[PGO] Make needsComdatForCounter() available (NFC)
Move needsComdatForCounter() to lib/ProfileData/InstrProf.cpp from
lib/Transforms/Instrumentation/InstrProfiling.cpp to make is available for
other files.
Differential Revision: https://reviews.llvm.org/D22643
llvm-svn: 276330
diff --git a/llvm/lib/ProfileData/InstrProf.cpp b/llvm/lib/ProfileData/InstrProf.cpp
index 6962f82..a040072 100644
--- a/llvm/lib/ProfileData/InstrProf.cpp
+++ b/llvm/lib/ProfileData/InstrProf.cpp
@@ -14,6 +14,7 @@
#include "llvm/ProfileData/InstrProf.h"
#include "llvm/ADT/StringExtras.h"
+#include "llvm/ADT/Triple.h"
#include "llvm/IR/Constants.h"
#include "llvm/IR/Function.h"
#include "llvm/IR/GlobalVariable.h"
@@ -780,4 +781,29 @@
F.setMetadata(getPGOFuncNameMetadataName(), N);
}
+bool needsComdatForCounter(const Function &F, const Module &M) {
+ if (F.hasComdat())
+ return true;
+
+ Triple TT(M.getTargetTriple());
+ if (!TT.isOSBinFormatELF())
+ return false;
+
+ // See createPGOFuncNameVar for more details. To avoid link errors, profile
+ // counters for function with available_externally linkage needs to be changed
+ // to linkonce linkage. On ELF based systems, this leads to weak symbols to be
+ // created. Without using comdat, duplicate entries won't be removed by the
+ // linker leading to increased data segement size and raw profile size. Even
+ // worse, since the referenced counter from profile per-function data object
+ // will be resolved to the common strong definition, the profile counts for
+ // available_externally functions will end up being duplicated in raw profile
+ // data. This can result in distorted profile as the counts of those dups
+ // will be accumulated by the profile merger.
+ GlobalValue::LinkageTypes Linkage = F.getLinkage();
+ if (Linkage != GlobalValue::ExternalWeakLinkage &&
+ Linkage != GlobalValue::AvailableExternallyLinkage)
+ return false;
+
+ return true;
+}
} // end namespace llvm