diff options
Diffstat (limited to 'gcc-4.4.3/libstdc++-v3/libsupc++/vmi_class_type_info.cc')
| -rw-r--r-- | gcc-4.4.3/libstdc++-v3/libsupc++/vmi_class_type_info.cc | 359 |
1 files changed, 359 insertions, 0 deletions
diff --git a/gcc-4.4.3/libstdc++-v3/libsupc++/vmi_class_type_info.cc b/gcc-4.4.3/libstdc++-v3/libsupc++/vmi_class_type_info.cc new file mode 100644 index 000000000..6904f7723 --- /dev/null +++ b/gcc-4.4.3/libstdc++-v3/libsupc++/vmi_class_type_info.cc @@ -0,0 +1,359 @@ +// 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; + } + + bool result_ambig = false; + 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 (!__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; + } + + 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; +} + +} |