Author: Nick Desaulniers Date: 2023-05-22T11:38:38-07:00 New Revision: 57c5c1ab2a188b7962c9de5ac0f95e3c7441940a
URL: https://github.com/llvm/llvm-project/commit/57c5c1ab2a188b7962c9de5ac0f95e3c7441940a DIFF: https://github.com/llvm/llvm-project/commit/57c5c1ab2a188b7962c9de5ac0f95e3c7441940a.diff LOG: [clang][ExprConstant] fix __builtin_object_size for flexible array members As reported by @kees, GCC treats __builtin_object_size of structures containing flexible array members (aka arrays with incomplete type) not just as the sizeof the underlying type, but additionally the size of the members in a designated initializer list. Fixes: https://github.com/llvm/llvm-project/issues/62789 Reviewed By: erichkeane Differential Revision: https://reviews.llvm.org/D150892 Added: Modified: clang/docs/ReleaseNotes.rst clang/lib/AST/ExprConstant.cpp clang/test/CodeGen/object-size.c Removed: ################################################################################ diff --git a/clang/docs/ReleaseNotes.rst b/clang/docs/ReleaseNotes.rst index a55e969fa21c..483b2d0110b7 100644 --- a/clang/docs/ReleaseNotes.rst +++ b/clang/docs/ReleaseNotes.rst @@ -51,6 +51,11 @@ C/C++ Language Potentially Breaking Changes foo: asm goto ("# %0 %1"::"i"(&&foo)::foo); +- ``__builtin_object_size`` and ``__builtin_dynamic_object_size`` now add the + ``sizeof`` the elements specified in designated initializers of flexible + array members for structs that contain them. This change is more consistent + with the behavior of GCC. + C++ Specific Potentially Breaking Changes ----------------------------------------- - Clang won't search for coroutine_traits in std::experimental namespace any more. @@ -422,6 +427,10 @@ Bug Fixes in This Version (`#61746 <https://github.com/llvm/llvm-project/issues/61746>`_). - Clang `TextNodeDumper` enabled through `-ast-dump` flag no longer evaluates the initializer of constexpr `VarDecl` if the declaration has a dependent type. +- Match GCC's behavior for ``__builtin_object_size`` and + ``__builtin_dynamic_object_size`` on structs containing flexible array + members. + (`#62789 <https://github.com/llvm/llvm-project/issues/62789>`_). Bug Fixes to Compiler Builtins ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ diff --git a/clang/lib/AST/ExprConstant.cpp b/clang/lib/AST/ExprConstant.cpp index ce3c5257e711..f1a30da1ff77 100644 --- a/clang/lib/AST/ExprConstant.cpp +++ b/clang/lib/AST/ExprConstant.cpp @@ -11733,7 +11733,14 @@ static bool determineEndOffset(EvalInfo &Info, SourceLocation ExprLoc, auto CheckedHandleSizeof = [&](QualType Ty, CharUnits &Result) { if (Ty.isNull() || Ty->isIncompleteType() || Ty->isFunctionType()) return false; - return HandleSizeof(Info, ExprLoc, Ty, Result); + bool Ret = HandleSizeof(Info, ExprLoc, Ty, Result); + if (Ty->isStructureType() && + Ty->getAsStructureType()->getDecl()->hasFlexibleArrayMember()) { + const auto *VD = + cast<VarDecl>(LVal.getLValueBase().get<const ValueDecl *>()); + Result += VD->getFlexibleArrayInitChars(Info.Ctx); + } + return Ret; }; // We want to evaluate the size of the entire object. This is a valid fallback diff --git a/clang/test/CodeGen/object-size.c b/clang/test/CodeGen/object-size.c index 157926dd719d..ac1551343d6f 100644 --- a/clang/test/CodeGen/object-size.c +++ b/clang/test/CodeGen/object-size.c @@ -525,6 +525,33 @@ void test31(void) { gi = OBJECT_SIZE_BUILTIN(&dsv[9].snd[0], 1); } +// CHECK-LABEL: @test32 +static struct DynStructVar D32 = { + .fst = {}, + .snd = { 0, 1, 2, }, +}; +unsigned long test32(void) { + // CHECK: ret i64 19 + return OBJECT_SIZE_BUILTIN(&D32, 1); +} +// CHECK-LABEL: @test33 +static struct DynStructVar D33 = { + .fst = {}, + .snd = {}, +}; +unsigned long test33(void) { + // CHECK: ret i64 16 + return OBJECT_SIZE_BUILTIN(&D33, 1); +} +// CHECK-LABEL: @test34 +static struct DynStructVar D34 = { + .fst = {}, +}; +unsigned long test34(void) { + // CHECK: ret i64 16 + return OBJECT_SIZE_BUILTIN(&D34, 1); +} + // CHECK-LABEL: @PR30346 void PR30346(void) { struct sa_family_t {}; _______________________________________________ cfe-commits mailing list cfe-commits@lists.llvm.org https://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits