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// Copyright (C) 1994, 1996, 1997, 1998, 1999, 2000, 2001, 2002, 2007, 2009

// Free Software Foundation

//

// This file is part of GCC.

//

// GCC 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 3, or (at your option)

// any later version.

// GCC 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.

// Under Section 7 of GPL version 3, you are granted additional

// permissions described in the GCC Runtime Library Exception, version

// 3.1, as published by the Free Software Foundation.

// You should have received a copy of the GNU General Public License and

// a copy of the GCC Runtime Library Exception along with this program;

// see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see

// <http://www.gnu.org/licenses/>.

#include "tinfo.h"

namespace __cxxabiv1 {

__vmi_class_type_info::

~__vmi_class_type_info ()

{}

__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 (std::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_type->__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;

}

// 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;

    }

  // If src_type is a unique non-virtual base of dst_type, we have a good

  // guess at the address we want, so in the first pass try skipping any

  // bases which don't contain that address.

  const void *dst_cand = NULL;

  if (src2dst >= 0)

    dst_cand = adjust_pointer<void>(src_ptr, -src2dst);

  bool first_pass = true;

  bool skipped = false;

  bool result_ambig = false;

 again:

  for (std::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 (dst_cand)

        {

          bool skip_on_first_pass = base > dst_cand;

          if (skip_on_first_pass == first_pass)

            {

              // We aren't interested in this base on this pass: either

              // we're on the first pass and this base doesn't contain the

              // likely address, or we're on the second pass and we checked

              // this base on the first pass.

              skipped = true;

              continue;

            }

        }

      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_type->__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 && result2.dst_ptr != 0)

               || (result.dst_ptr != 0 && result2_ambig)

               || (result2.dst_ptr != 0 && result_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 hierarchy 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;

    }

  if (skipped && first_pass)

    {

      // We didn't find dst where we expected it, so let's go back and try

      // the bases we skipped (if any).

      first_pass = false;

      goto again;

    }

  return result_ambig;

}

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 (std::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_type->__do_upcast (dst, base, result2))

        {

          if (result2.base_type == nonvirtual_base_type && is_virtual)

            result2.base_type = __base_info[i].__base_type;

          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;

}

}