2 files changed, 28 insertions, 16 deletions

diff --git a/llvm/lib/Transforms/Instrumentation/InstrProfiling.cpp b/llvm/lib/Transforms/Instrumentation/InstrProfiling.cpp
index 8da3e31200f..adea7e77244 100644
--- a/llvm/lib/Transforms/Instrumentation/InstrProfiling.cpp
+++ b/llvm/lib/Transforms/Instrumentation/InstrProfiling.cpp
@@ -32,6 +32,11 @@ cl::opt<bool> DoNameCompression("enable-name-compression",
                                 cl::desc("Enable name string compression"),
                                 cl::init(true));
 
+cl::opt<bool> DoHashBasedCounterSplit(
+    "hash-based-counter-split",
+    cl::desc("Rename counter variable of a comdat function based on cfg hash"),
+    cl::init(true));
+
 cl::opt<bool> ValueProfileStaticAlloc(
     "vp-static-alloc",
     cl::desc("Do static counter allocation for value profiler"),
@@ -272,7 +277,16 @@ void InstrProfiling::lowerCoverageData(GlobalVariable *CoverageNamesVar) {
 static std::string getVarName(InstrProfIncrementInst *Inc, StringRef Prefix) {
   StringRef NamePrefix = getInstrProfNameVarPrefix();
   StringRef Name = Inc->getName()->getName().substr(NamePrefix.size());
-  return (Prefix + Name).str();
+  Function *F = Inc->getParent()->getParent();
+  Module *M = F->getParent();
+  if (!DoHashBasedCounterSplit || !isIRPGOFlagSet(M) ||
+      !canRenameComdatFunc(*F))
+    return (Prefix + Name).str();
+  uint64_t FuncHash = Inc->getHash()->getZExtValue();
+  SmallVector<char, 24> HashPostfix;
+  if (Name.endswith((Twine(".") + Twine(FuncHash)).toStringRef(HashPostfix)))
+    return (Prefix + Name).str();
+  return (Prefix + Name + "." + Twine(FuncHash)).str();
 }
 
 static inline bool shouldRecordFunctionAddr(Function *F) {
diff --git a/llvm/lib/Transforms/Instrumentation/PGOInstrumentation.cpp b/llvm/lib/Transforms/Instrumentation/PGOInstrumentation.cpp
index 28f4f7ea145..04f9a64bef9 100644
--- a/llvm/lib/Transforms/Instrumentation/PGOInstrumentation.cpp
+++ b/llvm/lib/Transforms/Instrumentation/PGOInstrumentation.cpp
@@ -119,7 +119,7 @@ static cl::opt<unsigned> MaxNumAnnotations(
 // Command line option to control appending FunctionHash to the name of a COMDAT
 // function. This is to avoid the hash mismatch caused by the preinliner.
 static cl::opt<bool> DoComdatRenaming(
-    "do-comdat-renaming", cl::init(true), cl::Hidden,
+    "do-comdat-renaming", cl::init(false), cl::Hidden,
     cl::desc("Append function hash to the name of COMDAT function to avoid "
              "function hash mismatch due to the preinliner"));
 
@@ -134,6 +134,12 @@ static cl::opt<bool> PGOWarnMissing("pgo-warn-missing-function",
 static cl::opt<bool> NoPGOWarnMismatch("no-pgo-warn-mismatch", cl::init(false),
                                        cl::Hidden);
 
+// Command line option to enable/disable the warning about a hash mismatch in
+// the profile data for Comdat functions, which often turns out to be false
+// positive due to the pre-instrumentation inline.
+static cl::opt<bool> NoPGOWarnMismatchComdat("no-pgo-warn-mismatch-comdat",
+                                             cl::init(true), cl::Hidden);
+
 // Command line option to enable/disable select instruction instrumentation.
 static cl::opt<bool> PGOInstrSelect("pgo-instr-select", cl::init(true),
                                     cl::Hidden);
@@ -407,21 +413,9 @@ void FuncPGOInstrumentation<Edge, BBInfo>::computeCFGHash() {
 static bool canRenameComdat(
     Function &F,
     std::unordered_multimap<Comdat *, GlobalValue *> &ComdatMembers) {
-  if (F.getName().empty())
-    return false;
-  if (!needsComdatForCounter(F, *(F.getParent())))
-    return false;
-  // Only safe to do if this function may be discarded if it is not used
-  // in the compilation unit.
-  if (!GlobalValue::isDiscardableIfUnused(F.getLinkage()))
+  if (!DoComdatRenaming || !canRenameComdatFunc(F, true))
     return false;
 
-  // For AvailableExternallyLinkage functions.
-  if (!F.hasComdat()) {
-    assert(F.getLinkage() == GlobalValue::AvailableExternallyLinkage);
-    return true;
-  }
-
   // FIXME: Current only handle those Comdat groups that only containing one
   // function and function aliases.
   // (1) For a Comdat group containing multiple functions, we need to have a
@@ -803,7 +797,11 @@ bool PGOUseFunc::readCounters(IndexedInstrProfReader *PGOReader) {
       } else if (Err == instrprof_error::hash_mismatch ||
                  Err == instrprof_error::malformed) {
         NumOfPGOMismatch++;
-        SkipWarning = NoPGOWarnMismatch;
+        SkipWarning =
+            NoPGOWarnMismatch ||
+            (NoPGOWarnMismatchComdat &&
+             (F.hasComdat() ||
+              F.getLinkage() == GlobalValue::AvailableExternallyLinkage));
       }
 
       if (SkipWarning)