// Copyright (C) 1994-2013 Free Software Foundation, Inc.
//
// 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;
}
}