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Re-land r334417 "[MS] Use mangled names and comdats for string merging with ASan" 

The issue with -fprofile-generate was fixed and the dependent CL
relanded in r340232.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@341572 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Reid Kleckner 2018-09-06 18:25:39 +00:00
parent 20e2260b6c
commit 02714d5f34
2 changed files with 22 additions and 7 deletions
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12
lib/CodeGen/CodeGenModule.cpp
View File

@ -4305,15 +4305,13 @@ CodeGenModule::GetAddrOfConstantStringFromLiteral(const StringLiteral *S,
StringRef GlobalVariableName;
llvm::GlobalValue::LinkageTypes LT;
// Mangle the string literal if the ABI allows for it. However, we cannot
// do this if we are compiling with ASan or -fwritable-strings because they
// rely on strings having normal linkage.
if (!LangOpts.WritableStrings &&
!LangOpts.Sanitize.has(SanitizerKind::Address) &&
getCXXABI().getMangleContext().shouldMangleStringLiteral(S)) {
// Mangle the string literal if that's how the ABI merges duplicate strings.
// Don't do it if they are writable, since we don't want writes in one TU to
// affect strings in another.
if (getCXXABI().getMangleContext().shouldMangleStringLiteral(S) &&
!LangOpts.WritableStrings) {
llvm::raw_svector_ostream Out(MangledNameBuffer);
getCXXABI().getMangleContext().mangleStringLiteral(S, Out);
LT = llvm::GlobalValue::LinkOnceODRLinkage;
GlobalVariableName = MangledNameBuffer;
} else {

17
test/CodeGen/asan-strings.c Normal file
View File

@ -0,0 +1,17 @@
// RUN: %clang_cc1 -triple x86_64-linux-gnu -fsanitize=address -disable-llvm-passes -emit-llvm -o - %s | FileCheck %s --check-prefix=LINUX
// RUN: %clang_cc1 -triple x86_64-windows-msvc -fsanitize=address -disable-llvm-passes -emit-llvm -o - %s | FileCheck %s --check-prefix=WINDOWS
// RUN: %clang_cc1 -triple x86_64-windows-msvc -fsanitize=address -fwritable-strings -disable-llvm-passes -emit-llvm -o - %s | FileCheck %s --check-prefix=WINWRITE
// On Linux (and basically every non-MS target) string literals are emitted with
// private linkage, which means ASan can freely instrument them. On Windows,
// they are emitted with comdats. ASan's global instrumentation code for COFF
// knows how to make the metadata comdat associative, so the string literal
// global is only registered if the instrumented global prevails during linking.
const char *foo() { return "asdf"; }
// LINUX: @.str = private unnamed_addr constant [5 x i8] c"asdf\00", align 1
// WINDOWS: @"??_C@_04JIHMPGLA@asdf?$AA@" = linkonce_odr dso_local unnamed_addr constant [5 x i8] c"asdf\00", comdat, align 1
// WINWRITE: @.str = private unnamed_addr global [5 x i8] c"asdf\00", align 1