt/Makefile.in
new file mode 100644
index 0000000..63f6380
--- /dev/null
+++ b/mfbt/Makefile.in
@@ -0,0 +1,34 @@
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+DEPTH = @DEPTH@
+topsrcdir = @top_srcdir@
+srcdir = @srcdir@
+VPATH = @srcdir@
+
+include $(DEPTH)/config/autoconf.mk
+
+MODULE = mozglue
+LIBRARY_NAME = mfbt
+FORCE_STATIC_LIB = 1
+STL_FLAGS =
+
+TEST_DIRS = \
+  tests \
+  $(NULL)
+
+# exported_headers.mk defines the headers exported by mfbt.  It is included by
+# mfbt itself and by the JS engine, which, when built standalone, must do the
+# work to install mfbt's exported headers itself.
+include $(srcdir)/exported_headers.mk
+
+# sources.mk defines the source files built for mfbt. It is included by mfbt
+# itself and by the JS engine, which, when built standalone, must do the work
+# to build mfbt sources itself.
+MFBT_ROOT = $(srcdir)
+include $(MFBT_ROOT)/sources.mk
+
+DEFINES += -DIMPL_MFBT
+
+include $(topsrcdir)/config/rules.mk
diff --git a/mfbt/MathAlgorithms.h b/mfbt/MathAlgorithms.h
new file mode 100644
index 0000000..b545fa5
--- /dev/null
+++ b/mfbt/MathAlgorithms.h
@@ -0,0 +1,47 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+/* mfbt maths algorithms. */
+
+#ifndef mozilla_MathAlgorithms_h_
+#define mozilla_MathAlgorithms_h_
+
+#include "mozilla/Assertions.h"
+
+namespace mozilla {
+
+// Greatest Common Divisor
+template<typename IntegerType>
+MOZ_ALWAYS_INLINE IntegerType
+EuclidGCD(IntegerType a, IntegerType b)
+{
+  // Euclid's algorithm; O(N) in the worst case.  (There are better
+  // ways, but we don't need them for the current use of this algo.)
+  MOZ_ASSERT(a > 0);
+  MOZ_ASSERT(b > 0);
+
+  while (a != b) {
+    if (a > b) {
+      a = a - b;
+    } else {
+      b = b - a;
+    }
+  }
+
+  return a;
+}
+
+// Least Common Multiple
+template<typename IntegerType>
+MOZ_ALWAYS_INLINE IntegerType
+EuclidLCM(IntegerType a, IntegerType b)
+{
+  // Divide first to reduce overflow risk.
+  return (a / EuclidGCD(a, b)) * b;
+}
+
+} /* namespace mozilla */
+
+#endif  /* mozilla_MathAlgorithms_h_ */
diff --git a/mfbt/NullPtr.h b/mfbt/NullPtr.h
new file mode 100644
index 0000000..e6fc892
--- /dev/null
+++ b/mfbt/NullPtr.h
@@ -0,0 +1,46 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+/*
+ * Implements a workaround for compilers which do not support the C++11 nullptr
+ * constant.
+ */
+
+#ifndef mozilla_NullPtr_h_
+#define mozilla_NullPtr_h_
+
+#if defined(__clang__)
+#  ifndef __has_extension
+#    define __has_extension __has_feature
+#  endif
+#  if __has_extension(cxx_nullptr)
+#    define MOZ_HAVE_CXX11_NULLPTR
+#  endif
+#elif defined(__GNUC__)
+#  if defined(_GXX_EXPERIMENTAL_CXX0X__) || __cplusplus >= 201103L
+#    if (__GNUC__ * 1000 + __GNU_MINOR__) >= 4006
+#      define MOZ_HAVE_CXX11_NULLPTR
+#    endif
+#  endif
+#elif _MSC_VER >= 1600
+# define MOZ_HAVE_CXX11_NULLPTR
+#endif
+
+/**
+ * Use C++11 nullptr if available; otherwise use __null for gcc, or a 0 literal
+ * with the correct size to match the size of a pointer on a given platform.
+ */
+
+#ifndef MOZ_HAVE_CXX11_NULLPTR
+#  if defined(__GNUC__)
+#    define nullptr __null
+#  elif defined(_WIN64)
+#    define nullptr 0LL
+#  else
+#    define nullptr 0L
+#  endif
+#endif
+
+#endif  /* mozilla_NullPtr_h_ */
diff --git a/mfbt/RangedPtr.h b/mfbt/RangedPtr.h
new file mode 100644
index 0000000..7c8d581
--- /dev/null
+++ b/mfbt/RangedPtr.h
@@ -0,0 +1,248 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+/*
+ * Implements a smart pointer asserted to remain within a range specified at
+ * construction.
+ */
+
+#ifndef mozilla_RangedPtr_h_
+#define mozilla_RangedPtr_h_
+
+#include "mozilla/Assertions.h"
+#include "mozilla/Attributes.h"
+#include "mozilla/Util.h"
+
+namespace mozilla {
+
+/*
+ * RangedPtr is a smart pointer restricted to an address range specified at
+ * creation.  The pointer (and any smart pointers derived from it) must remain
+ * within the range [start, end] (inclusive of end to facilitate use as
+ * sentinels).  Dereferencing or indexing into the pointer (or pointers derived
+ * from it) must remain within the range [start, end).  All the standard pointer
+ * operators are defined on it; in debug builds these operations assert that the
+ * range specified at construction is respected.
+ *
+ * In theory passing a smart pointer instance as an argument can be slightly
+ * slower than passing a T* (due to ABI requirements for passing structs versus
+ * passing pointers), if the method being called isn't inlined.  If you are in
+ * extremely performance-critical code, you may want to be careful using this
+ * smart pointer as an argument type.
+ *
+ * RangedPtr<T> intentionally does not implicitly convert to T*.  Use get() to
+ * explicitly convert to T*.  Keep in mind that the raw pointer of course won't
+ * implement bounds checking in debug builds.
+ */
+template<typename T>
+class RangedPtr
+{
+    T* ptr;
+
+#ifdef DEBUG
+    T* const rangeStart;
+    T* const rangeEnd;
+#endif
+
+    void checkSanity() {
+      MOZ_ASSERT(rangeStart <= ptr);
+      MOZ_ASSERT(ptr <= rangeEnd);
+    }
+
+    /* Creates a new pointer for |ptr|, restricted to this pointer's range. */
+    RangedPtr<T> create(T *ptr) const {
+#ifdef DEBUG
+      return RangedPtr<T>(ptr, rangeStart, rangeEnd);
+#else
+      return RangedPtr<T>(ptr, NULL, size_t(0));
+#endif
+    }
+
+  public:
+    RangedPtr(T* p, T* start, T* end)
+      : ptr(p)
+#ifdef DEBUG
+      , rangeStart(start), rangeEnd(end)
+#endif
+    {
+      MOZ_ASSERT(rangeStart <= rangeEnd);
+      checkSanity();
+    }
+    RangedPtr(T* p, T* start, size_t length)
+      : ptr(p)
+#ifdef DEBUG
+      , rangeStart(start), rangeEnd(start + length)
+#endif
+    {
+      MOZ_ASSERT(length <= size_t(-1) / sizeof(T));
+      MOZ_ASSERT(uintptr_t(rangeStart) + length * sizeof(T) >= uintptr_t(rangeStart));
+      checkSanity();
+    }
+
+    /* Equivalent to RangedPtr(p, p, length). */
+    RangedPtr(T* p, size_t length)
+      : ptr(p)
+#ifdef DEBUG
+      , rangeStart(p), rangeEnd(p + length)
+#endif
+    {
+      MOZ_ASSERT(length <= size_t(-1) / sizeof(T));
+      MOZ_ASSERT(uintptr_t(rangeStart) + length * sizeof(T) >= uintptr_t(rangeStart));
+      checkSanity();
+    }
+
+    /* Equivalent to RangedPtr(arr, arr, N). */
+    template<size_t N>
+    RangedPtr(T arr[N])
+      : ptr(arr)
+#ifdef DEBUG
+      , rangeStart(arr), rangeEnd(arr + N)
+#endif
+    {
+      checkSanity();
+    }
+
+    T* get() const {
+      return ptr;
+    }
+
+    /*
+     * You can only assign one RangedPtr into another if the two pointers have
+     * the same valid range:
+     *
+     *   char arr1[] = "hi";
+     *   char arr2[] = "bye";
+     *   RangedPtr<char> p1(arr1, 2);
+     *   p1 = RangedPtr<char>(arr1 + 1, arr1, arr1 + 2); // works
+     *   p1 = RangedPtr<char>(arr2, 3);                  // asserts
+     */
+    RangedPtr<T>& operator=(const RangedPtr<T>& other) {
+      MOZ_ASSERT(rangeStart == other.rangeStart);
+      MOZ_ASSERT(rangeEnd == other.rangeEnd);
+      ptr = other.ptr;
+      checkSanity();
+      return *this;
+    }
+
+    RangedPtr<T> operator+(size_t inc) {
+      MOZ_ASSERT(inc <= size_t(-1) / sizeof(T));
+      MOZ_ASSERT(ptr + inc > ptr);
+      return create(ptr + inc);
+    }
+
+    RangedPtr<T> operator-(size_t dec) {
+      MOZ_ASSERT(dec <= size_t(-1) / sizeof(T));
+      MOZ_ASSERT(ptr - dec < ptr);
+      return create(ptr - dec);
+    }
+
+    /*
+     * You can assign a raw pointer into a RangedPtr if the raw pointer is
+     * within the range specified at creation.
+     */
+    template <typename U>
+    RangedPtr<T>& operator=(U* p) {
+      *this = create(p);
+      return *this;
+    }
+
+    template <typename U>
+    RangedPtr<T>& operator=(const RangedPtr<U>& p) {
+      MOZ_ASSERT(rangeStart <= p.ptr);
+      MOZ_ASSERT(p.ptr <= rangeEnd);
+      ptr = p.ptr;
+      checkSanity();
+      return *this;
+    }
+
+    RangedPtr<T>& operator++() {
+      return (*this += 1);
+    }
+
+    RangedPtr<T> operator++(int) {
+      RangedPtr<T> rcp = *this;
+      ++*this;
+      return rcp;
+    }
+
+    RangedPtr<T>& operator--() {
+      return (*this -= 1);
+    }
+
+    RangedPtr<T> operator--(int) {
+      RangedPtr<T> rcp = *this;
+      --*this;
+      return rcp;
+    }
+
+    RangedPtr<T>& operator+=(size_t inc) {
+      *this = *this + inc;
+      return *this;
+    }
+
+    RangedPtr<T>& operator-=(size_t dec) {
+      *this = *this - dec;
+      return *this;
+    }
+
+    T& operator[](int index) const {
+      MOZ_ASSERT(size_t(index > 0 ? index : -index) <= size_t(-1) / sizeof(T));
+      return *create(ptr + index);
+    }
+
+    T& operator*() const {
+      return *ptr;
+    }
+
+    template <typename U>
+    bool operator==(const RangedPtr<U>& other) const {
+      return ptr == other.ptr;
+    }
+    template <typename U>
+    bool operator!=(const RangedPtr<U>& other) const {
+      return !(*this == other);
+    }
+
+    template<typename U>
+    bool operator==(const U* u) const {
+      return ptr == u;
+    }
+    template<typename U>
+    bool operator!=(const U* u) const {
+      return !(*this == u);
+    }
+
+    template <typename U>
+    bool operator<(const RangedPtr<U>& other) const {
+      return ptr < other.ptr;
+    }
+    template <typename U>
+    bool operator<=(const RangedPtr<U>& other) const {
+      return ptr <= other.ptr;
+    }
+
+    template <typename U>
+    bool operator>(const RangedPtr<U>& other) const {
+      return ptr > other.ptr;
+    }
+    template <typename U>
+    bool operator>=(const RangedPtr<U>& other) const {
+      return ptr >= other.ptr;
+    }
+
+    size_t operator-(const RangedPtr<T>& other) const {
+      MOZ_ASSERT(ptr >= other.ptr);
+      return PointerRangeSize(other.ptr, ptr);
+    }
+
+  private:
+    RangedPtr() MOZ_DELETE;
+    T* operator&() MOZ_DELETE;
+    operator T*() const MOZ_DELETE;
+};
+
+} /* namespace mozilla */
+
+#endif  /* mozilla_RangedPtr_h_ */
diff --git a/mfbt/RefPtr.h b/mfbt/RefPtr.h
new file mode 100644
index 0000000..15ace62
--- /dev/null
+++ b/mfbt/RefPtr.h
@@ -0,0 +1,406 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+/* Helpers for defining and using refcounted objects. */
+
+#ifndef mozilla_RefPtr_h_
+#define mozilla_RefPtr_h_
+
+#include "mozilla/Assertions.h"
+#include "mozilla/Attributes.h"
+
+namespace mozilla {
+
+template<typename T> class RefCounted;
+template<typename T> class RefPtr;
+template<typename T> class TemporaryRef;
+template<typename T> class OutParamRef;
+template<typename T> OutParamRef<T> byRef(RefPtr<T>&);
+
+/**
+ * RefCounted<T> is a sort of a "mixin" for a class T.  RefCounted
+ * manages, well, refcounting for T, and because RefCounted is
+ * parameterized on T, RefCounted<T> can call T's destructor directly.
+ * This means T doesn't need to have a virtual dtor and so doesn't
+ * need a vtable.
+ *
+ * RefCounted<T> is created with refcount == 0.  Newly-allocated
+ * RefCounted<T> must immediately be assigned to a RefPtr to make the
+ * refcount > 0.  It's an error to allocate and free a bare
+ * RefCounted<T>, i.e. outside of the RefPtr machinery.  Attempts to
+ * do so will abort DEBUG builds.
+ *
+ * Live RefCounted<T> have refcount > 0.  The lifetime (refcounts) of
+ * live RefCounted<T> are controlled by RefPtr<T> and
+ * RefPtr<super/subclass of T>.  Upon a transition from refcounted==1
+ * to 0, the RefCounted<T> "dies" and is destroyed.  The "destroyed"
+ * state is represented in DEBUG builds by refcount==-0xdead.  This
+ * state distinguishes use-before-ref (refcount==0) from
+ * use-after-destroy (refcount==-0xdead).
+ */
+template<typename T>
+class RefCounted
+{
+    friend class RefPtr<T>;
+
+  public:
+    RefCounted() : refCnt(0) { }
+    ~RefCounted() { MOZ_ASSERT(refCnt == -0xdead); }
+
+    // Compatibility with nsRefPtr.
+    void AddRef() {
+      MOZ_ASSERT(refCnt >= 0);
+      ++refCnt;
+    }
+
+    void Release() {
+      MOZ_ASSERT(refCnt > 0);
+      if (0 == --refCnt) {
+#ifdef DEBUG
+        refCnt = -0xdead;
+#endif
+        delete static_cast<T*>(this);
+      }
+    }
+
+    // Compatibility with wtf::RefPtr.
+    void ref() { AddRef(); }
+    void deref() { Release(); }
+    int refCount() const { return refCnt; }
+    bool hasOneRef() const {
+      MOZ_ASSERT(refCnt > 0);
+      return refCnt == 1;
+    }
+
+  private:
+    int refCnt;
+};
+
+/**
+ * RefPtr points to a refcounted thing that has AddRef and Release
+ * methods to increase/decrease the refcount, respectively.  After a
+ * RefPtr<T> is assigned a T*, the T* can be used through the RefPtr
+ * as if it were a T*.
+ *
+ * A RefPtr can forget its underlying T*, which results in the T*
+ * being wrapped in a temporary object until the T* is either
+ * re-adopted from or released by the temporary.
+ */
+template<typename T>
+class RefPtr
+{
+    // To allow them to use unref()
+    friend class TemporaryRef<T>;
+    friend class OutParamRef<T>;
+
+    struct DontRef {};
+
+  public:
+    RefPtr() : ptr(0) { }
+    RefPtr(const RefPtr& o) : ptr(ref(o.ptr)) {}
+    RefPtr(const TemporaryRef<T>& o) : ptr(o.drop()) {}
+    RefPtr(T* t) : ptr(ref(t)) {}
+
+    template<typename U>
+    RefPtr(const RefPtr<U>& o) : ptr(ref(o.get())) {}
+
+    ~RefPtr() { unref(ptr); }
+
+    RefPtr& operator=(const RefPtr& o) {
+      assign(ref(o.ptr));
+      return *this;
+    }
+    RefPtr& operator=(const TemporaryRef<T>& o) {
+      assign(o.drop());
+      return *this;
+    }
+    RefPtr& operator=(T* t) {
+      assign(ref(t));
+      return *this;
+    }
+
+    template<typename U>
+    RefPtr& operator=(const RefPtr<U>& o) {
+      assign(ref(o.get()));
+      return *this;
+    }
+
+    TemporaryRef<T> forget() {
+      T* tmp = ptr;
+      ptr = 0;
+      return TemporaryRef<T>(tmp, DontRef());
+    }
+
+    T* get() const { return ptr; }
+    operator T*() const { return ptr; }
+    T* operator->() const { return ptr; }
+    T& operator*() const { return *ptr; }
+    template<typename U>
+    operator TemporaryRef<U>() { return TemporaryRef<U>(ptr); }
+
+  private:
+    void assign(T* t) {
+      unref(ptr);
+      ptr = t;
+    }
+
+    T* ptr;
+
+    static MOZ_ALWAYS_INLINE T* ref(T* t) {
+      if (t)
+        t->AddRef();
+      return t;
+    }
+
+    static MOZ_ALWAYS_INLINE void unref(T* t) {
+      if (t)
+        t->Release();
+    }
+};
+
+/**
+ * TemporaryRef<T> represents an object that holds a temporary
+ * reference to a T.  TemporaryRef objects can't be manually ref'd or
+ * unref'd (being temporaries, not lvalues), so can only relinquish
+ * references to other objects, or unref on destruction.
+ */
+template<typename T>
+class TemporaryRef
+{
+    // To allow it to construct TemporaryRef from a bare T*
+    friend class RefPtr<T>;
+
+    typedef typename RefPtr<T>::DontRef DontRef;
+
+  public:
+    TemporaryRef(T* t) : ptr(RefPtr<T>::ref(t)) {}
+    TemporaryRef(const TemporaryRef& o) : ptr(o.drop()) {}
+
+    template<typename U>
+    TemporaryRef(const TemporaryRef<U>& o) : ptr(o.drop()) {}
+
+    ~TemporaryRef() { RefPtr<T>::unref(ptr); }
+
+    T* drop() const {
+      T* tmp = ptr;
+      ptr = 0;
+      return tmp;
+    }
+
+  private:
+    TemporaryRef(T* t, const DontRef&) : ptr(t) {}
+
+    mutable T* ptr;
+
+    TemporaryRef() MOZ_DELETE;
+    void operator=(const TemporaryRef&) MOZ_DELETE;
+};
+
+/**
+ * OutParamRef is a wrapper that tracks a refcounted pointer passed as
+ * an outparam argument to a function.  OutParamRef implements COM T**
+ * outparam semantics: this requires the callee to AddRef() the T*
+ * returned through the T** outparam on behalf of the caller.  This
+ * means the caller (through OutParamRef) must Release() the old
+ * object contained in the tracked RefPtr.  It's OK if the callee
+ * returns the same T* passed to it through the T** outparam, as long
+ * as the callee obeys the COM discipline.
+ *
+ * Prefer returning TemporaryRef<T> from functions over creating T**
+ * outparams and passing OutParamRef<T> to T**.  Prefer RefPtr<T>*
+ * outparams over T** outparams.
+ */
+template<typename T>
+class OutParamRef
+{
+    friend OutParamRef byRef<T>(RefPtr<T>&);
+
+  public:
+    ~OutParamRef() {
+      RefPtr<T>::unref(refPtr.ptr);
+      refPtr.ptr = tmp;
+    }
+
+    operator T**() { return &tmp; }
+
+  private:
+    OutParamRef(RefPtr<T>& p) : refPtr(p), tmp(p.get()) {}
+
+    RefPtr<T>& refPtr;
+    T* tmp;
+
+    OutParamRef() MOZ_DELETE;
+    OutParamRef& operator=(const OutParamRef&) MOZ_DELETE;
+};
+
+/**
+ * byRef cooperates with OutParamRef to implement COM outparam semantics.
+ */
+template<typename T>
+OutParamRef<T>
+byRef(RefPtr<T>& ptr)
+{
+  return OutParamRef<T>(ptr);
+}
+
+} // namespace mozilla
+
+#endif // mozilla_RefPtr_h_
+
+
+#if 0
+
+// Command line that builds these tests
+//
+//   cp RefPtr.h test.cc && g++ -g -Wall -pedantic -DDEBUG -o test test.cc && ./test
+
+using namespace mozilla;
+
+struct Foo : public RefCounted<Foo>
+{
+  Foo() : dead(false) { }
+  ~Foo() {
+    MOZ_ASSERT(!dead);
+    dead = true;
+    numDestroyed++;
+  }
+
+  bool dead;
+  static int numDestroyed;
+};
+int Foo::numDestroyed;
+
+struct Bar : public Foo { };
+
+TemporaryRef<Foo>
+NewFoo()
+{
+  return RefPtr<Foo>(new Foo());
+}
+
+TemporaryRef<Foo>
+NewBar()
+{
+  return new Bar();
+}
+
+void
+GetNewFoo(Foo** f)
+{
+  *f = new Bar();
+  // Kids, don't try this at home
+  (*f)->AddRef();
+}
+
+void
+GetPassedFoo(Foo** f)
+{
+  // Kids, don't try this at home
+  (*f)->AddRef();
+}
+
+void
+GetNewFoo(RefPtr<Foo>* f)
+{
+  *f = new Bar();
+}
+
+void
+GetPassedFoo(RefPtr<Foo>* f)
+{}
+
+TemporaryRef<Foo>
+GetNullFoo()
+{
+  return 0;
+}
+
+int
+main(int argc, char** argv)
+{
+  // This should blow up
+//    Foo* f = new Foo(); delete f;
+
+  MOZ_ASSERT(0 == Foo::numDestroyed);
+  {
+    RefPtr<Foo> f = new Foo();
+    MOZ_ASSERT(f->refCount() == 1);
+  }
+  MOZ_ASSERT(1 == Foo::numDestroyed);
+
+  {
+    RefPtr<Foo> f1 = NewFoo();
+    RefPtr<Foo> f2(NewFoo());
+    MOZ_ASSERT(1 == Foo::numDestroyed);
+  }
+  MOZ_ASSERT(3 == Foo::numDestroyed);
+
+  {
+    RefPtr<Foo> b = NewBar();
+    MOZ_ASSERT(3 == Foo::numDestroyed);
+  }
+  MOZ_ASSERT(4 == Foo::numDestroyed);
+
+  {
+    RefPtr<Foo> f1;
+    {
+      f1 = new Foo();
+      RefPtr<Foo> f2(f1);
+      RefPtr<Foo> f3 = f2;
+      MOZ_ASSERT(4 == Foo::numDestroyed);
+    }
+    MOZ_ASSERT(4 == Foo::numDestroyed);
+  }
+  MOZ_ASSERT(5 == Foo::numDestroyed);
+
+  {
+    RefPtr<Foo> f = new Foo();
+    f.forget();
+    MOZ_ASSERT(6 == Foo::numDestroyed);
+  }
+
+  {
+    RefPtr<Foo> f = new Foo();
+    GetNewFoo(byRef(f));
+    MOZ_ASSERT(7 == Foo::numDestroyed);
+  }
+  MOZ_ASSERT(8 == Foo::numDestroyed);
+
+  {
+    RefPtr<Foo> f = new Foo();
+    GetPassedFoo(byRef(f));
+    MOZ_ASSERT(8 == Foo::numDestroyed);
+  }
+  MOZ_ASSERT(9 == Foo::numDestroyed);
+
+  {
+    RefPtr<Foo> f = new Foo();
+    GetNewFoo(&f);
+    MOZ_ASSERT(10 == Foo::numDestroyed);
+  }
+  MOZ_ASSERT(11 == Foo::numDestroyed);
+
+  {
+    RefPtr<Foo> f = new Foo();
+    GetPassedFoo(&f);
+    MOZ_ASSERT(11 == Foo::numDestroyed);
+  }
+  MOZ_ASSERT(12 == Foo::numDestroyed);
+
+  {
+    RefPtr<Foo> f1 = new Bar();
+  }
+  MOZ_ASSERT(13 == Foo::numDestroyed);
+
+  {
+    RefPtr<Foo> f = GetNullFoo();
+    MOZ_ASSERT(13 == Foo::numDestroyed);
+  }
+  MOZ_ASSERT(13 == Foo::numDestroyed);
+
+  return 0;
+}
+
+#endif
diff --git a/mfbt/SHA1.cpp b/mfbt/SHA1.cpp
new file mode 100644
index 0000000..ce9dfc2
--- /dev/null
+++ b/mfbt/SHA1.cpp
@@ -0,0 +1,342 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include <string.h>
+#include "mozilla/SHA1.h"
+#include "mozilla/Assertions.h"
+
+// FIXME: We should probably create a more complete mfbt/Endian.h. This assumes
+// that any compiler that doesn't define these macros is little endian.
+#if defined(__BYTE_ORDER__) && defined(__ORDER_LITTLE_ENDIAN__)
+#if __BYTE_ORDER__ == __ORDER_LITTLE_ENDIAN__
+#define MOZ_IS_LITTLE_ENDIAN
+#endif
+#else
+#define MOZ_IS_LITTLE_ENDIAN
+#endif
+
+using namespace mozilla;
+
+static inline uint32_t SHA_ROTL(uint32_t t, uint32_t n)
+{
+    return ((t << n) | (t >> (32 - n)));
+}
+
+#ifdef MOZ_IS_LITTLE_ENDIAN
+static inline unsigned SHA_HTONL(unsigned x) {
+  const unsigned int mask = 0x00FF00FF;
+  x = (x << 16) | (x >> 16);
+  return ((x & mask) << 8) | ((x >> 8) & mask);
+}
+#else
+static inline unsigned SHA_HTONL(unsigned x) {
+  return x;
+}
+#endif
+
+static void shaCompress(volatile unsigned *X, const uint32_t * datain);
+
+#define SHA_F1(X,Y,Z) ((((Y)^(Z))&(X))^(Z))
+#define SHA_F2(X,Y,Z) ((X)^(Y)^(Z))
+#define SHA_F3(X,Y,Z) (((X)&(Y))|((Z)&((X)|(Y))))
+#define SHA_F4(X,Y,Z) ((X)^(Y)^(Z))
+
+#define SHA_MIX(n,a,b,c)    XW(n) = SHA_ROTL(XW(a)^XW(b)^XW(c)^XW(n), 1)
+
+SHA1Sum::SHA1Sum() : size(0), mDone(false)
+{
+  // Initialize H with constants from FIPS180-1.
+  H[0] = 0x67452301L;
+  H[1] = 0xefcdab89L;
+  H[2] = 0x98badcfeL;
+  H[3] = 0x10325476L;
+  H[4] = 0xc3d2e1f0L;
+}
+
+/* Explanation of H array and index values:
+ * The context's H array is actually the concatenation of two arrays
+ * defined by SHA1, the H array of state variables (5 elements),
+ * and the W array of intermediate values, of which there are 16 elements.
+ * The W array starts at H[5], that is W[0] is H[5].
+ * Although these values are defined as 32-bit values, we use 64-bit
+ * variables to hold them because the AMD64 stores 64 bit values in
+ * memory MUCH faster than it stores any smaller values.
+ *
+ * Rather than passing the context structure to shaCompress, we pass
+ * this combined array of H and W values.  We do not pass the address
+ * of the first element of this array, but rather pass the address of an
+ * element in the middle of the array, element X.  Presently X[0] is H[11].
+ * So we pass the address of H[11] as the address of array X to shaCompress.
+ * Then shaCompress accesses the members of the array using positive AND
+ * negative indexes.
+ *
+ * Pictorially: (each element is 8 bytes)
+ * H | H0 H1 H2 H3 H4 W0 W1 W2 W3 W4 W5 W6 W7 W8 W9 Wa Wb Wc Wd We Wf |
+ * X |-11-10 -9 -8 -7 -6 -5 -4 -3 -2 -1 X0 X1 X2 X3 X4 X5 X6 X7 X8 X9 |
+ *
+ * The byte offset from X[0] to any member of H and W is always
+ * representable in a signed 8-bit value, which will be encoded
+ * as a single byte offset in the X86-64 instruction set.
+ * If we didn't pass the address of H[11], and instead passed the
+ * address of H[0], the offsets to elements H[16] and above would be
+ * greater than 127, not representable in a signed 8-bit value, and the
+ * x86-64 instruction set would encode every such offset as a 32-bit
+ * signed number in each instruction that accessed element H[16] or
+ * higher.  This results in much bigger and slower code.
+ */
+#define H2X 11 /* X[0] is H[11], and H[0] is X[-11] */
+#define W2X  6 /* X[0] is W[6],  and W[0] is X[-6]  */
+
+/*
+ *  SHA: Add data to context.
+ */
+void SHA1Sum::update(const uint8_t *dataIn, uint32_t len)
+{
+  MOZ_ASSERT(!mDone);
+  register unsigned int lenB;
+  register unsigned int togo;
+
+  if (!len)
+    return;
+
+  /* accumulate the byte count. */
+  lenB = (unsigned int)(size) & 63U;
+
+  size += len;
+
+  /*
+   *  Read the data into W and process blocks as they get full
+   */
+  if (lenB > 0) {
+    togo = 64U - lenB;
+    if (len < togo)
+      togo = len;
+    memcpy(u.b + lenB, dataIn, togo);
+    len    -= togo;
+    dataIn += togo;
+    lenB    = (lenB + togo) & 63U;
+    if (!lenB) {
+      shaCompress(&H[H2X], u.w);
+    }
+  }
+  while (len >= 64U) {
+    len    -= 64U;
+    shaCompress(&H[H2X], (uint32_t *)dataIn);
+    dataIn += 64U;
+  }
+  if (len) {
+    memcpy(u.b, dataIn, len);
+  }
+}
+
+
+/*
+ *  SHA: Generate hash value
+ */
+void SHA1Sum::finish(uint8_t hashout[20])
+{
+  MOZ_ASSERT(!mDone);
+  register uint64_t size2 = size;
+  register uint32_t lenB = (uint32_t)size2 & 63;
+
+  static const uint8_t bulk_pad[64] = { 0x80,0,0,0,0,0,0,0,0,0,
+          0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,
+          0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0  };
+
+  /*
+   *  Pad with a binary 1 (e.g. 0x80), then zeroes, then length in bits
+   */
+
+  update(bulk_pad, (((55+64) - lenB) & 63) + 1);
+  MOZ_ASSERT(((uint32_t)size & 63) == 56);
+  /* Convert size from bytes to bits. */
+  size2 <<= 3;
+  u.w[14] = SHA_HTONL((uint32_t)(size2 >> 32));
+  u.w[15] = SHA_HTONL((uint32_t)size2);
+  shaCompress(&H[H2X], u.w);
+
+  /*
+   *  Output hash
+   */
+  u.w[0] = SHA_HTONL(H[0]);
+  u.w[1] = SHA_HTONL(H[1]);
+  u.w[2] = SHA_HTONL(H[2]);
+  u.w[3] = SHA_HTONL(H[3]);
+  u.w[4] = SHA_HTONL(H[4]);
+  memcpy(hashout, u.w, 20);
+  mDone = true;
+}
+
+/*
+ *  SHA: Compression function, unrolled.
+ *
+ * Some operations in shaCompress are done as 5 groups of 16 operations.
+ * Others are done as 4 groups of 20 operations.
+ * The code below shows that structure.
+ *
+ * The functions that compute the new values of the 5 state variables
+ * A-E are done in 4 groups of 20 operations (or you may also think
+ * of them as being done in 16 groups of 5 operations).  They are
+ * done by the SHA_RNDx macros below, in the right column.
+ *
+ * The functions that set the 16 values of the W array are done in
+ * 5 groups of 16 operations.  The first group is done by the
+ * LOAD macros below, the latter 4 groups are done by SHA_MIX below,
+ * in the left column.
+ *
+ * gcc's optimizer observes that each member of the W array is assigned
+ * a value 5 times in this code.  It reduces the number of store
+ * operations done to the W array in the context (that is, in the X array)
+ * by creating a W array on the stack, and storing the W values there for
+ * the first 4 groups of operations on W, and storing the values in the
+ * context's W array only in the fifth group.  This is undesirable.
+ * It is MUCH bigger code than simply using the context's W array, because
+ * all the offsets to the W array in the stack are 32-bit signed offsets,
+ * and it is no faster than storing the values in the context's W array.
+ *
+ * The original code for sha_fast.c prevented this creation of a separate
+ * W array in the stack by creating a W array of 80 members, each of
+ * whose elements is assigned only once. It also separated the computations
+ * of the W array values and the computations of the values for the 5
+ * state variables into two separate passes, W's, then A-E's so that the 
+ * second pass could be done all in registers (except for accessing the W
+ * array) on machines with fewer registers.  The method is suboptimal
+ * for machines with enough registers to do it all in one pass, and it
+ * necessitates using many instructions with 32-bit offsets.
+ *
+ * This code eliminates the separate W array on the stack by a completely
+ * different means: by declaring the X array volatile.  This prevents
+ * the optimizer from trying to reduce the use of the X array by the
+ * creation of a MORE expensive W array on the stack. The result is
+ * that all instructions use signed 8-bit offsets and not 32-bit offsets.
+ *
+ * The combination of this code and the -O3 optimizer flag on GCC 3.4.3
+ * results in code that is 3 times faster than the previous NSS sha_fast
+ * code on AMD64.
+ */
+static void
+shaCompress(volatile unsigned *X, const uint32_t *inbuf)
+{
+  register unsigned A, B, C, D, E;
+
+
+#define XH(n) X[n-H2X]
+#define XW(n) X[n-W2X]
+
+#define K0 0x5a827999L
+#define K1 0x6ed9eba1L
+#define K2 0x8f1bbcdcL
+#define K3 0xca62c1d6L
+
+#define SHA_RND1(a,b,c,d,e,n) \
+  a = SHA_ROTL(b,5)+SHA_F1(c,d,e)+a+XW(n)+K0; c=SHA_ROTL(c,30) 
+#define SHA_RND2(a,b,c,d,e,n) \
+  a = SHA_ROTL(b,5)+SHA_F2(c,d,e)+a+XW(n)+K1; c=SHA_ROTL(c,30) 
+#define SHA_RND3(a,b,c,d,e,n) \
+  a = SHA_ROTL(b,5)+SHA_F3(c,d,e)+a+XW(n)+K2; c=SHA_ROTL(c,30) 
+#define SHA_RND4(a,b,c,d,e,n) \
+  a = SHA_ROTL(b,5)+SHA_F4(c,d,e)+a+XW(n)+K3; c=SHA_ROTL(c,30) 
+
+#define LOAD(n) XW(n) = SHA_HTONL(inbuf[n])
+
+  A = XH(0);
+  B = XH(1);
+  C = XH(2);
+  D = XH(3);
+  E = XH(4);
+
+  LOAD(0);		   SHA_RND1(E,A,B,C,D, 0);
+  LOAD(1);		   SHA_RND1(D,E,A,B,C, 1);
+  LOAD(2);		   SHA_RND1(C,D,E,A,B, 2);
+  LOAD(3);		   SHA_RND1(B,C,D,E,A, 3);
+  LOAD(4);		   SHA_RND1(A,B,C,D,E, 4);
+  LOAD(5);		   SHA_RND1(E,A,B,C,D, 5);
+  LOAD(6);		   SHA_RND1(D,E,A,B,C, 6);
+  LOAD(7);		   SHA_RND1(C,D,E,A,B, 7);
+  LOAD(8);		   SHA_RND1(B,C,D,E,A, 8);
+  LOAD(9);		   SHA_RND1(A,B,C,D,E, 9);
+  LOAD(10);		   SHA_RND1(E,A,B,C,D,10);
+  LOAD(11);		   SHA_RND1(D,E,A,B,C,11);
+  LOAD(12);		   SHA_RND1(C,D,E,A,B,12);
+  LOAD(13);		   SHA_RND1(B,C,D,E,A,13);
+  LOAD(14);		   SHA_RND1(A,B,C,D,E,14);
+  LOAD(15);		   SHA_RND1(E,A,B,C,D,15);
+
+  SHA_MIX( 0, 13,  8,  2); SHA_RND1(D,E,A,B,C, 0);
+  SHA_MIX( 1, 14,  9,  3); SHA_RND1(C,D,E,A,B, 1);
+  SHA_MIX( 2, 15, 10,  4); SHA_RND1(B,C,D,E,A, 2);
+  SHA_MIX( 3,  0, 11,  5); SHA_RND1(A,B,C,D,E, 3);
+
+  SHA_MIX( 4,  1, 12,  6); SHA_RND2(E,A,B,C,D, 4);
+  SHA_MIX( 5,  2, 13,  7); SHA_RND2(D,E,A,B,C, 5);
+  SHA_MIX( 6,  3, 14,  8); SHA_RND2(C,D,E,A,B, 6);
+  SHA_MIX( 7,  4, 15,  9); SHA_RND2(B,C,D,E,A, 7);
+  SHA_MIX( 8,  5,  0, 10); SHA_RND2(A,B,C,D,E, 8);
+  SHA_MIX( 9,  6,  1, 11); SHA_RND2(E,A,B,C,D, 9);
+  SHA_MIX(10,  7,  2, 12); SHA_RND2(D,E,A,B,C,10);
+  SHA_MIX(11,  8,  3, 13); SHA_RND2(C,D,E,A,B,11);
+  SHA_MIX(12,  9,  4, 14); SHA_RND2(B,C,D,E,A,12);
+  SHA_MIX(13, 10,  5, 15); SHA_RND2(A,B,C,D,E,13);
+  SHA_MIX(14, 11,  6,  0); SHA_RND2(E,A,B,C,D,14);
+  SHA_MIX(15, 12,  7,  1); SHA_RND2(D,E,A,B,C,15);
+
+  SHA_MIX( 0, 13,  8,  2); SHA_RND2(C,D,E,A,B, 0);
+  SHA_MIX( 1, 14,  9,  3); SHA_RND2(B,C,D,E,A, 1);
+  SHA_MIX( 2, 15, 10,  4); SHA_RND2(A,B,C,D,E, 2);
+  SHA_MIX( 3,  0, 11,  5); SHA_RND2(E,A,B,C,D, 3);
+  SHA_MIX( 4,  1, 12,  6); SHA_RND2(D,E,A,B,C, 4);
+  SHA_MIX( 5,  2, 13,  7); SHA_RND2(C,D,E,A,B, 5);
+  SHA_MIX( 6,  3, 14,  8); SHA_RND2(B,C,D,E,A, 6);
+  SHA_MIX( 7,  4, 15,  9); SHA_RND2(A,B,C,D,E, 7);
+
+  SHA_MIX( 8,  5,  0, 10); SHA_RND3(E,A,B,C,D, 8);
+  SHA_MIX( 9,  6,  1, 11); SHA_RND3(D,E,A,B,C, 9);
+  SHA_MIX(10,  7,  2, 12); SHA_RND3(C,D,E,A,B,10);
+  SHA_MIX(11,  8,  3, 13); SHA_RND3(B,C,D,E,A,11);
+  SHA_MIX(12,  9,  4, 14); SHA_RND3(A,B,C,D,E,12);
+  SHA_MIX(13, 10,  5, 15); SHA_RND3(E,A,B,C,D,13);
+  SHA_MIX(14, 11,  6,  0); SHA_RND3(D,E,A,B,C,14);
+  SHA_MIX(15, 12,  7,  1); SHA_RND3(C,D,E,A,B,15);
+
+  SHA_MIX( 0, 13,  8,  2); SHA_RND3(B,C,D,E,A, 0);
+  SHA_MIX( 1, 14,  9,  3); SHA_RND3(A,B,C,D,E, 1);
+  SHA_MIX( 2, 15, 10,  4); SHA_RND3(E,A,B,C,D, 2);
+  SHA_MIX( 3,  0, 11,  5); SHA_RND3(D,E,A,B,C, 3);
+  SHA_MIX( 4,  1, 12,  6); SHA_RND3(C,D,E,A,B, 4);
+  SHA_MIX( 5,  2, 13,  7); SHA_RND3(B,C,D,E,A, 5);
+  SHA_MIX( 6,  3, 14,  8); SHA_RND3(A,B,C,D,E, 6);
+  SHA_MIX( 7,  4, 15,  9); SHA_RND3(E,A,B,C,D, 7);
+  SHA_MIX( 8,  5,  0, 10); SHA_RND3(D,E,A,B,C, 8);
+  SHA_MIX( 9,  6,  1, 11); SHA_RND3(C,D,E,A,B, 9);
+  SHA_MIX(10,  7,  2, 12); SHA_RND3(B,C,D,E,A,10);
+  SHA_MIX(11,  8,  3, 13); SHA_RND3(A,B,C,D,E,11);
+
+  SHA_MIX(12,  9,  4, 14); SHA_RND4(E,A,B,C,D,12);
+  SHA_MIX(13, 10,  5, 15); SHA_RND4(D,E,A,B,C,13);
+  SHA_MIX(14, 11,  6,  0); SHA_RND4(C,D,E,A,B,14);
+  SHA_MIX(15, 12,  7,  1); SHA_RND4(B,C,D,E,A,15);
+
+  SHA_MIX( 0, 13,  8,  2); SHA_RND4(A,B,C,D,E, 0);
+  SHA_MIX( 1, 14,  9,  3); SHA_RND4(E,A,B,C,D, 1);
+  SHA_MIX( 2, 15, 10,  4); SHA_RND4(D,E,A,B,C, 2);
+  SHA_MIX( 3,  0, 11,  5); SHA_RND4(C,D,E,A,B, 3);
+  SHA_MIX( 4,  1, 12,  6); SHA_RND4(B,C,D,E,A, 4);
+  SHA_MIX( 5,  2, 13,  7); SHA_RND4(A,B,C,D,E, 5);
+  SHA_MIX( 6,  3, 14,  8); SHA_RND4(E,A,B,C,D, 6);
+  SHA_MIX( 7,  4, 15,  9); SHA_RND4(D,E,A,B,C, 7);
+  SHA_MIX( 8,  5,  0, 10); SHA_RND4(C,D,E,A,B, 8);
+  SHA_MIX( 9,  6,  1, 11); SHA_RND4(B,C,D,E,A, 9);
+  SHA_MIX(10,  7,  2, 12); SHA_RND4(A,B,C,D,E,10);
+  SHA_MIX(11,  8,  3, 13); SHA_RND4(E,A,B,C,D,11);
+  SHA_MIX(12,  9,  4, 14); SHA_RND4(D,E,A,B,C,12);
+  SHA_MIX(13, 10,  5, 15); SHA_RND4(C,D,E,A,B,13);
+  SHA_MIX(14, 11,  6,  0); SHA_RND4(B,C,D,E,A,14);
+  SHA_MIX(15, 12,  7,  1); SHA_RND4(A,B,C,D,E,15);
+
+  XH(0) += A;
+  XH(1) += B;
+  XH(2) += C;
+  XH(3) += D;
+  XH(4) += E;
+}
diff --git a/mfbt/SHA1.h b/mfbt/SHA1.h
new file mode 100644
index 0000000..fdb2150
--- /dev/null
+++ b/mfbt/SHA1.h
@@ -0,0 +1,46 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+/* Simple class for computing SHA1. */
+
+/*
+ * To compute the SHA1 of a buffer using this class you should write something
+ * like:
+ * void SHA1(const uint8_t* buf, unsigned size, uint8_t hash[20])
+ * {
+ *   SHA1Sum S;
+ *   S.update(buf, size);
+ *   S.finish(hash);
+ * }
+ * If there are multiple buffers or chunks, the update method can be called
+ * multiple times and the SHA1 is computed on the concatenation of all the
+ * buffers passed to it.
+ * The finish method may only be called once and cannot be followed by calls
+ * to update.
+ */
+
+#ifndef mozilla_SHA1_h_
+#define mozilla_SHA1_h_
+
+#include "mozilla/StandardInteger.h"
+namespace mozilla {
+class SHA1Sum {
+  union {
+    uint32_t w[16];         /* input buffer */
+    uint8_t  b[64];
+  } u;
+  uint64_t size;            /* count of hashed bytes. */
+  unsigned H[22];           /* 5 state variables, 16 tmp values, 1 extra */
+  bool mDone;
+
+public:
+  static const unsigned int HashSize = 20;
+  SHA1Sum();
+  void update(const uint8_t *dataIn, uint32_t len);
+  void finish(uint8_t hashout[20]);
+};
+}
+
+#endif /* mozilla_SHA1_h_ */
diff --git a/mfbt/STYLE b/mfbt/STYLE
new file mode 100644
index 0000000..2d94c3a
--- /dev/null
+++ b/mfbt/STYLE
@@ -0,0 +1,383 @@
+= mfbt style rules =
+
+== Line length ==
+
+The line limit is 80 characters, except that excessively long blocks of
+preprocessor directives may exceed this if it makes the code more readable (e.g.
+MOZ_STATIC_ASSERT in Assertions.h.), and unbreakable text in comments (e.g.
+URLs) may exceed this as well.  Wrap expressions after binary operators.
+
+== Capitalization ==
+
+Standalone functions, classes, structs, and template parameters are named
+InterCaps-style.  Member functions and fields in classes and structs are named
+camelCaps-style.
+
+== Indentation ==
+
+Indentation is two spaces, never tabs.
+
+  if (x == 2)
+    return 17;
+
+== Whitespace ==
+
+Surround binary operators with a single space on either side.
+
+  if (x == 2)
+    return 17;
+
+When describing pointer types, the * shall be adjacent to the type name.  (Same
+goes for references -- & goes by the type name.)
+
+  int
+  Foo(int* p)
+  {
+    typedef void* VoidPtr;
+    int& i = *p;
+  }
+
+A corollary: don't mix declaration types by declaring a T and a T* (or a T**,
+&c.) in the same declaration.
+
+  T* foo, bar; // BAD
+
+== Expressions ==
+
+Ternary expressions (a ? b : c) should use only one line if sufficiently short.
+Longer ternary expressions should use multiple lines.  The condition,
+consequent, and alternative should each be on separate lines (each part
+overflowing to additional lines as necessary), and the ? and : should be aligned
+with the start of the condition:
+
+  size_t
+  BinaryTree::height()
+  {
+    return isLeaf()
+           ? 0
+           : 1 + std::max(left()->height(),
+                          right()->height());
+  }
+
+== Bracing ==
+
+Don't brace single statements.
+
+  if (y == 7)
+    return 3;
+  for (size_t i = 0; i < 5; i++)
+    frob(i);
+
+But do brace them if the statement (or condition(s) or any additional
+consequents, if the braces would be associated with an if statement) occupies
+multiple lines.
+
+  if (cond1 ||
+      cond2)
+  {
+    action();
+  }
+  if (cond1) {
+    consequent();
+  } else {
+    alternative(arg1,
+                arg2);
+  }
+  if (cond1 || cond2) {
+    callMethod(arg1,
+               arg2);
+  }
+  for (size_t j = 0;
+       j < 17;
+       j++)
+  {
+    action();
+  }
+
+Braces in control flow go at the end of the line except when associated with an
+|if| or loop-head where the condition covers multiple lines
+
+== Classes and structs ==
+
+Inside class and structure definitions, public/private consume one level of
+indentation.
+
+  class Baz
+  {
+    public:
+      Baz() { }
+  };
+
+The absence of public/private in structs in which all members are public still
+consumes a level.
+
+  struct Foo
+  {
+      int field;
+  };
+
+Braces delimiting a class or struct go on their own lines.
+
+Member initialization in constructors should be formatted as follows:
+
+  class Fnord
+  {
+      size_t s1, s2, s3, s4, s5;
+
+    public:
+      Fnord(size_t s) : s1(s), s2(s), s3(s), s4(s), s5(s) { }
+      Fnord()
+        : s1(0), /* member initialization can be compressed if desired */
+          s2(0),
+          s3(0),
+          s4(0),
+          s5(0)
+      {
+        ...
+      }
+  };
+
+Fields should go first in the class so that the basic structure is all in one
+place, consistently.
+
+Use the inline keyword to annotate functions defined inline in a header.  (If
+the function is defined inline in the class, don't bother adding it
+redundantly.)
+
+Explicitly delete (using Attributes.h's MOZ_DELETE) the copy constructor and
+assignment operator from classes not intended to be copied or assigned to avoid
+mistakes.
+
+  class Funky
+  {
+    public:
+      Funky() { }
+
+    private:
+      Funky(const Funky& other) MOZ_DELETE;
+      void operator=(const Funky& other) MOZ_DELETE;
+  };
+
+Include a blank line between sections of structs and classes with different
+access control.
+
+The "get" prefix is used when a method is fallible.  If it's infallible, don't
+use it.
+
+  class String
+  {
+    public:
+      size_t length() const; // not getLength()
+  };
+
+== Templates ==
+
+Capitalize template parameter names to distinguish them from fields.
+
+  template<size_t KeySize, typename T>
+  class BloomFilter
+  {
+  };
+
+Use single-letter names if it makes sense (T for an arbitrary type, K for key
+type, V for value type, &c.).  Otherwise use InterCaps-style names.
+
+When declaring or defining a function, template<...> goes on one line, the
+return type and other specifiers go on another line, and the function name and
+argument list go on a third line.
+
+  template<typename T>
+  inline bool
+  Vector::add(T t)
+  {
+  }
+
+== Namespaces ==
+
+All C++ code shall be in the mozilla namespace, except that functionality only
+used to implement external-facing API should be in the mozilla::detail
+namespace, indicating that it should not be directly used.
+
+Namespace opening braces go on the same line as the namespace declaration.
+Namespace closing braces shall be commented.  Namespace contents are not
+indented.
+
+  namespace mozilla {
+  ...
+  } // namespace mozilla
+
+Don't use |using| in a header unless it's confined to a class or method.
+Implementation files for out-of-line functionality may use |using|.
+
+Name data structures and methods which must be usable in C code with a Moz*
+prefix, e.g. MozCustomStructure.  If the data structure is not meant to be used
+outside of the header in which it is found (i.e. it would be in mozilla::detail
+but for its being required to work in C code), add a corresponding comment to
+highlight this.
+
+== #includes ==
+
+Headers that include mfbt headers use a fully-qualified include path, even if
+full qualification is not strictly necessary.
+
+  #include "mozilla/Assertions.h"
+
+mfbt headers should be included first, alphabetically.  Standard includes should
+follow, separated from mfbt includes by a blank line.
+
+  #include "mozilla/Assertions.h"
+  #include "mozilla/Attributes.h"
+  
+  #include <string.h>
+
+If a header dependency is limited simply to the existence of a class,
+forward-declare it rather than #include that header.
+
+  namespace mozilla {
+  
+  class BloomFilter;
+  extern bool
+  Test(BloomFilter* bf);
+  
+  } // namespace mozilla
+
+== Preprocessor ==
+
+Include guards should be named by determining the fully-qualified include path,
+then substituting _ for / and . in it, and finally appending a trailing _.  For
+example, "mozilla/Assertions.h" becomes mozilla_Assertions_h_.
+
+Nested preprocessor directives indent the directive name (but not the #) by two
+spaces.
+
+  #ifdef __clang__
+  #  define FOO ...
+  #else
+  #  define FOO ...
+  #endif
+
+Comments within nested preprocessor directives align with directive names at
+that nesting depth.
+
+  #if defined(__GNUC__)
+     /* gcc supports C++11 override syntax. */
+  #  define MOZ_OVERRIDE override
+  #else
+  #  define MOZ_OVERRIDE /* unsupported */
+  #endif
+
+Feature-testing macros may be defined to nothing.  Macros intended to be
+textually expanded should be defined to a comment indicating non-support, as
+above or as appropriate to the situation.
+
+No particular preference is expressed between testing for a macro being defined
+using defined(...) and using #ifdef.
+
+When defining a macro with different expansions for different compilers, the top
+level of distinction should be the compiler, and the next nested level should be
+the compiler version.  Clang seems likely to be around for awhile, so to reduce
+confusion test for it separately from gcc even when it's not strictly necessary.
+
+  #if defined(__clang__)
+  #elif defined(__GNUC__)
+  #  if __GNUC__ > 4 || (__GNUC__ == 4 && __GNUC_MINOR__ >= 6)
+  #  else
+  #  endif
+  #elif defined(_MSC_VER)
+  #endif
+
+But don't distinguish clang's feature support using version checks: use the
+__has_feature() and __has_extension() macros instead, because vendors may
+customize clang's version numbers.
+
+Use a MOZ_* prefix when defining macros (e.g. MOZ_OVERRIDE, MOZ_LIKELY, and so
+on) that are part of the mfbt interface.  (C++ implementation files implementing
+mfbt's interface but which are not directly part of that interface may ignore
+this rule.)
+
+Prefer inline functions to macros whenever possible.
+
+== Comments ==
+
+Header files shall have a short descriptive comment underneath license
+boilerplate indicating what functionality the file implements, to be picked up
+by MXR and displayed in directory listings.  (But see bug 717196, which
+currently prevents MXR from doing this if the MPL2 boilerplate is used.)
+
+  Assertions.h:
+  ...license boilerplate...
+  
+  /* Implementations of runtime and static assertion macros for C and C++. */
+
+Classes intended for public use shall have interface comments explaining their
+functionality from the user's perspective.  These comments shall include
+examples of how the relevant functionality might be used.  These interface
+comments use /** */ doxygen/Javadoc-style comments.
+
+  /**
+   * The Frobber class simplifies the process of frobbing.
+   */
+  class Frobber
+  {
+  };
+
+Comments describing implementation details (tradeoffs considered, assumptions
+made, mathematical background, &c.) occur separately from interface comments so
+that users need not consider them.  They should go inside the class definition
+or inside the appropriate method, depending on the specificity of the comment.
+
+Headers which are intended to be C-compatible shall use only /**/-style
+comments.  (Code examples nested inside documentation comments may use //-style
+comments.)  Headers which are C++-compatible may also use //-style comments.
+
+Non-interface comments that are /**/-style shall not also be doxygen-style.
+
+Use Python-style ** to denote exponentiation inside comments, not ^ (which can
+be confused with C-style bitwise xor).  If you're writing sufficiently complex
+math, feel free to descend into LaTeX math mode ;-) inside implementation
+comments if you need to.  (But keep it out of interface comments, because most
+people probably haven't seen LaTeX.)
+
+== Miscellaneous ==
+
+Enclose C-compatible code in |extern "C"| blocks, and #ifdef __cplusplus the
+block start/end as needed.  The contents of these blocks should not be indented.
+
+Add new functionality to new headers unless an existing header makes sense.
+Err on the side of more headers rather than fewer, as this helps to minimize
+dependencies.  Don't add anything to Util.h, which will be split into multiple
+headers at some point (bug 713082).
+
+Don't use bool for argument types unless the method is a "set" or "enable"-style
+method where the method name and bool value together indicate the sense of its
+effect.  Use well-named enums in all other places, so that the semantics of the
+argument are clear at a glance and do not require knowing how the method
+interprets that argument.
+
+  void
+  setVisible(bool visible); // true clearly means visible, false clearly not
+  enum Enumerability {
+    Enumerable,
+    NonEnumerable
+  };
+  bool
+  DefineProperty(JSObject* obj, const char* name, Value v, Enumerability e);
+
+Use NULL for the null pointer constant.
+
+If a consequent in an if-statement ends with a return, don't specify an else.
+The else would be redundant with the return, and not using it avoids excess
+indentation.  If you feel the if-else alternation is important as a way to
+think about the choice being made, consider a ternary expression instead.
+
+  // BAD
+  if (f())
+    return 2;
+  else
+    return 5;
+  // GOOD
+  if (f())
+    return 2;
+  return 5;
+  // GOOD
+  return f() ? 2 : 5
diff --git a/mfbt/Scoped.h b/mfbt/Scoped.h
new file mode 100644
index 0000000..b811a47
--- /dev/null
+++ b/mfbt/Scoped.h
@@ -0,0 +1,228 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this file,
+ * You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+/* A number of structures to simplify scope-based RAII management. */
+
+#ifndef mozilla_Scoped_h_
+#define mozilla_Scoped_h_
+
+/*
+ * Resource Acquisition Is Initialization is a programming idiom used
+ * to write robust code that is able to deallocate resources properly,
+ * even in presence of execution errors or exceptions that need to be
+ * propagated.  The Scoped* classes defined in this header perform the
+ * deallocation of the resource they hold once program execution
+ * reaches the end of the scope for which they have been defined.
+ *
+ * This header provides the following RAII classes:
+ *
+ * - |ScopedFreePtr| - a container for a pointer, that automatically calls
+ *   |free()| at the end of the scope;
+ * - |ScopedDeletePtr| - a container for a pointer, that automatically calls
+ *   |delete| at the end of the scope;
+ * - |ScopedDeleteArray| - a container for a pointer to an array, that
+ *   automatically calls |delete[]| at the end of the scope.
+ *
+ * The general scenario for each of the RAII classes is the following:
+ *
+ * ScopedClass foo(create_value());
+ * // ... In this scope, |foo| is defined. Use |foo.get()| or |foo.rwget()|
+ *        to access the value.
+ * // ... In case of |return| or |throw|, |foo| is deallocated automatically.
+ * // ... If |foo| needs to be returned or stored, use |foo.forget()|
+ *
+ * Note that the RAII classes defined in this header do _not_ perform any form
+ * of reference-counting or garbage-collection. These classes have exactly two
+ * behaviors:
+ *
+ * - if |forget()| has not been called, the resource is always deallocated at
+ *   the end of the scope;
+ * - if |forget()| has been called, any control on the resource is unbound
+ *   and the resource is not deallocated by the class.
+ *
+ * Extension:
+ *
+ * In addition, this header provides class |Scoped| and macro |SCOPED_TEMPLATE|
+ * to simplify the definition of RAII classes for other scenarios. These macros
+ * have been used to automatically close file descriptors/file handles when
+ * reaching the end of the scope, graphics contexts, etc.
+ */
+
+#include "mozilla/Attributes.h"
+#include "mozilla/GuardObjects.h"
+
+namespace mozilla {
+
+/*
+ * Scoped is a helper to create RAII wrappers
+ * Type argument |Traits| is expected to have the following structure:
+ *
+ *   struct Traits {
+ *     // Define the type of the value stored in the wrapper
+ *     typedef value_type type;
+ *     // Returns the value corresponding to the uninitialized or freed state
+ *     const static type empty();
+ *     // Release resources corresponding to the wrapped value
+ *     // This function is responsible for not releasing an |empty| value
+ *     const static void release(type);
+ *   }
+ */
+template<typename Traits>
+class Scoped
+{
+  public:
+    typedef typename Traits::type Resource;
+
+    explicit Scoped(MOZ_GUARD_OBJECT_NOTIFIER_ONLY_PARAM)
+      : value(Traits::empty())
+    {
+      MOZ_GUARD_OBJECT_NOTIFIER_INIT;
+    }
+    explicit Scoped(const Resource& value
+                    MOZ_GUARD_OBJECT_NOTIFIER_PARAM)
+      : value(value)
+    {
+      MOZ_GUARD_OBJECT_NOTIFIER_INIT;
+    }
+    ~Scoped() {
+      Traits::release(value);
+    }
+
+    // Constant getter
+    operator const Resource&() const { return value; }
+    const Resource& operator->() const { return value; }
+    const Resource& get() const { return value; }
+    // Non-constant getter.
+    Resource& rwget() { return value; }
+
+    /*
+     * Forget the resource.
+     *
+     * Once |forget| has been called, the |Scoped| is neutralized, i.e. it will
+     * have no effect at destruction (unless it is reset to another resource by
+     * |operator=|).
+     *
+     * @return The original resource.
+     */
+    Resource forget() {
+      Resource tmp = value;
+      value = Traits::empty();
+      return tmp;
+    }
+
+    /*
+     * Perform immediate clean-up of this |Scoped|.
+     *
+     * If this |Scoped| is currently empty, this method has no effect.
+     */
+    void dispose() {
+      Traits::release(value);
+      value = Traits::empty();
+    }
+
+    bool operator==(const Resource& other) const {
+      return value == other;
+    }
+
+    /*
+     * Replace the resource with another resource.
+     *
+     * Calling |operator=| has the side-effect of triggering clean-up. If you do
+     * not want to trigger clean-up, you should first invoke |forget|.
+     *
+     * @return this
+     */
+    Scoped<Traits>& operator=(const Resource& other) {
+      return reset(other);
+    }
+    Scoped<Traits>& reset(const Resource& other) {
+      Traits::release(value);
+      value = other;
+      return *this;
+    }
+
+  private:
+    explicit Scoped(const Scoped<Traits>& value) MOZ_DELETE;
+    Scoped<Traits>& operator=(const Scoped<Traits>& value) MOZ_DELETE;
+
+  private:
+    Resource value;
+    MOZ_DECL_USE_GUARD_OBJECT_NOTIFIER
+};
+
+/*
+ * SCOPED_TEMPLATE defines a templated class derived from Scoped
+ * This allows to implement templates such as ScopedFreePtr.
+ *
+ * @param name The name of the class to define.
+ * @param Traits A struct implementing clean-up. See the implementations
+ * for more details.
+ */
+#define SCOPED_TEMPLATE(name, Traits)                          \
+template<typename Type>                                        \
+struct name : public mozilla::Scoped<Traits<Type> >            \
+{                                                              \
+    typedef mozilla::Scoped<Traits<Type> > Super;              \
+    typedef typename Super::Resource Resource;                 \
+    name& operator=(Resource ptr) {                            \
+      Super::operator=(ptr);                                   \
+      return *this;                                            \
+    }                                                          \
+    explicit name(MOZ_GUARD_OBJECT_NOTIFIER_ONLY_PARAM)        \
+      : Super(MOZ_GUARD_OBJECT_NOTIFIER_ONLY_PARAM_TO_PARENT)  \
+    {}                                                         \
+    explicit name(Resource ptr                                 \
+                  MOZ_GUARD_OBJECT_NOTIFIER_PARAM)             \
+      : Super(ptr MOZ_GUARD_OBJECT_NOTIFIER_PARAM_TO_PARENT)   \
+    {}                                                         \
+  private:                                                     \
+    explicit name(name& source) MOZ_DELETE;                    \
+    name& operator=(name& source) MOZ_DELETE;                  \
+};
+
+/*
+ * ScopedFreePtr is a RAII wrapper for pointers that need to be free()d.
+ *
+ *   struct S { ... };
+ *   ScopedFreePtr<S> foo = malloc(sizeof(S));
+ *   ScopedFreePtr<char> bar = strdup(str);
+ */
+template<typename T>
+struct ScopedFreePtrTraits
+{
+    typedef T* type;
+    static T* empty() { return NULL; }
+    static void release(T* ptr) { free(ptr); }
+};
+SCOPED_TEMPLATE(ScopedFreePtr, ScopedFreePtrTraits)
+
+/*
+ * ScopedDeletePtr is a RAII wrapper for pointers that need to be deleted.
+ *
+ *   struct S { ... };
+ *   ScopedDeletePtr<S> foo = new S();
+ */
+template<typename T>
+struct ScopedDeletePtrTraits : public ScopedFreePtrTraits<T>
+{
+    static void release(T* ptr) { delete ptr; }
+};
+SCOPED_TEMPLATE(ScopedDeletePtr, ScopedDeletePtrTraits)
+
+/*
+ * ScopedDeleteArray is a RAII wrapper for pointers that need to be delete[]ed.
+ *
+ *   struct S { ... };
+ *   ScopedDeleteArray<S> foo = new S[42];
+ */
+template<typename T>
+struct ScopedDeleteArrayTraits : public ScopedFreePtrTraits<T>
+{
+    static void release(T* ptr) { delete [] ptr; }
+};
+SCOPED_TEMPLATE(ScopedDeleteArray, ScopedDeleteArrayTraits)
+
+} /* namespace mozilla */
+
+#endif // mozilla_Scoped_h_
diff --git a/mfbt/StandardInteger.h b/mfbt/StandardInteger.h
new file mode 100644
index 0000000..8e4c857
--- /dev/null
+++ b/mfbt/StandardInteger.h
@@ -0,0 +1,43 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+/* Implements the C99 <stdint.h> interface for C and C++ code. */
+
+#ifndef mozilla_StandardInteger_h_
+#define mozilla_StandardInteger_h_
+
+/*
+ * The C99 standard header <stdint.h> exposes typedefs for common fixed-width
+ * integer types.  It would be feasible to simply #include <stdint.h>, but
+ * MSVC++ versions prior to 2010 don't provide <stdint.h>.  We could solve this
+ * by reimplementing <stdint.h> for MSVC++ 2008 and earlier.  But then we reach
+ * a second problem: our custom <stdint.h> might conflict with a <stdint.h>
+ * defined by an embedder already looking to work around the MSVC++ <stdint.h>
+ * absence.
+ *
+ * We address these issues in this manner:
+ *
+ *   1. If the preprocessor macro MOZ_CUSTOM_STDINT_H is defined to a path to a
+ *      custom <stdint.h> implementation, we will #include it.  Embedders using
+ *      a custom <stdint.h> must define this macro to an implementation that
+ *      will work with their embedding.
+ *   2. Otherwise, if we are compiling with a an MSVC++ version without
+ *      <stdint.h>, #include our custom <stdint.h> reimplementation.
+ *   3. Otherwise, #include the standard <stdint.h> provided by the compiler.
+ *
+ * Note that we can't call this file "stdint.h" or something case-insensitively
+ * equal to "stdint.h" because then MSVC (and other compilers on
+ * case-insensitive file systems) will include this file, rather than the system
+ * stdint.h, when we ask for <stdint.h> below.
+ */
+#if defined(MOZ_CUSTOM_STDINT_H)
+#  include MOZ_CUSTOM_STDINT_H
+#elif defined(_MSC_VER) && _MSC_VER < 1600
+#  include "mozilla/MSStdInt.h"
+#else
+#  include <stdint.h>
+#endif
+
+#endif  /* mozilla_StandardInteger_h_ */
diff --git a/mfbt/ThreadLocal.h b/mfbt/ThreadLocal.h
new file mode 100644
index 0000000..712f1f1
--- /dev/null
+++ b/mfbt/ThreadLocal.h
@@ -0,0 +1,144 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this file,
+ * You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+/* Cross-platform lightweight thread local data wrappers. */
+
+#ifndef mozilla_TLS_h_
+#define mozilla_TLS_h_
+
+#if defined(XP_WIN)
+// This file will get included in any file that wants to add a profiler mark.
+// In order to not bring <windows.h> together we could include windef.h and
+// winbase.h which are sufficient to get the prototypes for the Tls* functions.
+// # include <windef.h>
+// # include <winbase.h>
+// Unfortunately, even including these headers causes us to add a bunch of ugly
+// stuff to our namespace e.g #define CreateEvent CreateEventW
+extern "C" {
+__declspec(dllimport) void * __stdcall TlsGetValue(unsigned long);
+__declspec(dllimport) int __stdcall TlsSetValue(unsigned long, void *);
+__declspec(dllimport) unsigned long __stdcall TlsAlloc();
+}
+#else
+#  include <pthread.h>
+#  include <signal.h>
+#endif
+
+#include "mozilla/Assertions.h"
+#include "mozilla/Attributes.h"
+
+namespace mozilla {
+
+// sig_safe_t denotes an atomic type which can be read or stored in a single
+// instruction.  This means that data of this type is safe to be manipulated
+// from a signal handler, or other similar asynchronous execution contexts.
+#if defined(XP_WIN)
+typedef unsigned long sig_safe_t;
+#else
+typedef sig_atomic_t sig_safe_t;
+#endif
+
+/*
+ * Thread Local Storage helpers.
+ *
+ * Usage:
+ *
+ * Only static-storage-duration (e.g. global variables, or static class members)
+ * objects of this class should be instantiated. This class relies on
+ * zero-initialization, which is implicit for static-storage-duration objects.
+ * It doesn't have a custom default constructor, to avoid static initializers.
+ *
+ * API usage:
+ *
+ * // Create a TLS item
+ * mozilla::ThreadLocal<int> tlsKey;
+ * if (!tlsKey.init()) {
+ *   // deal with the error
+ * }
+ *
+ * // Set the TLS value
+ * tlsKey.set(123);
+ *
+ * // Get the TLS value
+ * int value = tlsKey.get();
+ */
+template<typename T>
+class ThreadLocal
+{
+#if defined(XP_WIN)
+    typedef unsigned long key_t;
+#else
+    typedef pthread_key_t key_t;
+#endif
+
+    union Helper {
+      void* ptr;
+      T value;
+    };
+
+  public:
+    MOZ_WARN_UNUSED_RESULT inline bool init();
+
+    inline T get() const;
+
+    inline bool set(const T value);
+
+    bool initialized() const {
+      return inited;
+    }
+
+  private:
+    key_t key;
+    bool inited;
+};
+
+template<typename T>
+inline bool
+ThreadLocal<T>::init()
+{
+  MOZ_STATIC_ASSERT(sizeof(T) <= sizeof(void *),
+                    "mozilla::ThreadLocal can't be used for types larger than "
+                    "a pointer");
+  MOZ_ASSERT(!initialized());
+#ifdef XP_WIN
+  key = TlsAlloc();
+  inited = key != 0xFFFFFFFFUL; // TLS_OUT_OF_INDEXES
+#else
+  inited = !pthread_key_create(&key, NULL);
+#endif
+  return inited;
+}
+
+template<typename T>
+inline T
+ThreadLocal<T>::get() const
+{
+  MOZ_ASSERT(initialized());
+  Helper h;
+#ifdef XP_WIN
+  h.ptr = TlsGetValue(key);
+#else
+  h.ptr = pthread_getspecific(key);
+#endif
+  return h.value;
+}
+
+template<typename T>
+inline bool
+ThreadLocal<T>::set(const T value)
+{
+  MOZ_ASSERT(initialized());
+  Helper h;
+  h.value = value;
+#ifdef XP_WIN
+  return TlsSetValue(key, h.ptr);
+#else
+  return !pthread_setspecific(key, h.ptr);
+#endif
+}
+
+} // namespace mozilla
+
+#endif // mozilla_TLS_h_
diff --git a/mfbt/TypeTraits.h b/mfbt/TypeTraits.h
new file mode 100644
index 0000000..8f04e7a
--- /dev/null
+++ b/mfbt/TypeTraits.h
@@ -0,0 +1,122 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+/* Template-based metaprogramming and type-testing facilities. */
+
+#ifndef mozilla_TypeTraits_h_
+#define mozilla_TypeTraits_h_
+
+namespace mozilla {
+
+/*
+ * IsBaseOf allows to know whether a given class is derived from another.
+ *
+ * Consider the following class definitions:
+ *
+ *   class A {};
+ *   class B : public A {};
+ *   class C {};
+ *
+ * mozilla::IsBaseOf<A, B>::value is true;
+ * mozilla::IsBaseOf<A, C>::value is false;
+ */
+template<class Base, class Derived>
+class IsBaseOf
+{
+  private:
+    static char test(Base* b);
+    static int test(...);
+
+  public:
+    static const bool value =
+      sizeof(test(static_cast<Derived*>(0))) == sizeof(char);
+};
+
+/*
+ * IsConvertible determines whether a value of type From will implicitly convert
+ * to a value of type To.  For example:
+ *
+ *   struct A {};
+ *   struct B : public A {};
+ *   struct C {};
+ *
+ * mozilla::IsConvertible<A, A>::value is true;
+ * mozilla::IsConvertible<A*, A*>::value is true;
+ * mozilla::IsConvertible<B, A>::value is true;
+ * mozilla::IsConvertible<B*, A*>::value is true;
+ * mozilla::IsConvertible<C, A>::value is false;
+ * mozilla::IsConvertible<A, C>::value is false;
+ * mozilla::IsConvertible<A*, C*>::value is false;
+ * mozilla::IsConvertible<C*, A*>::value is false.
+ *
+ * For obscure reasons, you can't use IsConvertible when the types being tested
+ * are related through private inheritance, and you'll get a compile error if
+ * you try.  Just don't do it!
+ */
+template<typename From, typename To>
+struct IsConvertible
+{
+  private:
+    static From create();
+
+    template<typename From1, typename To1>
+    static char test(To to);
+
+    template<typename From1, typename To1>
+    static int test(...);
+
+  public:
+    static const bool value =
+      sizeof(test<From, To>(create())) == sizeof(char);
+};
+
+/*
+ * Conditional selects a class between two, depending on a given boolean value.
+ *
+ * mozilla::Conditional<true, A, B>::Type is A;
+ * mozilla::Conditional<false, A, B>::Type is B;
+ */
+template<bool condition, class A, class B>
+struct Conditional
+{
+    typedef A Type;
+};
+
+template<class A, class B>
+struct Conditional<false, A, B>
+{
+    typedef B Type;
+};
+
+/*
+ * EnableIf is a struct containing a typedef of T if and only if B is true.
+ *
+ * mozilla::EnableIf<true, int>::Type is int;
+ * mozilla::EnableIf<false, int>::Type is a compile-time error.
+ *
+ * Use this template to implement SFINAE-style (Substitution Failure Is not An
+ * Error) requirements.  For example, you might use it to impose a restriction
+ * on a template parameter:
+ *
+ *   template<typename T>
+ *   class PodVector // vector optimized to store POD (memcpy-able) types
+ *   {
+ *      EnableIf<IsPodType<T>, T>::Type* vector;
+ *      size_t length;
+ *      ...
+ *   };
+ */
+template<bool B, typename T = void>
+struct EnableIf
+{};
+
+template<typename T>
+struct EnableIf<true, T>
+{
+    typedef T Type;
+};
+
+} /* namespace mozilla */
+
+#endif  /* mozilla_TypeTraits_h_ */
diff --git a/mfbt/Types.h b/mfbt/Types.h
new file mode 100644
index 0000000..f803586
--- /dev/null
+++ b/mfbt/Types.h
@@ -0,0 +1,136 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+/* mfbt foundational types and macros. */
+
+#ifndef mozilla_Types_h_
+#define mozilla_Types_h_
+
+/*
+ * This header must be valid C and C++, includable by code embedding either
+ * SpiderMonkey or Gecko.
+ */
+
+/*
+ * Expose all the integer types defined in C99's <stdint.h> (and the integer
+ * limit and constant macros, if compiling C code or if compiling C++ code and
+ * the right __STDC_*_MACRO has been defined for each).  These are all usable
+ * throughout mfbt code, and throughout Mozilla code more generally.
+ */
+#include "mozilla/StandardInteger.h"
+
+/* Also expose size_t. */
+#include <stddef.h>
+
+/* Implement compiler and linker macros needed for APIs. */
+
+/*
+ * MOZ_EXPORT_API is used to declare and define a method which is externally
+ * visible to users of the current library.  It encapsulates various decorations
+ * needed to properly export the method's symbol.  MOZ_EXPORT_DATA serves the
+ * same purpose for data.
+ *
+ *   api.h:
+ *     extern MOZ_EXPORT_API(int) MeaningOfLife(void);
+ *     extern MOZ_EXPORT_DATA(int) LuggageCombination;
+ *
+ *   api.c:
+ *     MOZ_EXPORT_API(int) MeaningOfLife(void) { return 42; }
+ *     MOZ_EXPORT_DATA(int) LuggageCombination = 12345;
+ *
+ * If you are merely sharing a method across files, just use plain |extern|.
+ * These macros are designed for use by library interfaces -- not for normal
+ * methods or data used cross-file.
+ */
+#if defined(WIN32) || defined(XP_OS2)
+#  define MOZ_EXPORT_API(type)    __declspec(dllexport) type
+#  define MOZ_EXPORT_DATA(type)   __declspec(dllexport) type
+#else /* Unix */
+#  ifdef HAVE_VISIBILITY_ATTRIBUTE
+#    define MOZ_EXTERNAL_VIS       __attribute__((visibility("default")))
+#  elif defined(__SUNPRO_C) || defined(__SUNPRO_CC)
+#    define MOZ_EXTERNAL_VIS      __global
+#  else
+#    define MOZ_EXTERNAL_VIS
+#  endif
+#  define MOZ_EXPORT_API(type)    MOZ_EXTERNAL_VIS type
+#  define MOZ_EXPORT_DATA(type)   MOZ_EXTERNAL_VIS type
+#endif
+
+/*
+ * Whereas implementers use MOZ_EXPORT_API and MOZ_EXPORT_DATA to declare and
+ * define library symbols, users use MOZ_IMPORT_API and MOZ_IMPORT_DATA to
+ * access them.  Most often the implementer of the library will expose an API
+ * macro which expands to either the export or import version of the macro,
+ * depending upon the compilation mode.
+ */
+#ifdef _WIN32
+#  if defined(__MWERKS__)
+#    define MOZ_IMPORT_API(x)    x
+#  else
+#    define MOZ_IMPORT_API(x)    __declspec(dllimport) x
+#  endif
+#elif defined(XP_OS2)
+#  define MOZ_IMPORT_API(x)     __declspec(dllimport) x
+#else
+#  define MOZ_IMPORT_API(x)     MOZ_EXPORT_API(x)
+#endif
+
+#if defined(_WIN32) && !defined(__MWERKS__)
+#  define MOZ_IMPORT_DATA(x)     __declspec(dllimport) x
+#elif defined(XP_OS2)
+#  define MOZ_IMPORT_DATA(x)     __declspec(dllimport) x
+#else
+#  define MOZ_IMPORT_DATA(x)     MOZ_EXPORT_DATA(x)
+#endif
+
+/*
+ * Consistent with the above comment, the MFBT_API and MFBT_DATA macros expose
+ * export mfbt declarations when building mfbt, and they expose import mfbt
+ * declarations when using mfbt.
+ */
+#if defined(IMPL_MFBT)
+#  define MFBT_API(type)        MOZ_EXPORT_API(type)
+#  define MFBT_DATA(type)       MOZ_EXPORT_DATA(type)
+#else
+  /*
+   * When mozglue is linked in the program, we need the MFBT API symbols
+   * to be weak.
+   */
+#  if defined(MOZ_GLUE_IN_PROGRAM)
+#    define MFBT_API(type)        __attribute__((weak)) MOZ_IMPORT_API(type)
+#    define MFBT_DATA(type)       __attribute__((weak)) MOZ_IMPORT_DATA(type)
+#  else
+#    define MFBT_API(type)        MOZ_IMPORT_API(type)
+#    define MFBT_DATA(type)       MOZ_IMPORT_DATA(type)
+#  endif
+#endif
+
+/*
+ * C symbols in C++ code must be declared immediately within |extern "C"|
+ * blocks.  However, in C code, they need not be declared specially.  This
+ * difference is abstracted behind the MOZ_BEGIN_EXTERN_C and MOZ_END_EXTERN_C
+ * macros, so that the user need not know whether he is being used in C or C++
+ * code.
+ *
+ *   MOZ_BEGIN_EXTERN_C
+ *
+ *   extern MOZ_EXPORT_API(int) MostRandomNumber(void);
+ *   ...other declarations...
+ *
+ *   MOZ_END_EXTERN_C
+ *
+ * This said, it is preferable to just use |extern "C"| in C++ header files for
+ * its greater clarity.
+ */
+#ifdef __cplusplus
+#  define MOZ_BEGIN_EXTERN_C    extern "C" {
+#  define MOZ_END_EXTERN_C      }
+#else
+#  define MOZ_BEGIN_EXTERN_C
+#  define MOZ_END_EXTERN_C
+#endif
+
+#endif  /* mozilla_Types_h_ */
diff --git a/mfbt/Util.h b/mfbt/Util.h
new file mode 100644
index 0000000..735c067
--- /dev/null
+++ b/mfbt/Util.h
@@ -0,0 +1,330 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+/*
+ * Miscellaneous uncategorized functionality.  Please add new functionality to
+ * new headers, or to other appropriate existing headers, not here.
+ */
+
+#ifndef mozilla_Util_h_
+#define mozilla_Util_h_
+
+#include "mozilla/Assertions.h"
+#include "mozilla/Attributes.h"
+#include "mozilla/Types.h"
+
+#ifdef __cplusplus
+
+namespace mozilla {
+
+/**
+ * DebugOnly contains a value of type T, but only in debug builds.  In release
+ * builds, it does not contain a value.  This helper is intended to be used with
+ * MOZ_ASSERT()-style macros, allowing one to write:
+ *
+ *   DebugOnly<bool> check = func();
+ *   MOZ_ASSERT(check);
+ *
+ * more concisely than declaring |check| conditional on #ifdef DEBUG, but also
+ * without allocating storage space for |check| in release builds.
+ *
+ * DebugOnly instances can only be coerced to T in debug builds.  In release
+ * builds they don't have a value, so type coercion is not well defined.
+ */
+template<typename T>
+struct DebugOnly
+{
+#ifdef DEBUG
+    T value;
+
+    DebugOnly() { }
+    DebugOnly(const T& other) : value(other) { }
+    DebugOnly(const DebugOnly& other) : value(other.value) { }
+    DebugOnly& operator=(const T& rhs) {
+      value = rhs;
+      return *this;
+    }
+    void operator++(int) {
+      value++;
+    }
+    void operator--(int) {
+      value--;
+    }
+
+    T *operator&() { return &value; }
+
+    operator T&() { return value; }
+    operator const T&() const { return value; }
+
+    T& operator->() { return value; }
+
+#else
+    DebugOnly() { }
+    DebugOnly(const T&) { }
+    DebugOnly(const DebugOnly&) { }
+    DebugOnly& operator=(const T&) { return *this; }
+    void operator++(int) { }
+    void operator--(int) { }
+#endif
+
+    /*
+     * DebugOnly must always have a destructor or else it will
+     * generate "unused variable" warnings, exactly what it's intended
+     * to avoid!
+     */
+    ~DebugOnly() {}
+};
+
+/*
+ * This class, and the corresponding macro MOZ_ALIGNOF, figure out how many 
+ * bytes of alignment a given type needs.
+ */
+template<class T>
+class AlignmentFinder
+{
+    struct Aligner
+    {
+        char c;
+        T t;
+    };
+
+  public:
+    static const size_t alignment = sizeof(Aligner) - sizeof(T);
+};
+
+#define MOZ_ALIGNOF(T) mozilla::AlignmentFinder<T>::alignment
+
+/*
+ * Declare the MOZ_ALIGNED_DECL macro for declaring aligned types.
+ *
+ * For instance,
+ *
+ *   MOZ_ALIGNED_DECL(char arr[2], 8);
+ *
+ * will declare a two-character array |arr| aligned to 8 bytes.
+ */
+
+#if defined(__GNUC__)
+#  define MOZ_ALIGNED_DECL(_type, _align) \
+     _type __attribute__((aligned(_align)))
+#elif defined(_MSC_VER)
+#  define MOZ_ALIGNED_DECL(_type, _align) \
+     __declspec(align(_align)) _type
+#else
+#  warning "We don't know how to align variables on this compiler."
+#  define MOZ_ALIGNED_DECL(_type, _align) _type
+#endif
+
+/*
+ * AlignedElem<N> is a structure whose alignment is guaranteed to be at least N
+ * bytes.
+ *
+ * We support 1, 2, 4, 8, and 16-bit alignment.
+ */
+template<size_t align>
+struct AlignedElem;
+
+/*
+ * We have to specialize this template because GCC doesn't like __attribute__((aligned(foo))) where
+ * foo is a template parameter.
+ */
+
+template<>
+struct AlignedElem<1>
+{
+    MOZ_ALIGNED_DECL(uint8_t elem, 1);
+};
+
+template<>
+struct AlignedElem<2>
+{
+    MOZ_ALIGNED_DECL(uint8_t elem, 2);
+};
+
+template<>
+struct AlignedElem<4>
+{
+    MOZ_ALIGNED_DECL(uint8_t elem, 4);
+};
+
+template<>
+struct AlignedElem<8>
+{
+    MOZ_ALIGNED_DECL(uint8_t elem, 8);
+};
+
+template<>
+struct AlignedElem<16>
+{
+    MOZ_ALIGNED_DECL(uint8_t elem, 16);
+};
+
+/*
+ * This utility pales in comparison to Boost's aligned_storage. The utility
+ * simply assumes that uint64_t is enough alignment for anyone. This may need
+ * to be extended one day...
+ *
+ * As an important side effect, pulling the storage into this template is
+ * enough obfuscation to confuse gcc's strict-aliasing analysis into not giving
+ * false negatives when we cast from the char buffer to whatever type we've
+ * constructed using the bytes.
+ */
+template<size_t nbytes>
+struct AlignedStorage
+{
+    union U {
+      char bytes[nbytes];
+      uint64_t _;
+    } u;
+
+    const void* addr() const { return u.bytes; }
+    void* addr() { return u.bytes; }
+};
+
+template<class T>
+struct AlignedStorage2
+{
+    union U {
+      char bytes[sizeof(T)];
+      uint64_t _;
+    } u;
+
+    const T* addr() const { return reinterpret_cast<const T*>(u.bytes); }
+    T* addr() { return static_cast<T*>(static_cast<void*>(u.bytes)); }
+};
+
+/*
+ * Small utility for lazily constructing objects without using dynamic storage.
+ * When a Maybe<T> is constructed, it is |empty()|, i.e., no value of T has
+ * been constructed and no T destructor will be called when the Maybe<T> is
+ * destroyed. Upon calling |construct|, a T object will be constructed with the
+ * given arguments and that object will be destroyed when the owning Maybe<T>
+ * is destroyed.
+ *
+ * N.B. GCC seems to miss some optimizations with Maybe and may generate extra
+ * branches/loads/stores. Use with caution on hot paths.
+ */
+template<class T>
+class Maybe
+{
+    AlignedStorage2<T> storage;
+    bool constructed;
+
+    T& asT() { return *storage.addr(); }
+
+  public:
+    Maybe() { constructed = false; }
+    ~Maybe() { if (constructed) asT().~T(); }
+
+    bool empty() const { return !constructed; }
+
+    void construct() {
+      MOZ_ASSERT(!constructed);
+      new (storage.addr()) T();
+      constructed = true;
+    }
+
+    template<class T1>
+    void construct(const T1& t1) {
+      MOZ_ASSERT(!constructed);
+      new (storage.addr()) T(t1);
+      constructed = true;
+    }
+
+    template<class T1, class T2>
+    void construct(const T1& t1, const T2& t2) {
+      MOZ_ASSERT(!constructed);
+      new (storage.addr()) T(t1, t2);
+      constructed = true;
+    }
+
+    template<class T1, class T2, class T3>
+    void construct(const T1& t1, const T2& t2, const T3& t3) {
+      MOZ_ASSERT(!constructed);
+      new (storage.addr()) T(t1, t2, t3);
+      constructed = true;
+    }
+
+    template<class T1, class T2, class T3, class T4>
+    void construct(const T1& t1, const T2& t2, const T3& t3, const T4& t4) {
+      MOZ_ASSERT(!constructed);
+      new (storage.addr()) T(t1, t2, t3, t4);
+      constructed = true;
+    }
+
+    T* addr() {
+      MOZ_ASSERT(constructed);
+      return &asT();
+    }
+
+    T& ref() {
+      MOZ_ASSERT(constructed);
+      return asT();
+    }
+
+    const T& ref() const {
+      MOZ_ASSERT(constructed);
+      return const_cast<Maybe*>(this)->asT();
+    }
+
+    void destroy() {
+      ref().~T();
+      constructed = false;
+    }
+
+    void destroyIfConstructed() {
+      if (!empty())
+        destroy();
+    }
+
+  private:
+    Maybe(const Maybe& other) MOZ_DELETE;
+    const Maybe& operator=(const Maybe& other) MOZ_DELETE;
+};
+
+/*
+ * Safely subtract two pointers when it is known that end >= begin.  This avoids
+ * the common compiler bug that if (size_t(end) - size_t(begin)) has the MSB
+ * set, the unsigned subtraction followed by right shift will produce -1, or
+ * size_t(-1), instead of the real difference.
+ */
+template<class T>
+MOZ_ALWAYS_INLINE size_t
+PointerRangeSize(T* begin, T* end)
+{
+  MOZ_ASSERT(end >= begin);
+  return (size_t(end) - size_t(begin)) / sizeof(T);
+}
+
+/*
+ * Compute the length of an array with constant length.  (Use of this method
+ * with a non-array pointer will not compile.)
+ *
+ * Beware of the implicit trailing '\0' when using this with string constants.
+ */
+template<typename T, size_t N>
+size_t
+ArrayLength(T (&arr)[N])
+{
+  return N;
+}
+
+/*
+ * Compute the address one past the last element of a constant-length array.
+ *
+ * Beware of the implicit trailing '\0' when using this with string constants.
+ */
+template<typename T, size_t N>
+T*
+ArrayEnd(T (&arr)[N])
+{
+  return arr + ArrayLength(arr);
+}
+
+} /* namespace mozilla */
+
+#endif /* __cplusplus */
+
+#endif  /* mozilla_Util_h_ */
diff --git a/mfbt/WeakPtr.h b/mfbt/WeakPtr.h
new file mode 100644
index 0000000..e207671
--- /dev/null
+++ b/mfbt/WeakPtr.h
@@ -0,0 +1,139 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this file,
+ * You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+/* Weak pointer functionality, implemented as a mixin for use with any class. */
+
+/**
+ * SupportsWeakPtr lets you have a pointer to an object 'Foo' without affecting
+ * its lifetime. It works by creating a single shared reference counted object
+ * (WeakReference) that each WeakPtr will access 'Foo' through. This lets 'Foo'
+ * clear the pointer in the WeakReference without having to know about all of
+ * the WeakPtrs to it and allows the WeakReference to live beyond the lifetime
+ * of 'Foo'.
+ *
+ * The overhead of WeakPtr is that accesses to 'Foo' becomes an additional
+ * dereference, and an additional heap allocated pointer sized object shared
+ * between all of the WeakPtrs.
+ *
+ * Example of usage:
+ *
+ *   // To have a class C support weak pointers, inherit from SupportsWeakPtr<C>.
+ *   class C : public SupportsWeakPtr<C>
+ *   {
+ *    public:
+ *      int num;
+ *      void act();
+ *   };
+ *
+ *   C* ptr =  new C();
+ *
+ *   // Get weak pointers to ptr. The first time asWeakPtr is called
+ *   // a reference counted WeakReference object is created that
+ *   // can live beyond the lifetime of 'ptr'. The WeakReference
+ *   // object will be notified of 'ptr's destruction.
+ *   WeakPtr<C> weak = ptr->asWeakPtr();
+ *   WeakPtr<C> other = ptr->asWeakPtr();
+ *
+ *   // Test a weak pointer for validity before using it.
+ *   if (weak) {
+ *     weak->num = 17;
+ *     weak->act();
+ *   }
+ *
+ *   // Destroying the underlying object clears weak pointers to it.
+ *   delete ptr;
+ *
+ *   MOZ_ASSERT(!weak, "Deleting |ptr| clears weak pointers to it.");
+ *   MOZ_ASSERT(!other, "Deleting |ptr| clears all weak pointers to it.");
+ *
+ * WeakPtr is typesafe and may be used with any class. It is not required that
+ * the class be reference-counted or allocated in any particular way.
+ *
+ * The API was loosely inspired by Chromium's weak_ptr.h:
+ * http://src.chromium.org/svn/trunk/src/base/memory/weak_ptr.h
+ */
+
+#ifndef mozilla_WeakPtr_h_
+#define mozilla_WeakPtr_h_
+
+#include "mozilla/Assertions.h"
+#include "mozilla/NullPtr.h"
+#include "mozilla/RefPtr.h"
+#include "mozilla/TypeTraits.h"
+
+namespace mozilla {
+
+template <typename T> class WeakPtr;
+
+template <typename T>
+class SupportsWeakPtr
+{
+  public:
+    WeakPtr<T> asWeakPtr() {
+      if (!weakRef)
+        weakRef = new WeakReference(static_cast<T*>(this));
+      return WeakPtr<T>(weakRef);
+    }
+
+  protected:
+    ~SupportsWeakPtr() {
+      MOZ_STATIC_ASSERT((IsBaseOf<SupportsWeakPtr<T>, T>::value), "T must derive from SupportsWeakPtr<T>");
+      if (weakRef)
+        weakRef->detach();
+    }
+
+  private:
+    friend class WeakPtr<T>;
+
+    // This can live beyond the lifetime of the class derived from SupportsWeakPtr.
+    class WeakReference : public RefCounted<WeakReference>
+    {
+      public:
+        explicit WeakReference(T* ptr) : ptr(ptr) {}
+        T* get() const {
+          return ptr;
+        }
+
+      private:
+        friend class WeakPtr<T>;
+        friend class SupportsWeakPtr<T>;
+        void detach() {
+          ptr = nullptr;
+        }
+        T* ptr;
+    };
+
+    RefPtr<WeakReference> weakRef;
+};
+
+template <typename T>
+class WeakPtr
+{
+  public:
+    WeakPtr(const WeakPtr<T>& o) : ref(o.ref) {}
+    WeakPtr() : ref(nullptr) {}
+
+    operator T*() const {
+      return ref->get();
+    }
+    T& operator*() const {
+      return *ref->get();
+    }
+
+    T* operator->() const {
+      return ref->get();
+    }
+
+  private:
+    friend class SupportsWeakPtr<T>;
+
+    explicit WeakPtr(const RefPtr<typename SupportsWeakPtr<T>::WeakReference> &o) : ref(o) {}
+
+    RefPtr<typename SupportsWeakPtr<T>::WeakReference> ref;
+};
+
+} // namespace mozilla
+
+#endif /* ifdef mozilla_WeakPtr_h_ */
diff --git a/mfbt/double-conversion/LICENSE b/mfbt/double-conversion/LICENSE
new file mode 100644
index 0000000..933718a
--- /dev/null
+++ b/mfbt/double-conversion/LICENSE
@@ -0,0 +1,26 @@
+Copyright 2006-2011, the V8 project authors. All rights reserved.
+Redistribution and use in source and binary forms, with or without
+modification, are permitted provided that the following conditions are
+met:
+
+    * Redistributions of source code must retain the above copyright
+      notice, this list of conditions and the following disclaimer.
+    * Redistributions in binary form must reproduce the above
+      copyright notice, this list of conditions and the following
+      disclaimer in the documentation and/or other materials provided
+      with the distribution.
+    * Neither the name of Google Inc. nor the names of its
+      contributors may be used to endorse or promote products derived
+      from this software without specific prior written permission.
+
+THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+"AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+(INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
diff --git a/mfbt/double-conversion/README b/mfbt/double-conversion/README
new file mode 100644
index 0000000..f186b42
--- /dev/null
+++ b/mfbt/double-conversion/README
@@ -0,0 +1,11 @@
+http://code.google.com/p/double-conversion
+
+This project (double-conversion) provides binary-decimal and decimal-binary
+routines for IEEE doubles.
+
+The library consists of efficient conversion routines that have been extracted
+from the V8 JavaScript engine. The code has been refactored and improved so that
+it can be used more easily in other projects.
+
+There is extensive documentation in src/double-conversion.h. Other examples can
+be found in test/cctest/test-conversions.cc.
diff --git a/mfbt/double-conversion/add-mfbt-api-markers.patch b/mfbt/double-conversion/add-mfbt-api-markers.patch
new file mode 100644
index 0000000..b98ec74
--- /dev/null
+++ b/mfbt/double-conversion/add-mfbt-api-markers.patch
@@ -0,0 +1,94 @@
+diff --git a/mfbt/double-conversion/double-conversion.h b/mfbt/double-conversion/double-conversion.h
+index f98edae..e536a01 100644
+--- a/mfbt/double-conversion/double-conversion.h
++++ b/mfbt/double-conversion/double-conversion.h
+@@ -28,6 +28,7 @@
+ #ifndef DOUBLE_CONVERSION_DOUBLE_CONVERSION_H_
+ #define DOUBLE_CONVERSION_DOUBLE_CONVERSION_H_
+ 
++#include "mozilla/Types.h"
+ #include "utils.h"
+ 
+ namespace double_conversion {
+@@ -129,7 +130,7 @@ class DoubleToStringConverter {
+   }
+ 
+   // Returns a converter following the EcmaScript specification.
+-  static const DoubleToStringConverter& EcmaScriptConverter();
++  static MFBT_API(const DoubleToStringConverter&) EcmaScriptConverter();
+ 
+   // Computes the shortest string of digits that correctly represent the input
+   // number. Depending on decimal_in_shortest_low and decimal_in_shortest_high
+@@ -197,7 +198,7 @@ class DoubleToStringConverter {
+   // The last two conditions imply that the result will never contain more than
+   // 1 + kMaxFixedDigitsBeforePoint + 1 + kMaxFixedDigitsAfterPoint characters
+   // (one additional character for the sign, and one for the decimal point).
+-  bool ToFixed(double value,
++  MFBT_API(bool) ToFixed(double value,
+                int requested_digits,
+                StringBuilder* result_builder) const;
+ 
+@@ -229,7 +230,7 @@ class DoubleToStringConverter {
+   // kMaxExponentialDigits + 8 characters (the sign, the digit before the
+   // decimal point, the decimal point, the exponent character, the
+   // exponent's sign, and at most 3 exponent digits).
+-  bool ToExponential(double value,
++  MFBT_API(bool) ToExponential(double value,
+                      int requested_digits,
+                      StringBuilder* result_builder) const;
+ 
+@@ -267,7 +268,7 @@ class DoubleToStringConverter {
+   // The last condition implies that the result will never contain more than
+   // kMaxPrecisionDigits + 7 characters (the sign, the decimal point, the
+   // exponent character, the exponent's sign, and at most 3 exponent digits).
+-  bool ToPrecision(double value,
++  MFBT_API(bool) ToPrecision(double value,
+                    int precision,
+                    StringBuilder* result_builder) const;
+ 
+@@ -292,7 +293,7 @@ class DoubleToStringConverter {
+   // kBase10MaximalLength.
+   // Note that DoubleToAscii null-terminates its input. So the given buffer
+   // should be at least kBase10MaximalLength + 1 characters long.
+-  static const int kBase10MaximalLength = 17;
++  static const MFBT_DATA(int) kBase10MaximalLength = 17;
+ 
+   // Converts the given double 'v' to ascii. 'v' must not be NaN, +Infinity, or
+   // -Infinity. In SHORTEST_SINGLE-mode this restriction also applies to 'v'
+@@ -332,7 +333,7 @@ class DoubleToStringConverter {
+   // terminating null-character when computing the maximal output size.
+   // The given length is only used in debug mode to ensure the buffer is big
+   // enough.
+-  static void DoubleToAscii(double v,
++  static MFBT_API(void) DoubleToAscii(double v,
+                             DtoaMode mode,
+                             int requested_digits,
+                             char* buffer,
+@@ -343,7 +344,7 @@ class DoubleToStringConverter {
+ 
+  private:
+   // Implementation for ToShortest and ToShortestSingle.
+-  bool ToShortestIeeeNumber(double value,
++  MFBT_API(bool) ToShortestIeeeNumber(double value,
+                             StringBuilder* result_builder,
+                             DtoaMode mode) const;
+ 
+@@ -351,15 +352,15 @@ class DoubleToStringConverter {
+   // corresponding string using the configured infinity/nan-symbol.
+   // If either of them is NULL or the value is not special then the
+   // function returns false.
+-  bool HandleSpecialValues(double value, StringBuilder* result_builder) const;
++  MFBT_API(bool) HandleSpecialValues(double value, StringBuilder* result_builder) const;
+   // Constructs an exponential representation (i.e. 1.234e56).
+   // The given exponent assumes a decimal point after the first decimal digit.
+-  void CreateExponentialRepresentation(const char* decimal_digits,
++  MFBT_API(void) CreateExponentialRepresentation(const char* decimal_digits,
+                                        int length,
+                                        int exponent,
+                                        StringBuilder* result_builder) const;
+   // Creates a decimal representation (i.e 1234.5678).
+-  void CreateDecimalRepresentation(const char* decimal_digits,
++  MFBT_API(void) CreateDecimalRepresentation(const char* decimal_digits,
+                                    int length,
+                                    int decimal_point,
+                                    int digits_after_point,
diff --git a/mfbt/double-conversion/bignum-dtoa.cc b/mfbt/double-conversion/bignum-dtoa.cc
new file mode 100644
index 0000000..b6c2e85
--- /dev/null
+++ b/mfbt/double-conversion/bignum-dtoa.cc
@@ -0,0 +1,640 @@
+// Copyright 2010 the V8 project authors. All rights reserved.
+// Redistribution and use in source and binary forms, with or without
+// modification, are permitted provided that the following conditions are
+// met:
+//
+//     * Redistributions of source code must retain the above copyright
+//       notice, this list of conditions and the following disclaimer.
+//     * Redistributions in binary form must reproduce the above
+//       copyright notice, this list of conditions and the following
+//       disclaimer in the documentation and/or other materials provided
+//       with the distribution.
+//     * Neither the name of Google Inc. nor the names of its
+//       contributors may be used to endorse or promote products derived
+//       from this software without specific prior written permission.
+//
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+#include <math.h>
+
+#include "bignum-dtoa.h"
+
+#include "bignum.h"
+#include "ieee.h"
+
+namespace double_conversion {
+
+static int NormalizedExponent(uint64_t significand, int exponent) {
+  ASSERT(significand != 0);
+  while ((significand & Double::kHiddenBit) == 0) {
+    significand = significand << 1;
+    exponent = exponent - 1;
+  }
+  return exponent;
+}
+
+
+// Forward declarations:
+// Returns an estimation of k such that 10^(k-1) <= v < 10^k.
+static int EstimatePower(int exponent);
+// Computes v / 10^estimated_power exactly, as a ratio of two bignums, numerator
+// and denominator.
+static void InitialScaledStartValues(uint64_t significand,
+                                     int exponent,
+                                     bool lower_boundary_is_closer,
+                                     int estimated_power,
+                                     bool need_boundary_deltas,
+                                     Bignum* numerator,
+                                     Bignum* denominator,
+                                     Bignum* delta_minus,
+                                     Bignum* delta_plus);
+// Multiplies numerator/denominator so that its values lies in the range 1-10.
+// Returns decimal_point s.t.
+//  v = numerator'/denominator' * 10^(decimal_point-1)
+//     where numerator' and denominator' are the values of numerator and
+//     denominator after the call to this function.
+static void FixupMultiply10(int estimated_power, bool is_even,
+                            int* decimal_point,
+                            Bignum* numerator, Bignum* denominator,
+                            Bignum* delta_minus, Bignum* delta_plus);
+// Generates digits from the left to the right and stops when the generated
+// digits yield the shortest decimal representation of v.
+static void GenerateShortestDigits(Bignum* numerator, Bignum* denominator,
+                                   Bignum* delta_minus, Bignum* delta_plus,
+                                   bool is_even,
+                                   Vector<char> buffer, int* length);
+// Generates 'requested_digits' after the decimal point.
+static void BignumToFixed(int requested_digits, int* decimal_point,
+                          Bignum* numerator, Bignum* denominator,
+                          Vector<char>(buffer), int* length);
+// Generates 'count' digits of numerator/denominator.
+// Once 'count' digits have been produced rounds the result depending on the
+// remainder (remainders of exactly .5 round upwards). Might update the
+// decimal_point when rounding up (for example for 0.9999).
+static void GenerateCountedDigits(int count, int* decimal_point,
+                                  Bignum* numerator, Bignum* denominator,
+                                  Vector<char>(buffer), int* length);
+
+
+void BignumDtoa(double v, BignumDtoaMode mode, int requested_digits,
+                Vector<char> buffer, int* length, int* decimal_point) {
+  ASSERT(v > 0);
+  ASSERT(!Double(v).IsSpecial());
+  uint64_t significand;
+  int exponent;
+  bool lower_boundary_is_closer;
+  if (mode == BIGNUM_DTOA_SHORTEST_SINGLE) {
+    float f = static_cast<float>(v);
+    ASSERT(f == v);
+    significand = Single(f).Significand();
+    exponent = Single(f).Exponent();
+    lower_boundary_is_closer = Single(f).LowerBoundaryIsCloser();
+  } else {
+    significand = Double(v).Significand();
+    exponent = Double(v).Exponent();
+    lower_boundary_is_closer = Double(v).LowerBoundaryIsCloser();
+  }
+  bool need_boundary_deltas =
+      (mode == BIGNUM_DTOA_SHORTEST || mode == BIGNUM_DTOA_SHORTEST_SINGLE);
+
+  bool is_even = (significand & 1) == 0;
+  int normalized_exponent = NormalizedExponent(significand, exponent);
+  // estimated_power might be too low by 1.
+  int estimated_power = EstimatePower(normalized_exponent);
+
+  // Shortcut for Fixed.
+  // The requested digits correspond to the digits after the point. If the
+  // number is much too small, then there is no need in trying to get any
+  // digits.
+  if (mode == BIGNUM_DTOA_FIXED && -estimated_power - 1 > requested_digits) {
+    buffer[0] = '\0';
+    *length = 0;
+    // Set decimal-point to -requested_digits. This is what Gay does.
+    // Note that it should not have any effect anyways since the string is
+    // empty.
+    *decimal_point = -requested_digits;
+    return;
+  }
+
+  Bignum numerator;
+  Bignum denominator;
+  Bignum delta_minus;
+  Bignum delta_plus;
+  // Make sure the bignum can grow large enough. The smallest double equals
+  // 4e-324. In this case the denominator needs fewer than 324*4 binary digits.
+  // The maximum double is 1.7976931348623157e308 which needs fewer than
+  // 308*4 binary digits.
+  ASSERT(Bignum::kMaxSignificantBits >= 324*4);
+  InitialScaledStartValues(significand, exponent, lower_boundary_is_closer,
+                           estimated_power, need_boundary_deltas,
+                           &numerator, &denominator,
+                           &delta_minus, &delta_plus);
+  // We now have v = (numerator / denominator) * 10^estimated_power.
+  FixupMultiply10(estimated_power, is_even, decimal_point,
+                  &numerator, &denominator,
+                  &delta_minus, &delta_plus);
+  // We now have v = (numerator / denominator) * 10^(decimal_point-1), and
+  //  1 <= (numerator + delta_plus) / denominator < 10
+  switch (mode) {
+    case BIGNUM_DTOA_SHORTEST:
+    case BIGNUM_DTOA_SHORTEST_SINGLE:
+      GenerateShortestDigits(&numerator, &denominator,
+                             &delta_minus, &delta_plus,
+                             is_even, buffer, length);
+      break;
+    case BIGNUM_DTOA_FIXED:
+      BignumToFixed(requested_digits, decimal_point,
+                    &numerator, &denominator,
+                    buffer, length);
+      break;
+    case BIGNUM_DTOA_PRECISION:
+      GenerateCountedDigits(requested_digits, decimal_point,
+                            &numerator, &denominator,
+                            buffer, length);
+      break;
+    default:
+      UNREACHABLE();
+  }
+  buffer[*length] = '\0';
+}
+
+
+// The procedure starts generating digits from the left to the right and stops
+// when the generated digits yield the shortest decimal representation of v. A
+// decimal representation of v is a number lying closer to v than to any other
+// double, so it converts to v when read.
+//
+// This is true if d, the decimal representation, is between m- and m+, the
+// upper and lower boundaries. d must be strictly between them if !is_even.
+//           m- := (numerator - delta_minus) / denominator
+//           m+ := (numerator + delta_plus) / denominator
+//
+// Precondition: 0 <= (numerator+delta_plus) / denominator < 10.
+//   If 1 <= (numerator+delta_plus) / denominator < 10 then no leading 0 digit
+//   will be produced. This should be the standard precondition.
+static void GenerateShortestDigits(Bignum* numerator, Bignum* denominator,
+                                   Bignum* delta_minus, Bignum* delta_plus,
+                                   bool is_even,
+                                   Vector<char> buffer, int* length) {
+  // Small optimization: if delta_minus and delta_plus are the same just reuse
+  // one of the two bignums.
+  if (Bignum::Equal(*delta_minus, *delta_plus)) {
+    delta_plus = delta_minus;
+  }
+  *length = 0;
+  while (true) {
+    uint16_t digit;
+    digit = numerator->DivideModuloIntBignum(*denominator);
+    ASSERT(digit <= 9);  // digit is a uint16_t and therefore always positive.
+    // digit = numerator / denominator (integer division).
+    // numerator = numerator % denominator.
+    buffer[(*length)++] = digit + '0';
+
+    // Can we stop already?
+    // If the remainder of the division is less than the distance to the lower
+    // boundary we can stop. In this case we simply round down (discarding the
+    // remainder).
+    // Similarly we test if we can round up (using the upper boundary).
+    bool in_delta_room_minus;
+    bool in_delta_room_plus;
+    if (is_even) {
+      in_delta_room_minus = Bignum::LessEqual(*numerator, *delta_minus);
+    } else {
+      in_delta_room_minus = Bignum::Less(*numerator, *delta_minus);
+    }
+    if (is_even) {
+      in_delta_room_plus =
+          Bignum::PlusCompare(*numerator, *delta_plus, *denominator) >= 0;
+    } else {
+      in_delta_room_plus =
+          Bignum::PlusCompare(*numerator, *delta_plus, *denominator) > 0;
+    }
+    if (!in_delta_room_minus && !in_delta_room_plus) {
+      // Prepare for next iteration.
+      numerator->Times10();
+      delta_minus->Times10();
+      // We optimized delta_plus to be equal to delta_minus (if they share the
+      // same value). So don't multiply delta_plus if they point to the same
+      // object.
+      if (delta_minus != delta_plus) {
+        delta_plus->Times10();
+      }
+    } else if (in_delta_room_minus && in_delta_room_plus) {
+      // Let's see if 2*numerator < denominator.
+      // If yes, then the next digit would be < 5 and we can round down.
+      int compare = Bignum::PlusCompare(*numerator, *numerator, *denominator);
+      if (compare < 0) {
+        // Remaining digits are less than .5. -> Round down (== do nothing).
+      } else if (compare > 0) {
+        // Remaining digits are more than .5 of denominator. -> Round up.
+        // Note that the last digit could not be a '9' as otherwise the whole
+        // loop would have stopped earlier.
+        // We still have an assert here in case the preconditions were not
+        // satisfied.
+        ASSERT(buffer[(*length) - 1] != '9');
+        buffer[(*length) - 1]++;
+      } else {
+        // Halfway case.
+        // TODO(floitsch): need a way to solve half-way cases.
+        //   For now let's round towards even (since this is what Gay seems to
+        //   do).
+
+        if ((buffer[(*length) - 1] - '0') % 2 == 0) {
+          // Round down => Do nothing.
+        } else {
+          ASSERT(buffer[(*length) - 1] != '9');
+          buffer[(*length) - 1]++;
+        }
+      }
+      return;
+    } else if (in_delta_room_minus) {
+      // Round down (== do nothing).
+      return;
+    } else {  // in_delta_room_plus
+      // Round up.
+      // Note again that the last digit could not be '9' since this would have
+      // stopped the loop earlier.
+      // We still have an ASSERT here, in case the preconditions were not
+      // satisfied.
+      ASSERT(buffer[(*length) -1] != '9');
+      buffer[(*length) - 1]++;
+      return;
+    }
+  }
+}
+
+
+// Let v = numerator / denominator < 10.
+// Then we generate 'count' digits of d = x.xxxxx... (without the decimal point)
+// from left to right. Once 'count' digits have been produced we decide wether
+// to round up or down. Remainders of exactly .5 round upwards. Numbers such
+// as 9.999999 propagate a carry all the way, and change the
+// exponent (decimal_point), when rounding upwards.
+static void GenerateCountedDigits(int count, int* decimal_point,
+                                  Bignum* numerator, Bignum* denominator,
+                                  Vector<char>(buffer), int* length) {
+  ASSERT(count >= 0);
+  for (int i = 0; i < count - 1; ++i) {
+    uint16_t digit;
+    digit = numerator->DivideModuloIntBignum(*denominator);
+    ASSERT(digit <= 9);  // digit is a uint16_t and therefore always positive.
+    // digit = numerator / denominator (integer division).
+    // numerator = numerator % denominator.
+    buffer[i] = digit + '0';
+    // Prepare for next iteration.
+    numerator->Times10();
+  }
+  // Generate the last digit.
+  uint16_t digit;
+  digit = numerator->DivideModuloIntBignum(*denominator);
+  if (Bignum::PlusCompare(*numerator, *numerator, *denominator) >= 0) {
+    digit++;
+  }
+  buffer[count - 1] = digit + '0';
+  // Correct bad digits (in case we had a sequence of '9's). Propagate the
+  // carry until we hat a non-'9' or til we reach the first digit.
+  for (int i = count - 1; i > 0; --i) {
+    if (buffer[i] != '0' + 10) break;
+    buffer[i] = '0';
+    buffer[i - 1]++;
+  }
+  if (buffer[0] == '0' + 10) {
+    // Propagate a carry past the top place.
+    buffer[0] = '1';
+    (*decimal_point)++;
+  }
+  *length = count;
+}
+
+
+// Generates 'requested_digits' after the decimal point. It might omit
+// trailing '0's. If the input number is too small then no digits at all are
+// generated (ex.: 2 fixed digits for 0.00001).
+//
+// Input verifies:  1 <= (numerator + delta) / denominator < 10.
+static void BignumToFixed(int requested_digits, int* decimal_point,
+                          Bignum* numerator, Bignum* denominator,
+                          Vector<char>(buffer), int* length) {
+  // Note that we have to look at more than just the requested_digits, since
+  // a number could be rounded up. Example: v=0.5 with requested_digits=0.
+  // Even though the power of v equals 0 we can't just stop here.
+  if (-(*decimal_point) > requested_digits) {
+    // The number is definitively too small.
+    // Ex: 0.001 with requested_digits == 1.
+    // Set decimal-point to -requested_digits. This is what Gay does.
+    // Note that it should not have any effect anyways since the string is
+    // empty.
+    *decimal_point = -requested_digits;
+    *length = 0;
+    return;
+  } else if (-(*decimal_point) == requested_digits) {
+    // We only need to verify if the number rounds down or up.
+    // Ex: 0.04 and 0.06 with requested_digits == 1.
+    ASSERT(*decimal_point == -requested_digits);
+    // Initially the fraction lies in range (1, 10]. Multiply the denominator
+    // by 10 so that we can compare more easily.
+    denominator->Times10();
+    if (Bignum::PlusCompare(*numerator, *numerator, *denominator) >= 0) {
+      // If the fraction is >= 0.5 then we have to include the rounded
+      // digit.
+      buffer[0] = '1';
+      *length = 1;
+      (*decimal_point)++;
+    } else {
+      // Note that we caught most of similar cases earlier.
+      *length = 0;
+    }
+    return;
+  } else {
+    // The requested digits correspond to the digits after the point.
+    // The variable 'needed_digits' includes the digits before the point.
+    int needed_digits = (*decimal_point) + requested_digits;
+    GenerateCountedDigits(needed_digits, decimal_point,
+                          numerator, denominator,
+                          buffer, length);
+  }
+}
+
+
+// Returns an estimation of k such that 10^(k-1) <= v < 10^k where
+// v = f * 2^exponent and 2^52 <= f < 2^53.
+// v is hence a normalized double with the given exponent. The output is an
+// approximation for the exponent of the decimal approimation .digits * 10^k.
+//
+// The result might undershoot by 1 in which case 10^k <= v < 10^k+1.
+// Note: this property holds for v's upper boundary m+ too.
+//    10^k <= m+ < 10^k+1.
+//   (see explanation below).
+//
+// Examples:
+//  EstimatePower(0)   => 16
+//  EstimatePower(-52) => 0
+//
+// Note: e >= 0 => EstimatedPower(e) > 0. No similar claim can be made for e<0.
+static int EstimatePower(int exponent) {
+  // This function estimates log10 of v where v = f*2^e (with e == exponent).
+  // Note that 10^floor(log10(v)) <= v, but v <= 10^ceil(log10(v)).
+  // Note that f is bounded by its container size. Let p = 53 (the double's
+  // significand size). Then 2^(p-1) <= f < 2^p.
+  //
+  // Given that log10(v) == log2(v)/log2(10) and e+(len(f)-1) is quite close
+  // to log2(v) the function is simplified to (e+(len(f)-1)/log2(10)).
+  // The computed number undershoots by less than 0.631 (when we compute log3
+  // and not log10).
+  //
+  // Optimization: since we only need an approximated result this computation
+  // can be performed on 64 bit integers. On x86/x64 architecture the speedup is
+  // not really measurable, though.
+  //
+  // Since we want to avoid overshooting we decrement by 1e10 so that
+  // floating-point imprecisions don't affect us.
+  //
+  // Explanation for v's boundary m+: the computation takes advantage of
+  // the fact that 2^(p-1) <= f < 2^p. Boundaries still satisfy this requirement
+  // (even for denormals where the delta can be much more important).
+
+  const double k1Log10 = 0.30102999566398114;  // 1/lg(10)
+
+  // For doubles len(f) == 53 (don't forget the hidden bit).
+  const int kSignificandSize = Double::kSignificandSize;
+  double estimate = ceil((exponent + kSignificandSize - 1) * k1Log10 - 1e-10);
+  return static_cast<int>(estimate);
+}
+
+
+// See comments for InitialScaledStartValues.
+static void InitialScaledStartValuesPositiveExponent(
+    uint64_t significand, int exponent,
+    int estimated_power, bool need_boundary_deltas,
+    Bignum* numerator, Bignum* denominator,
+    Bignum* delta_minus, Bignum* delta_plus) {
+  // A positive exponent implies a positive power.
+  ASSERT(estimated_power >= 0);
+  // Since the estimated_power is positive we simply multiply the denominator
+  // by 10^estimated_power.
+
+  // numerator = v.
+  numerator->AssignUInt64(significand);
+  numerator->ShiftLeft(exponent);
+  // denominator = 10^estimated_power.
+  denominator->AssignPowerUInt16(10, estimated_power);
+
+  if (need_boundary_deltas) {
+    // Introduce a common denominator so that the deltas to the boundaries are
+    // integers.
+    denominator->ShiftLeft(1);
+    numerator->ShiftLeft(1);
+    // Let v = f * 2^e, then m+ - v = 1/2 * 2^e; With the common
+    // denominator (of 2) delta_plus equals 2^e.
+    delta_plus->AssignUInt16(1);
+    delta_plus->ShiftLeft(exponent);
+    // Same for delta_minus. The adjustments if f == 2^p-1 are done later.
+    delta_minus->AssignUInt16(1);
+    delta_minus->ShiftLeft(exponent);
+  }
+}
+
+
+// See comments for InitialScaledStartValues
+static void InitialScaledStartValuesNegativeExponentPositivePower(
+    uint64_t significand, int exponent,
+    int estimated_power, bool need_boundary_deltas,
+    Bignum* numerator, Bignum* denominator,
+    Bignum* delta_minus, Bignum* delta_plus) {
+  // v = f * 2^e with e < 0, and with estimated_power >= 0.
+  // This means that e is close to 0 (have a look at how estimated_power is
+  // computed).
+
+  // numerator = significand
+  //  since v = significand * 2^exponent this is equivalent to
+  //  numerator = v * / 2^-exponent
+  numerator->AssignUInt64(significand);
+  // denominator = 10^estimated_power * 2^-exponent (with exponent < 0)
+  denominator->AssignPowerUInt16(10, estimated_power);
+  denominator->ShiftLeft(-exponent);
+
+  if (need_boundary_deltas) {
+    // Introduce a common denominator so that the deltas to the boundaries are
+    // integers.
+    denominator->ShiftLeft(1);
+    numerator->ShiftLeft(1);
+    // Let v = f * 2^e, then m+ - v = 1/2 * 2^e; With the common
+    // denominator (of 2) delta_plus equals 2^e.
+    // Given that the denominator already includes v's exponent the distance
+    // to the boundaries is simply 1.
+    delta_plus->AssignUInt16(1);
+    // Same for delta_minus. The adjustments if f == 2^p-1 are done later.
+    delta_minus->AssignUInt16(1);
+  }
+}
+
+
+// See comments for InitialScaledStartValues
+static void InitialScaledStartValuesNegativeExponentNegativePower(
+    uint64_t significand, int exponent,
+    int estimated_power, bool need_boundary_deltas,
+    Bignum* numerator, Bignum* denominator,
+    Bignum* delta_minus, Bignum* delta_plus) {
+  // Instead of multiplying the denominator with 10^estimated_power we
+  // multiply all values (numerator and deltas) by 10^-estimated_power.
+
+  // Use numerator as temporary container for power_ten.
+  Bignum* power_ten = numerator;
+  power_ten->AssignPowerUInt16(10, -estimated_power);
+
+  if (need_boundary_deltas) {
+    // Since power_ten == numerator we must make a copy of 10^estimated_power
+    // before we complete the computation of the numerator.
+    // delta_plus = delta_minus = 10^estimated_power
+    delta_plus->AssignBignum(*power_ten);
+    delta_minus->AssignBignum(*power_ten);
+  }
+
+  // numerator = significand * 2 * 10^-estimated_power
+  //  since v = significand * 2^exponent this is equivalent to
+  // numerator = v * 10^-estimated_power * 2 * 2^-exponent.
+  // Remember: numerator has been abused as power_ten. So no need to assign it
+  //  to itself.
+  ASSERT(numerator == power_ten);
+  numerator->MultiplyByUInt64(significand);
+
+  // denominator = 2 * 2^-exponent with exponent < 0.
+  denominator->AssignUInt16(1);
+  denominator->ShiftLeft(-exponent);
+
+  if (need_boundary_deltas) {
+    // Introduce a common denominator so that the deltas to the boundaries are
+    // integers.
+    numerator->ShiftLeft(1);
+    denominator->ShiftLeft(1);
+    // With this shift the boundaries have their correct value, since
+    // delta_plus = 10^-estimated_power, and
+    // delta_minus = 10^-estimated_power.
+    // These assignments have been done earlier.
+    // The adjustments if f == 2^p-1 (lower boundary is closer) are done later.
+  }
+}
+
+
+// Let v = significand * 2^exponent.
+// Computes v / 10^estimated_power exactly, as a ratio of two bignums, numerator
+// and denominator. The functions GenerateShortestDigits and
+// GenerateCountedDigits will then convert this ratio to its decimal
+// representation d, with the required accuracy.
+// Then d * 10^estimated_power is the representation of v.
+// (Note: the fraction and the estimated_power might get adjusted before
+// generating the decimal representation.)
+//
+// The initial start values consist of:
+//  - a scaled numerator: s.t. numerator/denominator == v / 10^estimated_power.
+//  - a scaled (common) denominator.
+//  optionally (used by GenerateShortestDigits to decide if it has the shortest
+//  decimal converting back to v):
+//  - v - m-: the distance to the lower boundary.
+//  - m+ - v: the distance to the upper boundary.
+//
+// v, m+, m-, and therefore v - m- and m+ - v all share the same denominator.
+//
+// Let ep == estimated_power, then the returned values will satisfy:
+//  v / 10^ep = numerator / denominator.
+//  v's boundarys m- and m+:
+//    m- / 10^ep == v / 10^ep - delta_minus / denominator
+//    m+ / 10^ep == v / 10^ep + delta_plus / denominator
+//  Or in other words:
+//    m- == v - delta_minus * 10^ep / denominator;
+//    m+ == v + delta_plus * 10^ep / denominator;
+//
+// Since 10^(k-1) <= v < 10^k    (with k == estimated_power)
+//  or       10^k <= v < 10^(k+1)
+//  we then have 0.1 <= numerator/denominator < 1
+//           or    1 <= numerator/denominator < 10
+//
+// It is then easy to kickstart the digit-generation routine.
+//
+// The boundary-deltas are only filled if the mode equals BIGNUM_DTOA_SHORTEST
+// or BIGNUM_DTOA_SHORTEST_SINGLE.
+
+static void InitialScaledStartValues(uint64_t significand,
+                                     int exponent,
+                                     bool lower_boundary_is_closer,
+                                     int estimated_power,
+                                     bool need_boundary_deltas,
+                                     Bignum* numerator,
+                                     Bignum* denominator,
+                                     Bignum* delta_minus,
+                                     Bignum* delta_plus) {
+  if (exponent >= 0) {
+    InitialScaledStartValuesPositiveExponent(
+        significand, exponent, estimated_power, need_boundary_deltas,
+        numerator, denominator, delta_minus, delta_plus);
+  } else if (estimated_power >= 0) {
+    InitialScaledStartValuesNegativeExponentPositivePower(
+        significand, exponent, estimated_power, need_boundary_deltas,
+        numerator, denominator, delta_minus, delta_plus);
+  } else {
+    InitialScaledStartValuesNegativeExponentNegativePower(
+        significand, exponent, estimated_power, need_boundary_deltas,
+        numerator, denominator, delta_minus, delta_plus);
+  }
+
+  if (need_boundary_deltas && lower_boundary_is_closer) {
+    // The lower boundary is closer at half the distance of "normal" numbers.
+    // Increase the common denominator and adapt all but the delta_minus.
+    denominator->ShiftLeft(1);  // *2
+    numerator->ShiftLeft(1);    // *2
+    delta_plus->ShiftLeft(1);   // *2
+  }
+}
+
+
+// This routine multiplies numerator/denominator so that its values lies in the
+// range 1-10. That is after a call to this function we have:
+//    1 <= (numerator + delta_plus) /denominator < 10.
+// Let numerator the input before modification and numerator' the argument
+// after modification, then the output-parameter decimal_point is such that
+//  numerator / denominator * 10^estimated_power ==
+//    numerator' / denominator' * 10^(decimal_point - 1)
+// In some cases estimated_power was too low, and this is already the case. We
+// then simply adjust the power so that 10^(k-1) <= v < 10^k (with k ==
+// estimated_power) but do not touch the numerator or denominator.
+// Otherwise the routine multiplies the numerator and the deltas by 10.
+static void FixupMultiply10(int estimated_power, bool is_even,
+                            int* decimal_point,
+                            Bignum* numerator, Bignum* denominator,
+                            Bignum* delta_minus, Bignum* delta_plus) {
+  bool in_range;
+  if (is_even) {
+    // For IEEE doubles half-way cases (in decimal system numbers ending with 5)
+    // are rounded to the closest floating-point number with even significand.
+    in_range = Bignum::PlusCompare(*numerator, *delta_plus, *denominator) >= 0;
+  } else {
+    in_range = Bignum::PlusCompare(*numerator, *delta_plus, *denominator) > 0;
+  }
+  if (in_range) {
+    // Since numerator + delta_plus >= denominator we already have
+    // 1 <= numerator/denominator < 10. Simply update the estimated_power.
+    *decimal_point = estimated_power + 1;
+  } else {
+    *decimal_point = estimated_power;
+    numerator->Times10();
+    if (Bignum::Equal(*delta_minus, *delta_plus)) {
+      delta_minus->Times10();
+      delta_plus->AssignBignum(*delta_minus);
+    } else {
+      delta_minus->Times10();
+      delta_plus->Times10();
+    }
+  }
+}
+
+}  // namespace double_conversion
diff --git a/mfbt/double-conversion/bignum-dtoa.h b/mfbt/double-conversion/bignum-dtoa.h
new file mode 100644
index 0000000..34b9619
--- /dev/null
+++ b/mfbt/double-conversion/bignum-dtoa.h
@@ -0,0 +1,84 @@
+// Copyright 2010 the V8 project authors. All rights reserved.
+// Redistribution and use in source and binary forms, with or without
+// modification, are permitted provided that the following conditions are
+// met:
+//
+//     * Redistributions of source code must retain the above copyright
+//       notice, this list of conditions and the following disclaimer.
+//     * Redistributions in binary form must reproduce the above
+//       copyright notice, this list of conditions and the following
+//       disclaimer in the documentation and/or other materials provided
+//       with the distribution.
+//     * Neither the name of Google Inc. nor the names of its
+//       contributors may be used to endorse or promote products derived
+//       from this software without specific prior written permission.
+//
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+#ifndef DOUBLE_CONVERSION_BIGNUM_DTOA_H_
+#define DOUBLE_CONVERSION_BIGNUM_DTOA_H_
+
+#include "utils.h"
+
+namespace double_conversion {
+
+enum BignumDtoaMode {
+  // Return the shortest correct representation.
+  // For example the output of 0.299999999999999988897 is (the less accurate but
+  // correct) 0.3.
+  BIGNUM_DTOA_SHORTEST,
+  // Same as BIGNUM_DTOA_SHORTEST but for single-precision floats.
+  BIGNUM_DTOA_SHORTEST_SINGLE,
+  // Return a fixed number of digits after the decimal point.
+  // For instance fixed(0.1, 4) becomes 0.1000
+  // If the input number is big, the output will be big.
+  BIGNUM_DTOA_FIXED,
+  // Return a fixed number of digits, no matter what the exponent is.
+  BIGNUM_DTOA_PRECISION
+};
+
+// Converts the given double 'v' to ascii.
+// The result should be interpreted as buffer * 10^(point-length).
+// The buffer will be null-terminated.
+//
+// The input v must be > 0 and different from NaN, and Infinity.
+//
+// The output depends on the given mode:
+//  - SHORTEST: produce the least amount of digits for which the internal
+//   identity requirement is still satisfied. If the digits are printed
+//   (together with the correct exponent) then reading this number will give
+//   'v' again. The buffer will choose the representation that is closest to
+//   'v'. If there are two at the same distance, than the number is round up.
+//   In this mode the 'requested_digits' parameter is ignored.
+//  - FIXED: produces digits necessary to print a given number with
+//   'requested_digits' digits after the decimal point. The produced digits
+//   might be too short in which case the caller has to fill the gaps with '0's.
+//   Example: toFixed(0.001, 5) is allowed to return buffer="1", point=-2.
+//   Halfway cases are rounded up. The call toFixed(0.15, 2) thus returns
+//     buffer="2", point=0.
+//   Note: the length of the returned buffer has no meaning wrt the significance
+//   of its digits. That is, just because it contains '0's does not mean that
+//   any other digit would not satisfy the internal identity requirement.
+//  - PRECISION: produces 'requested_digits' where the first digit is not '0'.
+//   Even though the length of produced digits usually equals
+//   'requested_digits', the function is allowed to return fewer digits, in
+//   which case the caller has to fill the missing digits with '0's.
+//   Halfway cases are again rounded up.
+// 'BignumDtoa' expects the given buffer to be big enough to hold all digits
+// and a terminating null-character.
+void BignumDtoa(double v, BignumDtoaMode mode, int requested_digits,
+                Vector<char> buffer, int* length, int* point);
+
+}  // namespace double_conversion
+
+#endif  // DOUBLE_CONVERSION_BIGNUM_DTOA_H_
diff --git a/mfbt/double-conversion/bignum.cc b/mfbt/double-conversion/bignum.cc
new file mode 100644
index 0000000..747491a
--- /dev/null
+++ b/mfbt/double-conversion/bignum.cc
@@ -0,0 +1,764 @@
+// Copyright 2010 the V8 project authors. All rights reserved.
+// Redistribution and use in source and binary forms, with or without
+// modification, are permitted provided that the following conditions are
+// met:
+//
+//     * Redistributions of source code must retain the above copyright
+//       notice, this list of conditions and the following disclaimer.
+//     * Redistributions in binary form must reproduce the above
+//       copyright notice, this list of conditions and the following
+//       disclaimer in the documentation and/or other materials provided
+//       with the distribution.
+//     * Neither the name of Google Inc. nor the names of its
+//       contributors may be used to endorse or promote products derived
+//       from this software without specific prior written permission.
+//
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+#include "bignum.h"
+#include "utils.h"
+
+namespace double_conversion {
+
+Bignum::Bignum()
+    : bigits_(bigits_buffer_, kBigitCapacity), used_digits_(0), exponent_(0) {
+  for (int i = 0; i < kBigitCapacity; ++i) {
+    bigits_[i] = 0;
+  }
+}
+
+
+template<typename S>
+static int BitSize(S value) {
+  return 8 * sizeof(value);
+}
+
+// Guaranteed to lie in one Bigit.
+void Bignum::AssignUInt16(uint16_t value) {
+  ASSERT(kBigitSize >= BitSize(value));
+  Zero();
+  if (value == 0) return;
+
+  EnsureCapacity(1);
+  bigits_[0] = value;
+  used_digits_ = 1;
+}
+
+
+void Bignum::AssignUInt64(uint64_t value) {
+  const int kUInt64Size = 64;
+
+  Zero();
+  if (value == 0) return;
+
+  int needed_bigits = kUInt64Size / kBigitSize + 1;
+  EnsureCapacity(needed_bigits);
+  for (int i = 0; i < needed_bigits; ++i) {
+    bigits_[i] = value & kBigitMask;
+    value = value >> kBigitSize;
+  }
+  used_digits_ = needed_bigits;
+  Clamp();
+}
+
+
+void Bignum::AssignBignum(const Bignum& other) {
+  exponent_ = other.exponent_;
+  for (int i = 0; i < other.used_digits_; ++i) {
+    bigits_[i] = other.bigits_[i];
+  }
+  // Clear the excess digits (if there were any).
+  for (int i = other.used_digits_; i < used_digits_; ++i) {
+    bigits_[i] = 0;
+  }
+  used_digits_ = other.used_digits_;
+}
+
+
+static uint64_t ReadUInt64(Vector<const char> buffer,
+                           int from,
+                           int digits_to_read) {
+  uint64_t result = 0;
+  for (int i = from; i < from + digits_to_read; ++i) {
+    int digit = buffer[i] - '0';
+    ASSERT(0 <= digit && digit <= 9);
+    result = result * 10 + digit;
+  }
+  return result;
+}
+
+
+void Bignum::AssignDecimalString(Vector<const char> value) {
+  // 2^64 = 18446744073709551616 > 10^19
+  const int kMaxUint64DecimalDigits = 19;
+  Zero();
+  int length = value.length();
+  int pos = 0;
+  // Let's just say that each digit needs 4 bits.
+  while (length >= kMaxUint64DecimalDigits) {
+    uint64_t digits = ReadUInt64(value, pos, kMaxUint64DecimalDigits);
+    pos += kMaxUint64DecimalDigits;
+    length -= kMaxUint64DecimalDigits;
+    MultiplyByPowerOfTen(kMaxUint64DecimalDigits);
+    AddUInt64(digits);
+  }
+  uint64_t digits = ReadUInt64(value, pos, length);
+  MultiplyByPowerOfTen(length);
+  AddUInt64(digits);
+  Clamp();
+}
+
+
+static int HexCharValue(char c) {
+  if ('0' <= c && c <= '9') return c - '0';
+  if ('a' <= c && c <= 'f') return 10 + c - 'a';
+  if ('A' <= c && c <= 'F') return 10 + c - 'A';
+  UNREACHABLE();
+  return 0;  // To make compiler happy.
+}
+
+
+void Bignum::AssignHexString(Vector<const char> value) {
+  Zero();
+  int length = value.length();
+
+  int needed_bigits = length * 4 / kBigitSize + 1;
+  EnsureCapacity(needed_bigits);
+  int string_index = length - 1;
+  for (int i = 0; i < needed_bigits - 1; ++i) {
+    // These bigits are guaranteed to be "full".
+    Chunk current_bigit = 0;
+    for (int j = 0; j < kBigitSize / 4; j++) {
+      current_bigit += HexCharValue(value[string_index--]) << (j * 4);
+    }
+    bigits_[i] = current_bigit;
+  }
+  used_digits_ = needed_bigits - 1;
+
+  Chunk most_significant_bigit = 0;  // Could be = 0;
+  for (int j = 0; j <= string_index; ++j) {
+    most_significant_bigit <<= 4;
+    most_significant_bigit += HexCharValue(value[j]);
+  }
+  if (most_significant_bigit != 0) {
+    bigits_[used_digits_] = most_significant_bigit;
+    used_digits_++;
+  }
+  Clamp();
+}
+
+
+void Bignum::AddUInt64(uint64_t operand) {
+  if (operand == 0) return;
+  Bignum other;
+  other.AssignUInt64(operand);
+  AddBignum(other);
+}
+
+
+void Bignum::AddBignum(const Bignum& other) {
+  ASSERT(IsClamped());
+  ASSERT(other.IsClamped());
+
+  // If this has a greater exponent than other append zero-bigits to this.
+  // After this call exponent_ <= other.exponent_.
+  Align(other);
+
+  // There are two possibilities:
+  //   aaaaaaaaaaa 0000  (where the 0s represent a's exponent)
+  //     bbbbb 00000000
+  //   ----------------
+  //   ccccccccccc 0000
+  // or
+  //    aaaaaaaaaa 0000
+  //  bbbbbbbbb 0000000
+  //  -----------------
+  //  cccccccccccc 0000
+  // In both cases we might need a carry bigit.
+
+  EnsureCapacity(1 + Max(BigitLength(), other.BigitLength()) - exponent_);
+  Chunk carry = 0;
+  int bigit_pos = other.exponent_ - exponent_;
+  ASSERT(bigit_pos >= 0);
+  for (int i = 0; i < other.used_digits_; ++i) {
+    Chunk sum = bigits_[bigit_pos] + other.bigits_[i] + carry;
+    bigits_[bigit_pos] = sum & kBigitMask;
+    carry = sum >> kBigitSize;
+    bigit_pos++;
+  }
+
+  while (carry != 0) {
+    Chunk sum = bigits_[bigit_pos] + carry;
+    bigits_[bigit_pos] = sum & kBigitMask;
+    carry = sum >> kBigitSize;
+    bigit_pos++;
+  }
+  used_digits_ = Max(bigit_pos, used_digits_);
+  ASSERT(IsClamped());
+}
+
+
+void Bignum::SubtractBignum(const Bignum& other) {
+  ASSERT(IsClamped());
+  ASSERT(other.IsClamped());
+  // We require this to be bigger than other.
+  ASSERT(LessEqual(other, *this));
+
+  Align(other);
+
+  int offset = other.exponent_ - exponent_;
+  Chunk borrow = 0;
+  int i;
+  for (i = 0; i < other.used_digits_; ++i) {
+    ASSERT((borrow == 0) || (borrow == 1));
+    Chunk difference = bigits_[i + offset] - other.bigits_[i] - borrow;
+    bigits_[i + offset] = difference & kBigitMask;
+    borrow = difference >> (kChunkSize - 1);
+  }
+  while (borrow != 0) {
+    Chunk difference = bigits_[i + offset] - borrow;
+    bigits_[i + offset] = difference & kBigitMask;
+    borrow = difference >> (kChunkSize - 1);
+    ++i;
+  }
+  Clamp();
+}
+
+
+void Bignum::ShiftLeft(int shift_amount) {
+  if (used_digits_ == 0) return;
+  exponent_ += shift_amount / kBigitSize;
+  int local_shift = shift_amount % kBigitSize;
+  EnsureCapacity(used_digits_ + 1);
+  BigitsShiftLeft(local_shift);
+}
+
+
+void Bignum::MultiplyByUInt32(uint32_t factor) {
+  if (factor == 1) return;
+  if (factor == 0) {
+    Zero();
+    return;
+  }
+  if (used_digits_ == 0) return;
+
+  // The product of a bigit with the factor is of size kBigitSize + 32.
+  // Assert that this number + 1 (for the carry) fits into double chunk.
+  ASSERT(kDoubleChunkSize >= kBigitSize + 32 + 1);
+  DoubleChunk carry = 0;
+  for (int i = 0; i < used_digits_; ++i) {
+    DoubleChunk product = static_cast<DoubleChunk>(factor) * bigits_[i] + carry;
+    bigits_[i] = static_cast<Chunk>(product & kBigitMask);
+    carry = (product >> kBigitSize);
+  }
+  while (carry != 0) {
+    EnsureCapacity(used_digits_ + 1);
+    bigits_[used_digits_] = carry & kBigitMask;
+    used_digits_++;
+    carry >>= kBigitSize;
+  }
+}
+
+
+void Bignum::MultiplyByUInt64(uint64_t factor) {
+  if (factor == 1) return;
+  if (factor == 0) {
+    Zero();
+    return;
+  }
+  ASSERT(kBigitSize < 32);
+  uint64_t carry = 0;
+  uint64_t low = factor & 0xFFFFFFFF;
+  uint64_t high = factor >> 32;
+  for (int i = 0; i < used_digits_; ++i) {
+    uint64_t product_low = low * bigits_[i];
+    uint64_t product_high = high * bigits_[i];
+    uint64_t tmp = (carry & kBigitMask) + product_low;
+    bigits_[i] = tmp & kBigitMask;
+    carry = (carry >> kBigitSize) + (tmp >> kBigitSize) +
+        (product_high << (32 - kBigitSize));
+  }
+  while (carry != 0) {
+    EnsureCapacity(used_digits_ + 1);
+    bigits_[used_digits_] = carry & kBigitMask;
+    used_digits_++;
+    carry >>= kBigitSize;
+  }
+}
+
+
+void Bignum::MultiplyByPowerOfTen(int exponent) {
+  const uint64_t kFive27 = UINT64_2PART_C(0x6765c793, fa10079d);
+  const uint16_t kFive1 = 5;
+  const uint16_t kFive2 = kFive1 * 5;
+  const uint16_t kFive3 = kFive2 * 5;
+  const uint16_t kFive4 = kFive3 * 5;
+  const uint16_t kFive5 = kFive4 * 5;
+  const uint16_t kFive6 = kFive5 * 5;
+  const uint32_t kFive7 = kFive6 * 5;
+  const uint32_t kFive8 = kFive7 * 5;
+  const uint32_t kFive9 = kFive8 * 5;
+  const uint32_t kFive10 = kFive9 * 5;
+  const uint32_t kFive11 = kFive10 * 5;
+  const uint32_t kFive12 = kFive11 * 5;
+  const uint32_t kFive13 = kFive12 * 5;
+  const uint32_t kFive1_to_12[] =
+      { kFive1, kFive2, kFive3, kFive4, kFive5, kFive6,
+        kFive7, kFive8, kFive9, kFive10, kFive11, kFive12 };
+
+  ASSERT(exponent >= 0);
+  if (exponent == 0) return;
+  if (used_digits_ == 0) return;
+
+  // We shift by exponent at the end just before returning.
+  int remaining_exponent = exponent;
+  while (remaining_exponent >= 27) {
+    MultiplyByUInt64(kFive27);
+    remaining_exponent -= 27;
+  }
+  while (remaining_exponent >= 13) {
+    MultiplyByUInt32(kFive13);
+    remaining_exponent -= 13;
+  }
+  if (remaining_exponent > 0) {
+    MultiplyByUInt32(kFive1_to_12[remaining_exponent - 1]);
+  }
+  ShiftLeft(exponent);
+}
+
+
+void Bignum::Square() {
+  ASSERT(IsClamped());
+  int product_length = 2 * used_digits_;
+  EnsureCapacity(product_length);
+
+  // Comba multiplication: compute each column separately.
+  // Example: r = a2a1a0 * b2b1b0.
+  //    r =  1    * a0b0 +
+  //        10    * (a1b0 + a0b1) +
+  //        100   * (a2b0 + a1b1 + a0b2) +
+  //        1000  * (a2b1 + a1b2) +
+  //        10000 * a2b2
+  //
+  // In the worst case we have to accumulate nb-digits products of digit*digit.
+  //
+  // Assert that the additional number of bits in a DoubleChunk are enough to
+  // sum up used_digits of Bigit*Bigit.
+  if ((1 << (2 * (kChunkSize - kBigitSize))) <= used_digits_) {
+    UNIMPLEMENTED();
+  }
+  DoubleChunk accumulator = 0;
+  // First shift the digits so we don't overwrite them.
+  int copy_offset = used_digits_;
+  for (int i = 0; i < used_digits_; ++i) {
+    bigits_[copy_offset + i] = bigits_[i];
+  }
+  // We have two loops to avoid some 'if's in the loop.
+  for (int i = 0; i < used_digits_; ++i) {
+    // Process temporary digit i with power i.
+    // The sum of the two indices must be equal to i.
+    int bigit_index1 = i;
+    int bigit_index2 = 0;
+    // Sum all of the sub-products.
+    while (bigit_index1 >= 0) {
+      Chunk chunk1 = bigits_[copy_offset + bigit_index1];
+      Chunk chunk2 = bigits_[copy_offset + bigit_index2];
+      accumulator += static_cast<DoubleChunk>(chunk1) * chunk2;
+      bigit_index1--;
+      bigit_index2++;
+    }
+    bigits_[i] = static_cast<Chunk>(accumulator) & kBigitMask;
+    accumulator >>= kBigitSize;
+  }
+  for (int i = used_digits_; i < product_length; ++i) {
+    int bigit_index1 = used_digits_ - 1;
+    int bigit_index2 = i - bigit_index1;
+    // Invariant: sum of both indices is again equal to i.
+    // Inner loop runs 0 times on last iteration, emptying accumulator.
+    while (bigit_index2 < used_digits_) {
+      Chunk chunk1 = bigits_[copy_offset + bigit_index1];
+      Chunk chunk2 = bigits_[copy_offset + bigit_index2];
+      accumulator += static_cast<DoubleChunk>(chunk1) * chunk2;
+      bigit_index1--;
+      bigit_index2++;
+    }
+    // The overwritten bigits_[i] will never be read in further loop iterations,
+    // because bigit_index1 and bigit_index2 are always greater
+    // than i - used_digits_.
+    bigits_[i] = static_cast<Chunk>(accumulator) & kBigitMask;
+    accumulator >>= kBigitSize;
+  }
+  // Since the result was guaranteed to lie inside the number the
+  // accumulator must be 0 now.
+  ASSERT(accumulator == 0);
+
+  // Don't forget to update the used_digits and the exponent.
+  used_digits_ = product_length;
+  exponent_ *= 2;
+  Clamp();
+}
+
+
+void Bignum::AssignPowerUInt16(uint16_t base, int power_exponent) {
+  ASSERT(base != 0);
+  ASSERT(power_exponent >= 0);
+  if (power_exponent == 0) {
+    AssignUInt16(1);
+    return;
+  }
+  Zero();
+  int shifts = 0;
+  // We expect base to be in range 2-32, and most often to be 10.
+  // It does not make much sense to implement different algorithms for counting
+  // the bits.
+  while ((base & 1) == 0) {
+    base >>= 1;
+    shifts++;
+  }
+  int bit_size = 0;
+  int tmp_base = base;
+  while (tmp_base != 0) {
+    tmp_base >>= 1;
+    bit_size++;
+  }
+  int final_size = bit_size * power_exponent;
+  // 1 extra bigit for the shifting, and one for rounded final_size.
+  EnsureCapacity(final_size / kBigitSize + 2);
+
+  // Left to Right exponentiation.
+  int mask = 1;
+  while (power_exponent >= mask) mask <<= 1;
+
+  // The mask is now pointing to the bit above the most significant 1-bit of
+  // power_exponent.
+  // Get rid of first 1-bit;
+  mask >>= 2;
+  uint64_t this_value = base;
+
+  bool delayed_multipliciation = false;
+  const uint64_t max_32bits = 0xFFFFFFFF;
+  while (mask != 0 && this_value <= max_32bits) {
+    this_value = this_value * this_value;
+    // Verify that there is enough space in this_value to perform the
+    // multiplication.  The first bit_size bits must be 0.
+    if ((power_exponent & mask) != 0) {
+      uint64_t base_bits_mask =
+          ~((static_cast<uint64_t>(1) << (64 - bit_size)) - 1);
+      bool high_bits_zero = (this_value & base_bits_mask) == 0;
+      if (high_bits_zero) {
+        this_value *= base;
+      } else {
+        delayed_multipliciation = true;
+      }
+    }
+    mask >>= 1;
+  }
+  AssignUInt64(this_value);
+  if (delayed_multipliciation) {
+    MultiplyByUInt32(base);
+  }
+
+  // Now do the same thing as a bignum.
+  while (mask != 0) {
+    Square();
+    if ((power_exponent & mask) != 0) {
+      MultiplyByUInt32(base);
+    }
+    mask >>= 1;
+  }
+
+  // And finally add the saved shifts.
+  ShiftLeft(shifts * power_exponent);
+}
+
+
+// Precondition: this/other < 16bit.
+uint16_t Bignum::DivideModuloIntBignum(const Bignum& other) {
+  ASSERT(IsClamped());
+  ASSERT(other.IsClamped());
+  ASSERT(other.used_digits_ > 0);
+
+  // Easy case: if we have less digits than the divisor than the result is 0.
+  // Note: this handles the case where this == 0, too.
+  if (BigitLength() < other.BigitLength()) {
+    return 0;
+  }
+
+  Align(other);
+
+  uint16_t result = 0;
+
+  // Start by removing multiples of 'other' until both numbers have the same
+  // number of digits.
+  while (BigitLength() > other.BigitLength()) {
+    // This naive approach is extremely inefficient if the this divided other
+    // might be big. This function is implemented for doubleToString where
+    // the result should be small (less than 10).
+    ASSERT(other.bigits_[other.used_digits_ - 1] >= ((1 << kBigitSize) / 16));
+    // Remove the multiples of the first digit.
+    // Example this = 23 and other equals 9. -> Remove 2 multiples.
+    result += bigits_[used_digits_ - 1];
+    SubtractTimes(other, bigits_[used_digits_ - 1]);
+  }
+
+  ASSERT(BigitLength() == other.BigitLength());
+
+  // Both bignums are at the same length now.
+  // Since other has more than 0 digits we know that the access to
+  // bigits_[used_digits_ - 1] is safe.
+  Chunk this_bigit = bigits_[used_digits_ - 1];
+  Chunk other_bigit = other.bigits_[other.used_digits_ - 1];
+
+  if (other.used_digits_ == 1) {
+    // Shortcut for easy (and common) case.
+    int quotient = this_bigit / other_bigit;
+    bigits_[used_digits_ - 1] = this_bigit - other_bigit * quotient;
+    result += quotient;
+    Clamp();
+    return result;
+  }
+
+  int division_estimate = this_bigit / (other_bigit + 1);
+  result += division_estimate;
+  SubtractTimes(other, division_estimate);
+
+  if (other_bigit * (division_estimate + 1) > this_bigit) {
+    // No need to even try to subtract. Even if other's remaining digits were 0
+    // another subtraction would be too much.
+    return result;
+  }
+
+  while (LessEqual(other, *this)) {
+    SubtractBignum(other);
+    result++;
+  }
+  return result;
+}
+
+
+template<typename S>
+static int SizeInHexChars(S number) {
+  ASSERT(number > 0);
+  int result = 0;
+  while (number != 0) {
+    number >>= 4;
+    result++;
+  }
+  return result;
+}
+
+
+static char HexCharOfValue(int value) {
+  ASSERT(0 <= value && value <= 16);
+  if (value < 10) return value + '0';
+  return value - 10 + 'A';
+}
+
+
+bool Bignum::ToHexString(char* buffer, int buffer_size) const {
+  ASSERT(IsClamped());
+  // Each bigit must be printable as separate hex-character.
+  ASSERT(kBigitSize % 4 == 0);
+  const int kHexCharsPerBigit = kBigitSize / 4;
+
+  if (used_digits_ == 0) {
+    if (buffer_size < 2) return false;
+    buffer[0] = '0';
+    buffer[1] = '\0';
+    return true;
+  }
+  // We add 1 for the terminating '\0' character.
+  int needed_chars = (BigitLength() - 1) * kHexCharsPerBigit +
+      SizeInHexChars(bigits_[used_digits_ - 1]) + 1;
+  if (needed_chars > buffer_size) return false;
+  int string_index = needed_chars - 1;
+  buffer[string_index--] = '\0';
+  for (int i = 0; i < exponent_; ++i) {
+    for (int j = 0; j < kHexCharsPerBigit; ++j) {
+      buffer[string_index--] = '0';
+    }
+  }
+  for (int i = 0; i < used_digits_ - 1; ++i) {
+    Chunk current_bigit = bigits_[i];
+    for (int j = 0; j < kHexCharsPerBigit; ++j) {
+      buffer[string_index--] = HexCharOfValue(current_bigit & 0xF);
+      current_bigit >>= 4;
+    }
+  }
+  // And finally the last bigit.
+  Chunk most_significant_bigit = bigits_[used_digits_ - 1];
+  while (most_significant_bigit != 0) {
+    buffer[string_index--] = HexCharOfValue(most_significant_bigit & 0xF);
+    most_significant_bigit >>= 4;
+  }
+  return true;
+}
+
+
+Bignum::Chunk Bignum::BigitAt(int index) const {
+  if (index >= BigitLength()) return 0;
+  if (index < exponent_) return 0;
+  return bigits_[index - exponent_];
+}
+
+
+int Bignum::Compare(const Bignum& a, const Bignum& b) {
+  ASSERT(a.IsClamped());
+  ASSERT(b.IsClamped());
+  int bigit_length_a = a.BigitLength();
+  int bigit_length_b = b.BigitLength();
+  if (bigit_length_a < bigit_length_b) return -1;
+  if (bigit_length_a > bigit_length_b) return +1;
+  for (int i = bigit_length_a - 1; i >= Min(a.exponent_, b.exponent_); --i) {
+    Chunk bigit_a = a.BigitAt(i);
+    Chunk bigit_b = b.BigitAt(i);
+    if (bigit_a < bigit_b) return -1;
+    if (bigit_a > bigit_b) return +1;
+    // Otherwise they are equal up to this digit. Try the next digit.
+  }
+  return 0;
+}
+
+
+int Bignum::PlusCompare(const Bignum& a, const Bignum& b, const Bignum& c) {
+  ASSERT(a.IsClamped());
+  ASSERT(b.IsClamped());
+  ASSERT(c.IsClamped());
+  if (a.BigitLength() < b.BigitLength()) {
+    return PlusCompare(b, a, c);
+  }
+  if (a.BigitLength() + 1 < c.BigitLength()) return -1;
+  if (a.BigitLength() > c.BigitLength()) return +1;
+  // The exponent encodes 0-bigits. So if there are more 0-digits in 'a' than
+  // 'b' has digits, then the bigit-length of 'a'+'b' must be equal to the one
+  // of 'a'.
+  if (a.exponent_ >= b.BigitLength() && a.BigitLength() < c.BigitLength()) {
+    return -1;
+  }
+
+  Chunk borrow = 0;
+  // Starting at min_exponent all digits are == 0. So no need to compare them.
+  int min_exponent = Min(Min(a.exponent_, b.exponent_), c.exponent_);
+  for (int i = c.BigitLength() - 1; i >= min_exponent; --i) {
+    Chunk chunk_a = a.BigitAt(i);
+    Chunk chunk_b = b.BigitAt(i);
+    Chunk chunk_c = c.BigitAt(i);
+    Chunk sum = chunk_a + chunk_b;
+    if (sum > chunk_c + borrow) {
+      return +1;
+    } else {
+      borrow = chunk_c + borrow - sum;
+      if (borrow > 1) return -1;
+      borrow <<= kBigitSize;
+    }
+  }
+  if (borrow == 0) return 0;
+  return -1;
+}
+
+
+void Bignum::Clamp() {
+  while (used_digits_ > 0 && bigits_[used_digits_ - 1] == 0) {
+    used_digits_--;
+  }
+  if (used_digits_ == 0) {
+    // Zero.
+    exponent_ = 0;
+  }
+}
+
+
+bool Bignum::IsClamped() const {
+  return used_digits_ == 0 || bigits_[used_digits_ - 1] != 0;
+}
+
+
+void Bignum::Zero() {
+  for (int i = 0; i < used_digits_; ++i) {
+    bigits_[i] = 0;
+  }
+  used_digits_ = 0;
+  exponent_ = 0;
+}
+
+
+void Bignum::Align(const Bignum& other) {
+  if (exponent_ > other.exponent_) {
+    // If "X" represents a "hidden" digit (by the exponent) then we are in the
+    // following case (a == this, b == other):
+    // a:  aaaaaaXXXX   or a:   aaaaaXXX
+    // b:     bbbbbbX      b: bbbbbbbbXX
+    // We replace some of the hidden digits (X) of a with 0 digits.
+    // a:  aaaaaa000X   or a:   aaaaa0XX
+    int zero_digits = exponent_ - other.exponent_;
+    EnsureCapacity(used_digits_ + zero_digits);
+    for (int i = used_digits_ - 1; i >= 0; --i) {
+      bigits_[i + zero_digits] = bigits_[i];
+    }
+    for (int i = 0; i < zero_digits; ++i) {
+      bigits_[i] = 0;
+    }
+    used_digits_ += zero_digits;
+    exponent_ -= zero_digits;
+    ASSERT(used_digits_ >= 0);
+    ASSERT(exponent_ >= 0);
+  }
+}
+
+
+void Bignum::BigitsShiftLeft(int shift_amount) {
+  ASSERT(shift_amount < kBigitSize);
+  ASSERT(shift_amount >= 0);
+  Chunk carry = 0;
+  for (int i = 0; i < used_digits_; ++i) {
+    Chunk new_carry = bigits_[i] >> (kBigitSize - shift_amount);
+    bigits_[i] = ((bigits_[i] << shift_amount) + carry) & kBigitMask;
+    carry = new_carry;
+  }
+  if (carry != 0) {
+    bigits_[used_digits_] = carry;
+    used_digits_++;
+  }
+}
+
+
+void Bignum::SubtractTimes(const Bignum& other, int factor) {
+  ASSERT(exponent_ <= other.exponent_);
+  if (factor < 3) {
+    for (int i = 0; i < factor; ++i) {
+      SubtractBignum(other);
+    }
+    return;
+  }
+  Chunk borrow = 0;
+  int exponent_diff = other.exponent_ - exponent_;
+  for (int i = 0; i < other.used_digits_; ++i) {
+    DoubleChunk product = static_cast<DoubleChunk>(factor) * other.bigits_[i];
+    DoubleChunk remove = borrow + product;
+    Chunk difference = bigits_[i + exponent_diff] - (remove & kBigitMask);
+    bigits_[i + exponent_diff] = difference & kBigitMask;
+    borrow = static_cast<Chunk>((difference >> (kChunkSize - 1)) +
+                                (remove >> kBigitSize));
+  }
+  for (int i = other.used_digits_ + exponent_diff; i < used_digits_; ++i) {
+    if (borrow == 0) return;
+    Chunk difference = bigits_[i] - borrow;
+    bigits_[i] = difference & kBigitMask;
+    borrow = difference >> (kChunkSize - 1);
+    ++i;
+  }
+  Clamp();
+}
+
+
+}  // namespace double_conversion
diff --git a/mfbt/double-conversion/bignum.h b/mfbt/double-conversion/bignum.h
new file mode 100644
index 0000000..5ec3544
--- /dev/null
+++ b/mfbt/double-conversion/bignum.h
@@ -0,0 +1,145 @@
+// Copyright 2010 the V8 project authors. All rights reserved.
+// Redistribution and use in source and binary forms, with or without
+// modification, are permitted provided that the following conditions are
+// met:
+//
+//     * Redistributions of source code must retain the above copyright
+//       notice, this list of conditions and the following disclaimer.
+//     * Redistributions in binary form must reproduce the above
+//       copyright notice, this list of conditions and the following
+//       disclaimer in the documentation and/or other materials provided
+//       with the distribution.
+//     * Neither the name of Google Inc. nor the names of its
+//       contributors may be used to endorse or promote products derived
+//       from this software without specific prior written permission.
+//
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+#ifndef DOUBLE_CONVERSION_BIGNUM_H_
+#define DOUBLE_CONVERSION_BIGNUM_H_
+
+#include "utils.h"
+
+namespace double_conversion {
+
+class Bignum {
+ public:
+  // 3584 = 128 * 28. We can represent 2^3584 > 10^1000 accurately.
+  // This bignum can encode much bigger numbers, since it contains an
+  // exponent.
+  static const int kMaxSignificantBits = 3584;
+
+  Bignum();
+  void AssignUInt16(uint16_t value);
+  void AssignUInt64(uint64_t value);
+  void AssignBignum(const Bignum& other);
+
+  void AssignDecimalString(Vector<const char> value);
+  void AssignHexString(Vector<const char> value);
+
+  void AssignPowerUInt16(uint16_t base, int exponent);
+
+  void AddUInt16(uint16_t operand);
+  void AddUInt64(uint64_t operand);
+  void AddBignum(const Bignum& other);
+  // Precondition: this >= other.
+  void SubtractBignum(const Bignum& other);
+
+  void Square();
+  void ShiftLeft(int shift_amount);
+  void MultiplyByUInt32(uint32_t factor);
+  void MultiplyByUInt64(uint64_t factor);
+  void MultiplyByPowerOfTen(int exponent);
+  void Times10() { return MultiplyByUInt32(10); }
+  // Pseudocode:
+  //  int result = this / other;
+  //  this = this % other;
+  // In the worst case this function is in O(this/other).
+  uint16_t DivideModuloIntBignum(const Bignum& other);
+
+  bool ToHexString(char* buffer, int buffer_size) const;
+
+  // Returns
+  //  -1 if a < b,
+  //   0 if a == b, and
+  //  +1 if a > b.
+  static int Compare(const Bignum& a, const Bignum& b);
+  static bool Equal(const Bignum& a, const Bignum& b) {
+    return Compare(a, b) == 0;
+  }
+  static bool LessEqual(const Bignum& a, const Bignum& b) {
+    return Compare(a, b) <= 0;
+  }
+  static bool Less(const Bignum& a, const Bignum& b) {
+    return Compare(a, b) < 0;
+  }
+  // Returns Compare(a + b, c);
+  static int PlusCompare(const Bignum& a, const Bignum& b, const Bignum& c);
+  // Returns a + b == c
+  static bool PlusEqual(const Bignum& a, const Bignum& b, const Bignum& c) {
+    return PlusCompare(a, b, c) == 0;
+  }
+  // Returns a + b <= c
+  static bool PlusLessEqual(const Bignum& a, const Bignum& b, const Bignum& c) {
+    return PlusCompare(a, b, c) <= 0;
+  }
+  // Returns a + b < c
+  static bool PlusLess(const Bignum& a, const Bignum& b, const Bignum& c) {
+    return PlusCompare(a, b, c) < 0;
+  }
+ private:
+  typedef uint32_t Chunk;
+  typedef uint64_t DoubleChunk;
+
+  static const int kChunkSize = sizeof(Chunk) * 8;
+  static const int kDoubleChunkSize = sizeof(DoubleChunk) * 8;
+  // With bigit size of 28 we loose some bits, but a double still fits easily
+  // into two chunks, and more importantly we can use the Comba multiplication.
+  static const int kBigitSize = 28;
+  static const Chunk kBigitMask = (1 << kBigitSize) - 1;
+  // Every instance allocates kBigitLength chunks on the stack. Bignums cannot
+  // grow. There are no checks if the stack-allocated space is sufficient.
+  static const int kBigitCapacity = kMaxSignificantBits / kBigitSize;
+
+  void EnsureCapacity(int size) {
+    if (size > kBigitCapacity) {
+      UNREACHABLE();
+    }
+  }
+  void Align(const Bignum& other);
+  void Clamp();
+  bool IsClamped() const;
+  void Zero();
+  // Requires this to have enough capacity (no tests done).
+  // Updates used_digits_ if necessary.
+  // shift_amount must be < kBigitSize.
+  void BigitsShiftLeft(int shift_amount);
+  // BigitLength includes the "hidden" digits encoded in the exponent.
+  int BigitLength() const { return used_digits_ + exponent_; }
+  Chunk BigitAt(int index) const;
+  void SubtractTimes(const Bignum& other, int factor);
+
+  Chunk bigits_buffer_[kBigitCapacity];
+  // A vector backed by bigits_buffer_. This way accesses to the array are
+  // checked for out-of-bounds errors.
+  Vector<Chunk> bigits_;
+  int used_digits_;
+  // The Bignum's value equals value(bigits_) * 2^(exponent_ * kBigitSize).
+  int exponent_;
+
+  DISALLOW_COPY_AND_ASSIGN(Bignum);
+};
+
+}  // namespace double_conversion
+
+#endif  // DOUBLE_CONVERSION_BIGNUM_H_
diff --git a/mfbt/double-conversion/cached-powers.cc b/mfbt/double-conversion/cached-powers.cc
new file mode 100644
index 0000000..c676429
--- /dev/null
+++ b/mfbt/double-conversion/cached-powers.cc
@@ -0,0 +1,175 @@
+// Copyright 2006-2008 the V8 project authors. All rights reserved.
+// Redistribution and use in source and binary forms, with or without
+// modification, are permitted provided that the following conditions are
+// met:
+//
+//     * Redistributions of source code must retain the above copyright
+//       notice, this list of conditions and the following disclaimer.
+//     * Redistributions in binary form must reproduce the above
+//       copyright notice, this list of conditions and the following
+//       disclaimer in the documentation and/or other materials provided
+//       with the distribution.
+//     * Neither the name of Google Inc. nor the names of its
+//       contributors may be used to endorse or promote products derived
+//       from this software without specific prior written permission.
+//
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+#include <stdarg.h>
+#include <limits.h>
+#include <math.h>
+
+#include "utils.h"
+
+#include "cached-powers.h"
+
+namespace double_conversion {
+
+struct CachedPower {
+  uint64_t significand;
+  int16_t binary_exponent;
+  int16_t decimal_exponent;
+};
+
+static const CachedPower kCachedPowers[] = {
+  {UINT64_2PART_C(0xfa8fd5a0, 081c0288), -1220, -348},
+  {UINT64_2PART_C(0xbaaee17f, a23ebf76), -1193, -340},
+  {UINT64_2PART_C(0x8b16fb20, 3055ac76), -1166, -332},
+  {UINT64_2PART_C(0xcf42894a, 5dce35ea), -1140, -324},
+  {UINT64_2PART_C(0x9a6bb0aa, 55653b2d), -1113, -316},
+  {UINT64_2PART_C(0xe61acf03, 3d1a45df), -1087, -308},
+  {UINT64_2PART_C(0xab70fe17, c79ac6ca), -1060, -300},
+  {UINT64_2PART_C(0xff77b1fc, bebcdc4f), -1034, -292},
+  {UINT64_2PART_C(0xbe5691ef, 416bd60c), -1007, -284},
+  {UINT64_2PART_C(0x8dd01fad, 907ffc3c), -980, -276},
+  {UINT64_2PART_C(0xd3515c28, 31559a83), -954, -268},
+  {UINT64_2PART_C(0x9d71ac8f, ada6c9b5), -927, -260},
+  {UINT64_2PART_C(0xea9c2277, 23ee8bcb), -901, -252},
+  {UINT64_2PART_C(0xaecc4991, 4078536d), -874, -244},
+  {UINT64_2PART_C(0x823c1279, 5db6ce57), -847, -236},
+  {UINT64_2PART_C(0xc2109436, 4dfb5637), -821, -228},
+  {UINT64_2PART_C(0x9096ea6f, 3848984f), -794, -220},
+  {UINT64_2PART_C(0xd77485cb, 25823ac7), -768, -212},
+  {UINT64_2PART_C(0xa086cfcd, 97bf97f4), -741, -204},
+  {UINT64_2PART_C(0xef340a98, 172aace5), -715, -196},
+  {UINT64_2PART_C(0xb23867fb, 2a35b28e), -688, -188},
+  {UINT64_2PART_C(0x84c8d4df, d2c63f3b), -661, -180},
+  {UINT64_2PART_C(0xc5dd4427, 1ad3cdba), -635, -172},
+  {UINT64_2PART_C(0x936b9fce, bb25c996), -608, -164},
+  {UINT64_2PART_C(0xdbac6c24, 7d62a584), -582, -156},
+  {UINT64_2PART_C(0xa3ab6658, 0d5fdaf6), -555, -148},
+  {UINT64_2PART_C(0xf3e2f893, dec3f126), -529, -140},
+  {UINT64_2PART_C(0xb5b5ada8, aaff80b8), -502, -132},
+  {UINT64_2PART_C(0x87625f05, 6c7c4a8b), -475, -124},
+  {UINT64_2PART_C(0xc9bcff60, 34c13053), -449, -116},
+  {UINT64_2PART_C(0x964e858c, 91ba2655), -422, -108},
+  {UINT64_2PART_C(0xdff97724, 70297ebd), -396, -100},
+  {UINT64_2PART_C(0xa6dfbd9f, b8e5b88f), -369, -92},
+  {UINT64_2PART_C(0xf8a95fcf, 88747d94), -343, -84},
+  {UINT64_2PART_C(0xb9447093, 8fa89bcf), -316, -76},
+  {UINT64_2PART_C(0x8a08f0f8, bf0f156b), -289, -68},
+  {UINT64_2PART_C(0xcdb02555, 653131b6), -263, -60},
+  {UINT64_2PART_C(0x993fe2c6, d07b7fac), -236, -52},
+  {UINT64_2PART_C(0xe45c10c4, 2a2b3b06), -210, -44},
+  {UINT64_2PART_C(0xaa242499, 697392d3), -183, -36},
+  {UINT64_2PART_C(0xfd87b5f2, 8300ca0e), -157, -28},
+  {UINT64_2PART_C(0xbce50864, 92111aeb), -130, -20},
+  {UINT64_2PART_C(0x8cbccc09, 6f5088cc), -103, -12},
+  {UINT64_2PART_C(0xd1b71758, e219652c), -77, -4},
+  {UINT64_2PART_C(0x9c400000, 00000000), -50, 4},
+  {UINT64_2PART_C(0xe8d4a510, 00000000), -24, 12},
+  {UINT64_2PART_C(0xad78ebc5, ac620000), 3, 20},
+  {UINT64_2PART_C(0x813f3978, f8940984), 30, 28},
+  {UINT64_2PART_C(0xc097ce7b, c90715b3), 56, 36},
+  {UINT64_2PART_C(0x8f7e32ce, 7bea5c70), 83, 44},
+  {UINT64_2PART_C(0xd5d238a4, abe98068), 109, 52},
+  {UINT64_2PART_C(0x9f4f2726, 179a2245), 136, 60},
+  {UINT64_2PART_C(0xed63a231, d4c4fb27), 162, 68},
+  {UINT64_2PART_C(0xb0de6538, 8cc8ada8), 189, 76},
+  {UINT64_2PART_C(0x83c7088e, 1aab65db), 216, 84},
+  {UINT64_2PART_C(0xc45d1df9, 42711d9a), 242, 92},
+  {UINT64_2PART_C(0x924d692c, a61be758), 269, 100},
+  {UINT64_2PART_C(0xda01ee64, 1a708dea), 295, 108},
+  {UINT64_2PART_C(0xa26da399, 9aef774a), 322, 116},
+  {UINT64_2PART_C(0xf209787b, b47d6b85), 348, 124},
+  {UINT64_2PART_C(0xb454e4a1, 79dd1877), 375, 132},
+  {UINT64_2PART_C(0x865b8692, 5b9bc5c2), 402, 140},
+  {UINT64_2PART_C(0xc83553c5, c8965d3d), 428, 148},
+  {UINT64_2PART_C(0x952ab45c, fa97a0b3), 455, 156},
+  {UINT64_2PART_C(0xde469fbd, 99a05fe3), 481, 164},
+  {UINT64_2PART_C(0xa59bc234, db398c25), 508, 172},
+  {UINT64_2PART_C(0xf6c69a72, a3989f5c), 534, 180},
+  {UINT64_2PART_C(0xb7dcbf53, 54e9bece), 561, 188},
+  {UINT64_2PART_C(0x88fcf317, f22241e2), 588, 196},
+  {UINT64_2PART_C(0xcc20ce9b, d35c78a5), 614, 204},
+  {UINT64_2PART_C(0x98165af3, 7b2153df), 641, 212},
+  {UINT64_2PART_C(0xe2a0b5dc, 971f303a), 667, 220},
+  {UINT64_2PART_C(0xa8d9d153, 5ce3b396), 694, 228},
+  {UINT64_2PART_C(0xfb9b7cd9, a4a7443c), 720, 236},
+  {UINT64_2PART_C(0xbb764c4c, a7a44410), 747, 244},
+  {UINT64_2PART_C(0x8bab8eef, b6409c1a), 774, 252},
+  {UINT64_2PART_C(0xd01fef10, a657842c), 800, 260},
+  {UINT64_2PART_C(0x9b10a4e5, e9913129), 827, 268},
+  {UINT64_2PART_C(0xe7109bfb, a19c0c9d), 853, 276},
+  {UINT64_2PART_C(0xac2820d9, 623bf429), 880, 284},
+  {UINT64_2PART_C(0x80444b5e, 7aa7cf85), 907, 292},
+  {UINT64_2PART_C(0xbf21e440, 03acdd2d), 933, 300},
+  {UINT64_2PART_C(0x8e679c2f, 5e44ff8f), 960, 308},
+  {UINT64_2PART_C(0xd433179d, 9c8cb841), 986, 316},
+  {UINT64_2PART_C(0x9e19db92, b4e31ba9), 1013, 324},
+  {UINT64_2PART_C(0xeb96bf6e, badf77d9), 1039, 332},
+  {UINT64_2PART_C(0xaf87023b, 9bf0ee6b), 1066, 340},
+};
+
+static const int kCachedPowersLength = ARRAY_SIZE(kCachedPowers);
+static const int kCachedPowersOffset = 348;  // -1 * the first decimal_exponent.
+static const double kD_1_LOG2_10 = 0.30102999566398114;  //  1 / lg(10)
+// Difference between the decimal exponents in the table above.
+const int PowersOfTenCache::kDecimalExponentDistance = 8;
+const int PowersOfTenCache::kMinDecimalExponent = -348;
+const int PowersOfTenCache::kMaxDecimalExponent = 340;
+
+void PowersOfTenCache::GetCachedPowerForBinaryExponentRange(
+    int min_exponent,
+    int max_exponent,
+    DiyFp* power,
+    int* decimal_exponent) {
+  int kQ = DiyFp::kSignificandSize;
+  double k = ceil((min_exponent + kQ - 1) * kD_1_LOG2_10);
+  int foo = kCachedPowersOffset;
+  int index =
+      (foo + static_cast<int>(k) - 1) / kDecimalExponentDistance + 1;
+  ASSERT(0 <= index && index < kCachedPowersLength);
+  CachedPower cached_power = kCachedPowers[index];
+  ASSERT(min_exponent <= cached_power.binary_exponent);
+  ASSERT(cached_power.binary_exponent <= max_exponent);
+  *decimal_exponent = cached_power.decimal_exponent;
+  *power = DiyFp(cached_power.significand, cached_power.binary_exponent);
+}
+
+
+void PowersOfTenCache::GetCachedPowerForDecimalExponent(int requested_exponent,
+                                                        DiyFp* power,
+                                                        int* found_exponent) {
+  ASSERT(kMinDecimalExponent <= requested_exponent);
+  ASSERT(requested_exponent < kMaxDecimalExponent + kDecimalExponentDistance);
+  int index =
+      (requested_exponent + kCachedPowersOffset) / kDecimalExponentDistance;
+  CachedPower cached_power = kCachedPowers[index];
+  *power = DiyFp(cached_power.significand, cached_power.binary_exponent);
+  *found_exponent = cached_power.decimal_exponent;
+  ASSERT(*found_exponent <= requested_exponent);
+  ASSERT(requested_exponent < *found_exponent + kDecimalExponentDistance);
+}
+
+}  // namespace double_conversion
diff --git a/mfbt/double-conversion/cached-powers.h b/mfbt/double-conversion/cached-powers.h
new file mode 100644
index 0000000..61a5061
--- /dev/null
+++ b/mfbt/double-conversion/cached-powers.h
@@ -0,0 +1,64 @@
+// Copyright 2010 the V8 project authors. All rights reserved.
+// Redistribution and use in source and binary forms, with or without
+// modification, are permitted provided that the following conditions are
+// met:
+//
+//     * Redistributions of source code must retain the above copyright
+//       notice, this list of conditions and the following disclaimer.
+//     * Redistributions in binary form must reproduce the above
+//       copyright notice, this list of conditions and the following
+//       disclaimer in the documentation and/or other materials provided
+//       with the distribution.
+//     * Neither the name of Google Inc. nor the names of its
+//       contributors may be used to endorse or promote products derived
+//       from this software without specific prior written permission.
+//
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+#ifndef DOUBLE_CONVERSION_CACHED_POWERS_H_
+#define DOUBLE_CONVERSION_CACHED_POWERS_H_
+
+#include "diy-fp.h"
+
+namespace double_conversion {
+
+class PowersOfTenCache {
+ public:
+
+  // Not all powers of ten are cached. The decimal exponent of two neighboring
+  // cached numbers will differ by kDecimalExponentDistance.
+  static const int kDecimalExponentDistance;
+
+  static const int kMinDecimalExponent;
+  static const int kMaxDecimalExponent;
+
+  // Returns a cached power-of-ten with a binary exponent in the range
+  // [min_exponent; max_exponent] (boundaries included).
+  static void GetCachedPowerForBinaryExponentRange(int min_exponent,
+                                                   int max_exponent,
+                                                   DiyFp* power,
+                                                   int* decimal_exponent);
+
+  // Returns a cached power of ten x ~= 10^k such that
+  //   k <= decimal_exponent < k + kCachedPowersDecimalDistance.
+  // The given decimal_exponent must satisfy
+  //   kMinDecimalExponent <= requested_exponent, and
+  //   requested_exponent < kMaxDecimalExponent + kDecimalExponentDistance.
+  static void GetCachedPowerForDecimalExponent(int requested_exponent,
+                                               DiyFp* power,
+                                               int* found_exponent);
+};
+
+}  // namespace double_conversion
+
+#endif  // DOUBLE_CONVERSION_CACHED_POWERS_H_
diff --git a/mfbt/double-conversion/diy-fp.cc b/mfbt/double-conversion/diy-fp.cc
new file mode 100644
index 0000000..ddd1891
--- /dev/null
+++ b/mfbt/double-conversion/diy-fp.cc
@@ -0,0 +1,57 @@
+// Copyright 2010 the V8 project authors. All rights reserved.
+// Redistribution and use in source and binary forms, with or without
+// modification, are permitted provided that the following conditions are
+// met:
+//
+//     * Redistributions of source code must retain the above copyright
+//       notice, this list of conditions and the following disclaimer.
+//     * Redistributions in binary form must reproduce the above
+//       copyright notice, this list of conditions and the following
+//       disclaimer in the documentation and/or other materials provided
+//       with the distribution.
+//     * Neither the name of Google Inc. nor the names of its
+//       contributors may be used to endorse or promote products derived
+//       from this software without specific prior written permission.
+//
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+
+#include "diy-fp.h"
+#include "utils.h"
+
+namespace double_conversion {
+
+void DiyFp::Multiply(const DiyFp& other) {
+  // Simply "emulates" a 128 bit multiplication.
+  // However: the resulting number only contains 64 bits. The least
+  // significant 64 bits are only used for rounding the most significant 64
+  // bits.
+  const uint64_t kM32 = 0xFFFFFFFFU;
+  uint64_t a = f_ >> 32;
+  uint64_t b = f_ & kM32;
+  uint64_t c = other.f_ >> 32;
+  uint64_t d = other.f_ & kM32;
+  uint64_t ac = a * c;
+  uint64_t bc = b * c;
+  uint64_t ad = a * d;
+  uint64_t bd = b * d;
+  uint64_t tmp = (bd >> 32) + (ad & kM32) + (bc & kM32);
+  // By adding 1U << 31 to tmp we round the final result.
+  // Halfway cases will be round up.
+  tmp += 1U << 31;
+  uint64_t result_f = ac + (ad >> 32) + (bc >> 32) + (tmp >> 32);
+  e_ += other.e_ + 64;
+  f_ = result_f;
+}
+
+}  // namespace double_conversion
diff --git a/mfbt/double-conversion/diy-fp.h b/mfbt/double-conversion/diy-fp.h
new file mode 100644
index 0000000..9dcf8fb
--- /dev/null
+++ b/mfbt/double-conversion/diy-fp.h
@@ -0,0 +1,118 @@
+// Copyright 2010 the V8 project authors. All rights reserved.
+// Redistribution and use in source and binary forms, with or without
+// modification, are permitted provided that the following conditions are
+// met:
+//
+//     * Redistributions of source code must retain the above copyright
+//       notice, this list of conditions and the following disclaimer.
+//     * Redistributions in binary form must reproduce the above
+//       copyright notice, this list of conditions and the following
+//       disclaimer in the documentation and/or other materials provided
+//       with the distribution.
+//     * Neither the name of Google Inc. nor the names of its
+//       contributors may be used to endorse or promote products derived
+//       from this software without specific prior written permission.
+//
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+#ifndef DOUBLE_CONVERSION_DIY_FP_H_
+#define DOUBLE_CONVERSION_DIY_FP_H_
+
+#include "utils.h"
+
+namespace double_conversion {
+
+// This "Do It Yourself Floating Point" class implements a floating-point number
+// with a uint64 significand and an int exponent. Normalized DiyFp numbers will
+// have the most significant bit of the significand set.
+// Multiplication and Subtraction do not normalize their results.
+// DiyFp are not designed to contain special doubles (NaN and Infinity).
+class DiyFp {
+ public:
+  static const int kSignificandSize = 64;
+
+  DiyFp() : f_(0), e_(0) {}
+  DiyFp(uint64_t f, int e) : f_(f), e_(e) {}
+
+  // this = this - other.
+  // The exponents of both numbers must be the same and the significand of this
+  // must be bigger than the significand of other.
+  // The result will not be normalized.
+  void Subtract(const DiyFp& other) {
+    ASSERT(e_ == other.e_);
+    ASSERT(f_ >= other.f_);
+    f_ -= other.f_;
+  }
+
+  // Returns a - b.
+  // The exponents of both numbers must be the same and this must be bigger
+  // than other. The result will not be normalized.
+  static DiyFp Minus(const DiyFp& a, const DiyFp& b) {
+    DiyFp result = a;
+    result.Subtract(b);
+    return result;
+  }
+
+
+  // this = this * other.
+  void Multiply(const DiyFp& other);
+
+  // returns a * b;
+  static DiyFp Times(const DiyFp& a, const DiyFp& b) {
+    DiyFp result = a;
+    result.Multiply(b);
+    return result;
+  }
+
+  void Normalize() {
+    ASSERT(f_ != 0);
+    uint64_t f = f_;
+    int e = e_;
+
+    // This method is mainly called for normalizing boundaries. In general
+    // boundaries need to be shifted by 10 bits. We thus optimize for this case.
+    const uint64_t k10MSBits = UINT64_2PART_C(0xFFC00000, 00000000);
+    while ((f & k10MSBits) == 0) {
+      f <<= 10;
+      e -= 10;
+    }
+    while ((f & kUint64MSB) == 0) {
+      f <<= 1;
+      e--;
+    }
+    f_ = f;
+    e_ = e;
+  }
+
+  static DiyFp Normalize(const DiyFp& a) {
+    DiyFp result = a;
+    result.Normalize();
+    return result;
+  }
+
+  uint64_t f() const { return f_; }
+  int e() const { return e_; }
+
+  void set_f(uint64_t new_value) { f_ = new_value; }
+  void set_e(int new_value) { e_ = new_value; }
+
+ private:
+  static const uint64_t kUint64MSB = UINT64_2PART_C(0x80000000, 00000000);
+
+  uint64_t f_;
+  int e_;
+};
+
+}  // namespace double_conversion
+
+#endif  // DOUBLE_CONVERSION_DIY_FP_H_
diff --git a/mfbt/double-conversion/double-conversion.cc b/mfbt/double-conversion/double-conversion.cc
new file mode 100644
index 0000000..650137b
--- /dev/null
+++ b/mfbt/double-conversion/double-conversion.cc
@@ -0,0 +1,889 @@
+// Copyright 2010 the V8 project authors. All rights reserved.
+// Redistribution and use in source and binary forms, with or without
+// modification, are permitted provided that the following conditions are
+// met:
+//
+//     * Redistributions of source code must retain the above copyright
+//       notice, this list of conditions and the following disclaimer.
+//     * Redistributions in binary form must reproduce the above
+//       copyright notice, this list of conditions and the following
+//       disclaimer in the documentation and/or other materials provided
+//       with the distribution.
+//     * Neither the name of Google Inc. nor the names of its
+//       contributors may be used to endorse or promote products derived
+//       from this software without specific prior written permission.
+//
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+#include <limits.h>
+#include <math.h>
+
+#include "double-conversion.h"
+
+#include "bignum-dtoa.h"
+#include "fast-dtoa.h"
+#include "fixed-dtoa.h"
+#include "ieee.h"
+#include "strtod.h"
+#include "utils.h"
+
+namespace double_conversion {
+
+const DoubleToStringConverter& DoubleToStringConverter::EcmaScriptConverter() {
+  int flags = UNIQUE_ZERO | EMIT_POSITIVE_EXPONENT_SIGN;
+  static DoubleToStringConverter converter(flags,
+                                           "Infinity",
+                                           "NaN",
+                                           'e',
+                                           -6, 21,
+                                           6, 0);
+  return converter;
+}
+
+
+bool DoubleToStringConverter::HandleSpecialValues(
+    double value,
+    StringBuilder* result_builder) const {
+  Double double_inspect(value);
+  if (double_inspect.IsInfinite()) {
+    if (infinity_symbol_ == NULL) return false;
+    if (value < 0) {
+      result_builder->AddCharacter('-');
+    }
+    result_builder->AddString(infinity_symbol_);
+    return true;
+  }
+  if (double_inspect.IsNan()) {
+    if (nan_symbol_ == NULL) return false;
+    result_builder->AddString(nan_symbol_);
+    return true;
+  }
+  return false;
+}
+
+
+void DoubleToStringConverter::CreateExponentialRepresentation(
+    const char* decimal_digits,
+    int length,
+    int exponent,
+    StringBuilder* result_builder) const {
+  ASSERT(length != 0);
+  result_builder->AddCharacter(decimal_digits[0]);
+  if (length != 1) {
+    result_builder->AddCharacter('.');
+    result_builder->AddSubstring(&decimal_digits[1], length-1);
+  }
+  result_builder->AddCharacter(exponent_character_);
+  if (exponent < 0) {
+    result_builder->AddCharacter('-');
+    exponent = -exponent;
+  } else {
+    if ((flags_ & EMIT_POSITIVE_EXPONENT_SIGN) != 0) {
+      result_builder->AddCharacter('+');
+    }
+  }
+  if (exponent == 0) {
+    result_builder->AddCharacter('0');
+    return;
+  }
+  ASSERT(exponent < 1e4);
+  const int kMaxExponentLength = 5;
+  char buffer[kMaxExponentLength + 1];
+  buffer[kMaxExponentLength] = '\0';
+  int first_char_pos = kMaxExponentLength;
+  while (exponent > 0) {
+    buffer[--first_char_pos] = '0' + (exponent % 10);
+    exponent /= 10;
+  }
+  result_builder->AddSubstring(&buffer[first_char_pos],
+                               kMaxExponentLength - first_char_pos);
+}
+
+
+void DoubleToStringConverter::CreateDecimalRepresentation(
+    const char* decimal_digits,
+    int length,
+    int decimal_point,
+    int digits_after_point,
+    StringBuilder* result_builder) const {
+  // Create a representation that is padded with zeros if needed.
+  if (decimal_point <= 0) {
+      // "0.00000decimal_rep".
+    result_builder->AddCharacter('0');
+    if (digits_after_point > 0) {
+      result_builder->AddCharacter('.');
+      result_builder->AddPadding('0', -decimal_point);
+      ASSERT(length <= digits_after_point - (-decimal_point));
+      result_builder->AddSubstring(decimal_digits, length);
+      int remaining_digits = digits_after_point - (-decimal_point) - length;
+      result_builder->AddPadding('0', remaining_digits);
+    }
+  } else if (decimal_point >= length) {
+    // "decimal_rep0000.00000" or "decimal_rep.0000"
+    result_builder->AddSubstring(decimal_digits, length);
+    result_builder->AddPadding('0', decimal_point - length);
+    if (digits_after_point > 0) {
+      result_builder->AddCharacter('.');
+      result_builder->AddPadding('0', digits_after_point);
+    }
+  } else {
+    // "decima.l_rep000"
+    ASSERT(digits_after_point > 0);
+    result_builder->AddSubstring(decimal_digits, decimal_point);
+    result_builder->AddCharacter('.');
+    ASSERT(length - decimal_point <= digits_after_point);
+    result_builder->AddSubstring(&decimal_digits[decimal_point],
+                                 length - decimal_point);
+    int remaining_digits = digits_after_point - (length - decimal_point);
+    result_builder->AddPadding('0', remaining_digits);
+  }
+  if (digits_after_point == 0) {
+    if ((flags_ & EMIT_TRAILING_DECIMAL_POINT) != 0) {
+      result_builder->AddCharacter('.');
+    }
+    if ((flags_ & EMIT_TRAILING_ZERO_AFTER_POINT) != 0) {
+      result_builder->AddCharacter('0');
+    }
+  }
+}
+
+
+bool DoubleToStringConverter::ToShortestIeeeNumber(
+    double value,
+    StringBuilder* result_builder,
+    DoubleToStringConverter::DtoaMode mode) const {
+  assert(mode == SHORTEST || mode == SHORTEST_SINGLE);
+  if (Double(value).IsSpecial()) {
+    return HandleSpecialValues(value, result_builder);
+  }
+
+  int decimal_point;
+  bool sign;
+  const int kDecimalRepCapacity = kBase10MaximalLength + 1;
+  char decimal_rep[kDecimalRepCapacity];
+  int decimal_rep_length;
+
+  DoubleToAscii(value, mode, 0, decimal_rep, kDecimalRepCapacity,
+                &sign, &decimal_rep_length, &decimal_point);
+
+  bool unique_zero = (flags_ & UNIQUE_ZERO) != 0;
+  if (sign && (value != 0.0 || !unique_zero)) {
+    result_builder->AddCharacter('-');
+  }
+
+  int exponent = decimal_point - 1;
+  if ((decimal_in_shortest_low_ <= exponent) &&
+      (exponent < decimal_in_shortest_high_)) {
+    CreateDecimalRepresentation(decimal_rep, decimal_rep_length,
+                                decimal_point,
+                                Max(0, decimal_rep_length - decimal_point),
+                                result_builder);
+  } else {
+    CreateExponentialRepresentation(decimal_rep, decimal_rep_length, exponent,
+                                    result_builder);
+  }
+  return true;
+}
+
+
+bool DoubleToStringConverter::ToFixed(double value,
+                                      int requested_digits,
+                                      StringBuilder* result_builder) const {
+  ASSERT(kMaxFixedDigitsBeforePoint == 60);
+  const double kFirstNonFixed = 1e60;
+
+  if (Double(value).IsSpecial()) {
+    return HandleSpecialValues(value, result_builder);
+  }
+
+  if (requested_digits > kMaxFixedDigitsAfterPoint) return false;
+  if (value >= kFirstNonFixed || value <= -kFirstNonFixed) return false;
+
+  // Find a sufficiently precise decimal representation of n.
+  int decimal_point;
+  bool sign;
+  // Add space for the '\0' byte.
+  const int kDecimalRepCapacity =
+      kMaxFixedDigitsBeforePoint + kMaxFixedDigitsAfterPoint + 1;
+  char decimal_rep[kDecimalRepCapacity];
+  int decimal_rep_length;
+  DoubleToAscii(value, FIXED, requested_digits,
+                decimal_rep, kDecimalRepCapacity,
+                &sign, &decimal_rep_length, &decimal_point);
+
+  bool unique_zero = ((flags_ & UNIQUE_ZERO) != 0);
+  if (sign && (value != 0.0 || !unique_zero)) {
+    result_builder->AddCharacter('-');
+  }
+
+  CreateDecimalRepresentation(decimal_rep, decimal_rep_length, decimal_point,
+                              requested_digits, result_builder);
+  return true;
+}
+
+
+bool DoubleToStringConverter::ToExponential(
+    double value,
+    int requested_digits,
+    StringBuilder* result_builder) const {
+  if (Double(value).IsSpecial()) {
+    return HandleSpecialValues(value, result_builder);
+  }
+
+  if (requested_digits < -1) return false;
+  if (requested_digits > kMaxExponentialDigits) return false;
+
+  int decimal_point;
+  bool sign;
+  // Add space for digit before the decimal point and the '\0' character.
+  const int kDecimalRepCapacity = kMaxExponentialDigits + 2;
+  ASSERT(kDecimalRepCapacity > kBase10MaximalLength);
+  char decimal_rep[kDecimalRepCapacity];
+  int decimal_rep_length;
+
+  if (requested_digits == -1) {
+    DoubleToAscii(value, SHORTEST, 0,
+                  decimal_rep, kDecimalRepCapacity,
+                  &sign, &decimal_rep_length, &decimal_point);
+  } else {
+    DoubleToAscii(value, PRECISION, requested_digits + 1,
+                  decimal_rep, kDecimalRepCapacity,
+                  &sign, &decimal_rep_length, &decimal_point);
+    ASSERT(decimal_rep_length <= requested_digits + 1);
+
+    for (int i = decimal_rep_length; i < requested_digits + 1; ++i) {
+      decimal_rep[i] = '0';
+    }
+    decimal_rep_length = requested_digits + 1;
+  }
+
+  bool unique_zero = ((flags_ & UNIQUE_ZERO) != 0);
+  if (sign && (value != 0.0 || !unique_zero)) {
+    result_builder->AddCharacter('-');
+  }
+
+  int exponent = decimal_point - 1;
+  CreateExponentialRepresentation(decimal_rep,
+                                  decimal_rep_length,
+                                  exponent,
+                                  result_builder);
+  return true;
+}
+
+
+bool DoubleToStringConverter::ToPrecision(double value,
+                                          int precision,
+                                          StringBuilder* result_builder) const {
+  if (Double(value).IsSpecial()) {
+    return HandleSpecialValues(value, result_builder);
+  }
+
+  if (precision < kMinPrecisionDigits || precision > kMaxPrecisionDigits) {
+    return false;
+  }
+
+  // Find a sufficiently precise decimal representation of n.
+  int decimal_point;
+  bool sign;
+  // Add one for the terminating null character.
+  const int kDecimalRepCapacity = kMaxPrecisionDigits + 1;
+  char decimal_rep[kDecimalRepCapacity];
+  int decimal_rep_length;
+
+  DoubleToAscii(value, PRECISION, precision,
+                decimal_rep, kDecimalRepCapacity,
+                &sign, &decimal_rep_length, &decimal_point);
+  ASSERT(decimal_rep_length <= precision);
+
+  bool unique_zero = ((flags_ & UNIQUE_ZERO) != 0);
+  if (sign && (value != 0.0 || !unique_zero)) {
+    result_builder->AddCharacter('-');
+  }
+
+  // The exponent if we print the number as x.xxeyyy. That is with the
+  // decimal point after the first digit.
+  int exponent = decimal_point - 1;
+
+  int extra_zero = ((flags_ & EMIT_TRAILING_ZERO_AFTER_POINT) != 0) ? 1 : 0;
+  if ((-decimal_point + 1 > max_leading_padding_zeroes_in_precision_mode_) ||
+      (decimal_point - precision + extra_zero >
+       max_trailing_padding_zeroes_in_precision_mode_)) {
+    // Fill buffer to contain 'precision' digits.
+    // Usually the buffer is already at the correct length, but 'DoubleToAscii'
+    // is allowed to return less characters.
+    for (int i = decimal_rep_length; i < precision; ++i) {
+      decimal_rep[i] = '0';
+    }
+
+    CreateExponentialRepresentation(decimal_rep,
+                                    precision,
+                                    exponent,
+                                    result_builder);
+  } else {
+    CreateDecimalRepresentation(decimal_rep, decimal_rep_length, decimal_point,
+                                Max(0, precision - decimal_point),
+                                result_builder);
+  }
+  return true;
+}
+
+
+static BignumDtoaMode DtoaToBignumDtoaMode(
+    DoubleToStringConverter::DtoaMode dtoa_mode) {
+  switch (dtoa_mode) {
+    case DoubleToStringConverter::SHORTEST:  return BIGNUM_DTOA_SHORTEST;
+    case DoubleToStringConverter::SHORTEST_SINGLE:
+        return BIGNUM_DTOA_SHORTEST_SINGLE;
+    case DoubleToStringConverter::FIXED:     return BIGNUM_DTOA_FIXED;
+    case DoubleToStringConverter::PRECISION: return BIGNUM_DTOA_PRECISION;
+    default:
+      UNREACHABLE();
+      return BIGNUM_DTOA_SHORTEST;  // To silence compiler.
+  }
+}
+
+
+void DoubleToStringConverter::DoubleToAscii(double v,
+                                            DtoaMode mode,
+                                            int requested_digits,
+                                            char* buffer,
+                                            int buffer_length,
+                                            bool* sign,
+                                            int* length,
+                                            int* point) {
+  Vector<char> vector(buffer, buffer_length);
+  ASSERT(!Double(v).IsSpecial());
+  ASSERT(mode == SHORTEST || mode == SHORTEST_SINGLE || requested_digits >= 0);
+
+  if (Double(v).Sign() < 0) {
+    *sign = true;
+    v = -v;
+  } else {
+    *sign = false;
+  }
+
+  if (mode == PRECISION && requested_digits == 0) {
+    vector[0] = '\0';
+    *length = 0;
+    return;
+  }
+
+  if (v == 0) {
+    vector[0] = '0';
+    vector[1] = '\0';
+    *length = 1;
+    *point = 1;
+    return;
+  }
+
+  bool fast_worked;
+  switch (mode) {
+    case SHORTEST:
+      fast_worked = FastDtoa(v, FAST_DTOA_SHORTEST, 0, vector, length, point);
+      break;
+    case SHORTEST_SINGLE:
+      fast_worked = FastDtoa(v, FAST_DTOA_SHORTEST_SINGLE, 0,
+                             vector, length, point);
+      break;
+    case FIXED:
+      fast_worked = FastFixedDtoa(v, requested_digits, vector, length, point);
+      break;
+    case PRECISION:
+      fast_worked = FastDtoa(v, FAST_DTOA_PRECISION, requested_digits,
+                             vector, length, point);
+      break;
+    default:
+      UNREACHABLE();
+      fast_worked = false;
+  }
+  if (fast_worked) return;
+
+  // If the fast dtoa didn't succeed use the slower bignum version.
+  BignumDtoaMode bignum_mode = DtoaToBignumDtoaMode(mode);
+  BignumDtoa(v, bignum_mode, requested_digits, vector, length, point);
+  vector[*length] = '\0';
+}
+
+
+// Consumes the given substring from the iterator.
+// Returns false, if the substring does not match.
+static bool ConsumeSubString(const char** current,
+                             const char* end,
+                             const char* substring) {
+  ASSERT(**current == *substring);
+  for (substring++; *substring != '\0'; substring++) {
+    ++*current;
+    if (*current == end || **current != *substring) return false;
+  }
+  ++*current;
+  return true;
+}
+
+
+// Maximum number of significant digits in decimal representation.
+// The longest possible double in decimal representation is
+// (2^53 - 1) * 2 ^ -1074 that is (2 ^ 53 - 1) * 5 ^ 1074 / 10 ^ 1074
+// (768 digits). If we parse a number whose first digits are equal to a
+// mean of 2 adjacent doubles (that could have up to 769 digits) the result
+// must be rounded to the bigger one unless the tail consists of zeros, so
+// we don't need to preserve all the digits.
+const int kMaxSignificantDigits = 772;
+
+
+// Returns true if a nonspace found and false if the end has reached.
+static inline bool AdvanceToNonspace(const char** current, const char* end) {
+  while (*current != end) {
+    if (**current != ' ') return true;
+    ++*current;
+  }
+  return false;
+}
+
+
+static bool isDigit(int x, int radix) {
+  return (x >= '0' && x <= '9' && x < '0' + radix)
+      || (radix > 10 && x >= 'a' && x < 'a' + radix - 10)
+      || (radix > 10 && x >= 'A' && x < 'A' + radix - 10);
+}
+
+
+static double SignedZero(bool sign) {
+  return sign ? -0.0 : 0.0;
+}
+
+
+// Parsing integers with radix 2, 4, 8, 16, 32. Assumes current != end.
+template <int radix_log_2>
+static double RadixStringToIeee(const char* current,
+                                const char* end,
+                                bool sign,
+                                bool allow_trailing_junk,
+                                double junk_string_value,
+                                bool read_as_double,
+                                const char** trailing_pointer) {
+  ASSERT(current != end);
+
+  const int kDoubleSize = Double::kSignificandSize;
+  const int kSingleSize = Single::kSignificandSize;
+  const int kSignificandSize = read_as_double? kDoubleSize: kSingleSize;
+
+  // Skip leading 0s.
+  while (*current == '0') {
+    ++current;
+    if (current == end) {
+      *trailing_pointer = end;
+      return SignedZero(sign);
+    }
+  }
+
+  int64_t number = 0;
+  int exponent = 0;
+  const int radix = (1 << radix_log_2);
+
+  do {
+    int digit;
+    if (*current >= '0' && *current <= '9' && *current < '0' + radix) {
+      digit = static_cast<char>(*current) - '0';
+    } else if (radix > 10 && *current >= 'a' && *current < 'a' + radix - 10) {
+      digit = static_cast<char>(*current) - 'a' + 10;
+    } else if (radix > 10 && *current >= 'A' && *current < 'A' + radix - 10) {
+      digit = static_cast<char>(*current) - 'A' + 10;
+    } else {
+      if (allow_trailing_junk || !AdvanceToNonspace(&current, end)) {
+        break;
+      } else {
+        return junk_string_value;
+      }
+    }
+
+    number = number * radix + digit;
+    int overflow = static_cast<int>(number >> kSignificandSize);
+    if (overflow != 0) {
+      // Overflow occurred. Need to determine which direction to round the
+      // result.
+      int overflow_bits_count = 1;
+      while (overflow > 1) {
+        overflow_bits_count++;
+        overflow >>= 1;
+      }
+
+      int dropped_bits_mask = ((1 << overflow_bits_count) - 1);
+      int dropped_bits = static_cast<int>(number) & dropped_bits_mask;
+      number >>= overflow_bits_count;
+      exponent = overflow_bits_count;
+
+      bool zero_tail = true;
+      while (true) {
+        ++current;
+        if (current == end || !isDigit(*current, radix)) break;
+        zero_tail = zero_tail && *current == '0';
+        exponent += radix_log_2;
+      }
+
+      if (!allow_trailing_junk && AdvanceToNonspace(&current, end)) {
+        return junk_string_value;
+      }
+
+      int middle_value = (1 << (overflow_bits_count - 1));
+      if (dropped_bits > middle_value) {
+        number++;  // Rounding up.
+      } else if (dropped_bits == middle_value) {
+        // Rounding to even to consistency with decimals: half-way case rounds
+        // up if significant part is odd and down otherwise.
+        if ((number & 1) != 0 || !zero_tail) {
+          number++;  // Rounding up.
+        }
+      }
+
+      // Rounding up may cause overflow.
+      if ((number & ((int64_t)1 << kSignificandSize)) != 0) {
+        exponent++;
+        number >>= 1;
+      }
+      break;
+    }
+    ++current;
+  } while (current != end);
+
+  ASSERT(number < ((int64_t)1 << kSignificandSize));
+  ASSERT(static_cast<int64_t>(static_cast<double>(number)) == number);
+
+  *trailing_pointer = current;
+
+  if (exponent == 0) {
+    if (sign) {
+      if (number == 0) return -0.0;
+      number = -number;
+    }
+    return static_cast<double>(number);
+  }
+
+  ASSERT(number != 0);
+  return Double(DiyFp(number, exponent)).value();
+}
+
+
+double StringToDoubleConverter::StringToIeee(
+    const char* input,
+    int length,
+    int* processed_characters_count,
+    bool read_as_double) {
+  const char* current = input;
+  const char* end = input + length;
+
+  *processed_characters_count = 0;
+
+  const bool allow_trailing_junk = (flags_ & ALLOW_TRAILING_JUNK) != 0;
+  const bool allow_leading_spaces = (flags_ & ALLOW_LEADING_SPACES) != 0;
+  const bool allow_trailing_spaces = (flags_ & ALLOW_TRAILING_SPACES) != 0;
+  const bool allow_spaces_after_sign = (flags_ & ALLOW_SPACES_AFTER_SIGN) != 0;
+
+  // To make sure that iterator dereferencing is valid the following
+  // convention is used:
+  // 1. Each '++current' statement is followed by check for equality to 'end'.
+  // 2. If AdvanceToNonspace returned false then current == end.
+  // 3. If 'current' becomes equal to 'end' the function returns or goes to
+  // 'parsing_done'.
+  // 4. 'current' is not dereferenced after the 'parsing_done' label.
+  // 5. Code before 'parsing_done' may rely on 'current != end'.
+  if (current == end) return empty_string_value_;
+
+  if (allow_leading_spaces || allow_trailing_spaces) {
+    if (!AdvanceToNonspace(&current, end)) {
+      *processed_characters_count = current - input;
+      return empty_string_value_;
+    }
+    if (!allow_leading_spaces && (input != current)) {
+      // No leading spaces allowed, but AdvanceToNonspace moved forward.
+      return junk_string_value_;
+    }
+  }
+
+  // The longest form of simplified number is: "-<significant digits>.1eXXX\0".
+  const int kBufferSize = kMaxSignificantDigits + 10;
+  char buffer[kBufferSize];  // NOLINT: size is known at compile time.
+  int buffer_pos = 0;
+
+  // Exponent will be adjusted if insignificant digits of the integer part
+  // or insignificant leading zeros of the fractional part are dropped.
+  int exponent = 0;
+  int significant_digits = 0;
+  int insignificant_digits = 0;
+  bool nonzero_digit_dropped = false;
+
+  bool sign = false;
+
+  if (*current == '+' || *current == '-') {
+    sign = (*current == '-');
+    ++current;
+    const char* next_non_space = current;
+    // Skip following spaces (if allowed).
+    if (!AdvanceToNonspace(&next_non_space, end)) return junk_string_value_;
+    if (!allow_spaces_after_sign && (current != next_non_space)) {
+      return junk_string_value_;
+    }
+    current = next_non_space;
+  }
+
+  if (infinity_symbol_ != NULL) {
+    if (*current == infinity_symbol_[0]) {
+      if (!ConsumeSubString(&current, end, infinity_symbol_)) {
+        return junk_string_value_;
+      }
+
+      if (!(allow_trailing_spaces || allow_trailing_junk) && (current != end)) {
+        return junk_string_value_;
+      }
+      if (!allow_trailing_junk && AdvanceToNonspace(&current, end)) {
+        return junk_string_value_;
+      }
+
+      ASSERT(buffer_pos == 0);
+      *processed_characters_count = current - input;
+      return sign ? -Double::Infinity() : Double::Infinity();
+    }
+  }
+
+  if (nan_symbol_ != NULL) {
+    if (*current == nan_symbol_[0]) {
+      if (!ConsumeSubString(&current, end, nan_symbol_)) {
+        return junk_string_value_;
+      }
+
+      if (!(allow_trailing_spaces || allow_trailing_junk) && (current != end)) {
+        return junk_string_value_;
+      }
+      if (!allow_trailing_junk && AdvanceToNonspace(&current, end)) {
+        return junk_string_value_;
+      }
+
+      ASSERT(buffer_pos == 0);
+      *processed_characters_count = current - input;
+      return sign ? -Double::NaN() : Double::NaN();
+    }
+  }
+
+  bool leading_zero = false;
+  if (*current == '0') {
+    ++current;
+    if (current == end) {
+      *processed_characters_count = current - input;
+      return SignedZero(sign);
+    }
+
+    leading_zero = true;
+
+    // It could be hexadecimal value.
+    if ((flags_ & ALLOW_HEX) && (*current == 'x' || *current == 'X')) {
+      ++current;
+      if (current == end || !isDigit(*current, 16)) {
+        return junk_string_value_;  // "0x".
+      }
+
+      const char* tail_pointer = NULL;
+      double result = RadixStringToIeee<4>(current,
+                                           end,
+                                           sign,
+                                           allow_trailing_junk,
+                                           junk_string_value_,
+                                           read_as_double,
+                                           &tail_pointer);
+      if (tail_pointer != NULL) {
+        if (allow_trailing_spaces) AdvanceToNonspace(&tail_pointer, end);
+        *processed_characters_count = tail_pointer - input;
+      }
+      return result;
+    }
+
+    // Ignore leading zeros in the integer part.
+    while (*current == '0') {
+      ++current;
+      if (current == end) {
+        *processed_characters_count = current - input;
+        return SignedZero(sign);
+      }
+    }
+  }
+
+  bool octal = leading_zero && (flags_ & ALLOW_OCTALS) != 0;
+
+  // Copy significant digits of the integer part (if any) to the buffer.
+  while (*current >= '0' && *current <= '9') {
+    if (significant_digits < kMaxSignificantDigits) {
+      ASSERT(buffer_pos < kBufferSize);
+      buffer[buffer_pos++] = static_cast<char>(*current);
+      significant_digits++;
+      // Will later check if it's an octal in the buffer.
+    } else {
+      insignificant_digits++;  // Move the digit into the exponential part.
+      nonzero_digit_dropped = nonzero_digit_dropped || *current != '0';
+    }
+    octal = octal && *current < '8';
+    ++current;
+    if (current == end) goto parsing_done;
+  }
+
+  if (significant_digits == 0) {
+    octal = false;
+  }
+
+  if (*current == '.') {
+    if (octal && !allow_trailing_junk) return junk_string_value_;
+    if (octal) goto parsing_done;
+
+    ++current;
+    if (current == end) {
+      if (significant_digits == 0 && !leading_zero) {
+        return junk_string_value_;
+      } else {
+        goto parsing_done;
+      }
+    }
+
+    if (significant_digits == 0) {
+      // octal = false;
+      // Integer part consists of 0 or is absent. Significant digits start after
+      // leading zeros (if any).
+      while (*current == '0') {
+        ++current;
+        if (current == end) {
+          *processed_characters_count = current - input;
+          return SignedZero(sign);
+        }
+        exponent--;  // Move this 0 into the exponent.
+      }
+    }
+
+    // There is a fractional part.
+    // We don't emit a '.', but adjust the exponent instead.
+    while (*current >= '0' && *current <= '9') {
+      if (significant_digits < kMaxSignificantDigits) {
+        ASSERT(buffer_pos < kBufferSize);
+        buffer[buffer_pos++] = static_cast<char>(*current);
+        significant_digits++;
+        exponent--;
+      } else {
+        // Ignore insignificant digits in the fractional part.
+        nonzero_digit_dropped = nonzero_digit_dropped || *current != '0';
+      }
+      ++current;
+      if (current == end) goto parsing_done;
+    }
+  }
+
+  if (!leading_zero && exponent == 0 && significant_digits == 0) {
+    // If leading_zeros is true then the string contains zeros.
+    // If exponent < 0 then string was [+-]\.0*...
+    // If significant_digits != 0 the string is not equal to 0.
+    // Otherwise there are no digits in the string.
+    return junk_string_value_;
+  }
+
+  // Parse exponential part.
+  if (*current == 'e' || *current == 'E') {
+    if (octal && !allow_trailing_junk) return junk_string_value_;
+    if (octal) goto parsing_done;
+    ++current;
+    if (current == end) {
+      if (allow_trailing_junk) {
+        goto parsing_done;
+      } else {
+        return junk_string_value_;
+      }
+    }
+    char sign = '+';
+    if (*current == '+' || *current == '-') {
+      sign = static_cast<char>(*current);
+      ++current;
+      if (current == end) {
+        if (allow_trailing_junk) {
+          goto parsing_done;
+        } else {
+          return junk_string_value_;
+        }
+      }
+    }
+
+    if (current == end || *current < '0' || *current > '9') {
+      if (allow_trailing_junk) {
+        goto parsing_done;
+      } else {
+        return junk_string_value_;
+      }
+    }
+
+    const int max_exponent = INT_MAX / 2;
+    ASSERT(-max_exponent / 2 <= exponent && exponent <= max_exponent / 2);
+    int num = 0;
+    do {
+      // Check overflow.
+      int digit = *current - '0';
+      if (num >= max_exponent / 10
+          && !(num == max_exponent / 10 && digit <= max_exponent % 10)) {
+        num = max_exponent;
+      } else {
+        num = num * 10 + digit;
+      }
+      ++current;
+    } while (current != end && *current >= '0' && *current <= '9');
+
+    exponent += (sign == '-' ? -num : num);
+  }
+
+  if (!(allow_trailing_spaces || allow_trailing_junk) && (current != end)) {
+    return junk_string_value_;
+  }
+  if (!allow_trailing_junk && AdvanceToNonspace(&current, end)) {
+    return junk_string_value_;
+  }
+  if (allow_trailing_spaces) {
+    AdvanceToNonspace(&current, end);
+  }
+
+  parsing_done:
+  exponent += insignificant_digits;
+
+  if (octal) {
+    double result;
+    const char* tail_pointer = NULL;
+    result = RadixStringToIeee<3>(buffer,
+                                  buffer + buffer_pos,
+                                  sign,
+                                  allow_trailing_junk,
+                                  junk_string_value_,
+                                  read_as_double,
+                                  &tail_pointer);
+    ASSERT(tail_pointer != NULL);
+    *processed_characters_count = current - input;
+    return result;
+  }
+
+  if (nonzero_digit_dropped) {
+    buffer[buffer_pos++] = '1';
+    exponent--;
+  }
+
+  ASSERT(buffer_pos < kBufferSize);
+  buffer[buffer_pos] = '\0';
+
+  double converted;
+  if (read_as_double) {
+    converted = Strtod(Vector<const char>(buffer, buffer_pos), exponent);
+  } else {
+    converted = Strtof(Vector<const char>(buffer, buffer_pos), exponent);
+  }
+  *processed_characters_count = current - input;
+  return sign? -converted: converted;
+}
+
+}  // namespace double_conversion
diff --git a/mfbt/double-conversion/double-conversion.h b/mfbt/double-conversion/double-conversion.h
new file mode 100644
index 0000000..0e7226d
--- /dev/null
+++ b/mfbt/double-conversion/double-conversion.h
@@ -0,0 +1,537 @@
+// Copyright 2012 the V8 project authors. All rights reserved.
+// Redistribution and use in source and binary forms, with or without
+// modification, are permitted provided that the following conditions are
+// met:
+//
+//     * Redistributions of source code must retain the above copyright
+//       notice, this list of conditions and the following disclaimer.
+//     * Redistributions in binary form must reproduce the above
+//       copyright notice, this list of conditions and the following
+//       disclaimer in the documentation and/or other materials provided
+//       with the distribution.
+//     * Neither the name of Google Inc. nor the names of its
+//       contributors may be used to endorse or promote products derived
+//       from this software without specific prior written permission.
+//
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+#ifndef DOUBLE_CONVERSION_DOUBLE_CONVERSION_H_
+#define DOUBLE_CONVERSION_DOUBLE_CONVERSION_H_
+
+#include "mozilla/Types.h"
+#include "utils.h"
+
+namespace double_conversion {
+
+class DoubleToStringConverter {
+ public:
+  // When calling ToFixed with a double > 10^kMaxFixedDigitsBeforePoint
+  // or a requested_digits parameter > kMaxFixedDigitsAfterPoint then the
+  // function returns false.
+  static const int kMaxFixedDigitsBeforePoint = 60;
+  static const int kMaxFixedDigitsAfterPoint = 60;
+
+  // When calling ToExponential with a requested_digits
+  // parameter > kMaxExponentialDigits then the function returns false.
+  static const int kMaxExponentialDigits = 120;
+
+  // When calling ToPrecision with a requested_digits
+  // parameter < kMinPrecisionDigits or requested_digits > kMaxPrecisionDigits
+  // then the function returns false.
+  static const int kMinPrecisionDigits = 1;
+  static const int kMaxPrecisionDigits = 120;
+
+  enum Flags {
+    NO_FLAGS = 0,
+    EMIT_POSITIVE_EXPONENT_SIGN = 1,
+    EMIT_TRAILING_DECIMAL_POINT = 2,
+    EMIT_TRAILING_ZERO_AFTER_POINT = 4,
+    UNIQUE_ZERO = 8
+  };
+
+  // Flags should be a bit-or combination of the possible Flags-enum.
+  //  - NO_FLAGS: no special flags.
+  //  - EMIT_POSITIVE_EXPONENT_SIGN: when the number is converted into exponent
+  //    form, emits a '+' for positive exponents. Example: 1.2e+2.
+  //  - EMIT_TRAILING_DECIMAL_POINT: when the input number is an integer and is
+  //    converted into decimal format then a trailing decimal point is appended.
+  //    Example: 2345.0 is converted to "2345.".
+  //  - EMIT_TRAILING_ZERO_AFTER_POINT: in addition to a trailing decimal point
+  //    emits a trailing '0'-character. This flag requires the
+  //    EXMIT_TRAILING_DECIMAL_POINT flag.
+  //    Example: 2345.0 is converted to "2345.0".
+  //  - UNIQUE_ZERO: "-0.0" is converted to "0.0".
+  //
+  // Infinity symbol and nan_symbol provide the string representation for these
+  // special values. If the string is NULL and the special value is encountered
+  // then the conversion functions return false.
+  //
+  // The exponent_character is used in exponential representations. It is
+  // usually 'e' or 'E'.
+  //
+  // When converting to the shortest representation the converter will
+  // represent input numbers in decimal format if they are in the interval
+  // [10^decimal_in_shortest_low; 10^decimal_in_shortest_high[
+  //    (lower boundary included, greater boundary excluded).
+  // Example: with decimal_in_shortest_low = -6 and
+  //               decimal_in_shortest_high = 21:
+  //   ToShortest(0.000001)  -> "0.000001"
+  //   ToShortest(0.0000001) -> "1e-7"
+  //   ToShortest(111111111111111111111.0)  -> "111111111111111110000"
+  //   ToShortest(100000000000000000000.0)  -> "100000000000000000000"
+  //   ToShortest(1111111111111111111111.0) -> "1.1111111111111111e+21"
+  //
+  // When converting to precision mode the converter may add
+  // max_leading_padding_zeroes before returning the number in exponential
+  // format.
+  // Example with max_leading_padding_zeroes_in_precision_mode = 6.
+  //   ToPrecision(0.0000012345, 2) -> "0.0000012"
+  //   ToPrecision(0.00000012345, 2) -> "1.2e-7"
+  // Similarily the converter may add up to
+  // max_trailing_padding_zeroes_in_precision_mode in precision mode to avoid
+  // returning an exponential representation. A zero added by the
+  // EMIT_TRAILING_ZERO_AFTER_POINT flag is counted for this limit.
+  // Examples for max_trailing_padding_zeroes_in_precision_mode = 1:
+  //   ToPrecision(230.0, 2) -> "230"
+  //   ToPrecision(230.0, 2) -> "230."  with EMIT_TRAILING_DECIMAL_POINT.
+  //   ToPrecision(230.0, 2) -> "2.3e2" with EMIT_TRAILING_ZERO_AFTER_POINT.
+  DoubleToStringConverter(int flags,
+                          const char* infinity_symbol,
+                          const char* nan_symbol,
+                          char exponent_character,
+                          int decimal_in_shortest_low,
+                          int decimal_in_shortest_high,
+                          int max_leading_padding_zeroes_in_precision_mode,
+                          int max_trailing_padding_zeroes_in_precision_mode)
+      : flags_(flags),
+        infinity_symbol_(infinity_symbol),
+        nan_symbol_(nan_symbol),
+        exponent_character_(exponent_character),
+        decimal_in_shortest_low_(decimal_in_shortest_low),
+        decimal_in_shortest_high_(decimal_in_shortest_high),
+        max_leading_padding_zeroes_in_precision_mode_(
+            max_leading_padding_zeroes_in_precision_mode),
+        max_trailing_padding_zeroes_in_precision_mode_(
+            max_trailing_padding_zeroes_in_precision_mode) {
+    // When 'trailing zero after the point' is set, then 'trailing point'
+    // must be set too.
+    ASSERT(((flags & EMIT_TRAILING_DECIMAL_POINT) != 0) ||
+        !((flags & EMIT_TRAILING_ZERO_AFTER_POINT) != 0));
+  }
+
+  // Returns a converter following the EcmaScript specification.
+  static MFBT_API(const DoubleToStringConverter&) EcmaScriptConverter();
+
+  // Computes the shortest string of digits that correctly represent the input
+  // number. Depending on decimal_in_shortest_low and decimal_in_shortest_high
+  // (see constructor) it then either returns a decimal representation, or an
+  // exponential representation.
+  // Example with decimal_in_shortest_low = -6,
+  //              decimal_in_shortest_high = 21,
+  //              EMIT_POSITIVE_EXPONENT_SIGN activated, and
+  //              EMIT_TRAILING_DECIMAL_POINT deactived:
+  //   ToShortest(0.000001)  -> "0.000001"
+  //   ToShortest(0.0000001) -> "1e-7"
+  //   ToShortest(111111111111111111111.0)  -> "111111111111111110000"
+  //   ToShortest(100000000000000000000.0)  -> "100000000000000000000"
+  //   ToShortest(1111111111111111111111.0) -> "1.1111111111111111e+21"
+  //
+  // Note: the conversion may round the output if the returned string
+  // is accurate enough to uniquely identify the input-number.
+  // For example the most precise representation of the double 9e59 equals
+  // "899999999999999918767229449717619953810131273674690656206848", but
+  // the converter will return the shorter (but still correct) "9e59".
+  //
+  // Returns true if the conversion succeeds. The conversion always succeeds
+  // except when the input value is special and no infinity_symbol or
+  // nan_symbol has been given to the constructor.
+  bool ToShortest(double value, StringBuilder* result_builder) const {
+    return ToShortestIeeeNumber(value, result_builder, SHORTEST);
+  }
+
+  // Same as ToShortest, but for single-precision floats.
+  bool ToShortestSingle(float value, StringBuilder* result_builder) const {
+    return ToShortestIeeeNumber(value, result_builder, SHORTEST_SINGLE);
+  }
+
+
+  // Computes a decimal representation with a fixed number of digits after the
+  // decimal point. The last emitted digit is rounded.
+  //
+  // Examples:
+  //   ToFixed(3.12, 1) -> "3.1"
+  //   ToFixed(3.1415, 3) -> "3.142"
+  //   ToFixed(1234.56789, 4) -> "1234.5679"
+  //   ToFixed(1.23, 5) -> "1.23000"
+  //   ToFixed(0.1, 4) -> "0.1000"
+  //   ToFixed(1e30, 2) -> "1000000000000000019884624838656.00"
+  //   ToFixed(0.1, 30) -> "0.100000000000000005551115123126"
+  //   ToFixed(0.1, 17) -> "0.10000000000000001"
+  //
+  // If requested_digits equals 0, then the tail of the result depends on
+  // the EMIT_TRAILING_DECIMAL_POINT and EMIT_TRAILING_ZERO_AFTER_POINT.
+  // Examples, for requested_digits == 0,
+  //   let EMIT_TRAILING_DECIMAL_POINT and EMIT_TRAILING_ZERO_AFTER_POINT be
+  //    - false and false: then 123.45 -> 123
+  //                             0.678 -> 1
+  //    - true and false: then 123.45 -> 123.
+  //                            0.678 -> 1.
+  //    - true and true: then 123.45 -> 123.0
+  //                           0.678 -> 1.0
+  //
+  // Returns true if the conversion succeeds. The conversion always succeeds
+  // except for the following cases:
+  //   - the input value is special and no infinity_symbol or nan_symbol has
+  //     been provided to the constructor,
+  //   - 'value' > 10^kMaxFixedDigitsBeforePoint, or
+  //   - 'requested_digits' > kMaxFixedDigitsAfterPoint.
+  // The last two conditions imply that the result will never contain more than
+  // 1 + kMaxFixedDigitsBeforePoint + 1 + kMaxFixedDigitsAfterPoint characters
+  // (one additional character for the sign, and one for the decimal point).
+  MFBT_API(bool) ToFixed(double value,
+               int requested_digits,
+               StringBuilder* result_builder) const;
+
+  // Computes a representation in exponential format with requested_digits
+  // after the decimal point. The last emitted digit is rounded.
+  // If requested_digits equals -1, then the shortest exponential representation
+  // is computed.
+  //
+  // Examples with EMIT_POSITIVE_EXPONENT_SIGN deactivated, and
+  //               exponent_character set to 'e'.
+  //   ToExponential(3.12, 1) -> "3.1e0"
+  //   ToExponential(5.0, 3) -> "5.000e0"
+  //   ToExponential(0.001, 2) -> "1.00e-3"
+  //   ToExponential(3.1415, -1) -> "3.1415e0"
+  //   ToExponential(3.1415, 4) -> "3.1415e0"
+  //   ToExponential(3.1415, 3) -> "3.142e0"
+  //   ToExponential(123456789000000, 3) -> "1.235e14"
+  //   ToExponential(1000000000000000019884624838656.0, -1) -> "1e30"
+  //   ToExponential(1000000000000000019884624838656.0, 32) ->
+  //                     "1.00000000000000001988462483865600e30"
+  //   ToExponential(1234, 0) -> "1e3"
+  //
+  // Returns true if the conversion succeeds. The conversion always succeeds
+  // except for the following cases:
+  //   - the input value is special and no infinity_symbol or nan_symbol has
+  //     been provided to the constructor,
+  //   - 'requested_digits' > kMaxExponentialDigits.
+  // The last condition implies that the result will never contain more than
+  // kMaxExponentialDigits + 8 characters (the sign, the digit before the
+  // decimal point, the decimal point, the exponent character, the
+  // exponent's sign, and at most 3 exponent digits).
+  MFBT_API(bool) ToExponential(double value,
+                     int requested_digits,
+                     StringBuilder* result_builder) const;
+
+  // Computes 'precision' leading digits of the given 'value' and returns them
+  // either in exponential or decimal format, depending on
+  // max_{leading|trailing}_padding_zeroes_in_precision_mode (given to the
+  // constructor).
+  // The last computed digit is rounded.
+  //
+  // Example with max_leading_padding_zeroes_in_precision_mode = 6.
+  //   ToPrecision(0.0000012345, 2) -> "0.0000012"
+  //   ToPrecision(0.00000012345, 2) -> "1.2e-7"
+  // Similarily the converter may add up to
+  // max_trailing_padding_zeroes_in_precision_mode in precision mode to avoid
+  // returning an exponential representation. A zero added by the
+  // EMIT_TRAILING_ZERO_AFTER_POINT flag is counted for this limit.
+  // Examples for max_trailing_padding_zeroes_in_precision_mode = 1:
+  //   ToPrecision(230.0, 2) -> "230"
+  //   ToPrecision(230.0, 2) -> "230."  with EMIT_TRAILING_DECIMAL_POINT.
+  //   ToPrecision(230.0, 2) -> "2.3e2" with EMIT_TRAILING_ZERO_AFTER_POINT.
+  // Examples for max_trailing_padding_zeroes_in_precision_mode = 3, and no
+  //    EMIT_TRAILING_ZERO_AFTER_POINT:
+  //   ToPrecision(123450.0, 6) -> "123450"
+  //   ToPrecision(123450.0, 5) -> "123450"
+  //   ToPrecision(123450.0, 4) -> "123500"
+  //   ToPrecision(123450.0, 3) -> "123000"
+  //   ToPrecision(123450.0, 2) -> "1.2e5"
+  //
+  // Returns true if the conversion succeeds. The conversion always succeeds
+  // except for the following cases:
+  //   - the input value is special and no infinity_symbol or nan_symbol has
+  //     been provided to the constructor,
+  //   - precision < kMinPericisionDigits
+  //   - precision > kMaxPrecisionDigits
+  // The last condition implies that the result will never contain more than
+  // kMaxPrecisionDigits + 7 characters (the sign, the decimal point, the
+  // exponent character, the exponent's sign, and at most 3 exponent digits).
+  MFBT_API(bool) ToPrecision(double value,
+                   int precision,
+                   StringBuilder* result_builder) const;
+
+  enum DtoaMode {
+    // Produce the shortest correct representation.
+    // For example the output of 0.299999999999999988897 is (the less accurate
+    // but correct) 0.3.
+    SHORTEST,
+    // Same as SHORTEST, but for single-precision floats.
+    SHORTEST_SINGLE,
+    // Produce a fixed number of digits after the decimal point.
+    // For instance fixed(0.1, 4) becomes 0.1000
+    // If the input number is big, the output will be big.
+    FIXED,
+    // Fixed number of digits (independent of the decimal point).
+    PRECISION
+  };
+
+  // The maximal number of digits that are needed to emit a double in base 10.
+  // A higher precision can be achieved by using more digits, but the shortest
+  // accurate representation of any double will never use more digits than
+  // kBase10MaximalLength.
+  // Note that DoubleToAscii null-terminates its input. So the given buffer
+  // should be at least kBase10MaximalLength + 1 characters long.
+  static const MFBT_DATA(int) kBase10MaximalLength = 17;
+
+  // Converts the given double 'v' to ascii. 'v' must not be NaN, +Infinity, or
+  // -Infinity. In SHORTEST_SINGLE-mode this restriction also applies to 'v'
+  // after it has been casted to a single-precision float. That is, in this
+  // mode static_cast<float>(v) must not be NaN, +Infinity or -Infinity.
+  //
+  // The result should be interpreted as buffer * 10^(point-length).
+  //
+  // The output depends on the given mode:
+  //  - SHORTEST: produce the least amount of digits for which the internal
+  //   identity requirement is still satisfied. If the digits are printed
+  //   (together with the correct exponent) then reading this number will give
+  //   'v' again. The buffer will choose the representation that is closest to
+  //   'v'. If there are two at the same distance, than the one farther away
+  //   from 0 is chosen (halfway cases - ending with 5 - are rounded up).
+  //   In this mode the 'requested_digits' parameter is ignored.
+  //  - SHORTEST_SINGLE: same as SHORTEST but with single-precision.
+  //  - FIXED: produces digits necessary to print a given number with
+  //   'requested_digits' digits after the decimal point. The produced digits
+  //   might be too short in which case the caller has to fill the remainder
+  //   with '0's.
+  //   Example: toFixed(0.001, 5) is allowed to return buffer="1", point=-2.
+  //   Halfway cases are rounded towards +/-Infinity (away from 0). The call
+  //   toFixed(0.15, 2) thus returns buffer="2", point=0.
+  //   The returned buffer may contain digits that would be truncated from the
+  //   shortest representation of the input.
+  //  - PRECISION: produces 'requested_digits' where the first digit is not '0'.
+  //   Even though the length of produced digits usually equals
+  //   'requested_digits', the function is allowed to return fewer digits, in
+  //   which case the caller has to fill the missing digits with '0's.
+  //   Halfway cases are again rounded away from 0.
+  // DoubleToAscii expects the given buffer to be big enough to hold all
+  // digits and a terminating null-character. In SHORTEST-mode it expects a
+  // buffer of at least kBase10MaximalLength + 1. In all other modes the
+  // requested_digits parameter and the padding-zeroes limit the size of the
+  // output. Don't forget the decimal point, the exponent character and the
+  // terminating null-character when computing the maximal output size.
+  // The given length is only used in debug mode to ensure the buffer is big
+  // enough.
+  static MFBT_API(void) DoubleToAscii(double v,
+                            DtoaMode mode,
+                            int requested_digits,
+                            char* buffer,
+                            int buffer_length,
+                            bool* sign,
+                            int* length,
+                            int* point);
+
+ private:
+  // Implementation for ToShortest and ToShortestSingle.
+  MFBT_API(bool) ToShortestIeeeNumber(double value,
+                            StringBuilder* result_builder,
+                            DtoaMode mode) const;
+
+  // If the value is a special value (NaN or Infinity) constructs the
+  // corresponding string using the configured infinity/nan-symbol.
+  // If either of them is NULL or the value is not special then the
+  // function returns false.
+  MFBT_API(bool) HandleSpecialValues(double value, StringBuilder* result_builder) const;
+  // Constructs an exponential representation (i.e. 1.234e56).
+  // The given exponent assumes a decimal point after the first decimal digit.
+  MFBT_API(void) CreateExponentialRepresentation(const char* decimal_digits,
+                                       int length,
+                                       int exponent,
+                                       StringBuilder* result_builder) const;
+  // Creates a decimal representation (i.e 1234.5678).
+  MFBT_API(void) CreateDecimalRepresentation(const char* decimal_digits,
+                                   int length,
+                                   int decimal_point,
+                                   int digits_after_point,
+                                   StringBuilder* result_builder) const;
+
+  const int flags_;
+  const char* const infinity_symbol_;
+  const char* const nan_symbol_;
+  const char exponent_character_;
+  const int decimal_in_shortest_low_;
+  const int decimal_in_shortest_high_;
+  const int max_leading_padding_zeroes_in_precision_mode_;
+  const int max_trailing_padding_zeroes_in_precision_mode_;
+
+  DISALLOW_IMPLICIT_CONSTRUCTORS(DoubleToStringConverter);
+};
+
+
+class StringToDoubleConverter {
+ public:
+  // Enumeration for allowing octals and ignoring junk when converting
+  // strings to numbers.
+  enum Flags {
+    NO_FLAGS = 0,
+    ALLOW_HEX = 1,
+    ALLOW_OCTALS = 2,
+    ALLOW_TRAILING_JUNK = 4,
+    ALLOW_LEADING_SPACES = 8,
+    ALLOW_TRAILING_SPACES = 16,
+    ALLOW_SPACES_AFTER_SIGN = 32
+  };
+
+  // Flags should be a bit-or combination of the possible Flags-enum.
+  //  - NO_FLAGS: no special flags.
+  //  - ALLOW_HEX: recognizes the prefix "0x". Hex numbers may only be integers.
+  //      Ex: StringToDouble("0x1234") -> 4660.0
+  //          In StringToDouble("0x1234.56") the characters ".56" are trailing
+  //          junk. The result of the call is hence dependent on
+  //          the ALLOW_TRAILING_JUNK flag and/or the junk value.
+  //      With this flag "0x" is a junk-string. Even with ALLOW_TRAILING_JUNK,
+  //      the string will not be parsed as "0" followed by junk.
+  //
+  //  - ALLOW_OCTALS: recognizes the prefix "0" for octals:
+  //      If a sequence of octal digits starts with '0', then the number is
+  //      read as octal integer. Octal numbers may only be integers.
+  //      Ex: StringToDouble("01234") -> 668.0
+  //          StringToDouble("012349") -> 12349.0  // Not a sequence of octal
+  //                                               // digits.
+  //          In StringToDouble("01234.56") the characters ".56" are trailing
+  //          junk. The result of the call is hence dependent on
+  //          the ALLOW_TRAILING_JUNK flag and/or the junk value.
+  //          In StringToDouble("01234e56") the characters "e56" are trailing
+  //          junk, too.
+  //  - ALLOW_TRAILING_JUNK: ignore trailing characters that are not part of
+  //      a double literal.
+  //  - ALLOW_LEADING_SPACES: skip over leading spaces.
+  //  - ALLOW_TRAILING_SPACES: ignore trailing spaces.
+  //  - ALLOW_SPACES_AFTER_SIGN: ignore spaces after the sign.
+  //       Ex: StringToDouble("-   123.2") -> -123.2.
+  //           StringToDouble("+   123.2") -> 123.2
+  //
+  // empty_string_value is returned when an empty string is given as input.
+  // If ALLOW_LEADING_SPACES or ALLOW_TRAILING_SPACES are set, then a string
+  // containing only spaces is converted to the 'empty_string_value', too.
+  //
+  // junk_string_value is returned when
+  //  a) ALLOW_TRAILING_JUNK is not set, and a junk character (a character not
+  //     part of a double-literal) is found.
+  //  b) ALLOW_TRAILING_JUNK is set, but the string does not start with a
+  //     double literal.
+  //
+  // infinity_symbol and nan_symbol are strings that are used to detect
+  // inputs that represent infinity and NaN. They can be null, in which case
+  // they are ignored.
+  // The conversion routine first reads any possible signs. Then it compares the
+  // following character of the input-string with the first character of
+  // the infinity, and nan-symbol. If either matches, the function assumes, that
+  // a match has been found, and expects the following input characters to match
+  // the remaining characters of the special-value symbol.
+  // This means that the following restrictions apply to special-value symbols:
+  //  - they must not start with signs ('+', or '-'),
+  //  - they must not have the same first character.
+  //  - they must not start with digits.
+  //
+  // Examples:
+  //  flags = ALLOW_HEX | ALLOW_TRAILING_JUNK,
+  //  empty_string_value = 0.0,
+  //  junk_string_value = NaN,
+  //  infinity_symbol = "infinity",
+  //  nan_symbol = "nan":
+  //    StringToDouble("0x1234") -> 4660.0.
+  //    StringToDouble("0x1234K") -> 4660.0.
+  //    StringToDouble("") -> 0.0  // empty_string_value.
+  //    StringToDouble(" ") -> NaN  // junk_string_value.
+  //    StringToDouble(" 1") -> NaN  // junk_string_value.
+  //    StringToDouble("0x") -> NaN  // junk_string_value.
+  //    StringToDouble("-123.45") -> -123.45.
+  //    StringToDouble("--123.45") -> NaN  // junk_string_value.
+  //    StringToDouble("123e45") -> 123e45.
+  //    StringToDouble("123E45") -> 123e45.
+  //    StringToDouble("123e+45") -> 123e45.
+  //    StringToDouble("123E-45") -> 123e-45.
+  //    StringToDouble("123e") -> 123.0  // trailing junk ignored.
+  //    StringToDouble("123e-") -> 123.0  // trailing junk ignored.
+  //    StringToDouble("+NaN") -> NaN  // NaN string literal.
+  //    StringToDouble("-infinity") -> -inf.  // infinity literal.
+  //    StringToDouble("Infinity") -> NaN  // junk_string_value.
+  //
+  //  flags = ALLOW_OCTAL | ALLOW_LEADING_SPACES,
+  //  empty_string_value = 0.0,
+  //  junk_string_value = NaN,
+  //  infinity_symbol = NULL,
+  //  nan_symbol = NULL:
+  //    StringToDouble("0x1234") -> NaN  // junk_string_value.
+  //    StringToDouble("01234") -> 668.0.
+  //    StringToDouble("") -> 0.0  // empty_string_value.
+  //    StringToDouble(" ") -> 0.0  // empty_string_value.
+  //    StringToDouble(" 1") -> 1.0
+  //    StringToDouble("0x") -> NaN  // junk_string_value.
+  //    StringToDouble("0123e45") -> NaN  // junk_string_value.
+  //    StringToDouble("01239E45") -> 1239e45.
+  //    StringToDouble("-infinity") -> NaN  // junk_string_value.
+  //    StringToDouble("NaN") -> NaN  // junk_string_value.
+  StringToDoubleConverter(int flags,
+                          double empty_string_value,
+                          double junk_string_value,
+                          const char* infinity_symbol,
+                          const char* nan_symbol)
+      : flags_(flags),
+        empty_string_value_(empty_string_value),
+        junk_string_value_(junk_string_value),
+        infinity_symbol_(infinity_symbol),
+        nan_symbol_(nan_symbol) {
+  }
+
+  // Performs the conversion.
+  // The output parameter 'processed_characters_count' is set to the number
+  // of characters that have been processed to read the number.
+  // Spaces than are processed with ALLOW_{LEADING|TRAILING}_SPACES are included
+  // in the 'processed_characters_count'. Trailing junk is never included.
+  double StringToDouble(const char* buffer,
+                        int length,
+                        int* processed_characters_count) {
+    return StringToIeee(buffer, length, processed_characters_count, true);
+  }
+
+  // Same as StringToDouble but reads a float.
+  // Note that this is not equivalent to static_cast<float>(StringToDouble(...))
+  // due to potential double-rounding.
+  float StringToFloat(const char* buffer,
+                      int length,
+                      int* processed_characters_count) {
+    return static_cast<float>(StringToIeee(buffer, length,
+                                           processed_characters_count, false));
+  }
+
+ private:
+  const int flags_;
+  const double empty_string_value_;
+  const double junk_string_value_;
+  const char* const infinity_symbol_;
+  const char* const nan_symbol_;
+
+  double StringToIeee(const char* buffer,
+                      int length,
+                      int* processed_characters_count,
+                      bool read_as_double);
+
+  DISALLOW_IMPLICIT_CONSTRUCTORS(StringToDoubleConverter);
+};
+
+}  // namespace double_conversion
+
+#endif  // DOUBLE_CONVERSION_DOUBLE_CONVERSION_H_
diff --git a/mfbt/double-conversion/fast-dtoa.cc b/mfbt/double-conversion/fast-dtoa.cc
new file mode 100644
index 0000000..0609422
--- /dev/null
+++ b/mfbt/double-conversion/fast-dtoa.cc
@@ -0,0 +1,664 @@
+// Copyright 2012 the V8 project authors. All rights reserved.
+// Redistribution and use in source and binary forms, with or without
+// modification, are permitted provided that the following conditions are
+// met:
+//
+//     * Redistributions of source code must retain the above copyright
+//       notice, this list of conditions and the following disclaimer.
+//     * Redistributions in binary form must reproduce the above
+//       copyright notice, this list of conditions and the following
+//       disclaimer in the documentation and/or other materials provided
+//       with the distribution.
+//     * Neither the name of Google Inc. nor the names of its
+//       contributors may be used to endorse or promote products derived
+//       from this software without specific prior written permission.
+//
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+#include "fast-dtoa.h"
+
+#include "cached-powers.h"
+#include "diy-fp.h"
+#include "ieee.h"
+
+namespace double_conversion {
+
+// The minimal and maximal target exponent define the range of w's binary
+// exponent, where 'w' is the result of multiplying the input by a cached power
+// of ten.
+//
+// A different range might be chosen on a different platform, to optimize digit
+// generation, but a smaller range requires more powers of ten to be cached.
+static const int kMinimalTargetExponent = -60;
+static const int kMaximalTargetExponent = -32;
+
+
+// Adjusts the last digit of the generated number, and screens out generated
+// solutions that may be inaccurate. A solution may be inaccurate if it is
+// outside the safe interval, or if we cannot prove that it is closer to the
+// input than a neighboring representation of the same length.
+//
+// Input: * buffer containing the digits of too_high / 10^kappa
+//        * the buffer's length
+//        * distance_too_high_w == (too_high - w).f() * unit
+//        * unsafe_interval == (too_high - too_low).f() * unit
+//        * rest = (too_high - buffer * 10^kappa).f() * unit
+//        * ten_kappa = 10^kappa * unit
+//        * unit = the common multiplier
+// Output: returns true if the buffer is guaranteed to contain the closest
+//    representable number to the input.
+//  Modifies the generated digits in the buffer to approach (round towards) w.
+static bool RoundWeed(Vector<char> buffer,
+                      int length,
+                      uint64_t distance_too_high_w,
+                      uint64_t unsafe_interval,
+                      uint64_t rest,
+                      uint64_t ten_kappa,
+                      uint64_t unit) {
+  uint64_t small_distance = distance_too_high_w - unit;
+  uint64_t big_distance = distance_too_high_w + unit;
+  // Let w_low  = too_high - big_distance, and
+  //     w_high = too_high - small_distance.
+  // Note: w_low < w < w_high
+  //
+  // The real w (* unit) must lie somewhere inside the interval
+  // ]w_low; w_high[ (often written as "(w_low; w_high)")
+
+  // Basically the buffer currently contains a number in the unsafe interval
+  // ]too_low; too_high[ with too_low < w < too_high
+  //
+  //  too_high - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
+  //                     ^v 1 unit            ^      ^                 ^      ^
+  //  boundary_high ---------------------     .      .                 .      .
+  //                     ^v 1 unit            .      .                 .      .
+  //   - - - - - - - - - - - - - - - - - - -  +  - - + - - - - - -     .      .
+  //                                          .      .         ^       .      .
+  //                                          .  big_distance  .       .      .
+  //                                          .      .         .       .    rest
+  //                              small_distance     .         .       .      .
+  //                                          v      .         .       .      .
+  //  w_high - - - - - - - - - - - - - - - - - -     .         .       .      .
+  //                     ^v 1 unit                   .         .       .      .
+  //  w ----------------------------------------     .         .       .      .
+  //                     ^v 1 unit                   v         .       .      .
+  //  w_low  - - - - - - - - - - - - - - - - - - - - -         .       .      .
+  //                                                           .       .      v
+  //  buffer --------------------------------------------------+-------+--------
+  //                                                           .       .
+  //                                                  safe_interval    .
+  //                                                           v       .
+  //   - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -     .
+  //                     ^v 1 unit                                     .
+  //  boundary_low -------------------------                     unsafe_interval
+  //                     ^v 1 unit                                     v
+  //  too_low  - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
+  //
+  //
+  // Note that the value of buffer could lie anywhere inside the range too_low
+  // to too_high.
+  //
+  // boundary_low, boundary_high and w are approximations of the real boundaries
+  // and v (the input number). They are guaranteed to be precise up to one unit.
+  // In fact the error is guaranteed to be strictly less than one unit.
+  //
+  // Anything that lies outside the unsafe interval is guaranteed not to round
+  // to v when read again.
+  // Anything that lies inside the safe interval is guaranteed to round to v
+  // when read again.
+  // If the number inside the buffer lies inside the unsafe interval but not
+  // inside the safe interval then we simply do not know and bail out (returning
+  // false).
+  //
+  // Similarly we have to take into account the imprecision of 'w' when finding
+  // the closest representation of 'w'. If we have two potential
+  // representations, and one is closer to both w_low and w_high, then we know
+  // it is closer to the actual value v.
+  //
+  // By generating the digits of too_high we got the largest (closest to
+  // too_high) buffer that is still in the unsafe interval. In the case where
+  // w_high < buffer < too_high we try to decrement the buffer.
+  // This way the buffer approaches (rounds towards) w.
+  // There are 3 conditions that stop the decrementation process:
+  //   1) the buffer is already below w_high
+  //   2) decrementing the buffer would make it leave the unsafe interval
+  //   3) decrementing the buffer would yield a number below w_high and farther
+  //      away than the current number. In other words:
+  //              (buffer{-1} < w_high) && w_high - buffer{-1} > buffer - w_high
+  // Instead of using the buffer directly we use its distance to too_high.
+  // Conceptually rest ~= too_high - buffer
+  // We need to do the following tests in this order to avoid over- and
+  // underflows.
+  ASSERT(rest <= unsafe_interval);
+  while (rest < small_distance &&  // Negated condition 1
+         unsafe_interval - rest >= ten_kappa &&  // Negated condition 2
+         (rest + ten_kappa < small_distance ||  // buffer{-1} > w_high
+          small_distance - rest >= rest + ten_kappa - small_distance)) {
+    buffer[length - 1]--;
+    rest += ten_kappa;
+  }
+
+  // We have approached w+ as much as possible. We now test if approaching w-
+  // would require changing the buffer. If yes, then we have two possible
+  // representations close to w, but we cannot decide which one is closer.
+  if (rest < big_distance &&
+      unsafe_interval - rest >= ten_kappa &&
+      (rest + ten_kappa < big_distance ||
+       big_distance - rest > rest + ten_kappa - big_distance)) {
+    return false;
+  }
+
+  // Weeding test.
+  //   The safe interval is [too_low + 2 ulp; too_high - 2 ulp]
+  //   Since too_low = too_high - unsafe_interval this is equivalent to
+  //      [too_high - unsafe_interval + 4 ulp; too_high - 2 ulp]
+  //   Conceptually we have: rest ~= too_high - buffer
+  return (2 * unit <= rest) && (rest <= unsafe_interval - 4 * unit);
+}
+
+
+// Rounds the buffer upwards if the result is closer to v by possibly adding
+// 1 to the buffer. If the precision of the calculation is not sufficient to
+// round correctly, return false.
+// The rounding might shift the whole buffer in which case the kappa is
+// adjusted. For example "99", kappa = 3 might become "10", kappa = 4.
+//
+// If 2*rest > ten_kappa then the buffer needs to be round up.
+// rest can have an error of +/- 1 unit. This function accounts for the
+// imprecision and returns false, if the rounding direction cannot be
+// unambiguously determined.
+//
+// Precondition: rest < ten_kappa.
+static bool RoundWeedCounted(Vector<char> buffer,
+                             int length,
+                             uint64_t rest,
+                             uint64_t ten_kappa,
+                             uint64_t unit,
+                             int* kappa) {
+  ASSERT(rest < ten_kappa);
+  // The following tests are done in a specific order to avoid overflows. They
+  // will work correctly with any uint64 values of rest < ten_kappa and unit.
+  //
+  // If the unit is too big, then we don't know which way to round. For example
+  // a unit of 50 means that the real number lies within rest +/- 50. If
+  // 10^kappa == 40 then there is no way to tell which way to round.
+  if (unit >= ten_kappa) return false;
+  // Even if unit is just half the size of 10^kappa we are already completely
+  // lost. (And after the previous test we know that the expression will not
+  // over/underflow.)
+  if (ten_kappa - unit <= unit) return false;
+  // If 2 * (rest + unit) <= 10^kappa we can safely round down.
+  if ((ten_kappa - rest > rest) && (ten_kappa - 2 * rest >= 2 * unit)) {
+    return true;
+  }
+  // If 2 * (rest - unit) >= 10^kappa, then we can safely round up.
+  if ((rest > unit) && (ten_kappa - (rest - unit) <= (rest - unit))) {
+    // Increment the last digit recursively until we find a non '9' digit.
+    buffer[length - 1]++;
+    for (int i = length - 1; i > 0; --i) {
+      if (buffer[i] != '0' + 10) break;
+      buffer[i] = '0';
+      buffer[i - 1]++;
+    }
+    // If the first digit is now '0'+ 10 we had a buffer with all '9's. With the
+    // exception of the first digit all digits are now '0'. Simply switch the
+    // first digit to '1' and adjust the kappa. Example: "99" becomes "10" and
+    // the power (the kappa) is increased.
+    if (buffer[0] == '0' + 10) {
+      buffer[0] = '1';
+      (*kappa) += 1;
+    }
+    return true;
+  }
+  return false;
+}
+
+// Returns the biggest power of ten that is less than or equal to the given
+// number. We furthermore receive the maximum number of bits 'number' has.
+//
+// Returns power == 10^(exponent_plus_one-1) such that
+//    power <= number < power * 10.
+// If number_bits == 0 then 0^(0-1) is returned.
+// The number of bits must be <= 32.
+// Precondition: number < (1 << (number_bits + 1)).
+
+// Inspired by the method for finding an integer log base 10 from here:
+// http://graphics.stanford.edu/~seander/bithacks.html#IntegerLog10
+static unsigned int const kSmallPowersOfTen[] =
+    {0, 1, 10, 100, 1000, 10000, 100000, 1000000, 10000000, 100000000,
+     1000000000};
+
+static void BiggestPowerTen(uint32_t number,
+                            int number_bits,
+                            uint32_t* power,
+                            int* exponent_plus_one) {
+  ASSERT(number < (1u << (number_bits + 1)));
+  // 1233/4096 is approximately 1/lg(10).
+  int exponent_plus_one_guess = ((number_bits + 1) * 1233 >> 12);
+  // We increment to skip over the first entry in the kPowersOf10 table.
+  // Note: kPowersOf10[i] == 10^(i-1).
+  exponent_plus_one_guess++;
+  // We don't have any guarantees that 2^number_bits <= number.
+  // TODO(floitsch): can we change the 'while' into an 'if'? We definitely see
+  // number < (2^number_bits - 1), but I haven't encountered
+  // number < (2^number_bits - 2) yet.
+  while (number < kSmallPowersOfTen[exponent_plus_one_guess]) {
+    exponent_plus_one_guess--;
+  }
+  *power = kSmallPowersOfTen[exponent_plus_one_guess];
+  *exponent_plus_one = exponent_plus_one_guess;
+}
+
+// Generates the digits of input number w.
+// w is a floating-point number (DiyFp), consisting of a significand and an
+// exponent. Its exponent is bounded by kMinimalTargetExponent and
+// kMaximalTargetExponent.
+//       Hence -60 <= w.e() <= -32.
+//
+// Returns false if it fails, in which case the generated digits in the buffer
+// should not be used.
+// Preconditions:
+//  * low, w and high are correct up to 1 ulp (unit in the last place). That
+//    is, their error must be less than a unit of their last digits.
+//  * low.e() == w.e() == high.e()
+//  * low < w < high, and taking into account their error: low~ <= high~
+//  * kMinimalTargetExponent <= w.e() <= kMaximalTargetExponent
+// Postconditions: returns false if procedure fails.
+//   otherwise:
+//     * buffer is not null-terminated, but len contains the number of digits.
+//     * buffer contains the shortest possible decimal digit-sequence
+//       such that LOW < buffer * 10^kappa < HIGH, where LOW and HIGH are the
+//       correct values of low and high (without their error).
+//     * if more than one decimal representation gives the minimal number of
+//       decimal digits then the one closest to W (where W is the correct value
+//       of w) is chosen.
+// Remark: this procedure takes into account the imprecision of its input
+//   numbers. If the precision is not enough to guarantee all the postconditions
+//   then false is returned. This usually happens rarely (~0.5%).
+//
+// Say, for the sake of example, that
+//   w.e() == -48, and w.f() == 0x1234567890abcdef
+// w's value can be computed by w.f() * 2^w.e()
+// We can obtain w's integral digits by simply shifting w.f() by -w.e().
+//  -> w's integral part is 0x1234
+//  w's fractional part is therefore 0x567890abcdef.
+// Printing w's integral part is easy (simply print 0x1234 in decimal).
+// In order to print its fraction we repeatedly multiply the fraction by 10 and
+// get each digit. Example the first digit after the point would be computed by
+//   (0x567890abcdef * 10) >> 48. -> 3
+// The whole thing becomes slightly more complicated because we want to stop
+// once we have enough digits. That is, once the digits inside the buffer
+// represent 'w' we can stop. Everything inside the interval low - high
+// represents w. However we have to pay attention to low, high and w's
+// imprecision.
+static bool DigitGen(DiyFp low,
+                     DiyFp w,
+                     DiyFp high,
+                     Vector<char> buffer,
+                     int* length,
+                     int* kappa) {
+  ASSERT(low.e() == w.e() && w.e() == high.e());
+  ASSERT(low.f() + 1 <= high.f() - 1);
+  ASSERT(kMinimalTargetExponent <= w.e() && w.e() <= kMaximalTargetExponent);
+  // low, w and high are imprecise, but by less than one ulp (unit in the last
+  // place).
+  // If we remove (resp. add) 1 ulp from low (resp. high) we are certain that
+  // the new numbers are outside of the interval we want the final
+  // representation to lie in.
+  // Inversely adding (resp. removing) 1 ulp from low (resp. high) would yield
+  // numbers that are certain to lie in the interval. We will use this fact
+  // later on.
+  // We will now start by generating the digits within the uncertain
+  // interval. Later we will weed out representations that lie outside the safe
+  // interval and thus _might_ lie outside the correct interval.
+  uint64_t unit = 1;
+  DiyFp too_low = DiyFp(low.f() - unit, low.e());
+  DiyFp too_high = DiyFp(high.f() + unit, high.e());
+  // too_low and too_high are guaranteed to lie outside the interval we want the
+  // generated number in.
+  DiyFp unsafe_interval = DiyFp::Minus(too_high, too_low);
+  // We now cut the input number into two parts: the integral digits and the
+  // fractionals. We will not write any decimal separator though, but adapt
+  // kappa instead.
+  // Reminder: we are currently computing the digits (stored inside the buffer)
+  // such that:   too_low < buffer * 10^kappa < too_high
+  // We use too_high for the digit_generation and stop as soon as possible.
+  // If we stop early we effectively round down.
+  DiyFp one = DiyFp(static_cast<uint64_t>(1) << -w.e(), w.e());
+  // Division by one is a shift.
+  uint32_t integrals = static_cast<uint32_t>(too_high.f() >> -one.e());
+  // Modulo by one is an and.
+  uint64_t fractionals = too_high.f() & (one.f() - 1);
+  uint32_t divisor;
+  int divisor_exponent_plus_one;
+  BiggestPowerTen(integrals, DiyFp::kSignificandSize - (-one.e()),
+                  &divisor, &divisor_exponent_plus_one);
+  *kappa = divisor_exponent_plus_one;
+  *length = 0;
+  // Loop invariant: buffer = too_high / 10^kappa  (integer division)
+  // The invariant holds for the first iteration: kappa has been initialized
+  // with the divisor exponent + 1. And the divisor is the biggest power of ten
+  // that is smaller than integrals.
+  while (*kappa > 0) {
+    int digit = integrals / divisor;
+    buffer[*length] = '0' + digit;
+    (*length)++;
+    integrals %= divisor;
+    (*kappa)--;
+    // Note that kappa now equals the exponent of the divisor and that the
+    // invariant thus holds again.
+    uint64_t rest =
+        (static_cast<uint64_t>(integrals) << -one.e()) + fractionals;
+    // Invariant: too_high = buffer * 10^kappa + DiyFp(rest, one.e())
+    // Reminder: unsafe_interval.e() == one.e()
+    if (rest < unsafe_interval.f()) {
+      // Rounding down (by not emitting the remaining digits) yields a number
+      // that lies within the unsafe interval.
+      return RoundWeed(buffer, *length, DiyFp::Minus(too_high, w).f(),
+                       unsafe_interval.f(), rest,
+                       static_cast<uint64_t>(divisor) << -one.e(), unit);
+    }
+    divisor /= 10;
+  }
+
+  // The integrals have been generated. We are at the point of the decimal
+  // separator. In the following loop we simply multiply the remaining digits by
+  // 10 and divide by one. We just need to pay attention to multiply associated
+  // data (like the interval or 'unit'), too.
+  // Note that the multiplication by 10 does not overflow, because w.e >= -60
+  // and thus one.e >= -60.
+  ASSERT(one.e() >= -60);
+  ASSERT(fractionals < one.f());
+  ASSERT(UINT64_2PART_C(0xFFFFFFFF, FFFFFFFF) / 10 >= one.f());
+  while (true) {
+    fractionals *= 10;
+    unit *= 10;
+    unsafe_interval.set_f(unsafe_interval.f() * 10);
+    // Integer division by one.
+    int digit = static_cast<int>(fractionals >> -one.e());
+    buffer[*length] = '0' + digit;
+    (*length)++;
+    fractionals &= one.f() - 1;  // Modulo by one.
+    (*kappa)--;
+    if (fractionals < unsafe_interval.f()) {
+      return RoundWeed(buffer, *length, DiyFp::Minus(too_high, w).f() * unit,
+                       unsafe_interval.f(), fractionals, one.f(), unit);
+    }
+  }
+}
+
+
+
+// Generates (at most) requested_digits digits of input number w.
+// w is a floating-point number (DiyFp), consisting of a significand and an
+// exponent. Its exponent is bounded by kMinimalTargetExponent and
+// kMaximalTargetExponent.
+//       Hence -60 <= w.e() <= -32.
+//
+// Returns false if it fails, in which case the generated digits in the buffer
+// should not be used.
+// Preconditions:
+//  * w is correct up to 1 ulp (unit in the last place). That
+//    is, its error must be strictly less than a unit of its last digit.
+//  * kMinimalTargetExponent <= w.e() <= kMaximalTargetExponent
+//
+// Postconditions: returns false if procedure fails.
+//   otherwise:
+//     * buffer is not null-terminated, but length contains the number of
+//       digits.
+//     * the representation in buffer is the most precise representation of
+//       requested_digits digits.
+//     * buffer contains at most requested_digits digits of w. If there are less
+//       than requested_digits digits then some trailing '0's have been removed.
+//     * kappa is such that
+//            w = buffer * 10^kappa + eps with |eps| < 10^kappa / 2.
+//
+// Remark: This procedure takes into account the imprecision of its input
+//   numbers. If the precision is not enough to guarantee all the postconditions
+//   then false is returned. This usually happens rarely, but the failure-rate
+//   increases with higher requested_digits.
+static bool DigitGenCounted(DiyFp w,
+                            int requested_digits,
+                            Vector<char> buffer,
+                            int* length,
+                            int* kappa) {
+  ASSERT(kMinimalTargetExponent <= w.e() && w.e() <= kMaximalTargetExponent);
+  ASSERT(kMinimalTargetExponent >= -60);
+  ASSERT(kMaximalTargetExponent <= -32);
+  // w is assumed to have an error less than 1 unit. Whenever w is scaled we
+  // also scale its error.
+  uint64_t w_error = 1;
+  // We cut the input number into two parts: the integral digits and the
+  // fractional digits. We don't emit any decimal separator, but adapt kappa
+  // instead. Example: instead of writing "1.2" we put "12" into the buffer and
+  // increase kappa by 1.
+  DiyFp one = DiyFp(static_cast<uint64_t>(1) << -w.e(), w.e());
+  // Division by one is a shift.
+  uint32_t integrals = static_cast<uint32_t>(w.f() >> -one.e());
+  // Modulo by one is an and.
+  uint64_t fractionals = w.f() & (one.f() - 1);
+  uint32_t divisor;
+  int divisor_exponent_plus_one;
+  BiggestPowerTen(integrals, DiyFp::kSignificandSize - (-one.e()),
+                  &divisor, &divisor_exponent_plus_one);
+  *kappa = divisor_exponent_plus_one;
+  *length = 0;
+
+  // Loop invariant: buffer = w / 10^kappa  (integer division)
+  // The invariant holds for the first iteration: kappa has been initialized
+  // with the divisor exponent + 1. And the divisor is the biggest power of ten
+  // that is smaller than 'integrals'.
+  while (*kappa > 0) {
+    int digit = integrals / divisor;
+    buffer[*length] = '0' + digit;
+    (*length)++;
+    requested_digits--;
+    integrals %= divisor;
+    (*kappa)--;
+    // Note that kappa now equals the exponent of the divisor and that the
+    // invariant thus holds again.
+    if (requested_digits == 0) break;
+    divisor /= 10;
+  }
+
+  if (requested_digits == 0) {
+    uint64_t rest =
+        (static_cast<uint64_t>(integrals) << -one.e()) + fractionals;
+    return RoundWeedCounted(buffer, *length, rest,
+                            static_cast<uint64_t>(divisor) << -one.e(), w_error,
+                            kappa);
+  }
+
+  // The integrals have been generated. We are at the point of the decimal
+  // separator. In the following loop we simply multiply the remaining digits by
+  // 10 and divide by one. We just need to pay attention to multiply associated
+  // data (the 'unit'), too.
+  // Note that the multiplication by 10 does not overflow, because w.e >= -60
+  // and thus one.e >= -60.
+  ASSERT(one.e() >= -60);
+  ASSERT(fractionals < one.f());
+  ASSERT(UINT64_2PART_C(0xFFFFFFFF, FFFFFFFF) / 10 >= one.f());
+  while (requested_digits > 0 && fractionals > w_error) {
+    fractionals *= 10;
+    w_error *= 10;
+    // Integer division by one.
+    int digit = static_cast<int>(fractionals >> -one.e());
+    buffer[*length] = '0' + digit;
+    (*length)++;
+    requested_digits--;
+    fractionals &= one.f() - 1;  // Modulo by one.
+    (*kappa)--;
+  }
+  if (requested_digits != 0) return false;
+  return RoundWeedCounted(buffer, *length, fractionals, one.f(), w_error,
+                          kappa);
+}
+
+
+// Provides a decimal representation of v.
+// Returns true if it succeeds, otherwise the result cannot be trusted.
+// There will be *length digits inside the buffer (not null-terminated).
+// If the function returns true then
+//        v == (double) (buffer * 10^decimal_exponent).
+// The digits in the buffer are the shortest representation possible: no
+// 0.09999999999999999 instead of 0.1. The shorter representation will even be
+// chosen even if the longer one would be closer to v.
+// The last digit will be closest to the actual v. That is, even if several
+// digits might correctly yield 'v' when read again, the closest will be
+// computed.
+static bool Grisu3(double v,
+                   FastDtoaMode mode,
+                   Vector<char> buffer,
+                   int* length,
+                   int* decimal_exponent) {
+  DiyFp w = Double(v).AsNormalizedDiyFp();
+  // boundary_minus and boundary_plus are the boundaries between v and its
+  // closest floating-point neighbors. Any number strictly between
+  // boundary_minus and boundary_plus will round to v when convert to a double.
+  // Grisu3 will never output representations that lie exactly on a boundary.
+  DiyFp boundary_minus, boundary_plus;
+  if (mode == FAST_DTOA_SHORTEST) {
+    Double(v).NormalizedBoundaries(&boundary_minus, &boundary_plus);
+  } else {
+    assert(mode == FAST_DTOA_SHORTEST_SINGLE);
+    float single_v = static_cast<float>(v);
+    Single(single_v).NormalizedBoundaries(&boundary_minus, &boundary_plus);
+  }
+  ASSERT(boundary_plus.e() == w.e());
+  DiyFp ten_mk;  // Cached power of ten: 10^-k
+  int mk;        // -k
+  int ten_mk_minimal_binary_exponent =
+     kMinimalTargetExponent - (w.e() + DiyFp::kSignificandSize);
+  int ten_mk_maximal_binary_exponent =
+     kMaximalTargetExponent - (w.e() + DiyFp::kSignificandSize);
+  PowersOfTenCache::GetCachedPowerForBinaryExponentRange(
+      ten_mk_minimal_binary_exponent,
+      ten_mk_maximal_binary_exponent,
+      &ten_mk, &mk);
+  ASSERT((kMinimalTargetExponent <= w.e() + ten_mk.e() +
+          DiyFp::kSignificandSize) &&
+         (kMaximalTargetExponent >= w.e() + ten_mk.e() +
+          DiyFp::kSignificandSize));
+  // Note that ten_mk is only an approximation of 10^-k. A DiyFp only contains a
+  // 64 bit significand and ten_mk is thus only precise up to 64 bits.
+
+  // The DiyFp::Times procedure rounds its result, and ten_mk is approximated
+  // too. The variable scaled_w (as well as scaled_boundary_minus/plus) are now
+  // off by a small amount.
+  // In fact: scaled_w - w*10^k < 1ulp (unit in the last place) of scaled_w.
+  // In other words: let f = scaled_w.f() and e = scaled_w.e(), then
+  //           (f-1) * 2^e < w*10^k < (f+1) * 2^e
+  DiyFp scaled_w = DiyFp::Times(w, ten_mk);
+  ASSERT(scaled_w.e() ==
+         boundary_plus.e() + ten_mk.e() + DiyFp::kSignificandSize);
+  // In theory it would be possible to avoid some recomputations by computing
+  // the difference between w and boundary_minus/plus (a power of 2) and to
+  // compute scaled_boundary_minus/plus by subtracting/adding from
+  // scaled_w. However the code becomes much less readable and the speed
+  // enhancements are not terriffic.
+  DiyFp scaled_boundary_minus = DiyFp::Times(boundary_minus, ten_mk);
+  DiyFp scaled_boundary_plus  = DiyFp::Times(boundary_plus,  ten_mk);
+
+  // DigitGen will generate the digits of scaled_w. Therefore we have
+  // v == (double) (scaled_w * 10^-mk).
+  // Set decimal_exponent == -mk and pass it to DigitGen. If scaled_w is not an
+  // integer than it will be updated. For instance if scaled_w == 1.23 then
+  // the buffer will be filled with "123" und the decimal_exponent will be
+  // decreased by 2.
+  int kappa;
+  bool result = DigitGen(scaled_boundary_minus, scaled_w, scaled_boundary_plus,
+                         buffer, length, &kappa);
+  *decimal_exponent = -mk + kappa;
+  return result;
+}
+
+
+// The "counted" version of grisu3 (see above) only generates requested_digits
+// number of digits. This version does not generate the shortest representation,
+// and with enough requested digits 0.1 will at some point print as 0.9999999...
+// Grisu3 is too imprecise for real halfway cases (1.5 will not work) and
+// therefore the rounding strategy for halfway cases is irrelevant.
+static bool Grisu3Counted(double v,
+                          int requested_digits,
+                          Vector<char> buffer,
+                          int* length,
+                          int* decimal_exponent) {
+  DiyFp w = Double(v).AsNormalizedDiyFp();
+  DiyFp ten_mk;  // Cached power of ten: 10^-k
+  int mk;        // -k
+  int ten_mk_minimal_binary_exponent =
+     kMinimalTargetExponent - (w.e() + DiyFp::kSignificandSize);
+  int ten_mk_maximal_binary_exponent =
+     kMaximalTargetExponent - (w.e() + DiyFp::kSignificandSize);
+  PowersOfTenCache::GetCachedPowerForBinaryExponentRange(
+      ten_mk_minimal_binary_exponent,
+      ten_mk_maximal_binary_exponent,
+      &ten_mk, &mk);
+  ASSERT((kMinimalTargetExponent <= w.e() + ten_mk.e() +
+          DiyFp::kSignificandSize) &&
+         (kMaximalTargetExponent >= w.e() + ten_mk.e() +
+          DiyFp::kSignificandSize));
+  // Note that ten_mk is only an approximation of 10^-k. A DiyFp only contains a
+  // 64 bit significand and ten_mk is thus only precise up to 64 bits.
+
+  // The DiyFp::Times procedure rounds its result, and ten_mk is approximated
+  // too. The variable scaled_w (as well as scaled_boundary_minus/plus) are now
+  // off by a small amount.
+  // In fact: scaled_w - w*10^k < 1ulp (unit in the last place) of scaled_w.
+  // In other words: let f = scaled_w.f() and e = scaled_w.e(), then
+  //           (f-1) * 2^e < w*10^k < (f+1) * 2^e
+  DiyFp scaled_w = DiyFp::Times(w, ten_mk);
+
+  // We now have (double) (scaled_w * 10^-mk).
+  // DigitGen will generate the first requested_digits digits of scaled_w and
+  // return together with a kappa such that scaled_w ~= buffer * 10^kappa. (It
+  // will not always be exactly the same since DigitGenCounted only produces a
+  // limited number of digits.)
+  int kappa;
+  bool result = DigitGenCounted(scaled_w, requested_digits,
+                                buffer, length, &kappa);
+  *decimal_exponent = -mk + kappa;
+  return result;
+}
+
+
+bool FastDtoa(double v,
+              FastDtoaMode mode,
+              int requested_digits,
+              Vector<char> buffer,
+              int* length,
+              int* decimal_point) {
+  ASSERT(v > 0);
+  ASSERT(!Double(v).IsSpecial());
+
+  bool result = false;
+  int decimal_exponent = 0;
+  switch (mode) {
+    case FAST_DTOA_SHORTEST:
+    case FAST_DTOA_SHORTEST_SINGLE:
+      result = Grisu3(v, mode, buffer, length, &decimal_exponent);
+      break;
+    case FAST_DTOA_PRECISION:
+      result = Grisu3Counted(v, requested_digits,
+                             buffer, length, &decimal_exponent);
+      break;
+    default:
+      UNREACHABLE();
+  }
+  if (result) {
+    *decimal_point = *length + decimal_exponent;
+    buffer[*length] = '\0';
+  }
+  return result;
+}
+
+}  // namespace double_conversion
diff --git a/mfbt/double-conversion/fast-dtoa.h b/mfbt/double-conversion/fast-dtoa.h
new file mode 100644
index 0000000..5f1e8ee
--- /dev/null
+++ b/mfbt/double-conversion/fast-dtoa.h
@@ -0,0 +1,88 @@
+// Copyright 2010 the V8 project authors. All rights reserved.
+// Redistribution and use in source and binary forms, with or without
+// modification, are permitted provided that the following conditions are
+// met:
+//
+//     * Redistributions of source code must retain the above copyright
+//       notice, this list of conditions and the following disclaimer.
+//     * Redistributions in binary form must reproduce the above
+//       copyright notice, this list of conditions and the following
+//       disclaimer in the documentation and/or other materials provided
+//       with the distribution.
+//     * Neither the name of Google Inc. nor the names of its
+//       contributors may be used to endorse or promote products derived
+//       from this software without specific prior written permission.
+//
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+#ifndef DOUBLE_CONVERSION_FAST_DTOA_H_
+#define DOUBLE_CONVERSION_FAST_DTOA_H_
+
+#include "utils.h"
+
+namespace double_conversion {
+
+enum FastDtoaMode {
+  // Computes the shortest representation of the given input. The returned
+  // result will be the most accurate number of this length. Longer
+  // representations might be more accurate.
+  FAST_DTOA_SHORTEST,
+  // Same as FAST_DTOA_SHORTEST but for single-precision floats.
+  FAST_DTOA_SHORTEST_SINGLE,
+  // Computes a representation where the precision (number of digits) is
+  // given as input. The precision is independent of the decimal point.
+  FAST_DTOA_PRECISION
+};
+
+// FastDtoa will produce at most kFastDtoaMaximalLength digits. This does not
+// include the terminating '\0' character.
+static const int kFastDtoaMaximalLength = 17;
+// Same for single-precision numbers.
+static const int kFastDtoaMaximalSingleLength = 9;
+
+// Provides a decimal representation of v.
+// The result should be interpreted as buffer * 10^(point - length).
+//
+// Precondition:
+//   * v must be a strictly positive finite double.
+//
+// Returns true if it succeeds, otherwise the result can not be trusted.
+// There will be *length digits inside the buffer followed by a null terminator.
+// If the function returns true and mode equals
+//   - FAST_DTOA_SHORTEST, then
+//     the parameter requested_digits is ignored.
+//     The result satisfies
+//         v == (double) (buffer * 10^(point - length)).
+//     The digits in the buffer are the shortest representation possible. E.g.
+//     if 0.099999999999 and 0.1 represent the same double then "1" is returned
+//     with point = 0.
+//     The last digit will be closest to the actual v. That is, even if several
+//     digits might correctly yield 'v' when read again, the buffer will contain
+//     the one closest to v.
+//   - FAST_DTOA_PRECISION, then
+//     the buffer contains requested_digits digits.
+//     the difference v - (buffer * 10^(point-length)) is closest to zero for
+//     all possible representations of requested_digits digits.
+//     If there are two values that are equally close, then FastDtoa returns
+//     false.
+// For both modes the buffer must be large enough to hold the result.
+bool FastDtoa(double d,
+              FastDtoaMode mode,
+              int requested_digits,
+              Vector<char> buffer,
+              int* length,
+              int* decimal_point);
+
+}  // namespace double_conversion
+
+#endif  // DOUBLE_CONVERSION_FAST_DTOA_H_
diff --git a/mfbt/double-conversion/fixed-dtoa.cc b/mfbt/double-conversion/fixed-dtoa.cc
new file mode 100644
index 0000000..d56b144
--- /dev/null
+++ b/mfbt/double-conversion/fixed-dtoa.cc
@@ -0,0 +1,402 @@
+// Copyright 2010 the V8 project authors. All rights reserved.
+// Redistribution and use in source and binary forms, with or without
+// modification, are permitted provided that the following conditions are
+// met:
+//
+//     * Redistributions of source code must retain the above copyright
+//       notice, this list of conditions and the following disclaimer.
+//     * Redistributions in binary form must reproduce the above
+//       copyright notice, this list of conditions and the following
+//       disclaimer in the documentation and/or other materials provided
+//       with the distribution.
+//     * Neither the name of Google Inc. nor the names of its
+//       contributors may be used to endorse or promote products derived
+//       from this software without specific prior written permission.
+//
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+#include <math.h>
+
+#include "fixed-dtoa.h"
+#include "ieee.h"
+
+namespace double_conversion {
+
+// Represents a 128bit type. This class should be replaced by a native type on
+// platforms that support 128bit integers.
+class UInt128 {
+ public:
+  UInt128() : high_bits_(0), low_bits_(0) { }
+  UInt128(uint64_t high, uint64_t low) : high_bits_(high), low_bits_(low) { }
+
+  void Multiply(uint32_t multiplicand) {
+    uint64_t accumulator;
+
+    accumulator = (low_bits_ & kMask32) * multiplicand;
+    uint32_t part = static_cast<uint32_t>(accumulator & kMask32);
+    accumulator >>= 32;
+    accumulator = accumulator + (low_bits_ >> 32) * multiplicand;
+    low_bits_ = (accumulator << 32) + part;
+    accumulator >>= 32;
+    accumulator = accumulator + (high_bits_ & kMask32) * multiplicand;
+    part = static_cast<uint32_t>(accumulator & kMask32);
+    accumulator >>= 32;
+    accumulator = accumulator + (high_bits_ >> 32) * multiplicand;
+    high_bits_ = (accumulator << 32) + part;
+    ASSERT((accumulator >> 32) == 0);
+  }
+
+  void Shift(int shift_amount) {
+    ASSERT(-64 <= shift_amount && shift_amount <= 64);
+    if (shift_amount == 0) {
+      return;
+    } else if (shift_amount == -64) {
+      high_bits_ = low_bits_;
+      low_bits_ = 0;
+    } else if (shift_amount == 64) {
+      low_bits_ = high_bits_;
+      high_bits_ = 0;
+    } else if (shift_amount <= 0) {
+      high_bits_ <<= -shift_amount;
+      high_bits_ += low_bits_ >> (64 + shift_amount);
+      low_bits_ <<= -shift_amount;
+    } else {
+      low_bits_ >>= shift_amount;
+      low_bits_ += high_bits_ << (64 - shift_amount);
+      high_bits_ >>= shift_amount;
+    }
+  }
+
+  // Modifies *this to *this MOD (2^power).
+  // Returns *this DIV (2^power).
+  int DivModPowerOf2(int power) {
+    if (power >= 64) {
+      int result = static_cast<int>(high_bits_ >> (power - 64));
+      high_bits_ -= static_cast<uint64_t>(result) << (power - 64);
+      return result;
+    } else {
+      uint64_t part_low = low_bits_ >> power;
+      uint64_t part_high = high_bits_ << (64 - power);
+      int result = static_cast<int>(part_low + part_high);
+      high_bits_ = 0;
+      low_bits_ -= part_low << power;
+      return result;
+    }
+  }
+
+  bool IsZero() const {
+    return high_bits_ == 0 && low_bits_ == 0;
+  }
+
+  int BitAt(int position) {
+    if (position >= 64) {
+      return static_cast<int>(high_bits_ >> (position - 64)) & 1;
+    } else {
+      return static_cast<int>(low_bits_ >> position) & 1;
+    }
+  }
+
+ private:
+  static const uint64_t kMask32 = 0xFFFFFFFF;
+  // Value == (high_bits_ << 64) + low_bits_
+  uint64_t high_bits_;
+  uint64_t low_bits_;
+};
+
+
+static const int kDoubleSignificandSize = 53;  // Includes the hidden bit.
+
+
+static void FillDigits32FixedLength(uint32_t number, int requested_length,
+                                    Vector<char> buffer, int* length) {
+  for (int i = requested_length - 1; i >= 0; --i) {
+    buffer[(*length) + i] = '0' + number % 10;
+    number /= 10;
+  }
+  *length += requested_length;
+}
+
+
+static void FillDigits32(uint32_t number, Vector<char> buffer, int* length) {
+  int number_length = 0;
+  // We fill the digits in reverse order and exchange them afterwards.
+  while (number != 0) {
+    int digit = number % 10;
+    number /= 10;
+    buffer[(*length) + number_length] = '0' + digit;
+    number_length++;
+  }
+  // Exchange the digits.
+  int i = *length;
+  int j = *length + number_length - 1;
+  while (i < j) {
+    char tmp = buffer[i];
+    buffer[i] = buffer[j];
+    buffer[j] = tmp;
+    i++;
+    j--;
+  }
+  *length += number_length;
+}
+
+
+static void FillDigits64FixedLength(uint64_t number, int requested_length,
+                                    Vector<char> buffer, int* length) {
+  const uint32_t kTen7 = 10000000;
+  // For efficiency cut the number into 3 uint32_t parts, and print those.
+  uint32_t part2 = static_cast<uint32_t>(number % kTen7);
+  number /= kTen7;
+  uint32_t part1 = static_cast<uint32_t>(number % kTen7);
+  uint32_t part0 = static_cast<uint32_t>(number / kTen7);
+
+  FillDigits32FixedLength(part0, 3, buffer, length);
+  FillDigits32FixedLength(part1, 7, buffer, length);
+  FillDigits32FixedLength(part2, 7, buffer, length);
+}
+
+
+static void FillDigits64(uint64_t number, Vector<char> buffer, int* length) {
+  const uint32_t kTen7 = 10000000;
+  // For efficiency cut the number into 3 uint32_t parts, and print those.
+  uint32_t part2 = static_cast<uint32_t>(number % kTen7);
+  number /= kTen7;
+  uint32_t part1 = static_cast<uint32_t>(number % kTen7);
+  uint32_t part0 = static_cast<uint32_t>(number / kTen7);
+
+  if (part0 != 0) {
+    FillDigits32(part0, buffer, length);
+    FillDigits32FixedLength(part1, 7, buffer, length);
+    FillDigits32FixedLength(part2, 7, buffer, length);
+  } else if (part1 != 0) {
+    FillDigits32(part1, buffer, length);
+    FillDigits32FixedLength(part2, 7, buffer, length);
+  } else {
+    FillDigits32(part2, buffer, length);
+  }
+}
+
+
+static void RoundUp(Vector<char> buffer, int* length, int* decimal_point) {
+  // An empty buffer represents 0.
+  if (*length == 0) {
+    buffer[0] = '1';
+    *decimal_point = 1;
+    *length = 1;
+    return;
+  }
+  // Round the last digit until we either have a digit that was not '9' or until
+  // we reached the first digit.
+  buffer[(*length) - 1]++;
+  for (int i = (*length) - 1; i > 0; --i) {
+    if (buffer[i] != '0' + 10) {
+      return;
+    }
+    buffer[i] = '0';
+    buffer[i - 1]++;
+  }
+  // If the first digit is now '0' + 10, we would need to set it to '0' and add
+  // a '1' in front. However we reach the first digit only if all following
+  // digits had been '9' before rounding up. Now all trailing digits are '0' and
+  // we simply switch the first digit to '1' and update the decimal-point
+  // (indicating that the point is now one digit to the right).
+  if (buffer[0] == '0' + 10) {
+    buffer[0] = '1';
+    (*decimal_point)++;
+  }
+}
+
+
+// The given fractionals number represents a fixed-point number with binary
+// point at bit (-exponent).
+// Preconditions:
+//   -128 <= exponent <= 0.
+//   0 <= fractionals * 2^exponent < 1
+//   The buffer holds the result.
+// The function will round its result. During the rounding-process digits not
+// generated by this function might be updated, and the decimal-point variable
+// might be updated. If this function generates the digits 99 and the buffer
+// already contained "199" (thus yielding a buffer of "19999") then a
+// rounding-up will change the contents of the buffer to "20000".
+static void FillFractionals(uint64_t fractionals, int exponent,
+                            int fractional_count, Vector<char> buffer,
+                            int* length, int* decimal_point) {
+  ASSERT(-128 <= exponent && exponent <= 0);
+  // 'fractionals' is a fixed-point number, with binary point at bit
+  // (-exponent). Inside the function the non-converted remainder of fractionals
+  // is a fixed-point number, with binary point at bit 'point'.
+  if (-exponent <= 64) {
+    // One 64 bit number is sufficient.
+    ASSERT(fractionals >> 56 == 0);
+    int point = -exponent;
+    for (int i = 0; i < fractional_count; ++i) {
+      if (fractionals == 0) break;
+      // Instead of multiplying by 10 we multiply by 5 and adjust the point
+      // location. This way the fractionals variable will not overflow.
+      // Invariant at the beginning of the loop: fractionals < 2^point.
+      // Initially we have: point <= 64 and fractionals < 2^56
+      // After each iteration the point is decremented by one.
+      // Note that 5^3 = 125 < 128 = 2^7.
+      // Therefore three iterations of this loop will not overflow fractionals
+      // (even without the subtraction at the end of the loop body). At this
+      // time point will satisfy point <= 61 and therefore fractionals < 2^point
+      // and any further multiplication of fractionals by 5 will not overflow.
+      fractionals *= 5;
+      point--;
+      int digit = static_cast<int>(fractionals >> point);
+      buffer[*length] = '0' + digit;
+      (*length)++;
+      fractionals -= static_cast<uint64_t>(digit) << point;
+    }
+    // If the first bit after the point is set we have to round up.
+    if (((fractionals >> (point - 1)) & 1) == 1) {
+      RoundUp(buffer, length, decimal_point);
+    }
+  } else {  // We need 128 bits.
+    ASSERT(64 < -exponent && -exponent <= 128);
+    UInt128 fractionals128 = UInt128(fractionals, 0);
+    fractionals128.Shift(-exponent - 64);
+    int point = 128;
+    for (int i = 0; i < fractional_count; ++i) {
+      if (fractionals128.IsZero()) break;
+      // As before: instead of multiplying by 10 we multiply by 5 and adjust the
+      // point location.
+      // This multiplication will not overflow for the same reasons as before.
+      fractionals128.Multiply(5);
+      point--;
+      int digit = fractionals128.DivModPowerOf2(point);
+      buffer[*length] = '0' + digit;
+      (*length)++;
+    }
+    if (fractionals128.BitAt(point - 1) == 1) {
+      RoundUp(buffer, length, decimal_point);
+    }
+  }
+}
+
+
+// Removes leading and trailing zeros.
+// If leading zeros are removed then the decimal point position is adjusted.
+static void TrimZeros(Vector<char> buffer, int* length, int* decimal_point) {
+  while (*length > 0 && buffer[(*length) - 1] == '0') {
+    (*length)--;
+  }
+  int first_non_zero = 0;
+  while (first_non_zero < *length && buffer[first_non_zero] == '0') {
+    first_non_zero++;
+  }
+  if (first_non_zero != 0) {
+    for (int i = first_non_zero; i < *length; ++i) {
+      buffer[i - first_non_zero] = buffer[i];
+    }
+    *length -= first_non_zero;
+    *decimal_point -= first_non_zero;
+  }
+}
+
+
+bool FastFixedDtoa(double v,
+                   int fractional_count,
+                   Vector<char> buffer,
+                   int* length,
+                   int* decimal_point) {
+  const uint32_t kMaxUInt32 = 0xFFFFFFFF;
+  uint64_t significand = Double(v).Significand();
+  int exponent = Double(v).Exponent();
+  // v = significand * 2^exponent (with significand a 53bit integer).
+  // If the exponent is larger than 20 (i.e. we may have a 73bit number) then we
+  // don't know how to compute the representation. 2^73 ~= 9.5*10^21.
+  // If necessary this limit could probably be increased, but we don't need
+  // more.
+  if (exponent > 20) return false;
+  if (fractional_count > 20) return false;
+  *length = 0;
+  // At most kDoubleSignificandSize bits of the significand are non-zero.
+  // Given a 64 bit integer we have 11 0s followed by 53 potentially non-zero
+  // bits:  0..11*..0xxx..53*..xx
+  if (exponent + kDoubleSignificandSize > 64) {
+    // The exponent must be > 11.
+    //
+    // We know that v = significand * 2^exponent.
+    // And the exponent > 11.
+    // We simplify the task by dividing v by 10^17.
+    // The quotient delivers the first digits, and the remainder fits into a 64
+    // bit number.
+    // Dividing by 10^17 is equivalent to dividing by 5^17*2^17.
+    const uint64_t kFive17 = UINT64_2PART_C(0xB1, A2BC2EC5);  // 5^17
+    uint64_t divisor = kFive17;
+    int divisor_power = 17;
+    uint64_t dividend = significand;
+    uint32_t quotient;
+    uint64_t remainder;
+    // Let v = f * 2^e with f == significand and e == exponent.
+    // Then need q (quotient) and r (remainder) as follows:
+    //   v            = q * 10^17       + r
+    //   f * 2^e      = q * 10^17       + r
+    //   f * 2^e      = q * 5^17 * 2^17 + r
+    // If e > 17 then
+    //   f * 2^(e-17) = q * 5^17        + r/2^17
+    // else
+    //   f  = q * 5^17 * 2^(17-e) + r/2^e
+    if (exponent > divisor_power) {
+      // We only allow exponents of up to 20 and therefore (17 - e) <= 3
+      dividend <<= exponent - divisor_power;
+      quotient = static_cast<uint32_t>(dividend / divisor);
+      remainder = (dividend % divisor) << divisor_power;
+    } else {
+      divisor <<= divisor_power - exponent;
+      quotient = static_cast<uint32_t>(dividend / divisor);
+      remainder = (dividend % divisor) << exponent;
+    }
+    FillDigits32(quotient, buffer, length);
+    FillDigits64FixedLength(remainder, divisor_power, buffer, length);
+    *decimal_point = *length;
+  } else if (exponent >= 0) {
+    // 0 <= exponent <= 11
+    significand <<= exponent;
+    FillDigits64(significand, buffer, length);
+    *decimal_point = *length;
+  } else if (exponent > -kDoubleSignificandSize) {
+    // We have to cut the number.
+    uint64_t integrals = significand >> -exponent;
+    uint64_t fractionals = significand - (integrals << -exponent);
+    if (integrals > kMaxUInt32) {
+      FillDigits64(integrals, buffer, length);
+    } else {
+      FillDigits32(static_cast<uint32_t>(integrals), buffer, length);
+    }
+    *decimal_point = *length;
+    FillFractionals(fractionals, exponent, fractional_count,
+                    buffer, length, decimal_point);
+  } else if (exponent < -128) {
+    // This configuration (with at most 20 digits) means that all digits must be
+    // 0.
+    ASSERT(fractional_count <= 20);
+    buffer[0] = '\0';
+    *length = 0;
+    *decimal_point = -fractional_count;
+  } else {
+    *decimal_point = 0;
+    FillFractionals(significand, exponent, fractional_count,
+                    buffer, length, decimal_point);
+  }
+  TrimZeros(buffer, length, decimal_point);
+  buffer[*length] = '\0';
+  if ((*length) == 0) {
+    // The string is empty and the decimal_point thus has no importance. Mimick
+    // Gay's dtoa and and set it to -fractional_count.
+    *decimal_point = -fractional_count;
+  }
+  return true;
+}
+
+}  // namespace double_conversion
diff --git a/mfbt/double-conversion/fixed-dtoa.h b/mfbt/double-conversion/fixed-dtoa.h
new file mode 100644
index 0000000..3bdd08e
--- /dev/null
+++ b/mfbt/double-conversion/fixed-dtoa.h
@@ -0,0 +1,56 @@
+// Copyright 2010 the V8 project authors. All rights reserved.
+// Redistribution and use in source and binary forms, with or without
+// modification, are permitted provided that the following conditions are
+// met:
+//
+//     * Redistributions of source code must retain the above copyright
+//       notice, this list of conditions and the following disclaimer.
+//     * Redistributions in binary form must reproduce the above
+//       copyright notice, this list of conditions and the following
+//       disclaimer in the documentation and/or other materials provided
+//       with the distribution.
+//     * Neither the name of Google Inc. nor the names of its
+//       contributors may be used to endorse or promote products derived
+//       from this software without specific prior written permission.
+//
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+#ifndef DOUBLE_CONVERSION_FIXED_DTOA_H_
+#define DOUBLE_CONVERSION_FIXED_DTOA_H_
+
+#include "utils.h"
+
+namespace double_conversion {
+
+// Produces digits necessary to print a given number with
+// 'fractional_count' digits after the decimal point.
+// The buffer must be big enough to hold the result plus one terminating null
+// character.
+//
+// The produced digits might be too short in which case the caller has to fill
+// the gaps with '0's.
+// Example: FastFixedDtoa(0.001, 5, ...) is allowed to return buffer = "1", and
+// decimal_point = -2.
+// Halfway cases are rounded towards +/-Infinity (away from 0). The call
+// FastFixedDtoa(0.15, 2, ...) thus returns buffer = "2", decimal_point = 0.
+// The returned buffer may contain digits that would be truncated from the
+// shortest representation of the input.
+//
+// This method only works for some parameters. If it can't handle the input it
+// returns false. The output is null-terminated when the function succeeds.
+bool FastFixedDtoa(double v, int fractional_count,
+                   Vector<char> buffer, int* length, int* decimal_point);
+
+}  // namespace double_conversion
+
+#endif  // DOUBLE_CONVERSION_FIXED_DTOA_H_
diff --git a/mfbt/double-conversion/ieee.h b/mfbt/double-conversion/ieee.h
new file mode 100644
index 0000000..839dc47
--- /dev/null
+++ b/mfbt/double-conversion/ieee.h
@@ -0,0 +1,398 @@
+// Copyright 2012 the V8 project authors. All rights reserved.
+// Redistribution and use in source and binary forms, with or without
+// modification, are permitted provided that the following conditions are
+// met:
+//
+//     * Redistributions of source code must retain the above copyright
+//       notice, this list of conditions and the following disclaimer.
+//     * Redistributions in binary form must reproduce the above
+//       copyright notice, this list of conditions and the following
+//       disclaimer in the documentation and/or other materials provided
+//       with the distribution.
+//     * Neither the name of Google Inc. nor the names of its
+//       contributors may be used to endorse or promote products derived
+//       from this software without specific prior written permission.
+//
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+#ifndef DOUBLE_CONVERSION_DOUBLE_H_
+#define DOUBLE_CONVERSION_DOUBLE_H_
+
+#include "diy-fp.h"
+
+namespace double_conversion {
+
+// We assume that doubles and uint64_t have the same endianness.
+static uint64_t double_to_uint64(double d) { return BitCast<uint64_t>(d); }
+static double uint64_to_double(uint64_t d64) { return BitCast<double>(d64); }
+static uint32_t float_to_uint32(float f) { return BitCast<uint32_t>(f); }
+static float uint32_to_float(uint32_t d32) { return BitCast<float>(d32); }
+
+// Helper functions for doubles.
+class Double {
+ public:
+  static const uint64_t kSignMask = UINT64_2PART_C(0x80000000, 00000000);
+  static const uint64_t kExponentMask = UINT64_2PART_C(0x7FF00000, 00000000);
+  static const uint64_t kSignificandMask = UINT64_2PART_C(0x000FFFFF, FFFFFFFF);
+  static const uint64_t kHiddenBit = UINT64_2PART_C(0x00100000, 00000000);
+  static const int kPhysicalSignificandSize = 52;  // Excludes the hidden bit.
+  static const int kSignificandSize = 53;
+
+  Double() : d64_(0) {}
+  explicit Double(double d) : d64_(double_to_uint64(d)) {}
+  explicit Double(uint64_t d64) : d64_(d64) {}
+  explicit Double(DiyFp diy_fp)
+    : d64_(DiyFpToUint64(diy_fp)) {}
+
+  // The value encoded by this Double must be greater or equal to +0.0.
+  // It must not be special (infinity, or NaN).
+  DiyFp AsDiyFp() const {
+    ASSERT(Sign() > 0);
+    ASSERT(!IsSpecial());
+    return DiyFp(Significand(), Exponent());
+  }
+
+  // The value encoded by this Double must be strictly greater than 0.
+  DiyFp AsNormalizedDiyFp() const {
+    ASSERT(value() > 0.0);
+    uint64_t f = Significand();
+    int e = Exponent();
+
+    // The current double could be a denormal.
+    while ((f & kHiddenBit) == 0) {
+      f <<= 1;
+      e--;
+    }
+    // Do the final shifts in one go.
+    f <<= DiyFp::kSignificandSize - kSignificandSize;
+    e -= DiyFp::kSignificandSize - kSignificandSize;
+    return DiyFp(f, e);
+  }
+
+  // Returns the double's bit as uint64.
+  uint64_t AsUint64() const {
+    return d64_;
+  }
+
+  // Returns the next greater double. Returns +infinity on input +infinity.
+  double NextDouble() const {
+    if (d64_ == kInfinity) return Double(kInfinity).value();
+    if (Sign() < 0 && Significand() == 0) {
+      // -0.0
+      return 0.0;
+    }
+    if (Sign() < 0) {
+      return Double(d64_ - 1).value();
+    } else {
+      return Double(d64_ + 1).value();
+    }
+  }
+
+  double PreviousDouble() const {
+    if (d64_ == (kInfinity | kSignMask)) return -Double::Infinity();
+    if (Sign() < 0) {
+      return Double(d64_ + 1).value();
+    } else {
+      if (Significand() == 0) return -0.0;
+      return Double(d64_ - 1).value();
+    }
+  }
+
+  int Exponent() const {
+    if (IsDenormal()) return kDenormalExponent;
+
+    uint64_t d64 = AsUint64();
+    int biased_e =
+        static_cast<int>((d64 & kExponentMask) >> kPhysicalSignificandSize);
+    return biased_e - kExponentBias;
+  }
+
+  uint64_t Significand() const {
+    uint64_t d64 = AsUint64();
+    uint64_t significand = d64 & kSignificandMask;
+    if (!IsDenormal()) {
+      return significand + kHiddenBit;
+    } else {
+      return significand;
+    }
+  }
+
+  // Returns true if the double is a denormal.
+  bool IsDenormal() const {
+    uint64_t d64 = AsUint64();
+    return (d64 & kExponentMask) == 0;
+  }
+
+  // We consider denormals not to be special.
+  // Hence only Infinity and NaN are special.
+  bool IsSpecial() const {
+    uint64_t d64 = AsUint64();
+    return (d64 & kExponentMask) == kExponentMask;
+  }
+
+  bool IsNan() const {
+    uint64_t d64 = AsUint64();
+    return ((d64 & kExponentMask) == kExponentMask) &&
+        ((d64 & kSignificandMask) != 0);
+  }
+
+  bool IsInfinite() const {
+    uint64_t d64 = AsUint64();
+    return ((d64 & kExponentMask) == kExponentMask) &&
+        ((d64 & kSignificandMask) == 0);
+  }
+
+  int Sign() const {
+    uint64_t d64 = AsUint64();
+    return (d64 & kSignMask) == 0? 1: -1;
+  }
+
+  // Precondition: the value encoded by this Double must be greater or equal
+  // than +0.0.
+  DiyFp UpperBoundary() const {
+    ASSERT(Sign() > 0);
+    return DiyFp(Significand() * 2 + 1, Exponent() - 1);
+  }
+
+  // Computes the two boundaries of this.
+  // The bigger boundary (m_plus) is normalized. The lower boundary has the same
+  // exponent as m_plus.
+  // Precondition: the value encoded by this Double must be greater than 0.
+  void NormalizedBoundaries(DiyFp* out_m_minus, DiyFp* out_m_plus) const {
+    ASSERT(value() > 0.0);
+    DiyFp v = this->AsDiyFp();
+    DiyFp m_plus = DiyFp::Normalize(DiyFp((v.f() << 1) + 1, v.e() - 1));
+    DiyFp m_minus;
+    if (LowerBoundaryIsCloser()) {
+      m_minus = DiyFp((v.f() << 2) - 1, v.e() - 2);
+    } else {
+      m_minus = DiyFp((v.f() << 1) - 1, v.e() - 1);
+    }
+    m_minus.set_f(m_minus.f() << (m_minus.e() - m_plus.e()));
+    m_minus.set_e(m_plus.e());
+    *out_m_plus = m_plus;
+    *out_m_minus = m_minus;
+  }
+
+  bool LowerBoundaryIsCloser() const {
+    // The boundary is closer if the significand is of the form f == 2^p-1 then
+    // the lower boundary is closer.
+    // Think of v = 1000e10 and v- = 9999e9.
+    // Then the boundary (== (v - v-)/2) is not just at a distance of 1e9 but
+    // at a distance of 1e8.
+    // The only exception is for the smallest normal: the largest denormal is
+    // at the same distance as its successor.
+    // Note: denormals have the same exponent as the smallest normals.
+    bool physical_significand_is_zero = ((AsUint64() & kSignificandMask) == 0);
+    return physical_significand_is_zero && (Exponent() != kDenormalExponent);
+  }
+
+  double value() const { return uint64_to_double(d64_); }
+
+  // Returns the significand size for a given order of magnitude.
+  // If v = f*2^e with 2^p-1 <= f <= 2^p then p+e is v's order of magnitude.
+  // This function returns the number of significant binary digits v will have
+  // once it's encoded into a double. In almost all cases this is equal to
+  // kSignificandSize. The only exceptions are denormals. They start with
+  // leading zeroes and their effective significand-size is hence smaller.
+  static int SignificandSizeForOrderOfMagnitude(int order) {
+    if (order >= (kDenormalExponent + kSignificandSize)) {
+      return kSignificandSize;
+    }
+    if (order <= kDenormalExponent) return 0;
+    return order - kDenormalExponent;
+  }
+
+  static double Infinity() {
+    return Double(kInfinity).value();
+  }
+
+  static double NaN() {
+    return Double(kNaN).value();
+  }
+
+ private:
+  static const int kExponentBias = 0x3FF + kPhysicalSignificandSize;
+  static const int kDenormalExponent = -kExponentBias + 1;
+  static const int kMaxExponent = 0x7FF - kExponentBias;
+  static const uint64_t kInfinity = UINT64_2PART_C(0x7FF00000, 00000000);
+  static const uint64_t kNaN = UINT64_2PART_C(0x7FF80000, 00000000);
+
+  const uint64_t d64_;
+
+  static uint64_t DiyFpToUint64(DiyFp diy_fp) {
+    uint64_t significand = diy_fp.f();
+    int exponent = diy_fp.e();
+    while (significand > kHiddenBit + kSignificandMask) {
+      significand >>= 1;
+      exponent++;
+    }
+    if (exponent >= kMaxExponent) {
+      return kInfinity;
+    }
+    if (exponent < kDenormalExponent) {
+      return 0;
+    }
+    while (exponent > kDenormalExponent && (significand & kHiddenBit) == 0) {
+      significand <<= 1;
+      exponent--;
+    }
+    uint64_t biased_exponent;
+    if (exponent == kDenormalExponent && (significand & kHiddenBit) == 0) {
+      biased_exponent = 0;
+    } else {
+      biased_exponent = static_cast<uint64_t>(exponent + kExponentBias);
+    }
+    return (significand & kSignificandMask) |
+        (biased_exponent << kPhysicalSignificandSize);
+  }
+};
+
+class Single {
+ public:
+  static const uint32_t kSignMask = 0x80000000;
+  static const uint32_t kExponentMask = 0x7F800000;
+  static const uint32_t kSignificandMask = 0x007FFFFF;
+  static const uint32_t kHiddenBit = 0x00800000;
+  static const int kPhysicalSignificandSize = 23;  // Excludes the hidden bit.
+  static const int kSignificandSize = 24;
+
+  Single() : d32_(0) {}
+  explicit Single(float f) : d32_(float_to_uint32(f)) {}
+  explicit Single(uint32_t d32) : d32_(d32) {}
+
+  // The value encoded by this Single must be greater or equal to +0.0.
+  // It must not be special (infinity, or NaN).
+  DiyFp AsDiyFp() const {
+    ASSERT(Sign() > 0);
+    ASSERT(!IsSpecial());
+    return DiyFp(Significand(), Exponent());
+  }
+
+  // Returns the single's bit as uint64.
+  uint32_t AsUint32() const {
+    return d32_;
+  }
+
+  int Exponent() const {
+    if (IsDenormal()) return kDenormalExponent;
+
+    uint32_t d32 = AsUint32();
+    int biased_e =
+        static_cast<int>((d32 & kExponentMask) >> kPhysicalSignificandSize);
+    return biased_e - kExponentBias;
+  }
+
+  uint32_t Significand() const {
+    uint32_t d32 = AsUint32();
+    uint32_t significand = d32 & kSignificandMask;
+    if (!IsDenormal()) {
+      return significand + kHiddenBit;
+    } else {
+      return significand;
+    }
+  }
+
+  // Returns true if the single is a denormal.
+  bool IsDenormal() const {
+    uint32_t d32 = AsUint32();
+    return (d32 & kExponentMask) == 0;
+  }
+
+  // We consider denormals not to be special.
+  // Hence only Infinity and NaN are special.
+  bool IsSpecial() const {
+    uint32_t d32 = AsUint32();
+    return (d32 & kExponentMask) == kExponentMask;
+  }
+
+  bool IsNan() const {
+    uint32_t d32 = AsUint32();
+    return ((d32 & kExponentMask) == kExponentMask) &&
+        ((d32 & kSignificandMask) != 0);
+  }
+
+  bool IsInfinite() const {
+    uint32_t d32 = AsUint32();
+    return ((d32 & kExponentMask) == kExponentMask) &&
+        ((d32 & kSignificandMask) == 0);
+  }
+
+  int Sign() const {
+    uint32_t d32 = AsUint32();
+    return (d32 & kSignMask) == 0? 1: -1;
+  }
+
+  // Computes the two boundaries of this.
+  // The bigger boundary (m_plus) is normalized. The lower boundary has the same
+  // exponent as m_plus.
+  // Precondition: the value encoded by this Single must be greater than 0.
+  void NormalizedBoundaries(DiyFp* out_m_minus, DiyFp* out_m_plus) const {
+    ASSERT(value() > 0.0);
+    DiyFp v = this->AsDiyFp();
+    DiyFp m_plus = DiyFp::Normalize(DiyFp((v.f() << 1) + 1, v.e() - 1));
+    DiyFp m_minus;
+    if (LowerBoundaryIsCloser()) {
+      m_minus = DiyFp((v.f() << 2) - 1, v.e() - 2);
+    } else {
+      m_minus = DiyFp((v.f() << 1) - 1, v.e() - 1);
+    }
+    m_minus.set_f(m_minus.f() << (m_minus.e() - m_plus.e()));
+    m_minus.set_e(m_plus.e());
+    *out_m_plus = m_plus;
+    *out_m_minus = m_minus;
+  }
+
+  // Precondition: the value encoded by this Single must be greater or equal
+  // than +0.0.
+  DiyFp UpperBoundary() const {
+    ASSERT(Sign() > 0);
+    return DiyFp(Significand() * 2 + 1, Exponent() - 1);
+  }
+
+  bool LowerBoundaryIsCloser() const {
+    // The boundary is closer if the significand is of the form f == 2^p-1 then
+    // the lower boundary is closer.
+    // Think of v = 1000e10 and v- = 9999e9.
+    // Then the boundary (== (v - v-)/2) is not just at a distance of 1e9 but
+    // at a distance of 1e8.
+    // The only exception is for the smallest normal: the largest denormal is
+    // at the same distance as its successor.
+    // Note: denormals have the same exponent as the smallest normals.
+    bool physical_significand_is_zero = ((AsUint32() & kSignificandMask) == 0);
+    return physical_significand_is_zero && (Exponent() != kDenormalExponent);
+  }
+
+  float value() const { return uint32_to_float(d32_); }
+
+  static float Infinity() {
+    return Single(kInfinity).value();
+  }
+
+  static float NaN() {
+    return Single(kNaN).value();
+  }
+
+ private:
+  static const int kExponentBias = 0x7F + kPhysicalSignificandSize;
+  static const int kDenormalExponent = -kExponentBias + 1;
+  static const int kMaxExponent = 0xFF - kExponentBias;
+  static const uint32_t kInfinity = 0x7F800000;
+  static const uint32_t kNaN = 0x7FC00000;
+
+  const uint32_t d32_;
+};
+
+}  // namespace double_conversion
+
+#endif  // DOUBLE_CONVERSION_DOUBLE_H_
diff --git a/mfbt/double-conversion/more-architectures.patch b/mfbt/double-conversion/more-architectures.patch
new file mode 100644
index 0000000..b8d3804
--- /dev/null
+++ b/mfbt/double-conversion/more-architectures.patch
@@ -0,0 +1,30 @@
+diff --git a/mfbt/double-conversion/utils.h b/mfbt/double-conversion/utils.h
+--- a/mfbt/double-conversion/utils.h
++++ b/mfbt/double-conversion/utils.h
+@@ -48,20 +48,24 @@
+ // An easy way to test if the floating-point operations are correct is to
+ // evaluate: 89255.0/1e22. If the floating-point stack is 64 bits wide then
+ // the result is equal to 89255e-22.
+ // The best way to test this, is to create a division-function and to compare
+ // the output of the division with the expected result. (Inlining must be
+ // disabled.)
+ // On Linux,x86 89255e-22 != Div_double(89255.0/1e22)
+ #if defined(_M_X64) || defined(__x86_64__) || \
+-    defined(__ARMEL__) || \
++    defined(__ARMEL__) || defined(__avr32__) || \
++    defined(__hppa__) || defined(__ia64__) || \
++    defined(__mips__) || defined(__powerpc__) || \
++    defined(__sparc__) || defined(__sparc) || defined(__s390__) || \
++    defined(__SH4__) || defined(__alpha__) || \
+     defined(_MIPS_ARCH_MIPS32R2)
+ #define DOUBLE_CONVERSION_CORRECT_DOUBLE_OPERATIONS 1
+-#elif defined(_M_IX86) || defined(__i386__)
++#elif defined(_M_IX86) || defined(__i386__) || defined(__i386)
+ #if defined(_WIN32)
+ // Windows uses a 64bit wide floating point stack.
+ #define DOUBLE_CONVERSION_CORRECT_DOUBLE_OPERATIONS 1
+ #else
+ #undef DOUBLE_CONVERSION_CORRECT_DOUBLE_OPERATIONS
+ #endif  // _WIN32
+ #else
+ #error Target architecture was not detected as supported by Double-Conversion.
diff --git a/mfbt/double-conversion/strtod.cc b/mfbt/double-conversion/strtod.cc
new file mode 100644
index 0000000..d773f44
--- /dev/null
+++ b/mfbt/double-conversion/strtod.cc
@@ -0,0 +1,555 @@
+// Copyright 2010 the V8 project authors. All rights reserved.
+// Redistribution and use in source and binary forms, with or without
+// modification, are permitted provided that the following conditions are
+// met:
+//
+//     * Redistributions of source code must retain the above copyright
+//       notice, this list of conditions and the following disclaimer.
+//     * Redistributions in binary form must reproduce the above
+//       copyright notice, this list of conditions and the following
+//       disclaimer in the documentation and/or other materials provided
+//       with the distribution.
+//     * Neither the name of Google Inc. nor the names of its
+//       contributors may be used to endorse or promote products derived
+//       from this software without specific prior written permission.
+//
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+#include <stdarg.h>
+#include <limits.h>
+
+#include "strtod.h"
+#include "bignum.h"
+#include "cached-powers.h"
+#include "ieee.h"
+
+namespace double_conversion {
+
+// 2^53 = 9007199254740992.
+// Any integer with at most 15 decimal digits will hence fit into a double
+// (which has a 53bit significand) without loss of precision.
+static const int kMaxExactDoubleIntegerDecimalDigits = 15;
+// 2^64 = 18446744073709551616 > 10^19
+static const int kMaxUint64DecimalDigits = 19;
+
+// Max double: 1.7976931348623157 x 10^308
+// Min non-zero double: 4.9406564584124654 x 10^-324
+// Any x >= 10^309 is interpreted as +infinity.
+// Any x <= 10^-324 is interpreted as 0.
+// Note that 2.5e-324 (despite being smaller than the min double) will be read
+// as non-zero (equal to the min non-zero double).
+static const int kMaxDecimalPower = 309;
+static const int kMinDecimalPower = -324;
+
+// 2^64 = 18446744073709551616
+static const uint64_t kMaxUint64 = UINT64_2PART_C(0xFFFFFFFF, FFFFFFFF);
+
+
+static const double exact_powers_of_ten[] = {
+  1.0,  // 10^0
+  10.0,
+  100.0,
+  1000.0,
+  10000.0,
+  100000.0,
+  1000000.0,
+  10000000.0,
+  100000000.0,
+  1000000000.0,
+  10000000000.0,  // 10^10
+  100000000000.0,
+  1000000000000.0,
+  10000000000000.0,
+  100000000000000.0,
+  1000000000000000.0,
+  10000000000000000.0,
+  100000000000000000.0,
+  1000000000000000000.0,
+  10000000000000000000.0,
+  100000000000000000000.0,  // 10^20
+  1000000000000000000000.0,
+  // 10^22 = 0x21e19e0c9bab2400000 = 0x878678326eac9 * 2^22
+  10000000000000000000000.0
+};
+static const int kExactPowersOfTenSize = ARRAY_SIZE(exact_powers_of_ten);
+
+// Maximum number of significant digits in the decimal representation.
+// In fact the value is 772 (see conversions.cc), but to give us some margin
+// we round up to 780.
+static const int kMaxSignificantDecimalDigits = 780;
+
+static Vector<const char> TrimLeadingZeros(Vector<const char> buffer) {
+  for (int i = 0; i < buffer.length(); i++) {
+    if (buffer[i] != '0') {
+      return buffer.SubVector(i, buffer.length());
+    }
+  }
+  return Vector<const char>(buffer.start(), 0);
+}
+
+
+static Vector<const char> TrimTrailingZeros(Vector<const char> buffer) {
+  for (int i = buffer.length() - 1; i >= 0; --i) {
+    if (buffer[i] != '0') {
+      return buffer.SubVector(0, i + 1);
+    }
+  }
+  return Vector<const char>(buffer.start(), 0);
+}
+
+
+static void CutToMaxSignificantDigits(Vector<const char> buffer,
+                                       int exponent,
+                                       char* significant_buffer,
+                                       int* significant_exponent) {
+  for (int i = 0; i < kMaxSignificantDecimalDigits - 1; ++i) {
+    significant_buffer[i] = buffer[i];
+  }
+  // The input buffer has been trimmed. Therefore the last digit must be
+  // different from '0'.
+  ASSERT(buffer[buffer.length() - 1] != '0');
+  // Set the last digit to be non-zero. This is sufficient to guarantee
+  // correct rounding.
+  significant_buffer[kMaxSignificantDecimalDigits - 1] = '1';
+  *significant_exponent =
+      exponent + (buffer.length() - kMaxSignificantDecimalDigits);
+}
+
+
+// Trims the buffer and cuts it to at most kMaxSignificantDecimalDigits.
+// If possible the input-buffer is reused, but if the buffer needs to be
+// modified (due to cutting), then the input needs to be copied into the
+// buffer_copy_space.
+static void TrimAndCut(Vector<const char> buffer, int exponent,
+                       char* buffer_copy_space, int space_size,
+                       Vector<const char>* trimmed, int* updated_exponent) {
+  Vector<const char> left_trimmed = TrimLeadingZeros(buffer);
+  Vector<const char> right_trimmed = TrimTrailingZeros(left_trimmed);
+  exponent += left_trimmed.length() - right_trimmed.length();
+  if (right_trimmed.length() > kMaxSignificantDecimalDigits) {
+    ASSERT(space_size >= kMaxSignificantDecimalDigits);
+    CutToMaxSignificantDigits(right_trimmed, exponent,
+                              buffer_copy_space, updated_exponent);
+    *trimmed = Vector<const char>(buffer_copy_space,
+                                 kMaxSignificantDecimalDigits);
+  } else {
+    *trimmed = right_trimmed;
+    *updated_exponent = exponent;
+  }
+}
+
+
+// Reads digits from the buffer and converts them to a uint64.
+// Reads in as many digits as fit into a uint64.
+// When the string starts with "1844674407370955161" no further digit is read.
+// Since 2^64 = 18446744073709551616 it would still be possible read another
+// digit if it was less or equal than 6, but this would complicate the code.
+static uint64_t ReadUint64(Vector<const char> buffer,
+                           int* number_of_read_digits) {
+  uint64_t result = 0;
+  int i = 0;
+  while (i < buffer.length() && result <= (kMaxUint64 / 10 - 1)) {
+    int digit = buffer[i++] - '0';
+    ASSERT(0 <= digit && digit <= 9);
+    result = 10 * result + digit;
+  }
+  *number_of_read_digits = i;
+  return result;
+}
+
+
+// Reads a DiyFp from the buffer.
+// The returned DiyFp is not necessarily normalized.
+// If remaining_decimals is zero then the returned DiyFp is accurate.
+// Otherwise it has been rounded and has error of at most 1/2 ulp.
+static void ReadDiyFp(Vector<const char> buffer,
+                      DiyFp* result,
+                      int* remaining_decimals) {
+  int read_digits;
+  uint64_t significand = ReadUint64(buffer, &read_digits);
+  if (buffer.length() == read_digits) {
+    *result = DiyFp(significand, 0);
+    *remaining_decimals = 0;
+  } else {
+    // Round the significand.
+    if (buffer[read_digits] >= '5') {
+      significand++;
+    }
+    // Compute the binary exponent.
+    int exponent = 0;
+    *result = DiyFp(significand, exponent);
+    *remaining_decimals = buffer.length() - read_digits;
+  }
+}
+
+
+static bool DoubleStrtod(Vector<const char> trimmed,
+                         int exponent,
+                         double* result) {
+#if !defined(DOUBLE_CONVERSION_CORRECT_DOUBLE_OPERATIONS)
+  // On x86 the floating-point stack can be 64 or 80 bits wide. If it is
+  // 80 bits wide (as is the case on Linux) then double-rounding occurs and the
+  // result is not accurate.
+  // We know that Windows32 uses 64 bits and is therefore accurate.
+  // Note that the ARM simulator is compiled for 32bits. It therefore exhibits
+  // the same problem.
+  return false;
+#endif
+  if (trimmed.length() <= kMaxExactDoubleIntegerDecimalDigits) {
+    int read_digits;
+    // The trimmed input fits into a double.
+    // If the 10^exponent (resp. 10^-exponent) fits into a double too then we
+    // can compute the result-double simply by multiplying (resp. dividing) the
+    // two numbers.
+    // This is possible because IEEE guarantees that floating-point operations
+    // return the best possible approximation.
+    if (exponent < 0 && -exponent < kExactPowersOfTenSize) {
+      // 10^-exponent fits into a double.
+      *result = static_cast<double>(ReadUint64(trimmed, &read_digits));
+      ASSERT(read_digits == trimmed.length());
+      *result /= exact_powers_of_ten[-exponent];
+      return true;
+    }
+    if (0 <= exponent && exponent < kExactPowersOfTenSize) {
+      // 10^exponent fits into a double.
+      *result = static_cast<double>(ReadUint64(trimmed, &read_digits));
+      ASSERT(read_digits == trimmed.length());
+      *result *= exact_powers_of_ten[exponent];
+      return true;
+    }
+    int remaining_digits =
+        kMaxExactDoubleIntegerDecimalDigits - trimmed.length();
+    if ((0 <= exponent) &&
+        (exponent - remaining_digits < kExactPowersOfTenSize)) {
+      // The trimmed string was short and we can multiply it with
+      // 10^remaining_digits. As a result the remaining exponent now fits
+      // into a double too.
+      *result = static_cast<double>(ReadUint64(trimmed, &read_digits));
+      ASSERT(read_digits == trimmed.length());
+      *result *= exact_powers_of_ten[remaining_digits];
+      *result *= exact_powers_of_ten[exponent - remaining_digits];
+      return true;
+    }
+  }
+  return false;
+}
+
+
+// Returns 10^exponent as an exact DiyFp.
+// The given exponent must be in the range [1; kDecimalExponentDistance[.
+static DiyFp AdjustmentPowerOfTen(int exponent) {
+  ASSERT(0 < exponent);
+  ASSERT(exponent < PowersOfTenCache::kDecimalExponentDistance);
+  // Simply hardcode the remaining powers for the given decimal exponent
+  // distance.
+  ASSERT(PowersOfTenCache::kDecimalExponentDistance == 8);
+  switch (exponent) {
+    case 1: return DiyFp(UINT64_2PART_C(0xa0000000, 00000000), -60);
+    case 2: return DiyFp(UINT64_2PART_C(0xc8000000, 00000000), -57);
+    case 3: return DiyFp(UINT64_2PART_C(0xfa000000, 00000000), -54);
+    case 4: return DiyFp(UINT64_2PART_C(0x9c400000, 00000000), -50);
+    case 5: return DiyFp(UINT64_2PART_C(0xc3500000, 00000000), -47);
+    case 6: return DiyFp(UINT64_2PART_C(0xf4240000, 00000000), -44);
+    case 7: return DiyFp(UINT64_2PART_C(0x98968000, 00000000), -40);
+    default:
+      UNREACHABLE();
+      return DiyFp(0, 0);
+  }
+}
+
+
+// If the function returns true then the result is the correct double.
+// Otherwise it is either the correct double or the double that is just below
+// the correct double.
+static bool DiyFpStrtod(Vector<const char> buffer,
+                        int exponent,
+                        double* result) {
+  DiyFp input;
+  int remaining_decimals;
+  ReadDiyFp(buffer, &input, &remaining_decimals);
+  // Since we may have dropped some digits the input is not accurate.
+  // If remaining_decimals is different than 0 than the error is at most
+  // .5 ulp (unit in the last place).
+  // We don't want to deal with fractions and therefore keep a common
+  // denominator.
+  const int kDenominatorLog = 3;
+  const int kDenominator = 1 << kDenominatorLog;
+  // Move the remaining decimals into the exponent.
+  exponent += remaining_decimals;
+  int error = (remaining_decimals == 0 ? 0 : kDenominator / 2);
+
+  int old_e = input.e();
+  input.Normalize();
+  error <<= old_e - input.e();
+
+  ASSERT(exponent <= PowersOfTenCache::kMaxDecimalExponent);
+  if (exponent < PowersOfTenCache::kMinDecimalExponent) {
+    *result = 0.0;
+    return true;
+  }
+  DiyFp cached_power;
+  int cached_decimal_exponent;
+  PowersOfTenCache::GetCachedPowerForDecimalExponent(exponent,
+                                                     &cached_power,
+                                                     &cached_decimal_exponent);
+
+  if (cached_decimal_exponent != exponent) {
+    int adjustment_exponent = exponent - cached_decimal_exponent;
+    DiyFp adjustment_power = AdjustmentPowerOfTen(adjustment_exponent);
+    input.Multiply(adjustment_power);
+    if (kMaxUint64DecimalDigits - buffer.length() >= adjustment_exponent) {
+      // The product of input with the adjustment power fits into a 64 bit
+      // integer.
+      ASSERT(DiyFp::kSignificandSize == 64);
+    } else {
+      // The adjustment power is exact. There is hence only an error of 0.5.
+      error += kDenominator / 2;
+    }
+  }
+
+  input.Multiply(cached_power);
+  // The error introduced by a multiplication of a*b equals
+  //   error_a + error_b + error_a*error_b/2^64 + 0.5
+  // Substituting a with 'input' and b with 'cached_power' we have
+  //   error_b = 0.5  (all cached powers have an error of less than 0.5 ulp),
+  //   error_ab = 0 or 1 / kDenominator > error_a*error_b/ 2^64
+  int error_b = kDenominator / 2;
+  int error_ab = (error == 0 ? 0 : 1);  // We round up to 1.
+  int fixed_error = kDenominator / 2;
+  error += error_b + error_ab + fixed_error;
+
+  old_e = input.e();
+  input.Normalize();
+  error <<= old_e - input.e();
+
+  // See if the double's significand changes if we add/subtract the error.
+  int order_of_magnitude = DiyFp::kSignificandSize + input.e();
+  int effective_significand_size =
+      Double::SignificandSizeForOrderOfMagnitude(order_of_magnitude);
+  int precision_digits_count =
+      DiyFp::kSignificandSize - effective_significand_size;
+  if (precision_digits_count + kDenominatorLog >= DiyFp::kSignificandSize) {
+    // This can only happen for very small denormals. In this case the
+    // half-way multiplied by the denominator exceeds the range of an uint64.
+    // Simply shift everything to the right.
+    int shift_amount = (precision_digits_count + kDenominatorLog) -
+        DiyFp::kSignificandSize + 1;
+    input.set_f(input.f() >> shift_amount);
+    input.set_e(input.e() + shift_amount);
+    // We add 1 for the lost precision of error, and kDenominator for
+    // the lost precision of input.f().
+    error = (error >> shift_amount) + 1 + kDenominator;
+    precision_digits_count -= shift_amount;
+  }
+  // We use uint64_ts now. This only works if the DiyFp uses uint64_ts too.
+  ASSERT(DiyFp::kSignificandSize == 64);
+  ASSERT(precision_digits_count < 64);
+  uint64_t one64 = 1;
+  uint64_t precision_bits_mask = (one64 << precision_digits_count) - 1;
+  uint64_t precision_bits = input.f() & precision_bits_mask;
+  uint64_t half_way = one64 << (precision_digits_count - 1);
+  precision_bits *= kDenominator;
+  half_way *= kDenominator;
+  DiyFp rounded_input(input.f() >> precision_digits_count,
+                      input.e() + precision_digits_count);
+  if (precision_bits >= half_way + error) {
+    rounded_input.set_f(rounded_input.f() + 1);
+  }
+  // If the last_bits are too close to the half-way case than we are too
+  // inaccurate and round down. In this case we return false so that we can
+  // fall back to a more precise algorithm.
+
+  *result = Double(rounded_input).value();
+  if (half_way - error < precision_bits && precision_bits < half_way + error) {
+    // Too imprecise. The caller will have to fall back to a slower version.
+    // However the returned number is guaranteed to be either the correct
+    // double, or the next-lower double.
+    return false;
+  } else {
+    return true;
+  }
+}
+
+
+// Returns
+//   - -1 if buffer*10^exponent < diy_fp.
+//   -  0 if buffer*10^exponent == diy_fp.
+//   - +1 if buffer*10^exponent > diy_fp.
+// Preconditions:
+//   buffer.length() + exponent <= kMaxDecimalPower + 1
+//   buffer.length() + exponent > kMinDecimalPower
+//   buffer.length() <= kMaxDecimalSignificantDigits
+static int CompareBufferWithDiyFp(Vector<const char> buffer,
+                                  int exponent,
+                                  DiyFp diy_fp) {
+  ASSERT(buffer.length() + exponent <= kMaxDecimalPower + 1);
+  ASSERT(buffer.length() + exponent > kMinDecimalPower);
+  ASSERT(buffer.length() <= kMaxSignificantDecimalDigits);
+  // Make sure that the Bignum will be able to hold all our numbers.
+  // Our Bignum implementation has a separate field for exponents. Shifts will
+  // consume at most one bigit (< 64 bits).
+  // ln(10) == 3.3219...
+  ASSERT(((kMaxDecimalPower + 1) * 333 / 100) < Bignum::kMaxSignificantBits);
+  Bignum buffer_bignum;
+  Bignum diy_fp_bignum;
+  buffer_bignum.AssignDecimalString(buffer);
+  diy_fp_bignum.AssignUInt64(diy_fp.f());
+  if (exponent >= 0) {
+    buffer_bignum.MultiplyByPowerOfTen(exponent);
+  } else {
+    diy_fp_bignum.MultiplyByPowerOfTen(-exponent);
+  }
+  if (diy_fp.e() > 0) {
+    diy_fp_bignum.ShiftLeft(diy_fp.e());
+  } else {
+    buffer_bignum.ShiftLeft(-diy_fp.e());
+  }
+  return Bignum::Compare(buffer_bignum, diy_fp_bignum);
+}
+
+
+// Returns true if the guess is the correct double.
+// Returns false, when guess is either correct or the next-lower double.
+static bool ComputeGuess(Vector<const char> trimmed, int exponent,
+                         double* guess) {
+  if (trimmed.length() == 0) {
+    *guess = 0.0;
+    return true;
+  }
+  if (exponent + trimmed.length() - 1 >= kMaxDecimalPower) {
+    *guess = Double::Infinity();
+    return true;
+  }
+  if (exponent + trimmed.length() <= kMinDecimalPower) {
+    *guess = 0.0;
+    return true;
+  }
+
+  if (DoubleStrtod(trimmed, exponent, guess) ||
+      DiyFpStrtod(trimmed, exponent, guess)) {
+    return true;
+  }
+  if (*guess == Double::Infinity()) {
+    return true;
+  }
+  return false;
+}
+
+double Strtod(Vector<const char> buffer, int exponent) {
+  char copy_buffer[kMaxSignificantDecimalDigits];
+  Vector<const char> trimmed;
+  int updated_exponent;
+  TrimAndCut(buffer, exponent, copy_buffer, kMaxSignificantDecimalDigits,
+             &trimmed, &updated_exponent);
+  exponent = updated_exponent;
+
+  double guess;
+  bool is_correct = ComputeGuess(trimmed, exponent, &guess);
+  if (is_correct) return guess;
+
+  DiyFp upper_boundary = Double(guess).UpperBoundary();
+  int comparison = CompareBufferWithDiyFp(trimmed, exponent, upper_boundary);
+  if (comparison < 0) {
+    return guess;
+  } else if (comparison > 0) {
+    return Double(guess).NextDouble();
+  } else if ((Double(guess).Significand() & 1) == 0) {
+    // Round towards even.
+    return guess;
+  } else {
+    return Double(guess).NextDouble();
+  }
+}
+
+float Strtof(Vector<const char> buffer, int exponent) {
+  char copy_buffer[kMaxSignificantDecimalDigits];
+  Vector<const char> trimmed;
+  int updated_exponent;
+  TrimAndCut(buffer, exponent, copy_buffer, kMaxSignificantDecimalDigits,
+             &trimmed, &updated_exponent);
+  exponent = updated_exponent;
+
+  double double_guess;
+  bool is_correct = ComputeGuess(trimmed, exponent, &double_guess);
+
+  float float_guess = static_cast<float>(double_guess);
+  if (float_guess == double_guess) {
+    // This shortcut triggers for integer values.
+    return float_guess;
+  }
+
+  // We must catch double-rounding. Say the double has been rounded up, and is
+  // now a boundary of a float, and rounds up again. This is why we have to
+  // look at previous too.
+  // Example (in decimal numbers):
+  //    input: 12349
+  //    high-precision (4 digits): 1235
+  //    low-precision (3 digits):
+  //       when read from input: 123
+  //       when rounded from high precision: 124.
+  // To do this we simply look at the neigbors of the correct result and see
+  // if they would round to the same float. If the guess is not correct we have
+  // to look at four values (since two different doubles could be the correct
+  // double).
+
+  double double_next = Double(double_guess).NextDouble();
+  double double_previous = Double(double_guess).PreviousDouble();
+
+  float f1 = static_cast<float>(double_previous);
+  float f2 = float_guess;
+  float f3 = static_cast<float>(double_next);
+  float f4;
+  if (is_correct) {
+    f4 = f3;
+  } else {
+    double double_next2 = Double(double_next).NextDouble();
+    f4 = static_cast<float>(double_next2);
+  }
+  (void)f2;
+  assert(f1 <= f2 && f2 <= f3 && f3 <= f4);
+
+  // If the guess doesn't lie near a single-precision boundary we can simply
+  // return its float-value.
+  if (f1 == f4) {
+    return float_guess;
+  }
+
+  assert((f1 != f2 && f2 == f3 && f3 == f4) ||
+         (f1 == f2 && f2 != f3 && f3 == f4) ||
+         (f1 == f2 && f2 == f3 && f3 != f4));
+
+  // guess and next are the two possible canditates (in the same way that
+  // double_guess was the lower candidate for a double-precision guess).
+  float guess = f1;
+  float next = f4;
+  DiyFp upper_boundary;
+  if (guess == 0.0f) {
+    float min_float = 1e-45f;
+    upper_boundary = Double(static_cast<double>(min_float) / 2).AsDiyFp();
+  } else {
+    upper_boundary = Single(guess).UpperBoundary();
+  }
+  int comparison = CompareBufferWithDiyFp(trimmed, exponent, upper_boundary);
+  if (comparison < 0) {
+    return guess;
+  } else if (comparison > 0) {
+    return next;
+  } else if ((Single(guess).Significand() & 1) == 0) {
+    // Round towards even.
+    return guess;
+  } else {
+    return next;
+  }
+}
+
+}  // namespace double_conversion
diff --git a/mfbt/double-conversion/strtod.h b/mfbt/double-conversion/strtod.h
new file mode 100644
index 0000000..ed0293b
--- /dev/null
+++ b/mfbt/double-conversion/strtod.h
@@ -0,0 +1,45 @@
+// Copyright 2010 the V8 project authors. All rights reserved.
+// Redistribution and use in source and binary forms, with or without
+// modification, are permitted provided that the following conditions are
+// met:
+//
+//     * Redistributions of source code must retain the above copyright
+//       notice, this list of conditions and the following disclaimer.
+//     * Redistributions in binary form must reproduce the above
+//       copyright notice, this list of conditions and the following
+//       disclaimer in the documentation and/or other materials provided
+//       with the distribution.
+//     * Neither the name of Google Inc. nor the names of its
+//       contributors may be used to endorse or promote products derived
+//       from this software without specific prior written permission.
+//
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+#ifndef DOUBLE_CONVERSION_STRTOD_H_
+#define DOUBLE_CONVERSION_STRTOD_H_
+
+#include "utils.h"
+
+namespace double_conversion {
+
+// The buffer must only contain digits in the range [0-9]. It must not
+// contain a dot or a sign. It must not start with '0', and must not be empty.
+double Strtod(Vector<const char> buffer, int exponent);
+
+// The buffer must only contain digits in the range [0-9]. It must not
+// contain a dot or a sign. It must not start with '0', and must not be empty.
+float Strtof(Vector<const char> buffer, int exponent);
+
+}  // namespace double_conversion
+
+#endif  // DOUBLE_CONVERSION_STRTOD_H_
diff --git a/mfbt/double-conversion/update.sh b/mfbt/double-conversion/update.sh
new file mode 100755
index 0000000..81add8e
--- /dev/null
+++ b/mfbt/double-conversion/update.sh
@@ -0,0 +1,17 @@
+# Usage: ./update.sh <double-conversion-src-directory>
+#
+# Copies the needed files from a directory containing the original
+# double-conversion source that we need.
+
+cp $1/LICENSE ./
+cp $1/README ./
+
+# Includes
+cp $1/src/*.h ./
+
+# Source
+cp $1/src/*.cc ./
+
+patch -p3 < add-mfbt-api-markers.patch
+patch -p3 < use-StandardInteger.patch
+patch -p3 < more-architectures.patch
diff --git a/mfbt/double-conversion/use-StandardInteger.patch b/mfbt/double-conversion/use-StandardInteger.patch
new file mode 100644
index 0000000..6cd49b3
--- /dev/null
+++ b/mfbt/double-conversion/use-StandardInteger.patch
@@ -0,0 +1,29 @@
+diff --git a/mfbt/double-conversion/utils.h b/mfbt/double-conversion/utils.h
+index cd3e330..bdc7d4b 100644
+--- a/mfbt/double-conversion/utils.h
++++ b/mfbt/double-conversion/utils.h
+@@ -68,23 +68,7 @@
+ #endif
+ 
+ 
+-#if defined(_WIN32) && !defined(__MINGW32__)
+-
+-typedef signed char int8_t;
+-typedef unsigned char uint8_t;
+-typedef short int16_t;  // NOLINT
+-typedef unsigned short uint16_t;  // NOLINT
+-typedef int int32_t;
+-typedef unsigned int uint32_t;
+-typedef __int64 int64_t;
+-typedef unsigned __int64 uint64_t;
+-// intptr_t and friends are defined in crtdefs.h through stdio.h.
+-
+-#else
+-
+-#include <stdint.h>
+-
+-#endif
++#include "mozilla/StandardInteger.h"
+ 
+ // The following macro works on both 32 and 64-bit platforms.
+ // Usage: instead of writing 0x1234567890123456
diff --git a/mfbt/double-conversion/utils.h b/mfbt/double-conversion/utils.h
new file mode 100644
index 0000000..0eec2d9
--- /dev/null
+++ b/mfbt/double-conversion/utils.h
@@ -0,0 +1,297 @@
+// Copyright 2010 the V8 project authors. All rights reserved.
+// Redistribution and use in source and binary forms, with or without
+// modification, are permitted provided that the following conditions are
+// met:
+//
+//     * Redistributions of source code must retain the above copyright
+//       notice, this list of conditions and the following disclaimer.
+//     * Redistributions in binary form must reproduce the above
+//       copyright notice, this list of conditions and the following
+//       disclaimer in the documentation and/or other materials provided
+//       with the distribution.
+//     * Neither the name of Google Inc. nor the names of its
+//       contributors may be used to endorse or promote products derived
+//       from this software without specific prior written permission.
+//
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+#ifndef DOUBLE_CONVERSION_UTILS_H_
+#define DOUBLE_CONVERSION_UTILS_H_
+
+#include <stdlib.h>
+#include <string.h>
+
+#include <assert.h>
+#ifndef ASSERT
+#define ASSERT(condition)      (assert(condition))
+#endif
+#ifndef UNIMPLEMENTED
+#define UNIMPLEMENTED() (abort())
+#endif
+#ifndef UNREACHABLE
+#define UNREACHABLE()   (abort())
+#endif
+
+// Double operations detection based on target architecture.
+// Linux uses a 80bit wide floating point stack on x86. This induces double
+// rounding, which in turn leads to wrong results.
+// An easy way to test if the floating-point operations are correct is to
+// evaluate: 89255.0/1e22. If the floating-point stack is 64 bits wide then
+// the result is equal to 89255e-22.
+// The best way to test this, is to create a division-function and to compare
+// the output of the division with the expected result. (Inlining must be
+// disabled.)
+// On Linux,x86 89255e-22 != Div_double(89255.0/1e22)
+#if defined(_M_X64) || defined(__x86_64__) || \
+    defined(__ARMEL__) || defined(__avr32__) || \
+    defined(__hppa__) || defined(__ia64__) || \
+    defined(__mips__) || defined(__powerpc__) || \
+    defined(__sparc__) || defined(__sparc) || defined(__s390__) || \
+    defined(__SH4__) || defined(__alpha__) || \
+    defined(_MIPS_ARCH_MIPS32R2)
+#define DOUBLE_CONVERSION_CORRECT_DOUBLE_OPERATIONS 1
+#elif defined(_M_IX86) || defined(__i386__) || defined(__i386)
+#if defined(_WIN32)
+// Windows uses a 64bit wide floating point stack.
+#define DOUBLE_CONVERSION_CORRECT_DOUBLE_OPERATIONS 1
+#else
+#undef DOUBLE_CONVERSION_CORRECT_DOUBLE_OPERATIONS
+#endif  // _WIN32
+#else
+#error Target architecture was not detected as supported by Double-Conversion.
+#endif
+
+
+#include "mozilla/StandardInteger.h"
+
+// The following macro works on both 32 and 64-bit platforms.
+// Usage: instead of writing 0x1234567890123456
+//      write UINT64_2PART_C(0x12345678,90123456);
+#define UINT64_2PART_C(a, b) (((static_cast<uint64_t>(a) << 32) + 0x##b##u))
+
+
+// The expression ARRAY_SIZE(a) is a compile-time constant of type
+// size_t which represents the number of elements of the given
+// array. You should only use ARRAY_SIZE on statically allocated
+// arrays.
+#ifndef ARRAY_SIZE
+#define ARRAY_SIZE(a)                                   \
+  ((sizeof(a) / sizeof(*(a))) /                         \
+  static_cast<size_t>(!(sizeof(a) % sizeof(*(a)))))
+#endif
+
+// A macro to disallow the evil copy constructor and operator= functions
+// This should be used in the private: declarations for a class
+#ifndef DISALLOW_COPY_AND_ASSIGN
+#define DISALLOW_COPY_AND_ASSIGN(TypeName)      \
+  TypeName(const TypeName&);                    \
+  void operator=(const TypeName&)
+#endif
+
+// A macro to disallow all the implicit constructors, namely the
+// default constructor, copy constructor and operator= functions.
+//
+// This should be used in the private: declarations for a class
+// that wants to prevent anyone from instantiating it. This is
+// especially useful for classes containing only static methods.
+#ifndef DISALLOW_IMPLICIT_CONSTRUCTORS
+#define DISALLOW_IMPLICIT_CONSTRUCTORS(TypeName) \
+  TypeName();                                    \
+  DISALLOW_COPY_AND_ASSIGN(TypeName)
+#endif
+
+namespace double_conversion {
+
+static const int kCharSize = sizeof(char);
+
+// Returns the maximum of the two parameters.
+template <typename T>
+static T Max(T a, T b) {
+  return a < b ? b : a;
+}
+
+
+// Returns the minimum of the two parameters.
+template <typename T>
+static T Min(T a, T b) {
+  return a < b ? a : b;
+}
+
+
+inline int StrLength(const char* string) {
+  size_t length = strlen(string);
+  ASSERT(length == static_cast<size_t>(static_cast<int>(length)));
+  return static_cast<int>(length);
+}
+
+// This is a simplified version of V8's Vector class.
+template <typename T>
+class Vector {
+ public:
+  Vector() : start_(NULL), length_(0) {}
+  Vector(T* data, int length) : start_(data), length_(length) {
+    ASSERT(length == 0 || (length > 0 && data != NULL));
+  }
+
+  // Returns a vector using the same backing storage as this one,
+  // spanning from and including 'from', to but not including 'to'.
+  Vector<T> SubVector(int from, int to) {
+    ASSERT(to <= length_);
+    ASSERT(from < to);
+    ASSERT(0 <= from);
+    return Vector<T>(start() + from, to - from);
+  }
+
+  // Returns the length of the vector.
+  int length() const { return length_; }
+
+  // Returns whether or not the vector is empty.
+  bool is_empty() const { return length_ == 0; }
+
+  // Returns the pointer to the start of the data in the vector.
+  T* start() const { return start_; }
+
+  // Access individual vector elements - checks bounds in debug mode.
+  T& operator[](int index) const {
+    ASSERT(0 <= index && index < length_);
+    return start_[index];
+  }
+
+  T& first() { return start_[0]; }
+
+  T& last() { return start_[length_ - 1]; }
+
+ private:
+  T* start_;
+  int length_;
+};
+
+
+// Helper class for building result strings in a character buffer. The
+// purpose of the class is to use safe operations that checks the
+// buffer bounds on all operations in debug mode.
+class StringBuilder {
+ public:
+  StringBuilder(char* buffer, int size)
+      : buffer_(buffer, size), position_(0) { }
+
+  ~StringBuilder() { if (!is_finalized()) Finalize(); }
+
+  int size() const { return buffer_.length(); }
+
+  // Get the current position in the builder.
+  int position() const {
+    ASSERT(!is_finalized());
+    return position_;
+  }
+
+  // Reset the position.
+  void Reset() { position_ = 0; }
+
+  // Add a single character to the builder. It is not allowed to add
+  // 0-characters; use the Finalize() method to terminate the string
+  // instead.
+  void AddCharacter(char c) {
+    ASSERT(c != '\0');
+    ASSERT(!is_finalized() && position_ < buffer_.length());
+    buffer_[position_++] = c;
+  }
+
+  // Add an entire string to the builder. Uses strlen() internally to
+  // compute the length of the input string.
+  void AddString(const char* s) {
+    AddSubstring(s, StrLength(s));
+  }
+
+  // Add the first 'n' characters of the given string 's' to the
+  // builder. The input string must have enough characters.
+  void AddSubstring(const char* s, int n) {
+    ASSERT(!is_finalized() && position_ + n < buffer_.length());
+    ASSERT(static_cast<size_t>(n) <= strlen(s));
+    memmove(&buffer_[position_], s, n * kCharSize);
+    position_ += n;
+  }
+
+
+  // Add character padding to the builder. If count is non-positive,
+  // nothing is added to the builder.
+  void AddPadding(char c, int count) {
+    for (int i = 0; i < count; i++) {
+      AddCharacter(c);
+    }
+  }
+
+  // Finalize the string by 0-terminating it and returning the buffer.
+  char* Finalize() {
+    ASSERT(!is_finalized() && position_ < buffer_.length());
+    buffer_[position_] = '\0';
+    // Make sure nobody managed to add a 0-character to the
+    // buffer while building the string.
+    ASSERT(strlen(buffer_.start()) == static_cast<size_t>(position_));
+    position_ = -1;
+    ASSERT(is_finalized());
+    return buffer_.start();
+  }
+
+ private:
+  Vector<char> buffer_;
+  int position_;
+
+  bool is_finalized() const { return position_ < 0; }
+
+  DISALLOW_IMPLICIT_CONSTRUCTORS(StringBuilder);
+};
+
+// The type-based aliasing rule allows the compiler to assume that pointers of
+// different types (for some definition of different) never alias each other.
+// Thus the following code does not work:
+//
+// float f = foo();
+// int fbits = *(int*)(&f);
+//
+// The compiler 'knows' that the int pointer can't refer to f since the types
+// don't match, so the compiler may cache f in a register, leaving random data
+// in fbits.  Using C++ style casts makes no difference, however a pointer to
+// char data is assumed to alias any other pointer.  This is the 'memcpy
+// exception'.
+//
+// Bit_cast uses the memcpy exception to move the bits from a variable of one
+// type of a variable of another type.  Of course the end result is likely to
+// be implementation dependent.  Most compilers (gcc-4.2 and MSVC 2005)
+// will completely optimize BitCast away.
+//
+// There is an additional use for BitCast.
+// Recent gccs will warn when they see casts that may result in breakage due to
+// the type-based aliasing rule.  If you have checked that there is no breakage
+// you can use BitCast to cast one pointer type to another.  This confuses gcc
+// enough that it can no longer see that you have cast one pointer type to
+// another thus avoiding the warning.
+template <class Dest, class Source>
+inline Dest BitCast(const Source& source) {
+  // Compile time assertion: sizeof(Dest) == sizeof(Source)
+  // A compile error here means your Dest and Source have different sizes.
+  typedef char VerifySizesAreEqual[sizeof(Dest) == sizeof(Source) ? 1 : -1];
+
+  Dest dest;
+  memmove(&dest, &source, sizeof(dest));
+  return dest;
+}
+
+template <class Dest, class Source>
+inline Dest BitCast(Source* source) {
+  return BitCast<Dest>(reinterpret_cast<uintptr_t>(source));
+}
+
+}  // namespace double_conversion
+
+#endif  // DOUBLE_CONVERSION_UTILS_H_
diff --git a/mfbt/exported_headers.mk b/mfbt/exported_headers.mk
new file mode 100644
index 0000000..adf07cf
--- /dev/null
+++ b/mfbt/exported_headers.mk
@@ -0,0 +1,35 @@
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+# This file defines the headers exported by mfbt.  It is included by mfbt
+# itself and by the JS engine, which, when built standalone, must install
+# mfbt's exported headers itself.
+
+EXPORTS_NAMESPACES += mozilla
+
+EXPORTS_mozilla += \
+  Assertions.h \
+  Attributes.h \
+  BloomFilter.h \
+  CheckedInt.h \
+  Constants.h \
+  FloatingPoint.h \
+  GuardObjects.h \
+  HashFunctions.h \
+  Likely.h \
+  LinkedList.h \
+  MathAlgorithms.h \
+  MSStdInt.h \
+  NullPtr.h \
+  RangedPtr.h \
+  RefPtr.h \
+  Scoped.h \
+  StandardInteger.h \
+  SHA1.h \
+  ThreadLocal.h \
+  TypeTraits.h \
+  Types.h \
+  Util.h \
+  WeakPtr.h \
+  $(NULL)
diff --git a/mfbt/sources.mk b/mfbt/sources.mk
new file mode 100644
index 0000000..eec2a2a
--- /dev/null
+++ b/mfbt/sources.mk
@@ -0,0 +1,28 @@
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+ifndef MFBT_ROOT
+$(error Before including this file, you must define MFBT_ROOT to point to \
+the MFBT source directory)
+endif
+
+CPPSRCS += \
+  HashFunctions.cpp \
+  SHA1.cpp \
+  $(NULL)
+
+# Imported double-conversion sources.
+VPATH += $(MFBT_ROOT)/double-conversion \
+  $(NULL)
+
+CPPSRCS += \
+  bignum-dtoa.cc \
+  bignum.cc \
+  cached-powers.cc \
+  diy-fp.cc \
+  double-conversion.cc \
+  fast-dtoa.cc \
+  fixed-dtoa.cc \
+  strtod.cc \
+  $(NULL)
diff --git a/mfbt/tests/Makefile.in b/mfbt/tests/Makefile.in
new file mode 100644
index 0000000..542cffa
--- /dev/null
+++ b/mfbt/tests/Makefile.in
@@ -0,0 +1,32 @@
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this file,
+# You can obtain one at http://mozilla.org/MPL/2.0/.
+
+DEPTH = @DEPTH@
+topsrcdir = @top_srcdir@
+srcdir = @srcdir@
+VPATH = @srcdir@
+
+include $(DEPTH)/config/autoconf.mk
+
+STL_FLAGS =
+
+CPP_UNIT_TESTS = \
+  TestCheckedInt.cpp \
+  TestTypeTraits.cpp \
+  TestSHA1.cpp \
+  TestWeakPtr.cpp \
+  $(NULL)
+
+# in order to prevent rules.mk from trying to link to libraries that are
+# not available to MFBT, we have to reset these MOZ_GLUE*_LDFLAGS before including it
+# and LIBS_ after including it. For WRAP_LDFLAGS, it shouldn't matter.
+# See later comments in bug 732875.
+
+MOZ_GLUE_PROGRAM_LDFLAGS=
+MOZ_GLUE_LDFLAGS =
+WRAP_LDFLAGS=
+
+include $(topsrcdir)/config/rules.mk
+
+LIBS= $(call EXPAND_LIBNAME_PATH,mfbt,$(DEPTH)/mfbt)
diff --git a/mfbt/tests/TestCheckedInt.cpp b/mfbt/tests/TestCheckedInt.cpp
new file mode 100644
index 0000000..c69db4b
--- /dev/null
+++ b/mfbt/tests/TestCheckedInt.cpp
@@ -0,0 +1,494 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this file,
+ * You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "mozilla/CheckedInt.h"
+
+#include <iostream>
+#include <climits>
+
+#ifndef MOZ_CHECKEDINT_ENABLE_MOZ_ASSERTS
+#  error MOZ_CHECKEDINT_ENABLE_MOZ_ASSERTS should be defined by CheckedInt.h
+#endif
+
+using namespace mozilla;
+
+int gIntegerTypesTested = 0;
+int gTestsPassed = 0;
+int gTestsFailed = 0;
+
+void verifyImplFunction(bool x, bool expected,
+                        const char* file, int line,
+                        int size, bool isTSigned)
+{
+  if (x == expected) {
+    gTestsPassed++;
+  } else {
+    gTestsFailed++;
+    std::cerr << "Test failed at " << file << ":" << line;
+    std::cerr << " with T a ";
+    if (isTSigned)
+      std::cerr << "signed";
+    else
+      std::cerr << "unsigned";
+    std::cerr << " " << CHAR_BIT*size << "-bit integer type" << std::endl;
+  }
+}
+
+#define VERIFY_IMPL(x, expected) \
+    verifyImplFunction((x), \
+    (expected), \
+    __FILE__, \
+    __LINE__, \
+    sizeof(T), \
+    detail::IsSigned<T>::value)
+
+#define VERIFY(x)            VERIFY_IMPL(x, true)
+#define VERIFY_IS_FALSE(x)   VERIFY_IMPL(x, false)
+#define VERIFY_IS_VALID(x)   VERIFY_IMPL((x).isValid(), true)
+#define VERIFY_IS_INVALID(x) VERIFY_IMPL((x).isValid(), false)
+#define VERIFY_IS_VALID_IF(x,condition) VERIFY_IMPL((x).isValid(), (condition))
+
+template<typename T, size_t Size = sizeof(T)>
+struct testTwiceBiggerType
+{
+    static void run()
+    {
+      VERIFY(detail::IsSupported<typename detail::TwiceBiggerType<T>::Type>::value);
+      VERIFY(sizeof(typename detail::TwiceBiggerType<T>::Type)
+               == 2 * sizeof(T));
+      VERIFY(bool(detail::IsSigned<typename detail::TwiceBiggerType<T>::Type>::value)
+               == bool(detail::IsSigned<T>::value));
+    }
+};
+
+template<typename T>
+struct testTwiceBiggerType<T, 8>
+{
+    static void run()
+    {
+      VERIFY_IS_FALSE(detail::IsSupported<
+                        typename detail::TwiceBiggerType<T>::Type
+                      >::value);
+    }
+};
+
+
+template<typename T>
+void test()
+{
+  static bool alreadyRun = false;
+  // Integer types from different families may just be typedefs for types from other families.
+  // e.g. int32_t might be just a typedef for int. No point re-running the same tests then.
+  if (alreadyRun)
+      return;
+  alreadyRun = true;
+
+  VERIFY(detail::IsSupported<T>::value);
+  const bool isTSigned = detail::IsSigned<T>::value;
+  VERIFY(bool(isTSigned) == !bool(T(-1) > T(0)));
+
+  testTwiceBiggerType<T>::run();
+
+  typedef typename detail::UnsignedType<T>::Type unsignedT;
+
+  VERIFY(sizeof(unsignedT) == sizeof(T));
+  VERIFY(detail::IsSigned<unsignedT>::value == false);
+
+  const CheckedInt<T> max(detail::MaxValue<T>::value);
+  const CheckedInt<T> min(detail::MinValue<T>::value);
+
+  // Check MinValue and MaxValue, since they are custom implementations and a mistake there
+  // could potentially NOT be caught by any other tests... while making everything wrong!
+
+  unsignedT bit = 1;
+  unsignedT unsignedMinValue(min.value());
+  unsignedT unsignedMaxValue(max.value());
+  for (size_t i = 0; i < sizeof(T) * CHAR_BIT - 1; i++)
+  {
+    VERIFY((unsignedMinValue & bit) == 0);
+    bit <<= 1;
+  }
+  VERIFY((unsignedMinValue & bit) == (isTSigned ? bit : unsignedT(0)));
+  VERIFY(unsignedMaxValue == unsignedT(~unsignedMinValue));
+
+  const CheckedInt<T> zero(0);
+  const CheckedInt<T> one(1);
+  const CheckedInt<T> two(2);
+  const CheckedInt<T> three(3);
+  const CheckedInt<T> four(4);
+
+  /* Addition / subtraction checks */
+
+  VERIFY_IS_VALID(zero + zero);
+  VERIFY(zero + zero == zero);
+  VERIFY_IS_FALSE(zero + zero == one); // Check that == doesn't always return true
+  VERIFY_IS_VALID(zero + one);
+  VERIFY(zero + one == one);
+  VERIFY_IS_VALID(one + one);
+  VERIFY(one + one == two);
+
+  const CheckedInt<T> maxMinusOne = max - one;
+  const CheckedInt<T> maxMinusTwo = max - two;
+  VERIFY_IS_VALID(maxMinusOne);
+  VERIFY_IS_VALID(maxMinusTwo);
+  VERIFY_IS_VALID(maxMinusOne + one);
+  VERIFY_IS_VALID(maxMinusTwo + one);
+  VERIFY_IS_VALID(maxMinusTwo + two);
+  VERIFY(maxMinusOne + one == max);
+  VERIFY(maxMinusTwo + one == maxMinusOne);
+  VERIFY(maxMinusTwo + two == max);
+
+  VERIFY_IS_VALID(max + zero);
+  VERIFY_IS_VALID(max - zero);
+  VERIFY_IS_INVALID(max + one);
+  VERIFY_IS_INVALID(max + two);
+  VERIFY_IS_INVALID(max + maxMinusOne);
+  VERIFY_IS_INVALID(max + max);
+
+  const CheckedInt<T> minPlusOne = min + one;
+  const CheckedInt<T> minPlusTwo = min + two;
+  VERIFY_IS_VALID(minPlusOne);
+  VERIFY_IS_VALID(minPlusTwo);
+  VERIFY_IS_VALID(minPlusOne - one);
+  VERIFY_IS_VALID(minPlusTwo - one);
+  VERIFY_IS_VALID(minPlusTwo - two);
+  VERIFY(minPlusOne - one == min);
+  VERIFY(minPlusTwo - one == minPlusOne);
+  VERIFY(minPlusTwo - two == min);
+
+  const CheckedInt<T> minMinusOne = min - one;
+  VERIFY_IS_VALID(min + zero);
+  VERIFY_IS_VALID(min - zero);
+  VERIFY_IS_INVALID(min - one);
+  VERIFY_IS_INVALID(min - two);
+  VERIFY_IS_INVALID(min - minMinusOne);
+  VERIFY_IS_VALID(min - min);
+
+  const CheckedInt<T> maxOverTwo = max / two;
+  VERIFY_IS_VALID(maxOverTwo + maxOverTwo);
+  VERIFY_IS_VALID(maxOverTwo + one);
+  VERIFY((maxOverTwo + one) - one == maxOverTwo);
+  VERIFY_IS_VALID(maxOverTwo - maxOverTwo);
+  VERIFY(maxOverTwo - maxOverTwo == zero);
+
+  const CheckedInt<T> minOverTwo = min / two;
+  VERIFY_IS_VALID(minOverTwo + minOverTwo);
+  VERIFY_IS_VALID(minOverTwo + one);
+  VERIFY((minOverTwo + one) - one == minOverTwo);
+  VERIFY_IS_VALID(minOverTwo - minOverTwo);
+  VERIFY(minOverTwo - minOverTwo == zero);
+
+  VERIFY_IS_INVALID(min - one);
+  VERIFY_IS_INVALID(min - two);
+
+  if (isTSigned) {
+    VERIFY_IS_INVALID(min + min);
+    VERIFY_IS_INVALID(minOverTwo + minOverTwo + minOverTwo);
+    VERIFY_IS_INVALID(zero - min + min);
+    VERIFY_IS_INVALID(one - min + min);
+  }
+
+  /* Unary operator- checks */
+
+  const CheckedInt<T> negOne = -one;
+  const CheckedInt<T> negTwo = -two;
+
+  if (isTSigned) {
+    VERIFY_IS_VALID(-max);
+    VERIFY_IS_VALID(-max - one);
+    VERIFY_IS_VALID(negOne);
+    VERIFY_IS_VALID(-max + negOne);
+    VERIFY_IS_VALID(negOne + one);
+    VERIFY(negOne + one == zero);
+    VERIFY_IS_VALID(negTwo);
+    VERIFY_IS_VALID(negOne + negOne);
+    VERIFY(negOne + negOne == negTwo);
+  } else {
+    VERIFY_IS_INVALID(negOne);
+  }
+
+  /* multiplication checks */
+
+  VERIFY_IS_VALID(zero * zero);
+  VERIFY(zero * zero == zero);
+  VERIFY_IS_VALID(zero * one);
+  VERIFY(zero * one == zero);
+  VERIFY_IS_VALID(one * zero);
+  VERIFY(one * zero == zero);
+  VERIFY_IS_VALID(one * one);
+  VERIFY(one * one == one);
+  VERIFY_IS_VALID(one * three);
+  VERIFY(one * three == three);
+  VERIFY_IS_VALID(two * two);
+  VERIFY(two * two == four);
+
+  VERIFY_IS_INVALID(max * max);
+  VERIFY_IS_INVALID(maxOverTwo * max);
+  VERIFY_IS_INVALID(maxOverTwo * maxOverTwo);
+
+  const CheckedInt<T> maxApproxSqrt(T(T(1) << (CHAR_BIT*sizeof(T)/2)));
+
+  VERIFY_IS_VALID(maxApproxSqrt);
+  VERIFY_IS_VALID(maxApproxSqrt * two);
+  VERIFY_IS_INVALID(maxApproxSqrt * maxApproxSqrt);
+  VERIFY_IS_INVALID(maxApproxSqrt * maxApproxSqrt * maxApproxSqrt);
+
+  if (isTSigned) {
+    VERIFY_IS_INVALID(min * min);
+    VERIFY_IS_INVALID(minOverTwo * min);
+    VERIFY_IS_INVALID(minOverTwo * minOverTwo);
+
+    const CheckedInt<T> minApproxSqrt = -maxApproxSqrt;
+
+    VERIFY_IS_VALID(minApproxSqrt);
+    VERIFY_IS_VALID(minApproxSqrt * two);
+    VERIFY_IS_INVALID(minApproxSqrt * maxApproxSqrt);
+    VERIFY_IS_INVALID(minApproxSqrt * minApproxSqrt);
+  }
+
+  // make sure to check all 4 paths in signed multiplication validity check.
+  // test positive * positive
+  VERIFY_IS_VALID(max * one);
+  VERIFY(max * one == max);
+  VERIFY_IS_INVALID(max * two);
+  VERIFY_IS_VALID(maxOverTwo * two);
+  VERIFY((maxOverTwo + maxOverTwo) == (maxOverTwo * two));
+
+  if (isTSigned) {
+    // test positive * negative
+    VERIFY_IS_VALID(max * negOne);
+    VERIFY_IS_VALID(-max);
+    VERIFY(max * negOne == -max);
+    VERIFY_IS_VALID(one * min);
+    VERIFY_IS_INVALID(max * negTwo);
+    VERIFY_IS_VALID(maxOverTwo * negTwo);
+    VERIFY_IS_VALID(two * minOverTwo);
+    VERIFY_IS_VALID((maxOverTwo + one) * negTwo);
+    VERIFY_IS_INVALID((maxOverTwo + two) * negTwo);
+    VERIFY_IS_INVALID(two * (minOverTwo - one));
+
+    // test negative * positive
+    VERIFY_IS_VALID(min * one);
+    VERIFY_IS_VALID(minPlusOne * one);
+    VERIFY_IS_INVALID(min * two);
+    VERIFY_IS_VALID(minOverTwo * two);
+    VERIFY(minOverTwo * two == min);
+    VERIFY_IS_INVALID((minOverTwo - one) * negTwo);
+    VERIFY_IS_INVALID(negTwo * max);
+    VERIFY_IS_VALID(minOverTwo * two);
+    VERIFY(minOverTwo * two == min);
+    VERIFY_IS_VALID(negTwo * maxOverTwo);
+    VERIFY_IS_INVALID((minOverTwo - one) * two);
+    VERIFY_IS_VALID(negTwo * (maxOverTwo + one));
+    VERIFY_IS_INVALID(negTwo * (maxOverTwo + two));
+
+    // test negative * negative
+    VERIFY_IS_INVALID(min * negOne);
+    VERIFY_IS_VALID(minPlusOne * negOne);
+    VERIFY(minPlusOne * negOne == max);
+    VERIFY_IS_INVALID(min * negTwo);
+    VERIFY_IS_INVALID(minOverTwo * negTwo);
+    VERIFY_IS_INVALID(negOne * min);
+    VERIFY_IS_VALID(negOne * minPlusOne);
+    VERIFY(negOne * minPlusOne == max);
+    VERIFY_IS_INVALID(negTwo * min);
+    VERIFY_IS_INVALID(negTwo * minOverTwo);
+  }
+
+  /* Division checks */
+
+  VERIFY_IS_VALID(one / one);
+  VERIFY(one / one == one);
+  VERIFY_IS_VALID(three / three);
+  VERIFY(three / three == one);
+  VERIFY_IS_VALID(four / two);
+  VERIFY(four / two == two);
+  VERIFY((four*three)/four == three);
+
+  // Check that div by zero is invalid
+  VERIFY_IS_INVALID(zero / zero);
+  VERIFY_IS_INVALID(one / zero);
+  VERIFY_IS_INVALID(two / zero);
+  VERIFY_IS_INVALID(negOne / zero);
+  VERIFY_IS_INVALID(max / zero);
+  VERIFY_IS_INVALID(min / zero);
+
+  if (isTSigned) {
+    // Check that min / -1 is invalid
+    VERIFY_IS_INVALID(min / negOne);
+
+    // Check that the test for div by -1 isn't banning other numerators than min
+    VERIFY_IS_VALID(one / negOne);
+    VERIFY_IS_VALID(zero / negOne);
+    VERIFY_IS_VALID(negOne / negOne);
+    VERIFY_IS_VALID(max / negOne);
+  }
+
+  /* Check that invalidity is correctly preserved by arithmetic ops */
+
+  const CheckedInt<T> someInvalid = max + max;
+  VERIFY_IS_INVALID(someInvalid + zero);
+  VERIFY_IS_INVALID(someInvalid - zero);
+  VERIFY_IS_INVALID(zero + someInvalid);
+  VERIFY_IS_INVALID(zero - someInvalid);
+  VERIFY_IS_INVALID(-someInvalid);
+  VERIFY_IS_INVALID(someInvalid * zero);
+  VERIFY_IS_INVALID(someInvalid * one);
+  VERIFY_IS_INVALID(zero * someInvalid);
+  VERIFY_IS_INVALID(one * someInvalid);
+  VERIFY_IS_INVALID(someInvalid / zero);
+  VERIFY_IS_INVALID(someInvalid / one);
+  VERIFY_IS_INVALID(zero / someInvalid);
+  VERIFY_IS_INVALID(one / someInvalid);
+  VERIFY_IS_INVALID(someInvalid + someInvalid);
+  VERIFY_IS_INVALID(someInvalid - someInvalid);
+  VERIFY_IS_INVALID(someInvalid * someInvalid);
+  VERIFY_IS_INVALID(someInvalid / someInvalid);
+
+  /* Check that mixing checked integers with plain integers in expressions is allowed */
+
+  VERIFY(one + T(2) == three);
+  VERIFY(2 + one == three);
+  {
+    CheckedInt<T> x = one;
+    x += 2;
+    VERIFY(x == three);
+  }
+  VERIFY(two - 1 == one);
+  VERIFY(2 - one == one);
+  {
+    CheckedInt<T> x = two;
+    x -= 1;
+    VERIFY(x == one);
+  }
+  VERIFY(one * 2 == two);
+  VERIFY(2 * one == two);
+  {
+    CheckedInt<T> x = one;
+    x *= 2;
+    VERIFY(x == two);
+  }
+  VERIFY(four / 2 == two);
+  VERIFY(4 / two == two);
+  {
+    CheckedInt<T> x = four;
+    x /= 2;
+    VERIFY(x == two);
+  }
+
+  VERIFY(one == 1);
+  VERIFY(1 == one);
+  VERIFY_IS_FALSE(two == 1);
+  VERIFY_IS_FALSE(1 == two);
+  VERIFY_IS_FALSE(someInvalid == 1);
+  VERIFY_IS_FALSE(1 == someInvalid);
+
+  /* Check that construction of CheckedInt from an integer value of a mismatched type is checked */
+
+  #define VERIFY_CONSTRUCTION_FROM_INTEGER_TYPE(U) \
+  { \
+    bool isUSigned = detail::IsSigned<U>::value; \
+    VERIFY_IS_VALID(CheckedInt<T>(U(0))); \
+    VERIFY_IS_VALID(CheckedInt<T>(U(1))); \
+    VERIFY_IS_VALID(CheckedInt<T>(U(100))); \
+    if (isUSigned) \
+      VERIFY_IS_VALID_IF(CheckedInt<T>(U(-1)), isTSigned); \
+    if (sizeof(U) > sizeof(T)) \
+      VERIFY_IS_INVALID(CheckedInt<T>(U(detail::MaxValue<T>::value) + one.value())); \
+    VERIFY_IS_VALID_IF(CheckedInt<T>(detail::MaxValue<U>::value), \
+      (sizeof(T) > sizeof(U) || ((sizeof(T) == sizeof(U)) && (isUSigned || !isTSigned)))); \
+    VERIFY_IS_VALID_IF(CheckedInt<T>(detail::MinValue<U>::value), \
+      isUSigned == false ? 1 : \
+      bool(isTSigned) == false ? 0 : \
+      sizeof(T) >= sizeof(U)); \
+  }
+  VERIFY_CONSTRUCTION_FROM_INTEGER_TYPE(int8_t)
+  VERIFY_CONSTRUCTION_FROM_INTEGER_TYPE(uint8_t)
+  VERIFY_CONSTRUCTION_FROM_INTEGER_TYPE(int16_t)
+  VERIFY_CONSTRUCTION_FROM_INTEGER_TYPE(uint16_t)
+  VERIFY_CONSTRUCTION_FROM_INTEGER_TYPE(int32_t)
+  VERIFY_CONSTRUCTION_FROM_INTEGER_TYPE(uint32_t)
+  VERIFY_CONSTRUCTION_FROM_INTEGER_TYPE(int64_t)
+  VERIFY_CONSTRUCTION_FROM_INTEGER_TYPE(uint64_t)
+
+  typedef unsigned char unsignedChar;
+  typedef unsigned short unsignedShort;
+  typedef unsigned int  unsignedInt;
+  typedef unsigned long unsignedLong;
+
+  VERIFY_CONSTRUCTION_FROM_INTEGER_TYPE(char)
+  VERIFY_CONSTRUCTION_FROM_INTEGER_TYPE(unsignedChar)
+  VERIFY_CONSTRUCTION_FROM_INTEGER_TYPE(short)
+  VERIFY_CONSTRUCTION_FROM_INTEGER_TYPE(unsignedShort)
+  VERIFY_CONSTRUCTION_FROM_INTEGER_TYPE(int)
+  VERIFY_CONSTRUCTION_FROM_INTEGER_TYPE(unsignedInt)
+  VERIFY_CONSTRUCTION_FROM_INTEGER_TYPE(long)
+  VERIFY_CONSTRUCTION_FROM_INTEGER_TYPE(unsignedLong)
+
+  /* Test increment/decrement operators */
+
+  CheckedInt<T> x, y;
+  x = one;
+  y = x++;
+  VERIFY(x == two);
+  VERIFY(y == one);
+  x = one;
+  y = ++x;
+  VERIFY(x == two);
+  VERIFY(y == two);
+  x = one;
+  y = x--;
+  VERIFY(x == zero);
+  VERIFY(y == one);
+  x = one;
+  y = --x;
+  VERIFY(x == zero);
+  VERIFY(y == zero);
+  x = max;
+  VERIFY_IS_VALID(x++);
+  x = max;
+  VERIFY_IS_INVALID(++x);
+  x = min;
+  VERIFY_IS_VALID(x--);
+  x = min;
+  VERIFY_IS_INVALID(--x);
+
+  gIntegerTypesTested++;
+}
+
+int main()
+{
+  test<int8_t>();
+  test<uint8_t>();
+  test<int16_t>();
+  test<uint16_t>();
+  test<int32_t>();
+  test<uint32_t>();
+  test<int64_t>();
+  test<uint64_t>();
+
+  test<char>();
+  test<unsigned char>();
+  test<short>();
+  test<unsigned short>();
+  test<int>();
+  test<unsigned int>();
+  test<long>();
+  test<unsigned long>();
+
+  if (gIntegerTypesTested < 8) {
+    std::cerr << "Only " << gIntegerTypesTested << " have been tested. "
+              << "This should not be less than 8." << std::endl;
+    gTestsFailed++;
+  }
+
+  std::cerr << gTestsFailed << " tests failed, "
+            << gTestsPassed << " tests passed out of "
+            << gTestsFailed + gTestsPassed
+            << " tests, covering " << gIntegerTypesTested
+            << " distinct integer types." << std::endl;
+
+  return gTestsFailed > 0;
+}
diff --git a/mfbt/tests/TestSHA1.cpp b/mfbt/tests/TestSHA1.cpp
new file mode 100644
index 0000000..4f78d96
--- /dev/null
+++ b/mfbt/tests/TestSHA1.cpp
@@ -0,0 +1,199 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "mozilla/SHA1.h"
+
+using namespace mozilla;
+
+static unsigned int TestV[1024] = {
+  0x048edc1a, 0x4345588c, 0x0ef03cbf, 0x1d6438f5, 0x094e0a1e, 0x68535f60,
+  0x14e8c927, 0x60190043, 0x5d640ab7, 0x73dc7c62, 0x364223f9, 0x47320292,
+  0x3924cae0, 0x5f6b26d3, 0x5efa04ef, 0x7aab361e, 0x2773b1aa, 0x1631b07d,
+  0x385b5dd1, 0x26c809b0, 0x28ad3a9f, 0x0315292a, 0x1a544e67, 0x1e79dcb9,
+  0x787683e8, 0x3a591c75, 0x1dd338c7, 0x01c539e5, 0x1c15b23e, 0x0697c25c,
+  0x4df5fd45, 0x672aa324, 0x39f74e6e, 0x269cdd5f, 0x087b6fce, 0x293509db,
+  0x0aef54a9, 0x210c4cc5, 0x29d6dc4a, 0x16320825, 0x3ab7b181, 0x56d6fd25,
+  0x6837fda2, 0x3e7994c2, 0x37f77529, 0x48c85472, 0x424fd84d, 0x00aba7fa,
+  0x6d8475de, 0x354634a7, 0x0c73bb49, 0x0a335de6, 0x0a9ea542, 0x5ffb31f1,
+  0x00a6a3f2, 0x76b14a03, 0x1e436a37, 0x173b766a, 0x33cf3ca0, 0x34eb0f1a,
+  0x4ca073ee, 0x27591fe6, 0x5eaf3356, 0x10c24493, 0x1bad88b6, 0x676f2309,
+  0x7f5e2d91, 0x74bd4c83, 0x66549b43, 0x52ffdf24, 0x2dfa0a83, 0x7c3e1cbf,
+  0x1edf87fc, 0x1f6fa930, 0x7c29bc74, 0x374bcd2f, 0x5b43de94, 0x0d09a3a6,
+  0x7437ecb0, 0x635117f8, 0x2aa78f65, 0x2c788958, 0x098cb9f3, 0x13ed5b3f,
+  0x41b7c7ba, 0x696b2d88, 0x42e20d63, 0x69585b1d, 0x4a9b027c, 0x0c761cba,
+  0x563bdbc4, 0x3bde2f5b, 0x0bab9730, 0x7740104c, 0x11641702, 0x26f03c32,
+  0x011a87c6, 0x2c5e4e6c, 0x46c34200, 0x6a167e84, 0x34205728, 0x0e8a6152,
+  0x0014604b, 0x6793bacd, 0x442bca9c, 0x6f2018ce, 0x4313e07e, 0x77f2c69c,
+  0x62621441, 0x47bf6358, 0x59c45e04, 0x16ba3426, 0x6ac0c19d, 0x20218c6b,
+  0x510b4ddc, 0x585f6c9d, 0x1ed02b0c, 0x366bf0a9, 0x131c7f59, 0x0ebcd320,
+  0x00ca858a, 0x5efbcb77, 0x2a7a1859, 0x64bb5afd, 0x76258886, 0x6505c895,
+  0x602cfa32, 0x17040942, 0x783df744, 0x3838e0ae, 0x6a021e39, 0x4c8c9c5a,
+  0x4a5e96b6, 0x10f4477d, 0x247fda4f, 0x4c390400, 0x0cbe048c, 0x7b547d26,
+  0x1e2e6897, 0x4ba7e01b, 0x5cfea1bb, 0x39a2d199, 0x45aee64a, 0x12615500,
+  0x0151615f, 0x1a9f5d33, 0x4542ed44, 0x101357eb, 0x35a16b1f, 0x3420b3e1,
+  0x6442bac7, 0x1c0f2a8c, 0x68d642f1, 0x45744fc4, 0x048e60cb, 0x5f217f44,
+  0x6cc7d151, 0x27f41984, 0x2d01eb09, 0x2bb15aea, 0x6dda49f8, 0x590dd6bc,
+  0x280cc20b, 0x7e2592b5, 0x043642f0, 0x292b5d29, 0x2e0a9b69, 0x41162471,
+  0x1e55db6b, 0x648b96fe, 0x05f8f9d1, 0x4a9d4cbb, 0x38517039, 0x2b0f8917,
+  0x4d1e67bb, 0x713e0974, 0x64fdf214, 0x11223963, 0x2bd09d24, 0x19924092,
+  0x4b4a70f0, 0x1ece6b03, 0x1780c9c1, 0x09b4c3ac, 0x58ac7e73, 0x5c9a4747,
+  0x321f943b, 0x41167667, 0x3a19cf8c, 0x53f4144d, 0x03a498de, 0x6fb4b742,
+  0x54d793cb, 0x7ee164e2, 0x501af74c, 0x43201e7f, 0x0ad581be, 0x497f046a,
+  0x3b1d2a9f, 0x53b88eb0, 0x2c3a26c5, 0x5ae970ba, 0x7d7ee4ff, 0x471366c5,
+  0x46119703, 0x3bfc2e58, 0x456d6c4f, 0x4b6bb181, 0x45d7c872, 0x0d023221,
+  0x021176d1, 0x4195ad44, 0x4621ec90, 0x3ae68279, 0x57952f71, 0x1796080c,
+  0x228077bb, 0x5e2b7fee, 0x3d71dd88, 0x4a651849, 0x7f1c8081, 0x04c333fc,
+  0x1f99bff6, 0x11b7754c, 0x740be324, 0x069bf2e2, 0x0802f3e0, 0x371cf30e,
+  0x1d44dda5, 0x6033b9e5, 0x5639a9b0, 0x6526bfff, 0x14d7d9b7, 0x4182b6a7,
+  0x01a5fa76, 0x7aa5e581, 0x762465e6, 0x386b3a2e, 0x495a3ab0, 0x04421b2e,
+  0x46e04591, 0x472af458, 0x6a007dd3, 0x2e8be484, 0x18660abe, 0x7969af82,
+  0x5a242a83, 0x581b5f72, 0x5f0eff6d, 0x38aea98c, 0x2acb5853, 0x6d650b35,
+  0x10b750d7, 0x18fdcd14, 0x09b4816c, 0x3ceef016, 0x6957153c, 0x27cf39fb,
+  0x60e3495d, 0x381e1da6, 0x4b5be02d, 0x14b6f309, 0x6380c589, 0x1a31f436,
+  0x4b5e50c1, 0x493ac048, 0x314baad1, 0x71e24ab7, 0x718af49c, 0x022f4658,
+  0x1a419d5b, 0x1854610d, 0x2ec4e99a, 0x7096ce50, 0x5467ba00, 0x404aab4c,
+  0x1a5ab015, 0x217580f7, 0x2d50071e, 0x71a9f437, 0x27f758b5, 0x11cd8b3f,
+  0x63b089c9, 0x53c860c1, 0x2fa6b7d7, 0x61e54771, 0x5c0ba6b9, 0x3138f796,
+  0x5c7359cd, 0x4c2c5654, 0x549d581c, 0x3129ebf7, 0x4958a248, 0x1a460541,
+  0x68e64964, 0x597c0609, 0x57afcbab, 0x2f1c6479, 0x57a0ad5c, 0x5936938f,
+  0x536a5cbe, 0x29aacf0b, 0x43eca70d, 0x6e7a3e4e, 0x563c1e3b, 0x32f23909,
+  0x12faa42d, 0x28b0bbde, 0x797e2842, 0x1b827bdf, 0x0df96a6e, 0x542ef7f4,
+  0x6226d368, 0x01cb4258, 0x77bcba08, 0x7e6dc041, 0x0571eda3, 0x0fdf5065,
+  0x5c9b9f7a, 0x2b496dd6, 0x02d3b40b, 0x3a5752db, 0x4843a293, 0x6fdc9c3f,
+  0x42963996, 0x39c9e4eb, 0x01db58ad, 0x7e79381c, 0x5bb207bb, 0x2df5de51,
+  0x1549ec82, 0x64f01e70, 0x536eb0d0, 0x10fa6e03, 0x5b7f9a20, 0x2d8b625d,
+  0x397410c7, 0x7778284e, 0x1ab75170, 0x254f304e, 0x395ba877, 0x0c2e2815,
+  0x5c723dec, 0x63b91327, 0x7c5954b5, 0x67dd69a3, 0x21d220c7, 0x5a287fcd,
+  0x0d0b9c59, 0x22444c9f, 0x6305cb43, 0x12f717cc, 0x77c11945, 0x0e79bda8,
+  0x6e014391, 0x441d0179, 0x5e17dd2f, 0x53e57a5c, 0x692f4b9a, 0x76c1e94b,
+  0x5a872d81, 0x044f7e7e, 0x0970844f, 0x25e34e73, 0x57865d3c, 0x640771d2,
+  0x12d410ed, 0x1424e079, 0x3e1c7fd7, 0x0e89295a, 0x48dcf262, 0x55a29550,
+  0x0fd4d360, 0x7494d449, 0x41e6f260, 0x2230d4e7, 0x5ad1cd49, 0x7f8dd428,
+  0x7722b48a, 0x7a14848d, 0x2a83335a, 0x548c0d9b, 0x24f5d43b, 0x33a417cb,
+  0x3061e078, 0x1a1bc935, 0x5aedb5df, 0x6755f3e4, 0x795e4cdb, 0x64dfcd1c,
+  0x6d5164fc, 0x34a3df0e, 0x2cc92142, 0x2569127d, 0x130f3d86, 0x43617cc2,
+  0x25eaf1fa, 0x044ae792, 0x4b47ee17, 0x6879ea87, 0x7eb455fa, 0x54481e19,
+  0x13bba2f0, 0x6da3fe79, 0x19c306ff, 0x42591e38, 0x2b0e205d, 0x60bd48bc,
+  0x550aa0ce, 0x2296a6ef, 0x551eb052, 0x76df1b8e, 0x242a2d22, 0x0ada0b06,
+  0x58b661ec, 0x490bec94, 0x20bd7c59, 0x760de8c3, 0x7a048ee8, 0x44ba6dcd,
+  0x3816abd9, 0x47e8527e, 0x2194a188, 0x6967a480, 0x7f7e2083, 0x0ec455f3,
+  0x78198eab, 0x3d710773, 0x05969198, 0x76ffcffe, 0x54be4797, 0x11105781,
+  0x3a851719, 0x516284b8, 0x4295de1c, 0x3905be43, 0x6d4e7d6a, 0x0877796d,
+  0x0b9e986a, 0x5e2b853f, 0x7e6c79cd, 0x4a44a54c, 0x1e28b9a2, 0x5b1e408e,
+  0x6a1c8eac, 0x62a87929, 0x4f075dac, 0x5c030e8c, 0x3df73ce9, 0x321c3c69,
+  0x2325cc45, 0x4eaf0759, 0x486a31fb, 0x12d04b94, 0x714e15d5, 0x420d1910,
+  0x092dc45b, 0x0119beac, 0x68b2bfdb, 0x74863a17, 0x3c7ab8e5, 0x035bc2df,
+  0x4e7a7965, 0x017f58d6, 0x6414074e, 0x3a1e64ae, 0x2d6725d8, 0x0f22f82a,
+  0x0a0affa0, 0x4159f31e, 0x4002cb9d, 0x234e393f, 0x6028169f, 0x3b804078,
+  0x0c16e2e1, 0x0e198020, 0x24b13c40, 0x1ceb2143, 0x38dd4246, 0x6f483590,
+  0x69b20a6e, 0x105580b1, 0x5d60f184, 0x065d18eb, 0x09a28739, 0x70345728,
+  0x595a5934, 0x14a78a43, 0x449f05c7, 0x6556fcfc, 0x260bc0b2, 0x3afb600e,
+  0x1f47bb91, 0x145c14b6, 0x541832fe, 0x54f10f23, 0x3013650e, 0x6c0d32ba,
+  0x4f202c8d, 0x66bcc661, 0x6131dc7f, 0x04828b25, 0x1737565d, 0x520e967f,
+  0x16cf0438, 0x6f2bc19e, 0x553c3dda, 0x356906b0, 0x333916d5, 0x2887c195,
+  0x11e7440b, 0x6354f182, 0x06b2f977, 0x6d2c9a5c, 0x2d02bfb7, 0x74fafcf6,
+  0x2b955161, 0x74035c38, 0x6e9bc991, 0x09a3a5b9, 0x460f416a, 0x11afabfc,
+  0x66e32d10, 0x4a56ac6e, 0x6448afa8, 0x680b0044, 0x05d0e296, 0x49569eac,
+  0x0adb563b, 0x4a9da168, 0x4f857004, 0x0f234600, 0x6db386ec, 0x280b94bf,
+  0x7cd258a5, 0x6165fd88, 0x3bf2aac9, 0x2cb47c44, 0x2381c2a4, 0x4fe42552,
+  0x21d4c81e, 0x24baa9af, 0x365231cb, 0x11b7fc81, 0x419748fb, 0x38ff637e,
+  0x065f3365, 0x21f1aba8, 0x2df41ace, 0x5cec1d95, 0x22c078a8, 0x7bb894fc,
+  0x2d66fc53, 0x7ed82ccc, 0x4485c9d7, 0x1af210fc, 0x5d2faa09, 0x3b33412e,
+  0x79d12ea8, 0x7bb8103b, 0x5cea1a7b, 0x2779db45, 0x1250ed5b, 0x0c4d8964,
+  0x6c18e9f5, 0x501ddc60, 0x3de43ae4, 0x6c0e8577, 0x0adfb426, 0x7ec718f5,
+  0x1991f387, 0x101ccb9c, 0x632360b4, 0x7d52ce4d, 0x0b58c91c, 0x1fa59d53,
+  0x0b0b48b0, 0x297315d0, 0x7f3132ff, 0x323b85d1, 0x2f852141, 0x23e84bdc,
+  0x3732cb25, 0x1274eb57, 0x21a882c3, 0x095288a9, 0x2120e253, 0x617799ce,
+  0x5e4926b3, 0x52575363, 0x696722e0, 0x509c9117, 0x3b60f14f, 0x423310fa,
+  0x4e694e80, 0x000a647e, 0x453e283a, 0x3f1d21ef, 0x527c91f0, 0x7ac2e88a,
+  0x1ba3b840, 0x1c3f253a, 0x04c40280, 0x437dc361, 0x7247859c, 0x61e5b34c,
+  0x20746a53, 0x58cfc2df, 0x79edf48e, 0x5b48e723, 0x7b08baac, 0x1d1035ea,
+  0x023fc918, 0x2de0427c, 0x71540904, 0x4030e8f5, 0x2b0961f6, 0x4ec98ef0,
+  0x781076ee, 0x0dac959b, 0x16f66214, 0x273411e5, 0x02334297, 0x3b568cd1,
+  0x7cf4e8c0, 0x0f4c2c91, 0x2d8dd28e, 0x4a7b3fb0, 0x237969ae, 0x363d6cb6,
+  0x75fee60a, 0x5825f4df, 0x29f79f9d, 0x22de4f33, 0x2309590e, 0x1977c2bd,
+  0x67f7bebe, 0x452b8330, 0x5dc70832, 0x5cddbea4, 0x59091e0b, 0x4d287830,
+  0x2bbc2ce6, 0x420ee023, 0x02d6e086, 0x228a7a14, 0x48207207, 0x1d5ccc5a,
+  0x37d32cdc, 0x50dc6508, 0x0b795304, 0x5b9fd543, 0x2a3f2925, 0x72e71606,
+  0x0dc8ba42, 0x3279a910, 0x6bd2c2e2, 0x775065d8, 0x547c59a6, 0x4b5374cf,
+  0x0c45cd18, 0x532096d6, 0x351c9bd1, 0x107fdce0, 0x3ae69075, 0x5dddd5de,
+  0x3bb0ba8b, 0x0b1a0019, 0x6c226525, 0x109e9002, 0x312191be, 0x16fa3de8,
+  0x4a5197aa, 0x0931b2d2, 0x79ee6e1b, 0x657a142b, 0x6ab74d38, 0x77440cff,
+  0x11e37956, 0x5c335799, 0x269d3be3, 0x18923cfd, 0x4dd71b00, 0x77c58014,
+  0x07145324, 0x1678546a, 0x5dfd4f6a, 0x207f4e13, 0x6b0a98c0, 0x015bc2cf,
+  0x1636d8fe, 0x7bc5f038, 0x183a0661, 0x573ec5f3, 0x54cf2255, 0x2fcc905c,
+  0x71bb70b9, 0x2b122a89, 0x59f86e5b, 0x5528273d, 0x464cf857, 0x27efdeec,
+  0x1d0bcfcc, 0x64d7837f, 0x1e7a659a, 0x02aa611c, 0x53969ad5, 0x0e83f59f,
+  0x50a6d11b, 0x79513c59, 0x0e5c3c98, 0x2ed7bbcf, 0x117de9d9, 0x375ec696,
+  0x19c830aa, 0x66950511, 0x2b6dbbaa, 0x5ca18c9b, 0x0a487514, 0x6f44a887,
+  0x6921bc6e, 0x3ef8130b, 0x26f6cde3, 0x686d7605, 0x6583553a, 0x29bcf7cc,
+  0x55d42201, 0x1c93497c, 0x64c53231, 0x32088f6e, 0x381c5770, 0x617574d8,
+  0x09757952, 0x1a616eb0, 0x1140e8aa, 0x0ff66ffb, 0x32039001, 0x5a455e7c,
+  0x0027b906, 0x21cf154c, 0x67d3527f, 0x56fd7602, 0x150f8b25, 0x2ae8e4c8,
+  0x0bf10aec, 0x3d26a40f, 0x5c4c8ffc, 0x3c291322, 0x737fd02c, 0x4b506209,
+  0x484ddaa4, 0x00b44669, 0x5974bdd1, 0x7d39d617, 0x12995404, 0x48f00bbe,
+  0x44f7c59a, 0x23cb9292, 0x6476f20b, 0x034fbd59, 0x2893161c, 0x1dbae8c0,
+  0x50348c2e, 0x797f0957, 0x685ddeaf, 0x36fb8a2e, 0x0fceb6f4, 0x10347ab4,
+  0x72720bfc, 0x292a4304, 0x0cbf8a27, 0x3cea6db7, 0x4b0c6b15, 0x57e8e716,
+  0x4e9c54cc, 0x4fc7f7ca, 0x49a6d3e2, 0x10fc2df3, 0x73db387e, 0x72cb89c3,
+  0x71dba437, 0x4b14048c, 0x6e1af265, 0x1084b213, 0x3842107d, 0x6ecdc171,
+  0x647919b2, 0x41a80841, 0x7b387c76, 0x46bc094b, 0x331b312a, 0x2f140cc4,
+  0x355d0a11, 0x19390200, 0x69b05263, 0x582963fa, 0x44897e31, 0x66a473f0,
+  0x0374f08d, 0x35879e45, 0x5e1dd7ef, 0x34d6a311, 0x6e4e18eb, 0x7b44734b,
+  0x0e421333, 0x3da026d8, 0x5becbf4b, 0x56db4a1f, 0x1f2089bc, 0x28c733f2,
+  0x04b0975d, 0x6156f224, 0x12d1f40f, 0x7f4d30f4, 0x2c0b9861, 0x769a083b,
+  0x739544fb, 0x1dbd1067, 0x0e8cd717, 0x4c246fb2, 0x115eff39, 0x19e22f2a,
+  0x4563ba61, 0x5d33a617, 0x54af83cf, 0x030bde73, 0x54b4736d, 0x0f01dfec,
+  0x08869c01, 0x4e9e4d7b, 0x4739855a, 0x62d964a3, 0x26948fde, 0x30adf212,
+  0x1f57b400, 0x3766c914, 0x1e7f9d1c, 0x33258b59, 0x522ab2c2, 0x3dc99798,
+  0x15f53fe2, 0x05636669, 0x354b59c3, 0x1c37ebd4, 0x0bb7ebf9, 0x0e4e87f9,
+  0x680d3124, 0x2770d549, 0x0c5e112e, 0x74aaa7ed, 0x06c0b550, 0x342b5922,
+  0x4532ab5b, 0x4257dbee, 0x087f32a9, 0x45ada3e3, 0x7a854272, 0x061625f2,
+  0x47c85a91, 0x25ad375d, 0x2809bd9d, 0x168b9348, 0x4381b0a3, 0x6f2dc6ca,
+  0x122e54f6, 0x6c3228a6, 0x653c1652, 0x60b60584, 0x1d304b77, 0x4cc74c58,
+  0x087e3dd5, 0x79bd540e, 0x79ab7a70, 0x26fcd1c9, 0x342abaaf, 0x644716b0,
+  0x01f076cb, 0x73628937, 0x20b01ff8, 0x5832b80b, 0x2f77fc92, 0x4468d962,
+  0x2bac2679, 0x7f850778, 0x47d2997c, 0x02690cb7, 0x7de54951, 0x54d80b14,
+  0x5e0c6854, 0x313cc749, 0x622b86ba, 0x38dbf6d3, 0x045d3e52, 0x574f87fd,
+  0x09f1b078, 0x31784f71, 0x4f01dd2f, 0x1874c9f9, 0x5837c7af, 0x2372f768,
+  0x531bd1e8, 0x61816c0b, 0x4592995f, 0x156463c0, 0x250c5afe, 0x40c83178,
+  0x4396f6b7, 0x29bdbec0, 0x43ea8ca5, 0x5c474696, 0x2c869192, 0x2ff2f51a,
+  0x7c963fe5, 0x294319c1, 0x019fbe26, 0x72fa8e68, 0x245ca463, 0x4ca88208,
+  0x72ac845a, 0x25307181, 0x2cdf88f7, 0x0adbfebd, 0x2eea465b, 0x52e4eee0,
+  0x084daacd, 0x717ce67e, 0x594087c2, 0x2b8ee5c7, 0x4558f811, 0x76b65ba4,
+  0x5de05e09, 0x3db76e27, 0x3c75110d, 0x04ca67e7, 0x51cd6d09, 0x7b4e9c3e,
+  0x7cdda4d2, 0x674fb021, 0x7d372d2d, 0x13f7978b, 0x5fb106b1, 0x034377d1,
+  0x2e5336f3, 0x099bb17d, 0x04e6755e, 0x34f73c1e, 0x004e0a0d, 0x7f2c32e2,
+  0x1fc8f910, 0x67d0859d, 0x76462b25, 0x59fa9a17, 0x028e53ef, 0x3d6d5fdd,
+  0x79a4671e, 0x5cbec506, 0x2c23ee6d, 0x628a2c1e, 0x4dae87bd, 0x07a189ea,
+  0x3a414a96, 0x5915f622, 0x6bea011e, 0x412674cf, 0x07ecc314, 0x6a7dbce8,
+  0x7e176f10, 0x68e60d47, 0x079ea970, 0x79f3b55c, 0x65a46098, 0x56155533,
+  0x7e5d0272, 0x795bfad5, 0x094da770, 0x05ba427c, 0x152e430e, 0x187d8470,
+  0x08e607bc, 0x45ce5ef9, 0x654231ae, 0x38d8cb48, 0x605632f8, 0x25cf8ee9,
+  0x11497170, 0x171a3b00, 0x0f103d49, 0x24826483, 0x2848e187, 0x7498919b,
+  0x1bb788cb, 0x791ad5c7, 0x5129330e, 0x016c4436, 0x430f05bf, 0x1f06b5cd,
+  0x62df1378, 0x0423b9b4, 0x0341acaf, 0x3189543c, 0x7b96b2ea, 0x6c4865c3,
+  0x4cc7adc3, 0x78a2bff6, 0x642db7c7, 0x70d02300, 0x7cd43ac0, 0x4f5fe414,
+  0x333b52c2, 0x500d3c74, 0x65782c01, 0x3f72a2c5, 0x278f59d8, 0x493bf7f8,
+  0x16bf51a0, 0x6cc70ced, 0x6ed15979, 0x1a77abae, 0x08cadbb7, 0x2f2e0bc0,
+  0x236f5e8d, 0x1a4b4495, 0x360bd008, 0x32227d40
+};
+
+int main()
+{
+  SHA1Sum S;
+  unsigned char hash[20];
+  S.update((const unsigned char*) TestV, sizeof(TestV));
+  S.finish(hash);
+  const unsigned char expected[20] = {
+    0xc8, 0xf2, 0x09, 0x59, 0x4e, 0x64, 0x40, 0xaa, 0x7b, 0xf7, 0xb8, 0xe0,
+    0xfa, 0x44, 0xb2, 0x31, 0x95, 0xad, 0x94, 0x81};
+
+  for (unsigned int i = 0; i < 20; ++i) {
+    if (hash[i] != expected[i]) {
+      return 1;
+    }
+  }
+  return 0;
+}
diff --git a/mfbt/tests/TestTypeTraits.cpp b/mfbt/tests/TestTypeTraits.cpp
new file mode 100644
index 0000000..269d384
--- /dev/null
+++ b/mfbt/tests/TestTypeTraits.cpp
@@ -0,0 +1,55 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this file,
+ * You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "mozilla/Assertions.h"
+#include "mozilla/TypeTraits.h"
+
+using mozilla::IsConvertible;
+
+class A { };
+class B : public A { };
+class C : private A { };
+class D { };
+
+static void
+TestIsConvertible()
+{
+  // Pointer type convertibility
+  MOZ_ASSERT((IsConvertible<A*, A*>::value),
+             "A* should convert to A*");
+  MOZ_ASSERT((IsConvertible<B*, A*>::value),
+             "B* should convert to A*");
+  MOZ_ASSERT((!IsConvertible<A*, B*>::value),
+             "A* shouldn't convert to B*");
+  MOZ_ASSERT((!IsConvertible<A*, C*>::value),
+             "A* shouldn't convert to C*");
+  MOZ_ASSERT((!IsConvertible<A*, D*>::value),
+             "A* shouldn't convert to unrelated D*");
+  MOZ_ASSERT((!IsConvertible<D*, A*>::value),
+             "D* shouldn't convert to unrelated A*");
+
+  // Instance type convertibility
+  MOZ_ASSERT((IsConvertible<A, A>::value),
+             "A is A");
+  MOZ_ASSERT((IsConvertible<B, A>::value),
+             "B converts to A");
+  MOZ_ASSERT((!IsConvertible<D, A>::value),
+             "D and A are unrelated");
+  MOZ_ASSERT((!IsConvertible<A, D>::value),
+             "A and D are unrelated");
+
+  // These cases seem to require C++11 support to properly implement them, so
+  // for now just disable them.
+  //MOZ_ASSERT((!IsConvertible<C*, A*>::value),
+  //           "C* shouldn't convert to A* (private inheritance)");
+  //MOZ_ASSERT((!IsConvertible<C, A>::value),
+  //           "C doesn't convert to A (private inheritance)");
+}
+
+int
+main()
+{
+  TestIsConvertible();
+}
diff --git a/mfbt/tests/TestWeakPtr.cpp b/mfbt/tests/TestWeakPtr.cpp
new file mode 100644
index 0000000..4b811a4
--- /dev/null
+++ b/mfbt/tests/TestWeakPtr.cpp
@@ -0,0 +1,76 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "mozilla/WeakPtr.h"
+
+using mozilla::SupportsWeakPtr;
+using mozilla::WeakPtr;
+
+// To have a class C support weak pointers, inherit from SupportsWeakPtr<C>.
+class C : public SupportsWeakPtr<C>
+{
+  public:
+    int num;
+    void act() {}
+};
+
+static void
+example()
+{
+
+  C* ptr =  new C();
+
+  // Get weak pointers to ptr. The first time asWeakPtr is called
+  // a reference counted WeakReference object is created that
+  // can live beyond the lifetime of 'ptr'. The WeakReference
+  // object will be notified of 'ptr's destruction.
+  WeakPtr<C> weak = ptr->asWeakPtr();
+  WeakPtr<C> other = ptr->asWeakPtr();
+
+  // Test a weak pointer for validity before using it.
+  if (weak) {
+    weak->num = 17;
+    weak->act();
+  }
+
+  // Destroying the underlying object clears weak pointers to it.
+  delete ptr;
+
+  MOZ_ASSERT(!weak, "Deleting |ptr| clears weak pointers to it.");
+  MOZ_ASSERT(!other, "Deleting |ptr| clears all weak pointers to it.");
+}
+
+struct A : public SupportsWeakPtr<A>
+{
+    int data;
+};
+
+
+int main()
+{
+
+  A* a = new A;
+
+  // a2 is unused to test the case when we haven't initialized
+  // the internal WeakReference pointer.
+  A* a2 = new A;
+
+  a->data = 5;
+  WeakPtr<A> ptr = a->asWeakPtr();
+  {
+      WeakPtr<A> ptr2 = a->asWeakPtr();
+      MOZ_ASSERT(ptr->data == 5);
+      WeakPtr<A> ptr3 = a->asWeakPtr();
+      MOZ_ASSERT(ptr->data == 5);
+  }
+
+  delete a;
+  MOZ_ASSERT(!ptr);
+
+  delete a2;
+
+  example();
+
+  return 0;
+}