391 lines
15 KiB
C++
391 lines
15 KiB
C++
// Copyright (C) 1994-2019 Free Software Foundation, Inc.
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//
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// This file is part of GCC.
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//
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// GCC is free software; you can redistribute it and/or modify
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// it under the terms of the GNU General Public License as published by
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// the Free Software Foundation; either version 3, or (at your option)
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// any later version.
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// GCC is distributed in the hope that it will be useful,
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// but WITHOUT ANY WARRANTY; without even the implied warranty of
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// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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// GNU General Public License for more details.
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// Under Section 7 of GPL version 3, you are granted additional
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// permissions described in the GCC Runtime Library Exception, version
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// 3.1, as published by the Free Software Foundation.
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// You should have received a copy of the GNU General Public License and
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// a copy of the GCC Runtime Library Exception along with this program;
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// see the files COPYING3 and COPYING.RUNTIME respectively. If not, see
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// <http://www.gnu.org/licenses/>.
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#include "tinfo.h"
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namespace __cxxabiv1 {
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__vmi_class_type_info::
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~__vmi_class_type_info ()
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{}
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__class_type_info::__sub_kind __vmi_class_type_info::
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__do_find_public_src (ptrdiff_t src2dst,
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const void *obj_ptr,
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const __class_type_info *src_type,
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const void *src_ptr) const
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{
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if (obj_ptr == src_ptr && *this == *src_type)
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return __contained_public;
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for (std::size_t i = __base_count; i--;)
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{
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if (!__base_info[i].__is_public_p ())
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continue; // Not public, can't be here.
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const void *base = obj_ptr;
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ptrdiff_t offset = __base_info[i].__offset ();
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bool is_virtual = __base_info[i].__is_virtual_p ();
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if (is_virtual)
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{
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if (src2dst == -3)
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continue; // Not a virtual base, so can't be here.
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}
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base = convert_to_base (base, is_virtual, offset);
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__sub_kind base_kind = __base_info[i].__base_type->__do_find_public_src
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(src2dst, base, src_type, src_ptr);
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if (contained_p (base_kind))
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{
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if (is_virtual)
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base_kind = __sub_kind (base_kind | __contained_virtual_mask);
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return base_kind;
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}
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}
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return __not_contained;
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}
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// This is a big hairy function. Although the run-time behaviour of
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// dynamic_cast is simple to describe, it gives rise to some non-obvious
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// behaviour. We also desire to determine as early as possible any definite
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// answer we can get. Because it is unknown what the run-time ratio of
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// succeeding to failing dynamic casts is, we do not know in which direction
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// to bias any optimizations. To that end we make no particular effort towards
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// early fail answers or early success answers. Instead we try to minimize
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// work by filling in things lazily (when we know we need the information),
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// and opportunisticly take early success or failure results.
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bool __vmi_class_type_info::
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__do_dyncast (ptrdiff_t src2dst,
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__sub_kind access_path,
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const __class_type_info *dst_type,
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const void *obj_ptr,
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const __class_type_info *src_type,
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const void *src_ptr,
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__dyncast_result &__restrict result) const
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{
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if (result.whole_details & __flags_unknown_mask)
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result.whole_details = __flags;
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if (obj_ptr == src_ptr && *this == *src_type)
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{
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// The src object we started from. Indicate how we are accessible from
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// the most derived object.
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result.whole2src = access_path;
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return false;
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}
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if (*this == *dst_type)
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{
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result.dst_ptr = obj_ptr;
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result.whole2dst = access_path;
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if (src2dst >= 0)
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result.dst2src = adjust_pointer <void> (obj_ptr, src2dst) == src_ptr
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? __contained_public : __not_contained;
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else if (src2dst == -2)
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result.dst2src = __not_contained;
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return false;
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}
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// If src_type is a unique non-virtual base of dst_type, we have a good
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// guess at the address we want, so in the first pass try skipping any
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// bases which don't contain that address.
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const void *dst_cand = NULL;
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if (src2dst >= 0)
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dst_cand = adjust_pointer<void>(src_ptr, -src2dst);
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bool first_pass = true;
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bool skipped = false;
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bool result_ambig = false;
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again:
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for (std::size_t i = __base_count; i--;)
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{
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__dyncast_result result2 (result.whole_details);
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void const *base = obj_ptr;
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__sub_kind base_access = access_path;
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ptrdiff_t offset = __base_info[i].__offset ();
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bool is_virtual = __base_info[i].__is_virtual_p ();
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if (is_virtual)
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base_access = __sub_kind (base_access | __contained_virtual_mask);
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base = convert_to_base (base, is_virtual, offset);
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if (dst_cand)
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{
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bool skip_on_first_pass = base > dst_cand;
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if (skip_on_first_pass == first_pass)
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{
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// We aren't interested in this base on this pass: either
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// we're on the first pass and this base doesn't contain the
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// likely address, or we're on the second pass and we checked
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// this base on the first pass.
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skipped = true;
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continue;
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}
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}
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if (!__base_info[i].__is_public_p ())
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{
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if (src2dst == -2 &&
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!(result.whole_details
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& (__non_diamond_repeat_mask | __diamond_shaped_mask)))
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// The hierarchy has no duplicate bases (which might ambiguate
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// things) and where we started is not a public base of what we
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// want (so it cannot be a downcast). There is nothing of interest
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// hiding in a non-public base.
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continue;
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base_access = __sub_kind (base_access & ~__contained_public_mask);
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}
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bool result2_ambig
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= __base_info[i].__base_type->__do_dyncast (src2dst, base_access,
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dst_type, base,
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src_type, src_ptr, result2);
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result.whole2src = __sub_kind (result.whole2src | result2.whole2src);
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if (result2.dst2src == __contained_public
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|| result2.dst2src == __contained_ambig)
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{
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result.dst_ptr = result2.dst_ptr;
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result.whole2dst = result2.whole2dst;
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result.dst2src = result2.dst2src;
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// Found a downcast which can't be bettered or an ambiguous downcast
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// which can't be disambiguated
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return result2_ambig;
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}
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if (!result_ambig && !result.dst_ptr)
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{
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// Not found anything yet.
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result.dst_ptr = result2.dst_ptr;
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result.whole2dst = result2.whole2dst;
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result_ambig = result2_ambig;
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if (result.dst_ptr && result.whole2src != __unknown
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&& !(__flags & __non_diamond_repeat_mask))
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// Found dst and src and we don't have repeated bases.
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return result_ambig;
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}
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else if (result.dst_ptr && result.dst_ptr == result2.dst_ptr)
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{
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// Found at same address, must be via virtual. Pick the most
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// accessible path.
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result.whole2dst =
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__sub_kind (result.whole2dst | result2.whole2dst);
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}
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else if ((result.dst_ptr != 0 && result2.dst_ptr != 0)
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|| (result.dst_ptr != 0 && result2_ambig)
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|| (result2.dst_ptr != 0 && result_ambig))
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{
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// Found two different DST_TYPE bases, or a valid one and a set of
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// ambiguous ones, must disambiguate. See whether SRC_PTR is
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// contained publicly within one of the non-ambiguous choices. If it
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// is in only one, then that's the choice. If it is in both, then
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// we're ambiguous and fail. If it is in neither, we're ambiguous,
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// but don't yet fail as we might later find a third base which does
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// contain SRC_PTR.
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__sub_kind new_sub_kind = result2.dst2src;
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__sub_kind old_sub_kind = result.dst2src;
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if (contained_p (result.whole2src)
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&& (!virtual_p (result.whole2src)
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|| !(result.whole_details & __diamond_shaped_mask)))
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{
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// We already found SRC_PTR as a base of most derived, and
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// either it was non-virtual, or the whole hierarchy is
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// not-diamond shaped. Therefore if it is in either choice, it
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// can only be in one of them, and we will already know.
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if (old_sub_kind == __unknown)
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old_sub_kind = __not_contained;
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if (new_sub_kind == __unknown)
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new_sub_kind = __not_contained;
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}
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else
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{
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if (old_sub_kind >= __not_contained)
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;// already calculated
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else if (contained_p (new_sub_kind)
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&& (!virtual_p (new_sub_kind)
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|| !(__flags & __diamond_shaped_mask)))
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// Already found inside the other choice, and it was
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// non-virtual or we are not diamond shaped.
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old_sub_kind = __not_contained;
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else
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old_sub_kind = dst_type->__find_public_src
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(src2dst, result.dst_ptr, src_type, src_ptr);
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if (new_sub_kind >= __not_contained)
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;// already calculated
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else if (contained_p (old_sub_kind)
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&& (!virtual_p (old_sub_kind)
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|| !(__flags & __diamond_shaped_mask)))
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// Already found inside the other choice, and it was
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// non-virtual or we are not diamond shaped.
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new_sub_kind = __not_contained;
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else
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new_sub_kind = dst_type->__find_public_src
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(src2dst, result2.dst_ptr, src_type, src_ptr);
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}
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// Neither sub_kind can be contained_ambig -- we bail out early
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// when we find those.
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if (contained_p (__sub_kind (new_sub_kind ^ old_sub_kind)))
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{
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// Only on one choice, not ambiguous.
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if (contained_p (new_sub_kind))
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{
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// Only in new.
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result.dst_ptr = result2.dst_ptr;
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result.whole2dst = result2.whole2dst;
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result_ambig = false;
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old_sub_kind = new_sub_kind;
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}
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result.dst2src = old_sub_kind;
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if (public_p (result.dst2src))
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return false; // Can't be an ambiguating downcast for later discovery.
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if (!virtual_p (result.dst2src))
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return false; // Found non-virtually can't be bettered
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}
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else if (contained_p (__sub_kind (new_sub_kind & old_sub_kind)))
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{
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// In both.
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result.dst_ptr = NULL;
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result.dst2src = __contained_ambig;
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return true; // Fail.
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}
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else
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{
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// In neither publicly, ambiguous for the moment, but keep
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// looking. It is possible that it was private in one or
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// both and therefore we should fail, but that's just tough.
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result.dst_ptr = NULL;
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result.dst2src = __not_contained;
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result_ambig = true;
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}
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}
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if (result.whole2src == __contained_private)
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// We found SRC_PTR as a private non-virtual base, therefore all
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// cross casts will fail. We have already found a down cast, if
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// there is one.
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return result_ambig;
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}
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if (skipped && first_pass)
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{
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// We didn't find dst where we expected it, so let's go back and try
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// the bases we skipped (if any).
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first_pass = false;
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goto again;
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}
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return result_ambig;
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}
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bool __vmi_class_type_info::
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__do_upcast (const __class_type_info *dst, const void *obj_ptr,
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__upcast_result &__restrict result) const
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{
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if (__class_type_info::__do_upcast (dst, obj_ptr, result))
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return true;
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int src_details = result.src_details;
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if (src_details & __flags_unknown_mask)
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src_details = __flags;
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for (std::size_t i = __base_count; i--;)
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{
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__upcast_result result2 (src_details);
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const void *base = obj_ptr;
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ptrdiff_t offset = __base_info[i].__offset ();
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bool is_virtual = __base_info[i].__is_virtual_p ();
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bool is_public = __base_info[i].__is_public_p ();
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if (!is_public && !(src_details & __non_diamond_repeat_mask))
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// original cannot have an ambiguous base, so skip private bases
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continue;
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if (base)
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base = convert_to_base (base, is_virtual, offset);
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if (__base_info[i].__base_type->__do_upcast (dst, base, result2))
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{
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if (result2.base_type == nonvirtual_base_type && is_virtual)
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result2.base_type = __base_info[i].__base_type;
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if (contained_p (result2.part2dst) && !is_public)
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result2.part2dst = __sub_kind (result2.part2dst & ~__contained_public_mask);
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if (!result.base_type)
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{
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result = result2;
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if (!contained_p (result.part2dst))
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return true; // found ambiguously
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if (result.part2dst & __contained_public_mask)
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{
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if (!(__flags & __non_diamond_repeat_mask))
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return true; // cannot have an ambiguous other base
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}
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else
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{
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if (!virtual_p (result.part2dst))
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return true; // cannot have another path
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if (!(__flags & __diamond_shaped_mask))
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return true; // cannot have a more accessible path
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}
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}
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else if (result.dst_ptr != result2.dst_ptr)
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{
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// Found an ambiguity.
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result.dst_ptr = NULL;
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result.part2dst = __contained_ambig;
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return true;
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}
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else if (result.dst_ptr)
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{
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// Ok, found real object via a virtual path.
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result.part2dst
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= __sub_kind (result.part2dst | result2.part2dst);
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}
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else
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{
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// Dealing with a null pointer, need to check vbase
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// containing each of the two choices.
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if (result2.base_type == nonvirtual_base_type
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|| result.base_type == nonvirtual_base_type
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|| !(*result2.base_type == *result.base_type))
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{
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// Already ambiguous, not virtual or via different virtuals.
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// Cannot match.
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result.part2dst = __contained_ambig;
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return true;
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}
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result.part2dst
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= __sub_kind (result.part2dst | result2.part2dst);
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}
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}
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}
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return result.part2dst != __unknown;
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}
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}
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