llvmbot wrote:
<!--LLVM PR SUMMARY COMMENT--> @llvm/pr-subscribers-clang-codegen Author: None (hstk30-hw) <details> <summary>Changes</summary> About https://github.com/llvm/llvm-project/issues/69872 , just for compatible C++ empty record with align UB with gcc https://godbolt.org/z/qsze8fqra --- Full diff: https://github.com/llvm/llvm-project/pull/72197.diff 2 Files Affected: - (modified) clang/lib/CodeGen/ABIInfoImpl.cpp (+7-1) - (modified) clang/test/CodeGen/aarch64-args.cpp (+6) ``````````diff diff --git a/clang/lib/CodeGen/ABIInfoImpl.cpp b/clang/lib/CodeGen/ABIInfoImpl.cpp index 2b20d5a13346d34..bc8ac937be37399 100644 --- a/clang/lib/CodeGen/ABIInfoImpl.cpp +++ b/clang/lib/CodeGen/ABIInfoImpl.cpp @@ -296,10 +296,16 @@ bool CodeGen::isEmptyRecord(ASTContext &Context, QualType T, bool AllowArrays, return false; // If this is a C++ record, check the bases first. - if (const CXXRecordDecl *CXXRD = dyn_cast<CXXRecordDecl>(RD)) + if (const CXXRecordDecl *CXXRD = dyn_cast<CXXRecordDecl>(RD)) { for (const auto &I : CXXRD->bases()) if (!isEmptyRecord(Context, I.getType(), true, AsIfNoUniqueAddr)) return false; + // C++ object size >= 1 byte, empty struct is 1 byte. + // FIXME: an alignment on a empty record is a UB, may just warning it， + // this code just want to compatible gcc. + if (Context.getTypeSize(T) > 8) + return false; + } for (const auto *I : RD->fields()) if (!isEmptyField(Context, I, AllowArrays, AsIfNoUniqueAddr)) diff --git a/clang/test/CodeGen/aarch64-args.cpp b/clang/test/CodeGen/aarch64-args.cpp index fe1298cc683a404..4794f0ae7c903dc 100644 --- a/clang/test/CodeGen/aarch64-args.cpp +++ b/clang/test/CodeGen/aarch64-args.cpp @@ -65,3 +65,9 @@ EXTERNC struct SortOfEmpty sort_of_empty_ret(void) { struct SortOfEmpty e; return e; } + +// CHECK-GNU-CXX: define{{.*}} i32 @empty_align_arg(i128 %a.coerce, i32 noundef %b) +struct EmptyAlign { long long int __attribute__((aligned)) : 0; }; +EXTERNC int empty_align_arg(struct EmptyAlign a, int b) { + return b; +} \ No newline at end of file `````````` </details> https://github.com/llvm/llvm-project/pull/72197 _______________________________________________ cfe-commits mailing list cfe-commits@lists.llvm.org https://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits
