| // Copyright (C) 1994-2021 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; |
| } |
| |
| } |
