[SanitizerCoverage] Add associated metadata to pc-tables.
Summary:
Using associated metadata rather than llvm.used allows linkers to
perform dead stripping with -fsanitize-coverage=pc-table. Unfortunately
in my local tests, LLD was the only linker that made use of this metadata.
Partially addresses https://bugs.llvm.org/show_bug.cgi?id=34636 and fixes
https://github.com/google/sanitizers/issues/971.
Reviewers: eugenis
Reviewed By: eugenis
Subscribers: Dor1s, hiraditya, llvm-commits, kcc
Differential Revision: https://reviews.llvm.org/D48203
llvm-svn: 334858
diff --git a/llvm/lib/Transforms/Instrumentation/SanitizerCoverage.cpp b/llvm/lib/Transforms/Instrumentation/SanitizerCoverage.cpp
index a19cd6d..fe08632 100644
--- a/llvm/lib/Transforms/Instrumentation/SanitizerCoverage.cpp
+++ b/llvm/lib/Transforms/Instrumentation/SanitizerCoverage.cpp
@@ -243,6 +243,7 @@
GlobalVariable *Function8bitCounterArray; // for inline-8bit-counters.
GlobalVariable *FunctionPCsArray; // for pc-table.
SmallVector<GlobalValue *, 20> GlobalsToAppendToUsed;
+ SmallVector<GlobalValue *, 20> GlobalsToAppendToCompilerUsed;
SanitizerCoverageOptions Options;
};
@@ -405,6 +406,7 @@
// so we need to prevent them from being dead stripped.
if (TargetTriple.isOSBinFormatMachO())
appendToUsed(M, GlobalsToAppendToUsed);
+ appendToCompilerUsed(M, GlobalsToAppendToCompilerUsed);
return true;
}
@@ -598,7 +600,9 @@
}
if (Options.PCTable) {
FunctionPCsArray = CreatePCArray(F, AllBlocks);
- GlobalsToAppendToUsed.push_back(FunctionPCsArray);
+ GlobalsToAppendToCompilerUsed.push_back(FunctionPCsArray);
+ MDNode *MD = MDNode::get(F.getContext(), ValueAsMetadata::get(&F));
+ FunctionPCsArray->addMetadata(LLVMContext::MD_associated, *MD);
}
}