From 6ce8e716bfab4a1d2d8777f9868af5759a515391 Mon Sep 17 00:00:00 2001 From: Fangrui Song Date: Wed, 8 Feb 2023 00:58:39 -0800 Subject: [PATCH] [SanitizerBinaryMetadata] Make module_[cd]tor external If a COMDAT key has a local linkage, it behaves as `comdat nodeduplicate` and llvm/lib/Linker/LinkModules.cpp does not deduplicate its members. This is not intended. Switch to an external linkage to allow deduplication. See also https://maskray.me/blog/2021-07-25-comdat-and-section-group#grp_comdat Reviewed By: melver Differential Revision: https://reviews.llvm.org/D143530 --- .../SanitizerBinaryMetadata.cpp | 5 ++++- .../SanitizerBinaryMetadata/ctor.ll | 22 +++++++++++++++++++ 2 files changed, 26 insertions(+), 1 deletion(-) create mode 100644 llvm/test/Instrumentation/SanitizerBinaryMetadata/ctor.ll diff --git a/llvm/lib/Transforms/Instrumentation/SanitizerBinaryMetadata.cpp b/llvm/lib/Transforms/Instrumentation/SanitizerBinaryMetadata.cpp index f3ff9fe8bac05..e990ea204d422 100644 --- a/llvm/lib/Transforms/Instrumentation/SanitizerBinaryMetadata.cpp +++ b/llvm/lib/Transforms/Instrumentation/SanitizerBinaryMetadata.cpp @@ -215,9 +215,12 @@ bool SanitizerBinaryMetadata::run() { Constant *CtorData = nullptr; Constant *DtorData = nullptr; if (TargetTriple.supportsCOMDAT()) { - // Use COMDAT to deduplicate constructor/destructor function. + // Use COMDAT to deduplicate constructor/destructor function. The COMDAT + // key needs to be a non-local linkage. Ctor->setComdat(Mod.getOrInsertComdat(Ctor->getName())); Dtor->setComdat(Mod.getOrInsertComdat(Dtor->getName())); + Ctor->setLinkage(GlobalValue::ExternalLinkage); + Dtor->setLinkage(GlobalValue::ExternalLinkage); CtorData = Ctor; DtorData = Dtor; } diff --git a/llvm/test/Instrumentation/SanitizerBinaryMetadata/ctor.ll b/llvm/test/Instrumentation/SanitizerBinaryMetadata/ctor.ll new file mode 100644 index 0000000000000..9e26c7525c5a6 --- /dev/null +++ b/llvm/test/Instrumentation/SanitizerBinaryMetadata/ctor.ll @@ -0,0 +1,22 @@ +; RUN: opt < %s -passes='module(sanmd-module)' -sanitizer-metadata-atomics -S | FileCheck %s + +; CHECK: $__sanitizer_metadata_atomics.module_ctor = comdat any +; CHECK: $__sanitizer_metadata_atomics.module_dtor = comdat any +; CHECK: $__sanitizer_metadata_covered.module_ctor = comdat any +; CHECK: $__sanitizer_metadata_covered.module_dtor = comdat any + +; CHECK: @llvm.used = appending global [4 x ptr] [ptr @__sanitizer_metadata_atomics.module_ctor, ptr @__sanitizer_metadata_atomics.module_dtor, ptr @__sanitizer_metadata_covered.module_ctor, ptr @__sanitizer_metadata_covered.module_dtor], section "llvm.metadata" +; CHECK: @llvm.global_ctors = appending global [2 x { i32, ptr, ptr }] [{ i32, ptr, ptr } { i32 2, ptr @__sanitizer_metadata_atomics.module_ctor, ptr @__sanitizer_metadata_atomics.module_ctor }, { i32, ptr, ptr } { i32 2, ptr @__sanitizer_metadata_covered.module_ctor, ptr @__sanitizer_metadata_covered.module_ctor }] +; CHECK: @llvm.global_dtors = appending global [2 x { i32, ptr, ptr }] [{ i32, ptr, ptr } { i32 2, ptr @__sanitizer_metadata_atomics.module_dtor, ptr @__sanitizer_metadata_atomics.module_dtor }, { i32, ptr, ptr } { i32 2, ptr @__sanitizer_metadata_covered.module_dtor, ptr @__sanitizer_metadata_covered.module_dtor }] + +; CHECK: define dso_local void @__sanitizer_metadata_covered.module_ctor() #1 comdat { +; CHECK: define dso_local void @__sanitizer_metadata_covered.module_dtor() #1 comdat { + +target datalayout = "e-m:e-p270:32:32-p271:32:32-p272:64:64-i64:64-f80:128-n8:16:32:64-S128" +target triple = "x86_64-unknown-linux-gnu" + +define i8 @foo(ptr %a) nounwind uwtable { +entry: + %0 = load atomic i8, ptr %a unordered, align 1 + ret i8 %0 +}