Initial import.

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diff --git a/chromium/v8/src/regexp-stack.h b/chromium/v8/src/regexp-stack.h
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+// Copyright 2009 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 V8_REGEXP_STACK_H_
+#define V8_REGEXP_STACK_H_
+
+namespace v8 {
+namespace internal {
+
+class RegExpStack;
+
+// Maintains a per-v8thread stack area that can be used by irregexp
+// implementation for its backtracking stack.
+// Since there is only one stack area, the Irregexp implementation is not
+// re-entrant. I.e., no regular expressions may be executed in the same thread
+// during a preempted Irregexp execution.
+class RegExpStackScope {
+ public:
+  // Create and delete an instance to control the life-time of a growing stack.
+
+  // Initializes the stack memory area if necessary.
+  explicit RegExpStackScope(Isolate* isolate);
+  ~RegExpStackScope();  // Releases the stack if it has grown.
+
+  RegExpStack* stack() const { return regexp_stack_; }
+
+ private:
+  RegExpStack* regexp_stack_;
+
+  DISALLOW_COPY_AND_ASSIGN(RegExpStackScope);
+};
+
+
+class RegExpStack {
+ public:
+  // Number of allocated locations on the stack below the limit.
+  // No sequence of pushes must be longer that this without doing a stack-limit
+  // check.
+  static const int kStackLimitSlack = 32;
+
+  // Gives the top of the memory used as stack.
+  Address stack_base() {
+    ASSERT(thread_local_.memory_size_ != 0);
+    return thread_local_.memory_ + thread_local_.memory_size_;
+  }
+
+  // The total size of the memory allocated for the stack.
+  size_t stack_capacity() { return thread_local_.memory_size_; }
+
+  // If the stack pointer gets below the limit, we should react and
+  // either grow the stack or report an out-of-stack exception.
+  // There is only a limited number of locations below the stack limit,
+  // so users of the stack should check the stack limit during any
+  // sequence of pushes longer that this.
+  Address* limit_address() { return &(thread_local_.limit_); }
+
+  // Ensures that there is a memory area with at least the specified size.
+  // If passing zero, the default/minimum size buffer is allocated.
+  Address EnsureCapacity(size_t size);
+
+  // Thread local archiving.
+  static int ArchiveSpacePerThread() {
+    return static_cast<int>(sizeof(ThreadLocal));
+  }
+  char* ArchiveStack(char* to);
+  char* RestoreStack(char* from);
+  void FreeThreadResources() { thread_local_.Free(); }
+
+ private:
+  RegExpStack();
+  ~RegExpStack();
+
+  // Artificial limit used when no memory has been allocated.
+  static const uintptr_t kMemoryTop = static_cast<uintptr_t>(-1);
+
+  // Minimal size of allocated stack area.
+  static const size_t kMinimumStackSize = 1 * KB;
+
+  // Maximal size of allocated stack area.
+  static const size_t kMaximumStackSize = 64 * MB;
+
+  // Structure holding the allocated memory, size and limit.
+  struct ThreadLocal {
+    ThreadLocal() { Clear(); }
+    // If memory_size_ > 0 then memory_ must be non-NULL.
+    Address memory_;
+    size_t memory_size_;
+    Address limit_;
+    void Clear() {
+      memory_ = NULL;
+      memory_size_ = 0;
+      limit_ = reinterpret_cast<Address>(kMemoryTop);
+    }
+    void Free();
+  };
+
+  // Address of allocated memory.
+  Address memory_address() {
+    return reinterpret_cast<Address>(&thread_local_.memory_);
+  }
+
+  // Address of size of allocated memory.
+  Address memory_size_address() {
+    return reinterpret_cast<Address>(&thread_local_.memory_size_);
+  }
+
+  // Resets the buffer if it has grown beyond the default/minimum size.
+  // After this, the buffer is either the default size, or it is empty, so
+  // you have to call EnsureCapacity before using it again.
+  void Reset();
+
+  ThreadLocal thread_local_;
+  Isolate* isolate_;
+
+  friend class ExternalReference;
+  friend class Isolate;
+  friend class RegExpStackScope;
+
+  DISALLOW_COPY_AND_ASSIGN(RegExpStack);
+};
+
+}}  // namespace v8::internal
+
+#endif  // V8_REGEXP_STACK_H_