libsupc++: New directory.

2000-10-06  Benjamin Kosnik  <bkoz@cygnus.com>
            Richard Henderson  <rth@cygnus.com>
	    Alexandre Oliva  <aoliva@redhat.com>

	* libsupc++: New directory.
	* libsupc++/*: Populate.
	* libsupc++/Makefile.am (INCLUDES): Add -I../../gcc for
	eh-common.h, gansidecl.h.
	* configure.in: Add in libsupc++/Makefile to AC_OUTPUT.
	* configure: Regenerate.
	* Makefile.am (SUBDIRS): Add libsupc++.
	* Makefile.in: Regenerate.
	* src/Makefile.am (libstdc___la_LIBADD): Add in libsupc++.la
	* src/Makefile.in: Regenerate.
	* libio/Makefile.am: Remove extraneous, confusing bits.
	* libio/Makefile.in: Regeneate.

From-SVN: r36763

1 files changed, 1210 insertions, 0 deletions

diff --git a/libstdc++-v3/libsupc++/tinfo.cc b/libstdc++-v3/libsupc++/tinfo.cc
new file mode 100644
index 00000000000..c381ff11101
--- /dev/null
+++ b/libstdc++-v3/libsupc++/tinfo.cc
@@ -0,0 +1,1210 @@
+// Methods for type_info for -*- C++ -*- Run Time Type Identification.
+// Copyright (C) 1994, 1996, 1998, 1999, 2000 Free Software Foundation
+
+// This file is part of GNU CC.
+
+// GNU CC is free software; you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation; either version 2, or (at your option)
+// any later version.
+
+// GNU CC is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+
+// You should have received a copy of the GNU General Public License
+// along with GNU CC; see the file COPYING.  If not, write to
+// the Free Software Foundation, 59 Temple Place - Suite 330,
+// Boston, MA 02111-1307, USA. 
+
+// As a special exception, you may use this file as part of a free software
+// library without restriction.  Specifically, if other files instantiate
+// templates or use macros or inline functions from this file, or you compile
+// this file and link it with other files to produce an executable, this
+// file does not by itself cause the resulting executable to be covered by
+// the GNU General Public License.  This exception does not however
+// invalidate any other reasons why the executable file might be covered by
+// the GNU General Public License.
+
+#pragma implementation "typeinfo"
+
+#include <stddef.h>
+#include "tinfo.h"
+#include "new"			// for placement new
+
+// This file contains the minimal working set necessary to link with code
+// that uses virtual functions and -frtti but does not actually use RTTI
+// functionality.
+
+std::type_info::
+~type_info ()
+{ }
+
+#if !defined(__GXX_ABI_VERSION) || __GXX_ABI_VERSION < 100
+// original (old) abi
+
+namespace
+{
+// ADDR is a pointer to an object.  Convert it to a pointer to a base,
+// using OFFSET.
+inline void*
+convert_to_base (void *addr, bool is_virtual, myint32 offset)
+{
+  if (!addr)
+    return NULL;
+
+  if (!is_virtual)
+    return (char *) addr + offset;
+
+  // Under the old ABI, the offset gives us the address of a pointer
+  // to the virtual base.
+  return *((void **) ((char *) addr + offset));
+}
+
+}
+
+// We can't rely on common symbols being shared between shared objects.
+bool std::type_info::
+operator== (const std::type_info& arg) const
+{
+  return (&arg == this) || (__builtin_strcmp (name (), arg.name ()) == 0);
+}
+
+extern "C" void
+__rtti_class (void *addr, const char *name,
+	      const __class_type_info::base_info *bl, size_t bn)
+{ new (addr) __class_type_info (name, bl, bn); }
+
+extern "C" void
+__rtti_si (void *addr, const char *n, const std::type_info *ti)
+{
+  new (addr) __si_type_info
+    (n, static_cast <const __user_type_info &> (*ti));
+}
+
+extern "C" void
+__rtti_user (void *addr, const char *name)
+{ new (addr) __user_type_info (name); }
+
+// Upcast for catch checking. OBJPTR points to the thrown object and might be
+// NULL. Return 0 on failure, non-zero on success. Set *ADJPTR to adjusted
+// object pointer.
+int __user_type_info::
+upcast (const type_info &target, void *objptr,
+        void **adjptr) const
+{
+  upcast_result result;
+  
+  if (do_upcast (contained_public, target, objptr, result))
+    return 0;
+  *adjptr = result.target_obj;
+  return contained_public_p (result.whole2target);
+}
+
+// Down or cross cast for dynamic_cast. OBJPTR points to the most derrived
+// object, SUBPTR points to the static base object. Both must not be NULL.
+// TARGET specifies the desired target type, SUBTYPE specifies the static
+// type. Both must be defined. Returns adjusted object pointer on success,
+// NULL on failure. [expr.dynamic.cast]/8 says 'unambiguous public base'. This
+// itself is an ambiguous statement. We choose it to mean the base must be
+// separately unambiguous and public, rather than unambiguous considering only
+// public bases.
+void *__user_type_info::
+dyncast (int boff,
+         const type_info &target, void *objptr,
+         const type_info &subtype, void *subptr) const
+{
+  dyncast_result result;
+  
+  do_dyncast (boff, contained_public,
+              target, objptr, subtype, subptr, result);
+  if (!result.target_obj)
+    return NULL;
+  if (contained_public_p (result.target2sub))
+    return result.target_obj;
+  if (contained_public_p (sub_kind (result.whole2sub & result.whole2target)))
+    // Found a valid cross cast
+    return result.target_obj;
+  if (contained_nonvirtual_p (result.whole2sub))
+    // Found an invalid cross cast, which cannot also be a down cast
+    return NULL;
+  if (result.target2sub == unknown)
+    result.target2sub = static_cast <const __user_type_info &> (target)
+                        .find_public_subobj (boff, subtype,
+                                             result.target_obj, subptr);
+  if (contained_public_p (result.target2sub))
+    // Found a valid down cast
+    return result.target_obj;
+  // Must be an invalid down cast, or the cross cast wasn't bettered
+  return NULL;
+}
+
+// Catch cast helper. ACCESS_PATH is the access from the complete thrown
+// object to this base. TARGET is the desired type we want to catch. OBJPTR
+// points to this base within the throw object, it might be NULL. Fill in
+// RESULT with what we find. Return true, should we determine catch must fail.
+bool __user_type_info::
+do_upcast (sub_kind access_path,
+           const type_info &target, void *objptr,
+           upcast_result &__restrict result) const
+{
+  if (*this == target)
+    {
+      result.target_obj = objptr;
+      result.base_type = nonvirtual_base_type;
+      result.whole2target = access_path;
+      return contained_nonpublic_p (access_path);
+    }
+  return false;
+}
+
+// dynamic cast helper. ACCESS_PATH gives the access from the most derived
+// object to this base. TARGET indicates the desired type we want. OBJPTR
+// points to this base within the object. SUBTYPE indicates the static type
+// started from and SUBPTR points to that base within the most derived object.
+// Fill in RESULT with what we find. Return true if we have located an
+// ambiguous match.
+bool __user_type_info::
+do_dyncast (int, sub_kind access_path,
+            const type_info &target, void *objptr,
+            const type_info &subtype, void *subptr,
+            dyncast_result &__restrict result) const
+{
+  if (objptr == subptr && *this == subtype)
+    {
+      // The subobject we started from. Indicate how we are accessible from
+      // the most derived object.
+      result.whole2sub = access_path;
+      return false;
+    }
+  if (*this == target)
+    {
+      result.target_obj = objptr;
+      result.whole2target = access_path;
+      result.target2sub = not_contained;
+      return false;
+    }
+  return false;
+}
+
+// find_public_subobj helper. Return contained_public if we are the desired
+// subtype. OBJPTR points to this base type, SUBPTR points to the desired base
+// object.
+__user_type_info::sub_kind __user_type_info::
+do_find_public_subobj (int, const type_info &, void *objptr, void *subptr) const
+{
+  if (subptr == objptr)
+    // Must be our type, as the pointers match.
+    return contained_public;
+  return not_contained;
+}
+
+// catch helper for single public inheritance types. See
+// __user_type_info::do_upcast for semantics.
+bool __si_type_info::
+do_upcast (sub_kind access_path,
+           const type_info &target, void *objptr,
+           upcast_result &__restrict result) const
+{
+  if (*this == target)
+    {
+      result.target_obj = objptr;
+      result.base_type = nonvirtual_base_type;
+      result.whole2target = access_path;
+      return contained_nonpublic_p (access_path);
+    }
+  return base.do_upcast (access_path, target, objptr, result);
+}
+
+// dynamic cast helper for single public inheritance types. See
+// __user_type_info::do_dyncast for semantics. BOFF indicates how SUBTYPE
+// types are inherited by TARGET types.
+bool __si_type_info::
+do_dyncast (int boff, sub_kind access_path,
+            const type_info &target, void *objptr,
+            const type_info &subtype, void *subptr,
+            dyncast_result &__restrict result) const
+{
+  if (objptr == subptr && *this == subtype)
+    {
+      // The subobject we started from. Indicate how we are accessible from
+      // the most derived object.
+      result.whole2sub = access_path;
+      return false;
+    }
+  if (*this == target)
+    {
+      result.target_obj = objptr;
+      result.whole2target = access_path;
+      if (boff >= 0)
+        result.target2sub = ((char *)subptr - (char *)objptr) == boff
+              ? contained_public : not_contained;
+      else if (boff == -2)
+        result.target2sub = not_contained;
+      return false;
+    }
+  return base.do_dyncast (boff, access_path,
+                          target, objptr, subtype, subptr, result);
+}
+
+// find_public_subobj helper. See __user_type_info::do_find_public_subobj or
+// semantics. BOFF indicates how SUBTYPE types are inherited by the original
+// target object.
+__user_type_info::sub_kind __si_type_info::
+do_find_public_subobj (int boff, const type_info &subtype, void *objptr, void *subptr) const
+{
+  if (subptr == objptr && subtype == *this)
+    return contained_public;
+  return base.do_find_public_subobj (boff, subtype, objptr, subptr);
+}
+
+// catch helper for multiple or non-public inheritance types. See
+// __user_type_info::do_upcast for semantics.
+bool __class_type_info::
+do_upcast (sub_kind access_path,
+           const type_info &target, void *objptr,
+           upcast_result &__restrict result) const
+{
+  if (*this == target)
+    {
+      result.target_obj = objptr;
+      result.base_type = nonvirtual_base_type;
+      result.whole2target = access_path;
+      return contained_nonpublic_p (access_path);
+    }
+  
+  for (size_t i = n_bases; i--;)
+    {
+      upcast_result result2;
+      void *p = objptr;
+      sub_kind sub_access = access_path;
+      p = convert_to_base (p, 
+			   base_list[i].is_virtual,
+			   base_list[i].offset);
+      if (base_list[i].is_virtual)
+	sub_access = sub_kind (sub_access | contained_virtual_mask);
+      if (base_list[i].access != PUBLIC)
+        sub_access = sub_kind (sub_access & ~contained_public_mask);
+      if (base_list[i].base->do_upcast (sub_access, target, p, result2)
+          && !contained_virtual_p (result2.whole2target))
+        return true; // must fail
+      if (result2.base_type)
+        {
+          if (result2.base_type == nonvirtual_base_type
+              && base_list[i].is_virtual)
+            result2.base_type = base_list[i].base;
+          if (!result.base_type)
+            result = result2;
+          else if (result.target_obj != result2.target_obj)
+            {
+              // Found an ambiguity.
+	      result.target_obj = NULL;
+	      result.whole2target = contained_ambig;
+	      return true;
+            }
+          else if (result.target_obj)
+            {
+              // Ok, found real object via a virtual path.
+              result.whole2target
+                  = sub_kind (result.whole2target | result2.whole2target);
+            }
+          else
+            {
+              // Dealing with a null pointer, need to check vbase
+              // containing each of the two choices.
+              if (result2.base_type == nonvirtual_base_type
+                  || result.base_type == nonvirtual_base_type
+                  || !(*result2.base_type == *result.base_type))
+                {
+                  // Already ambiguous, not virtual or via different virtuals.
+                  // Cannot match.
+                  result.whole2target = contained_ambig;
+                  return true;
+                }
+              result.whole2target
+                  = sub_kind (result.whole2target | result2.whole2target);
+            }
+        }
+    }
+  return false;
+}
+
+// dynamic cast helper for non-public or multiple inheritance types. See
+// __user_type_info::do_dyncast for overall semantics.
+// This is a big hairy function. Although the run-time behaviour of
+// dynamic_cast is simple to describe, it gives rise to some non-obvious
+// behaviour. We also desire to determine as early as possible any definite
+// answer we can get. Because it is unknown what the run-time ratio of
+// succeeding to failing dynamic casts is, we do not know in which direction
+// to bias any optimizations. To that end we make no particular effort towards
+// early fail answers or early success answers. Instead we try to minimize
+// work by filling in things lazily (when we know we need the information),
+// and opportunisticly take early success or failure results.
+bool __class_type_info::
+do_dyncast (int boff, sub_kind access_path,
+            const type_info &target, void *objptr,
+            const type_info &subtype, void *subptr,
+            dyncast_result &__restrict result) const
+{
+  if (objptr == subptr && *this == subtype)
+    {
+      // The subobject we started from. Indicate how we are accessible from
+      // the most derived object.
+      result.whole2sub = access_path;
+      return false;
+    }
+  if (*this == target)
+    {
+      result.target_obj = objptr;
+      result.whole2target = access_path;
+      if (boff >= 0)
+        result.target2sub = ((char *)subptr - (char *)objptr) == boff
+              ? contained_public : not_contained;
+      else if (boff == -2)
+        result.target2sub = not_contained;
+      return false;
+    }
+  bool result_ambig = false;
+  for (size_t i = n_bases; i--;)
+    {
+      dyncast_result result2;
+      void *p;
+      sub_kind sub_access = access_path;
+      p = convert_to_base (objptr, 
+			   base_list[i].is_virtual,
+			   base_list[i].offset);
+      if (base_list[i].is_virtual)
+	sub_access = sub_kind (sub_access | contained_virtual_mask);
+      if (base_list[i].access != PUBLIC)
+        sub_access = sub_kind (sub_access & ~contained_public_mask);
+      
+      bool result2_ambig
+          = base_list[i].base->do_dyncast (boff, sub_access,
+                                           target, p, subtype, subptr, result2);
+      result.whole2sub = sub_kind (result.whole2sub | result2.whole2sub);
+      if (result2.target2sub == contained_public
+          || result2.target2sub == contained_ambig)
+        {
+          result.target_obj = result2.target_obj;
+          result.whole2target = result2.whole2target;
+          result.target2sub = result2.target2sub;
+          // Found a downcast which can't be bettered or an ambiguous downcast
+          // which can't be disambiguated
+          return result2_ambig;
+        }
+      
+      if (!result_ambig && !result.target_obj)
+        {
+          // Not found anything yet.
+          result.target_obj = result2.target_obj;
+          result.whole2target = result2.whole2target;
+          result_ambig = result2_ambig;
+        }
+      else if (result.target_obj && result.target_obj == result2.target_obj)
+        {
+          // Found at same address, must be via virtual.  Pick the most
+          // accessible path.
+          result.whole2target =
+              sub_kind (result.whole2target | result2.whole2target);
+        }
+      else if ((result.target_obj && result2.target_obj)
+               || (result_ambig && result2.target_obj)
+               || (result2_ambig && result.target_obj))
+        {
+          // Found two different TARGET bases, or a valid one and a set of
+          // ambiguous ones, must disambiguate. See whether SUBOBJ is
+          // contained publicly within one of the non-ambiguous choices.
+          // If it is in only one, then that's the choice. If it is in
+          // both, then we're ambiguous and fail. If it is in neither,
+          // we're ambiguous, but don't yet fail as we might later find a
+          // third base which does contain SUBPTR.
+        
+          sub_kind new_sub_kind = result2.target2sub;
+          sub_kind old_sub_kind = result.target2sub;
+          
+          if (contained_nonvirtual_p (result.whole2sub))
+            {
+              // We already found SUBOBJ as a non-virtual base of most
+              // derived. Therefore if it is in either choice, it can only be
+              // in one of them, and we will already know.
+              if (old_sub_kind == unknown)
+                old_sub_kind = not_contained;
+              if (new_sub_kind == unknown)
+                new_sub_kind = not_contained;
+            }
+          else
+            {
+              const __user_type_info &t =
+                  static_cast <const __user_type_info &> (target);
+              
+              if (old_sub_kind >= not_contained)
+                ;// already calculated
+              else if (contained_nonvirtual_p (new_sub_kind))
+                // Already found non-virtually inside the other choice,
+                // cannot be in this.
+                old_sub_kind = not_contained;
+              else
+                old_sub_kind = t.find_public_subobj (boff, subtype,
+                                                     result.target_obj, subptr);
+          
+              if (new_sub_kind >= not_contained)
+                ;// already calculated
+              else if (contained_nonvirtual_p (old_sub_kind))
+                // Already found non-virtually inside the other choice,
+                // cannot be in this.
+                new_sub_kind = not_contained;
+              else
+                new_sub_kind = t.find_public_subobj (boff, subtype,
+                                                     result2.target_obj, subptr);
+            }
+          
+          // Neither sub_kind can be contained_ambig -- we bail out early
+          // when we find those.
+          if (contained_p (sub_kind (new_sub_kind ^ old_sub_kind)))
+            {
+              // Only on one choice, not ambiguous.
+              if (contained_p (new_sub_kind))
+                {
+                  // Only in new.
+                  result.target_obj = result2.target_obj;
+                  result.whole2target = result2.whole2target;
+                  result_ambig = false;
+                  old_sub_kind = new_sub_kind;
+                }
+              result.target2sub = old_sub_kind;
+              if (result.target2sub == contained_public)
+                return false; // Can't be an ambiguating downcast for later discovery.
+            }
+          else if (contained_p (sub_kind (new_sub_kind & old_sub_kind)))
+            {
+              // In both.
+              result.target_obj = NULL;
+              result.target2sub = contained_ambig;
+              return true;  // Fail.
+            }
+          else
+            {
+              // In neither publicly, ambiguous for the moment, but keep
+              // looking. It is possible that it was private in one or
+              // both and therefore we should fail, but that's just tough.
+              result.target_obj = NULL;
+              result.target2sub = not_contained;
+              result_ambig = true;
+            }
+        }
+      
+      if (result.whole2sub == contained_private)
+        // We found SUBOBJ as a private non-virtual base, therefore all
+        // cross casts will fail. We have already found a down cast, if
+        // there is one.
+        return result_ambig;
+    }
+
+  return result_ambig;
+}
+
+// find_public_subobj helper for non-public or multiple inheritance types. See
+// __user_type_info::do_find_public_subobj for semantics. We make use of BOFF
+// to prune the base class walk.
+__user_type_info::sub_kind __class_type_info::
+do_find_public_subobj (int boff, const type_info &subtype, void *objptr, void *subptr) const
+{
+  if (objptr == subptr && subtype == *this)
+    return contained_public;
+  
+  for (size_t i = n_bases; i--;)
+    {
+      if (base_list[i].access != PUBLIC)
+        continue; // Not public, can't be here.
+      void *p;
+
+      if (base_list[i].is_virtual && boff == -3)
+	// Not a virtual base, so can't be here.
+	continue;
+      
+      p = convert_to_base (objptr, 
+			   base_list[i].is_virtual,
+			   base_list[i].offset);
+
+      sub_kind base_kind = base_list[i].base->do_find_public_subobj
+                              (boff, subtype, p, subptr);
+      if (contained_p (base_kind))
+        {
+          if (base_list[i].is_virtual)
+            base_kind = sub_kind (base_kind | contained_virtual_mask);
+          return base_kind;
+        }
+    }
+  
+  return not_contained;
+}
+#else
+// new abi
+
+namespace std {
+
+// return true if this is a type_info for a pointer type
+bool type_info::
+__is_pointer_p () const
+{
+  return false;
+}
+
+// return true if this is a type_info for a function type
+bool type_info::
+__is_function_p () const
+{
+  return false;
+}
+
+// try and catch a thrown object.
+bool type_info::
+__do_catch (const type_info *thr_type, void **, unsigned) const
+{
+  return *this == *thr_type;
+}
+
+// upcast from this type to the target. __class_type_info will override
+bool type_info::
+__do_upcast (const abi::__class_type_info *, void **) const
+{
+  return false;
+}
+
+};
+
+namespace {
+
+using namespace std;
+using namespace abi;
+
+// initial part of a vtable, this structure is used with offsetof, so we don't
+// have to keep alignments consistent manually.
+struct vtable_prefix {
+  ptrdiff_t whole_object;           // offset to most derived object
+  const __class_type_info *whole_type;  // pointer to most derived type_info
+  const void *origin;               // what a class's vptr points to
+};
+
+template <typename T>
+inline const T *
+adjust_pointer (const void *base, ptrdiff_t offset)
+{
+  return reinterpret_cast <const T *>
+    (reinterpret_cast <const char *> (base) + offset);
+}
+
+// ADDR is a pointer to an object.  Convert it to a pointer to a base,
+// using OFFSET. IS_VIRTUAL is true, if we are getting a virtual base.
+inline void const *
+convert_to_base (void const *addr, bool is_virtual, ptrdiff_t offset)
+{
+  if (is_virtual)
+    {
+      const void *vtable = *static_cast <const void *const *> (addr);
+      
+      offset = *adjust_pointer<ptrdiff_t> (vtable, offset);
+    }
+
+  return adjust_pointer<void> (addr, offset);
+}
+
+// some predicate functions for __class_type_info::__sub_kind
+inline bool contained_p (__class_type_info::__sub_kind access_path)
+{
+  return access_path >= __class_type_info::__contained_mask;
+}
+inline bool public_p (__class_type_info::__sub_kind access_path)
+{
+  return access_path & __class_type_info::__contained_public_mask;
+}
+inline bool virtual_p (__class_type_info::__sub_kind access_path)
+{
+  return (access_path & __class_type_info::__contained_virtual_mask);
+}
+inline bool contained_public_p (__class_type_info::__sub_kind access_path)
+{
+  return ((access_path & __class_type_info::__contained_public)
+          == __class_type_info::__contained_public);
+}
+inline bool contained_nonpublic_p (__class_type_info::__sub_kind access_path)
+{
+  return ((access_path & __class_type_info::__contained_public)
+          == __class_type_info::__contained_mask);
+}
+inline bool contained_nonvirtual_p (__class_type_info::__sub_kind access_path)
+{
+  return ((access_path & (__class_type_info::__contained_mask
+                          | __class_type_info::__contained_virtual_mask))
+          == __class_type_info::__contained_mask);
+}
+
+static const __class_type_info *const nonvirtual_base_type =
+    static_cast <const __class_type_info *> (0) + 1;
+
+}; // namespace
+
+namespace __cxxabiv1
+{
+
+__class_type_info::
+~__class_type_info ()
+{}
+
+__si_class_type_info::
+~__si_class_type_info ()
+{}
+
+__vmi_class_type_info::
+~__vmi_class_type_info ()
+{}
+
+// __upcast_result is used to hold information during traversal of a class
+// heirarchy when catch matching.
+struct __class_type_info::__upcast_result
+{
+  const void *dst_ptr;        // pointer to caught object
+  __sub_kind part2dst;        // path from current base to target
+  int src_details;            // hints about the source type heirarchy
+  const __class_type_info *base_type; // where we found the target,
+                              // if in vbase the __class_type_info of vbase
+                              // if a non-virtual base then 1
+                              // else NULL
+  public:
+  __upcast_result (int d)
+    :dst_ptr (NULL), part2dst (__unknown), src_details (d), base_type (NULL)
+    {}
+};
+
+// __dyncast_result is used to hold information during traversal of a class
+// heirarchy when dynamic casting.
+struct __class_type_info::__dyncast_result
+{
+  const void *dst_ptr;        // pointer to target object or NULL
+  __sub_kind whole2dst;       // path from most derived object to target
+  __sub_kind whole2src;       // path from most derived object to sub object
+  __sub_kind dst2src;         // path from target to sub object
+  int whole_details;          // details of the whole class heirarchy
+  
+  public:
+  __dyncast_result (int details_ = __vmi_class_type_info::__flags_unknown_mask)
+    :dst_ptr (NULL), whole2dst (__unknown),
+     whole2src (__unknown), dst2src (__unknown),
+     whole_details (details_)
+    {}
+};
+
+bool __class_type_info::
+__do_catch (const type_info *thr_type,
+            void **thr_obj,
+            unsigned outer) const
+{
+  if (*this == *thr_type)
+    return true;
+  if (outer >= 4)
+    // Neither `A' nor `A *'.
+    return false;
+  return thr_type->__do_upcast (this, thr_obj);
+}
+
+bool __class_type_info::
+__do_upcast (const __class_type_info *dst_type,
+             void **obj_ptr) const
+{
+  __upcast_result result (__vmi_class_type_info::__flags_unknown_mask);
+  
+  __do_upcast (dst_type, *obj_ptr, result);
+  if (!contained_public_p (result.part2dst))
+    return false;
+  *obj_ptr = const_cast <void *> (result.dst_ptr);
+  return true;
+}
+
+inline __class_type_info::__sub_kind __class_type_info::
+__find_public_src (ptrdiff_t src2dst,
+                   const void *obj_ptr,
+                   const __class_type_info *src_type,
+                   const void *src_ptr) const
+{
+  if (src2dst >= 0)
+    return adjust_pointer <void> (obj_ptr, src2dst) == src_ptr
+            ? __contained_public : __not_contained;
+  if (src2dst == -2)
+    return __not_contained;
+  return __do_find_public_src (src2dst, obj_ptr, src_type, src_ptr);
+}
+
+__class_type_info::__sub_kind __class_type_info::
+__do_find_public_src (ptrdiff_t,
+                      const void *obj_ptr,
+                      const __class_type_info *,
+                      const void *src_ptr) const
+{
+  if (src_ptr == obj_ptr)
+    // Must be our type, as the pointers match.
+    return __contained_public;
+  return __not_contained;
+}
+
+__class_type_info::__sub_kind __si_class_type_info::
+__do_find_public_src (ptrdiff_t src2dst,
+                      const void *obj_ptr,
+                      const __class_type_info *src_type,
+                      const void *src_ptr) const
+{
+  if (src_ptr == obj_ptr && *this == *src_type)
+    return __contained_public;
+  return __base_type->__do_find_public_src (src2dst, obj_ptr, src_type, src_ptr);
+}
+
+__class_type_info::__sub_kind __vmi_class_type_info::
+__do_find_public_src (ptrdiff_t src2dst,
+                      const void *obj_ptr,
+                      const __class_type_info *src_type,
+                      const void *src_ptr) const
+{
+  if (obj_ptr == src_ptr && *this == *src_type)
+    return __contained_public;
+  
+  for (size_t i = __base_count; i--;)
+    {
+      if (!__base_info[i].__is_public_p ())
+        continue; // Not public, can't be here.
+      
+      const void *base = obj_ptr;
+      ptrdiff_t offset = __base_info[i].__offset ();
+      bool is_virtual = __base_info[i].__is_virtual_p ();
+      
+      if (is_virtual)
+        {
+          if (src2dst == -3)
+            continue; // Not a virtual base, so can't be here.
+        }
+      base = convert_to_base (base, is_virtual, offset);
+      
+      __sub_kind base_kind = __base_info[i].__base->__do_find_public_src
+                              (src2dst, base, src_type, src_ptr);
+      if (contained_p (base_kind))
+        {
+          if (is_virtual)
+            base_kind = __sub_kind (base_kind | __contained_virtual_mask);
+          return base_kind;
+        }
+    }
+  
+  return __not_contained;
+}
+
+bool __class_type_info::
+__do_dyncast (ptrdiff_t,
+              __sub_kind access_path,
+              const __class_type_info *dst_type,
+              const void *obj_ptr,
+              const __class_type_info *src_type,
+              const void *src_ptr,
+              __dyncast_result &__restrict result) const
+{
+  if (obj_ptr == src_ptr && *this == *src_type)
+    {
+      // The src object we started from. Indicate how we are accessible from
+      // the most derived object.
+      result.whole2src = access_path;
+      return false;
+    }
+  if (*this == *dst_type)
+    {
+      result.dst_ptr = obj_ptr;
+      result.whole2dst = access_path;
+      result.dst2src = __not_contained;
+      return false;
+    }
+  return false;
+}
+
+bool __si_class_type_info::
+__do_dyncast (ptrdiff_t src2dst,
+              __sub_kind access_path,
+              const __class_type_info *dst_type,
+              const void *obj_ptr,
+              const __class_type_info *src_type,
+              const void *src_ptr,
+              __dyncast_result &__restrict result) const
+{
+  if (*this == *dst_type)
+    {
+      result.dst_ptr = obj_ptr;
+      result.whole2dst = access_path;
+      if (src2dst >= 0)
+        result.dst2src = adjust_pointer <void> (obj_ptr, src2dst) == src_ptr
+              ? __contained_public : __not_contained;
+      else if (src2dst == -2)
+        result.dst2src = __not_contained;
+      return false;
+    }
+  if (obj_ptr == src_ptr && *this == *src_type)
+    {
+      // The src object we started from. Indicate how we are accessible from
+      // the most derived object.
+      result.whole2src = access_path;
+      return false;
+    }
+  return __base_type->__do_dyncast (src2dst, access_path, dst_type, obj_ptr,
+                             src_type, src_ptr, result);
+}
+
+// This is a big hairy function. Although the run-time behaviour of
+// dynamic_cast is simple to describe, it gives rise to some non-obvious
+// behaviour. We also desire to determine as early as possible any definite
+// answer we can get. Because it is unknown what the run-time ratio of
+// succeeding to failing dynamic casts is, we do not know in which direction
+// to bias any optimizations. To that end we make no particular effort towards
+// early fail answers or early success answers. Instead we try to minimize
+// work by filling in things lazily (when we know we need the information),
+// and opportunisticly take early success or failure results.
+bool __vmi_class_type_info::
+__do_dyncast (ptrdiff_t src2dst,
+              __sub_kind access_path,
+              const __class_type_info *dst_type,
+              const void *obj_ptr,
+              const __class_type_info *src_type,
+              const void *src_ptr,
+              __dyncast_result &__restrict result) const
+{
+  if (result.whole_details & __flags_unknown_mask)
+    result.whole_details = __flags;
+  
+  if (obj_ptr == src_ptr && *this == *src_type)
+    {
+      // The src object we started from. Indicate how we are accessible from
+      // the most derived object.
+      result.whole2src = access_path;
+      return false;
+    }
+  if (*this == *dst_type)
+    {
+      result.dst_ptr = obj_ptr;
+      result.whole2dst = access_path;
+      if (src2dst >= 0)
+        result.dst2src = adjust_pointer <void> (obj_ptr, src2dst) == src_ptr
+              ? __contained_public : __not_contained;
+      else if (src2dst == -2)
+        result.dst2src = __not_contained;
+      return false;
+    }
+
+  bool result_ambig = false;
+  for (size_t i = __base_count; i--;)
+    {
+      __dyncast_result result2 (result.whole_details);
+      void const *base = obj_ptr;
+      __sub_kind base_access = access_path;
+      ptrdiff_t offset = __base_info[i].__offset ();
+      bool is_virtual = __base_info[i].__is_virtual_p ();
+      
+      if (is_virtual)
+        base_access = __sub_kind (base_access | __contained_virtual_mask);
+      base = convert_to_base (base, is_virtual, offset);
+
+      if (!__base_info[i].__is_public_p ())
+        {
+          if (src2dst == -2 &&
+              !(result.whole_details
+                & (__non_diamond_repeat_mask | __diamond_shaped_mask)))
+            // The hierarchy has no duplicate bases (which might ambiguate
+            // things) and where we started is not a public base of what we
+            // want (so it cannot be a downcast). There is nothing of interest
+            // hiding in a non-public base.
+            continue;
+          base_access = __sub_kind (base_access & ~__contained_public_mask);
+        }
+      
+      bool result2_ambig
+          = __base_info[i].__base->__do_dyncast (src2dst, base_access,
+                                             dst_type, base,
+                                             src_type, src_ptr, result2);
+      result.whole2src = __sub_kind (result.whole2src | result2.whole2src);
+      if (result2.dst2src == __contained_public
+          || result2.dst2src == __contained_ambig)
+        {
+          result.dst_ptr = result2.dst_ptr;
+          result.whole2dst = result2.whole2dst;
+          result.dst2src = result2.dst2src;
+          // Found a downcast which can't be bettered or an ambiguous downcast
+          // which can't be disambiguated
+          return result2_ambig;
+        }
+      
+      if (!result_ambig && !result.dst_ptr)
+        {
+          // Not found anything yet.
+          result.dst_ptr = result2.dst_ptr;
+          result.whole2dst = result2.whole2dst;
+          result_ambig = result2_ambig;
+          if (result.dst_ptr && result.whole2src != __unknown
+              && !(__flags & __non_diamond_repeat_mask))
+            // Found dst and src and we don't have repeated bases.
+            return result_ambig;
+        }
+      else if (result.dst_ptr && result.dst_ptr == result2.dst_ptr)
+        {
+          // Found at same address, must be via virtual.  Pick the most
+          // accessible path.
+          result.whole2dst =
+              __sub_kind (result.whole2dst | result2.whole2dst);
+        }
+      else if ((result.dst_ptr != 0 | result_ambig)
+               && (result2.dst_ptr != 0 | result2_ambig))
+        {
+          // Found two different DST_TYPE bases, or a valid one and a set of
+          // ambiguous ones, must disambiguate. See whether SRC_PTR is
+          // contained publicly within one of the non-ambiguous choices. If it
+          // is in only one, then that's the choice. If it is in both, then
+          // we're ambiguous and fail. If it is in neither, we're ambiguous,
+          // but don't yet fail as we might later find a third base which does
+          // contain SRC_PTR.
+        
+          __sub_kind new_sub_kind = result2.dst2src;
+          __sub_kind old_sub_kind = result.dst2src;
+          
+          if (contained_p (result.whole2src)
+              && (!virtual_p (result.whole2src)
+                  || !(result.whole_details & __diamond_shaped_mask)))
+            {
+              // We already found SRC_PTR as a base of most derived, and
+              // either it was non-virtual, or the whole heirarchy is
+              // not-diamond shaped. Therefore if it is in either choice, it
+              // can only be in one of them, and we will already know.
+              if (old_sub_kind == __unknown)
+                old_sub_kind = __not_contained;
+              if (new_sub_kind == __unknown)
+                new_sub_kind = __not_contained;
+            }
+          else
+            {
+              if (old_sub_kind >= __not_contained)
+                ;// already calculated
+              else if (contained_p (new_sub_kind)
+                       && (!virtual_p (new_sub_kind)
+                           || !(__flags & __diamond_shaped_mask)))
+                // Already found inside the other choice, and it was
+                // non-virtual or we are not diamond shaped.
+                old_sub_kind = __not_contained;
+              else
+                old_sub_kind = dst_type->__find_public_src
+                                (src2dst, result.dst_ptr, src_type, src_ptr);
+          
+              if (new_sub_kind >= __not_contained)
+                ;// already calculated
+              else if (contained_p (old_sub_kind)
+                       && (!virtual_p (old_sub_kind)
+                           || !(__flags & __diamond_shaped_mask)))
+                // Already found inside the other choice, and it was
+                // non-virtual or we are not diamond shaped.
+                new_sub_kind = __not_contained;
+              else
+                new_sub_kind = dst_type->__find_public_src
+                                (src2dst, result2.dst_ptr, src_type, src_ptr);
+            }
+          
+          // Neither sub_kind can be contained_ambig -- we bail out early
+          // when we find those.
+          if (contained_p (__sub_kind (new_sub_kind ^ old_sub_kind)))
+            {
+              // Only on one choice, not ambiguous.
+              if (contained_p (new_sub_kind))
+                {
+                  // Only in new.
+                  result.dst_ptr = result2.dst_ptr;
+                  result.whole2dst = result2.whole2dst;
+                  result_ambig = false;
+                  old_sub_kind = new_sub_kind;
+                }
+              result.dst2src = old_sub_kind;
+              if (public_p (result.dst2src))
+                return false; // Can't be an ambiguating downcast for later discovery.
+              if (!virtual_p (result.dst2src))
+                return false; // Found non-virtually can't be bettered
+            }
+          else if (contained_p (__sub_kind (new_sub_kind & old_sub_kind)))
+            {
+              // In both.
+              result.dst_ptr = NULL;
+              result.dst2src = __contained_ambig;
+              return true;  // Fail.
+            }
+          else
+            {
+              // In neither publicly, ambiguous for the moment, but keep
+              // looking. It is possible that it was private in one or
+              // both and therefore we should fail, but that's just tough.
+              result.dst_ptr = NULL;
+              result.dst2src = __not_contained;
+              result_ambig = true;
+            }
+        }
+      
+      if (result.whole2src == __contained_private)
+        // We found SRC_PTR as a private non-virtual base, therefore all
+        // cross casts will fail. We have already found a down cast, if
+        // there is one.
+        return result_ambig;
+    }
+
+  return result_ambig;
+}
+
+bool __class_type_info::
+__do_upcast (const __class_type_info *dst, const void *obj,
+             __upcast_result &__restrict result) const
+{
+  if (*this == *dst)
+    {
+      result.dst_ptr = obj;
+      result.base_type = nonvirtual_base_type;
+      result.part2dst = __contained_public;
+      return true;
+    }
+  return false;
+}
+
+bool __si_class_type_info::
+__do_upcast (const __class_type_info *dst, const void *obj_ptr,
+             __upcast_result &__restrict result) const
+{
+  if (__class_type_info::__do_upcast (dst, obj_ptr, result))
+    return true;
+  
+  return __base_type->__do_upcast (dst, obj_ptr, result);
+}
+
+bool __vmi_class_type_info::
+__do_upcast (const __class_type_info *dst, const void *obj_ptr,
+             __upcast_result &__restrict result) const
+{
+  if (__class_type_info::__do_upcast (dst, obj_ptr, result))
+    return true;
+  
+  int src_details = result.src_details;
+  if (src_details & __flags_unknown_mask)
+    src_details = __flags;
+  
+  for (size_t i = __base_count; i--;)
+    {
+      __upcast_result result2 (src_details);
+      const void *base = obj_ptr;
+      ptrdiff_t offset = __base_info[i].__offset ();
+      bool is_virtual = __base_info[i].__is_virtual_p ();
+      bool is_public = __base_info[i].__is_public_p ();
+      
+      if (!is_public && !(src_details & __non_diamond_repeat_mask))
+        // original cannot have an ambiguous base, so skip private bases
+        continue;
+
+      if (base)
+        base = convert_to_base (base, is_virtual, offset);
+      
+      if (__base_info[i].__base->__do_upcast (dst, base, result2))
+        {
+          if (result2.base_type == nonvirtual_base_type && is_virtual)
+            result2.base_type = __base_info[i].__base;
+          if (contained_p (result2.part2dst) && !is_public)
+            result2.part2dst = __sub_kind (result2.part2dst & ~__contained_public_mask);
+          
+          if (!result.base_type)
+            {
+              result = result2;
+              if (!contained_p (result.part2dst))
+                return true; // found ambiguously
+              
+              if (result.part2dst & __contained_public_mask)
+                {
+                  if (!(__flags & __non_diamond_repeat_mask))
+                    return true;  // cannot have an ambiguous other base
+                }
+              else
+                {
+                  if (!virtual_p (result.part2dst))
+                    return true; // cannot have another path
+                  if (!(__flags & __diamond_shaped_mask))
+                    return true; // cannot have a more accessible path
+                }
+            }
+          else if (result.dst_ptr != result2.dst_ptr)
+            {
+              // Found an ambiguity.
+	      result.dst_ptr = NULL;
+	      result.part2dst = __contained_ambig;
+	      return true;
+            }
+          else if (result.dst_ptr)
+            {
+              // Ok, found real object via a virtual path.
+              result.part2dst
+                  = __sub_kind (result.part2dst | result2.part2dst);
+            }
+          else
+            {
+              // Dealing with a null pointer, need to check vbase
+              // containing each of the two choices.
+              if (result2.base_type == nonvirtual_base_type
+                  || result.base_type == nonvirtual_base_type
+                  || !(*result2.base_type == *result.base_type))
+                {
+                  // Already ambiguous, not virtual or via different virtuals.
+                  // Cannot match.
+                  result.part2dst = __contained_ambig;
+                  return true;
+                }
+              result.part2dst
+                  = __sub_kind (result.part2dst | result2.part2dst);
+            }
+        }
+    }
+  return result.part2dst != __unknown;
+}
+
+// this is the external interface to the dynamic cast machinery
+extern "C" void *
+__dynamic_cast (const void *src_ptr,    // object started from
+                const __class_type_info *src_type, // type of the starting object
+                const __class_type_info *dst_type, // desired target type
+                ptrdiff_t src2dst) // how src and dst are related
+{
+  const void *vtable = *static_cast <const void *const *> (src_ptr);
+  const vtable_prefix *prefix =
+      adjust_pointer <vtable_prefix> (vtable, 
+				      -offsetof (vtable_prefix, origin));
+  const void *whole_ptr =
+      adjust_pointer <void> (src_ptr, prefix->whole_object);
+  const __class_type_info *whole_type = prefix->whole_type;
+  __class_type_info::__dyncast_result result;
+  
+  whole_type->__do_dyncast (src2dst, __class_type_info::__contained_public,
+                            dst_type, whole_ptr, src_type, src_ptr, result);
+  if (!result.dst_ptr)
+    return NULL;
+  if (contained_public_p (result.dst2src))
+    // Src is known to be a public base of dst.
+    return const_cast <void *> (result.dst_ptr);
+  if (contained_public_p (__class_type_info::__sub_kind (result.whole2src & result.whole2dst)))
+    // Both src and dst are known to be public bases of whole. Found a valid
+    // cross cast.
+    return const_cast <void *> (result.dst_ptr);
+  if (contained_nonvirtual_p (result.whole2src))
+    // Src is known to be a non-public nonvirtual base of whole, and not a
+    // base of dst. Found an invalid cross cast, which cannot also be a down
+    // cast
+    return NULL;
+  if (result.dst2src == __class_type_info::__unknown)
+    result.dst2src = dst_type->__find_public_src (src2dst, result.dst_ptr,
+                                                  src_type, src_ptr);
+  if (contained_public_p (result.dst2src))
+    // Found a valid down cast
+    return const_cast <void *> (result.dst_ptr);
+  // Must be an invalid down cast, or the cross cast wasn't bettered
+  return NULL;
+}
+
+}; // namespace __cxxabiv1
+#endif