Author: ericwf Date: Fri May 18 13:51:38 2018 New Revision: 332767 URL: http://llvm.org/viewvc/llvm-project?rev=332767&view=rev Log: private_typeinfo: limit is_dst_type_derived_from_static_type optimization
Patch by Ryan Prichard If the destination type does not derive from the static type, we can skip the search_above_dst call, but we still need to run the !does_dst_type_point_to_our_static_type block of code. That block of code will increment info->number_to_dst_ptr to 2, and because dest isn't derived from static, the cast will ultimately fail. Fixes PR33439 Reviewed as https://reviews.llvm.org/D36447 Modified: libcxxabi/trunk/src/private_typeinfo.cpp libcxxabi/trunk/test/dynamic_cast.pass.cpp Modified: libcxxabi/trunk/src/private_typeinfo.cpp URL: http://llvm.org/viewvc/llvm-project/libcxxabi/trunk/src/private_typeinfo.cpp?rev=332767&r1=332766&r2=332767&view=diff ============================================================================== --- libcxxabi/trunk/src/private_typeinfo.cpp (original) +++ libcxxabi/trunk/src/private_typeinfo.cpp Fri May 18 13:51:38 2018 @@ -859,13 +859,14 @@ __vmi_class_type_info::search_below_dst( // Record the access path that got us here // If there is more than one dst_type this path doesn't matter. info->path_dynamic_ptr_to_dst_ptr = path_below; + bool does_dst_type_point_to_our_static_type = false; // Only search above here if dst_type derives from static_type, or // if it is unknown if dst_type derives from static_type. if (info->is_dst_type_derived_from_static_type != no) { // Set up flags to record results from all base classes bool is_dst_type_derived_from_static_type = false; - bool does_dst_type_point_to_our_static_type = false; + // We've found a dst_type with a potentially public path to here. // We have to assume the path is public because it may become // public later (if we get back to here with a public path). @@ -909,21 +910,6 @@ __vmi_class_type_info::search_below_dst( } } } - if (!does_dst_type_point_to_our_static_type) - { - // We found a dst_type that doesn't point to (static_ptr, static_type) - // So record the address of this dst_ptr and increment the - // count of the number of such dst_types found in the tree. - info->dst_ptr_not_leading_to_static_ptr = current_ptr; - info->number_to_dst_ptr += 1; - // If there exists another dst with a private path to - // (static_ptr, static_type), then the cast from - // (dynamic_ptr, dynamic_type) to dst_type is now ambiguous, - // so stop search. - if (info->number_to_static_ptr == 1 && - info->path_dst_ptr_to_static_ptr == not_public_path) - info->search_done = true; - } // If we found no static_type,s then dst_type doesn't derive // from static_type, else it does. Record this result so that // next time we hit a dst_type we will know not to search above @@ -932,7 +918,22 @@ __vmi_class_type_info::search_below_dst( info->is_dst_type_derived_from_static_type = yes; else info->is_dst_type_derived_from_static_type = no; - } + } + if (!does_dst_type_point_to_our_static_type) + { + // We found a dst_type that doesn't point to (static_ptr, static_type) + // So record the address of this dst_ptr and increment the + // count of the number of such dst_types found in the tree. + info->dst_ptr_not_leading_to_static_ptr = current_ptr; + info->number_to_dst_ptr += 1; + // If there exists another dst with a private path to + // (static_ptr, static_type), then the cast from + // (dynamic_ptr, dynamic_type) to dst_type is now ambiguous, + // so stop search. + if (info->number_to_static_ptr == 1 && + info->path_dst_ptr_to_static_ptr == not_public_path) + info->search_done = true; + } } } else @@ -1030,13 +1031,13 @@ __si_class_type_info::search_below_dst(_ // Record the access path that got us here // If there is more than one dst_type this path doesn't matter. info->path_dynamic_ptr_to_dst_ptr = path_below; + bool does_dst_type_point_to_our_static_type = false; // Only search above here if dst_type derives from static_type, or // if it is unknown if dst_type derives from static_type. if (info->is_dst_type_derived_from_static_type != no) { // Set up flags to record results from all base classes bool is_dst_type_derived_from_static_type = false; - bool does_dst_type_point_to_our_static_type = false; // Zero out found flags info->found_our_static_ptr = false; info->found_any_static_type = false; @@ -1047,20 +1048,6 @@ __si_class_type_info::search_below_dst(_ if (info->found_our_static_ptr) does_dst_type_point_to_our_static_type = true; } - if (!does_dst_type_point_to_our_static_type) - { - // We found a dst_type that doesn't point to (static_ptr, static_type) - // So record the address of this dst_ptr and increment the - // count of the number of such dst_types found in the tree. - info->dst_ptr_not_leading_to_static_ptr = current_ptr; - info->number_to_dst_ptr += 1; - // If there exists another dst with a private path to - // (static_ptr, static_type), then the cast from - // (dynamic_ptr, dynamic_type) to dst_type is now ambiguous. - if (info->number_to_static_ptr == 1 && - info->path_dst_ptr_to_static_ptr == not_public_path) - info->search_done = true; - } // If we found no static_type,s then dst_type doesn't derive // from static_type, else it does. Record this result so that // next time we hit a dst_type we will know not to search above @@ -1070,6 +1057,20 @@ __si_class_type_info::search_below_dst(_ else info->is_dst_type_derived_from_static_type = no; } + if (!does_dst_type_point_to_our_static_type) + { + // We found a dst_type that doesn't point to (static_ptr, static_type) + // So record the address of this dst_ptr and increment the + // count of the number of such dst_types found in the tree. + info->dst_ptr_not_leading_to_static_ptr = current_ptr; + info->number_to_dst_ptr += 1; + // If there exists another dst with a private path to + // (static_ptr, static_type), then the cast from + // (dynamic_ptr, dynamic_type) to dst_type is now ambiguous. + if (info->number_to_static_ptr == 1 && + info->path_dst_ptr_to_static_ptr == not_public_path) + info->search_done = true; + } } } else Modified: libcxxabi/trunk/test/dynamic_cast.pass.cpp URL: http://llvm.org/viewvc/llvm-project/libcxxabi/trunk/test/dynamic_cast.pass.cpp?rev=332767&r1=332766&r2=332767&view=diff ============================================================================== --- libcxxabi/trunk/test/dynamic_cast.pass.cpp (original) +++ libcxxabi/trunk/test/dynamic_cast.pass.cpp Fri May 18 13:51:38 2018 @@ -95,9 +95,60 @@ void test() } // t3 +namespace t4 +{ + +// PR33439 +struct C2 { virtual ~C2() {} Pad1 _; }; +struct C3 { virtual ~C3() {} Pad2 _; }; +struct C4 : C3 { Pad3 _; }; +struct C8 : C2, virtual C4 { Pad4 _; }; +struct C9 : C4, C8 { Pad5 _; }; + +C9 c9; +C2 *c2 = &c9; + +void test() +{ + assert(dynamic_cast<C2*>(c2) == static_cast<C2*>(&c9)); + assert(dynamic_cast<C3*>(c2) == 0); + assert(dynamic_cast<C4*>(c2) == 0); + assert(dynamic_cast<C8*>(c2) == static_cast<C8*>(&c9)); + assert(dynamic_cast<C9*>(c2) == static_cast<C9*>(&c9)); +} + +} // t4 + +namespace t5 +{ + +// PR33439 +struct Dummy { virtual ~Dummy() {} Pad1 _; }; +struct Src { virtual ~Src() {} Pad2 _; }; +struct Dest : Dummy { Pad3 _; }; +struct A1 : Dest { Pad4 _; }; +struct A2 : Dest { Pad5 _; }; +struct Root : Src, A1, A2 { Pad6 _; }; + +Root root; +Src *src = &root; + +void test() +{ + assert(dynamic_cast<Dummy*>(src) == 0); + assert(dynamic_cast<Src*>(src) == static_cast<Src*>(&root)); + assert(dynamic_cast<Dest*>(src) == 0); + assert(dynamic_cast<A1*>(src) == static_cast<A1*>(&root)); + assert(dynamic_cast<A2*>(src) == static_cast<A2*>(&root)); +} + +} // t5 + int main() { t1::test(); t2::test(); t3::test(); + t4::test(); + t5::test(); } _______________________________________________ cfe-commits mailing list cfe-commits@lists.llvm.org http://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits
