1 files changed, 36 insertions, 11 deletions

diff --git a/llvm/lib/Transforms/Instrumentation/PGOInstrumentation.cpp b/llvm/lib/Transforms/Instrumentation/PGOInstrumentation.cpp
index be6c8c631001..3d9261eb99ba 100644
--- a/llvm/lib/Transforms/Instrumentation/PGOInstrumentation.cpp
+++ b/llvm/lib/Transforms/Instrumentation/PGOInstrumentation.cpp
@@ -280,6 +280,7 @@ static cl::opt<unsigned> PGOVerifyBFICutoff(
     cl::desc("Set the threshold for pgo-verify-bfi -- skip the counts whose "
              "profile count value is below."));
 
+namespace llvm {
 // Command line option to turn on CFG dot dump after profile annotation.
 // Defined in Analysis/BlockFrequencyInfo.cpp:  -pgo-view-counts
 extern cl::opt<PGOViewCountsType> PGOViewCounts;
@@ -287,6 +288,7 @@ extern cl::opt<PGOViewCountsType> PGOViewCounts;
 // Command line option to specify the name of the function for CFG dump
 // Defined in Analysis/BlockFrequencyInfo.cpp:  -view-bfi-func-name=
 extern cl::opt<std::string> ViewBlockFreqFuncName;
+} // namespace llvm
 
 static cl::opt<bool>
     PGOOldCFGHashing("pgo-instr-old-cfg-hashing", cl::init(false), cl::Hidden,
@@ -529,7 +531,7 @@ struct PGOEdge {
       : SrcBB(Src), DestBB(Dest), Weight(W) {}
 
   // Return the information string of an edge.
-  const std::string infoString() const {
+  std::string infoString() const {
     return (Twine(Removed ? "-" : " ") + (InMST ? " " : "*") +
             (IsCritical ? "c" : " ") + "  W=" + Twine(Weight)).str();
   }
@@ -544,7 +546,7 @@ struct BBInfo {
   BBInfo(unsigned IX) : Group(this), Index(IX) {}
 
   // Return the information string of this object.
-  const std::string infoString() const {
+  std::string infoString() const {
     return (Twine("Index=") + Twine(Index)).str();
   }
 
@@ -987,7 +989,7 @@ struct PGOUseEdge : public PGOEdge {
   }
 
   // Return the information string for this object.
-  const std::string infoString() const {
+  std::string infoString() const {
     if (!CountValid)
       return PGOEdge::infoString();
     return (Twine(PGOEdge::infoString()) + "  Count=" + Twine(CountValue))
@@ -1018,7 +1020,7 @@ struct UseBBInfo : public BBInfo {
   }
 
   // Return the information string of this object.
-  const std::string infoString() const {
+  std::string infoString() const {
     if (!CountValid)
       return BBInfo::infoString();
     return (Twine(BBInfo::infoString()) + "  Count=" + Twine(CountValue)).str();
@@ -1147,7 +1149,7 @@ private:
   void setEdgeCount(DirectEdges &Edges, uint64_t Value);
 
   // Return FuncName string;
-  const std::string getFuncName() const { return FuncInfo.FuncName; }
+  std::string getFuncName() const { return FuncInfo.FuncName; }
 
   // Set the hot/cold inline hints based on the count values.
   // FIXME: This function should be removed once the functionality in
@@ -1245,6 +1247,28 @@ void PGOUseFunc::setEdgeCount(DirectEdges &Edges, uint64_t Value) {
   llvm_unreachable("Cannot find the unknown count edge");
 }
 
+// Emit function metadata indicating PGO profile mismatch.
+static void annotateFunctionWithHashMismatch(Function &F,
+                                             LLVMContext &ctx) {
+  const char MetadataName[] = "instr_prof_hash_mismatch";
+  SmallVector<Metadata *, 2> Names;
+  // If this metadata already exists, ignore.
+  auto *Existing = F.getMetadata(LLVMContext::MD_annotation);
+  if (Existing) {
+    MDTuple *Tuple = cast<MDTuple>(Existing);
+    for (auto &N : Tuple->operands()) {
+      if (cast<MDString>(N.get())->getString() ==  MetadataName)
+        return;
+      Names.push_back(N.get());
+    }
+  }
+
+  MDBuilder MDB(ctx);
+  Names.push_back(MDB.createString(MetadataName));
+  MDNode *MD = MDTuple::get(ctx, Names);
+  F.setMetadata(LLVMContext::MD_annotation, MD);
+}
+
 // Read the profile from ProfileFileName and assign the value to the
 // instrumented BB and the edges. This function also updates ProgramMaxCount.
 // Return true if the profile are successfully read, and false on errors.
@@ -1272,6 +1296,8 @@ bool PGOUseFunc::readCounters(IndexedInstrProfReader *PGOReader, bool &AllZeros,
              (F.hasComdat() ||
               F.getLinkage() == GlobalValue::AvailableExternallyLinkage));
         LLVM_DEBUG(dbgs() << "hash mismatch (skip=" << SkipWarning << ")");
+        // Emit function metadata indicating PGO profile mismatch.
+        annotateFunctionWithHashMismatch(F, M->getContext());
       }
 
       LLVM_DEBUG(dbgs() << " IsCS=" << IsCS << "\n");
@@ -1441,8 +1467,8 @@ void PGOUseFunc::setBranchWeights() {
 }
 
 static bool isIndirectBrTarget(BasicBlock *BB) {
-  for (pred_iterator PI = pred_begin(BB), E = pred_end(BB); PI != E; ++PI) {
-    if (isa<IndirectBrInst>((*PI)->getTerminator()))
+  for (BasicBlock *Pred : predecessors(BB)) {
+    if (isa<IndirectBrInst>(Pred->getTerminator()))
       return true;
   }
   return false;
@@ -2100,14 +2126,13 @@ template <> struct DOTGraphTraits<PGOUseFunc *> : DefaultDOTGraphTraits {
     if (!PGOInstrSelect)
       return Result;
 
-    for (auto BI = Node->begin(); BI != Node->end(); ++BI) {
-      auto *I = &*BI;
-      if (!isa<SelectInst>(I))
+    for (const Instruction &I : *Node) {
+      if (!isa<SelectInst>(&I))
         continue;
       // Display scaled counts for SELECT instruction:
       OS << "SELECT : { T = ";
       uint64_t TC, FC;
-      bool HasProf = I->extractProfMetadata(TC, FC);
+      bool HasProf = I.extractProfMetadata(TC, FC);
       if (!HasProf)
         OS << "Unknown, F = Unknown }\\l";
       else