Author: Florian Mayer Date: 2025-04-17T09:55:41-07:00 New Revision: 6bac20b391edce2bde348e59f5be2143157304b5
URL: https://github.com/llvm/llvm-project/commit/6bac20b391edce2bde348e59f5be2143157304b5 DIFF: https://github.com/llvm/llvm-project/commit/6bac20b391edce2bde348e59f5be2143157304b5.diff LOG: [MTE] do not tag zero sized globals (#136020) Added: Modified: clang/test/CodeGen/memtag-globals-asm.cpp llvm/lib/CodeGen/AsmPrinter/AsmPrinter.cpp Removed: ################################################################################ diff --git a/clang/test/CodeGen/memtag-globals-asm.cpp b/clang/test/CodeGen/memtag-globals-asm.cpp index 57e3cedc083fd..fb3958dd8bcb6 100644 --- a/clang/test/CodeGen/memtag-globals-asm.cpp +++ b/clang/test/CodeGen/memtag-globals-asm.cpp @@ -21,6 +21,7 @@ // RUN: FileCheck %s --input-file=%t.out --check-prefix=CHECK-P // RUN: FileCheck %s --input-file=%t.out --check-prefix=CHECK-Q // RUN: FileCheck %s --input-file=%t.out --check-prefix=CHECK-R +// RUN: FileCheck %s --input-file=%t.out --check-prefix=CHECK-S // RUN: %clang_cc1 -O3 -S -x c++ -std=c++11 -triple aarch64-linux-android31 \ // RUN: -fsanitize=memtag-globals -o %t.out %s @@ -43,6 +44,7 @@ // RUN: FileCheck %s --input-file=%t.out --check-prefix=CHECK-P // RUN: FileCheck %s --input-file=%t.out --check-prefix=CHECK-Q // RUN: FileCheck %s --input-file=%t.out --check-prefix=CHECK-R +// RUN: FileCheck %s --input-file=%t.out --check-prefix=CHECK-S /// Ensure that emulated TLS also doesn't get sanitized. // RUN: %clang_cc1 -S -x c++ -std=c++11 -triple aarch64-linux-android31 \ @@ -99,6 +101,10 @@ static char* global_buffer_local_end = &global_buffer[16]; // CHECK-H: .size global_buffer_global_end, 16 char* global_buffer_global_end = &global_buffer[16]; +// CHECK-S-NOT: .memtag zero_sized +struct empty {}; +char zero_sized[0]; + class MyClass { public: virtual ~MyClass() {} diff --git a/llvm/lib/CodeGen/AsmPrinter/AsmPrinter.cpp b/llvm/lib/CodeGen/AsmPrinter/AsmPrinter.cpp index 6b1f3df12ee44..bdcd54a135da9 100644 --- a/llvm/lib/CodeGen/AsmPrinter/AsmPrinter.cpp +++ b/llvm/lib/CodeGen/AsmPrinter/AsmPrinter.cpp @@ -2398,6 +2398,12 @@ void AsmPrinter::emitRemarksSection(remarks::RemarkStreamer &RS) { OutStreamer->emitBinaryData(Buf); } +static uint64_t globalSize(const llvm::GlobalVariable &G) { + const Constant *Initializer = G.getInitializer(); + return G.getParent()->getDataLayout().getTypeAllocSize( + Initializer->getType()); +} + static bool shouldTagGlobal(const llvm::GlobalVariable &G) { // We used to do this in clang, but there are optimization passes that turn // non-constant globals into constants. So now, clang only tells us whether @@ -2430,19 +2436,18 @@ static bool shouldTagGlobal(const llvm::GlobalVariable &G) { if (G.hasSection()) return false; - return true; + return globalSize(G) > 0; } static void tagGlobalDefinition(Module &M, GlobalVariable *G) { - Constant *Initializer = G->getInitializer(); - uint64_t SizeInBytes = - M.getDataLayout().getTypeAllocSize(Initializer->getType()); + uint64_t SizeInBytes = globalSize(*G); uint64_t NewSize = alignTo(SizeInBytes, 16); if (SizeInBytes != NewSize) { // Pad the initializer out to the next multiple of 16 bytes. llvm::SmallVector<uint8_t> Init(NewSize - SizeInBytes, 0); Constant *Padding = ConstantDataArray::get(M.getContext(), Init); + Constant *Initializer = G->getInitializer(); Initializer = ConstantStruct::getAnon({Initializer, Padding}); auto *NewGV = new GlobalVariable( M, Initializer->getType(), G->isConstant(), G->getLinkage(), _______________________________________________ cfe-commits mailing list cfe-commits@lists.llvm.org https://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits
