[NFC][IndirectCallProm] Refactor function-based conditional devirtualization and indirect call value profile update into one helper function (#80762)

* The motivation is to move indirect callee profile update inside the
function-based speculative indirect-call promotion, so that there are
fewer diffs the vtable-based transformation and profile update is
implemented in a follow-up patch.
* The Parent patch is #79381

Author: mingmingl-llvm

llvm/include/llvm/ProfileData/InstrProf.h

@@ -277,6 +277,8 @@ void annotateValueSite(Module &M, Instruction &Inst,
                        uint32_t MaxMDCount = 3);
 
 /// Same as the above interface but using an ArrayRef, as well as \p Sum.
+/// This function will not annotate !prof metadata on the instruction if the
+/// referenced array is empty.
 void annotateValueSite(Module &M, Instruction &Inst,
                        ArrayRef<InstrProfValueData> VDs, uint64_t Sum,
                        InstrProfValueKind ValueKind, uint32_t MaxMDCount);
@@ -465,7 +467,6 @@ class InstrProfSymtab {
   StringSet<> VTableNames;
   // A map from MD5 keys to function name strings.
   std::vector<std::pair<uint64_t, StringRef>> MD5NameMap;
-
   // A map from MD5 keys to function define. We only populate this map
   // when build the Symtab from a Module.
   std::vector<std::pair<uint64_t, Function *>> MD5FuncMap;

llvm/lib/ProfileData/InstrProf.cpp

@@ -1246,6 +1246,8 @@ void annotateValueSite(Module &M, Instruction &Inst,
                        ArrayRef<InstrProfValueData> VDs,
                        uint64_t Sum, InstrProfValueKind ValueKind,
                        uint32_t MaxMDCount) {
+  if (VDs.empty())
+    return;
   LLVMContext &Ctx = M.getContext();
   MDBuilder MDHelper(Ctx);
   SmallVector<Metadata *, 3> Vals;

llvm/lib/Transforms/Instrumentation/IndirectCallPromotion.cpp

@@ -136,11 +136,13 @@ class IndirectCallPromoter {
       const CallBase &CB, const ArrayRef<InstrProfValueData> &ValueDataRef,
       uint64_t TotalCount, uint32_t NumCandidates);
 
-  // Promote a list of targets for one indirect-call callsite. Return
-  // the number of promotions.
-  uint32_t tryToPromote(CallBase &CB,
-                        const std::vector<PromotionCandidate> &Candidates,
-                        uint64_t &TotalCount);
+  // Promote a list of targets for one indirect-call callsite by comparing
+  // indirect callee with functions. Returns true if there are IR
+  // transformations and false otherwise.
+  bool tryToPromoteWithFuncCmp(
+      CallBase &CB, const std::vector<PromotionCandidate> &Candidates,
+      uint64_t TotalCount, ArrayRef<InstrProfValueData> ICallProfDataRef,
+      uint32_t NumCandidates);
 
 public:
   IndirectCallPromoter(Function &Func, InstrProfSymtab *Symtab, bool SamplePGO,
@@ -273,9 +275,10 @@ CallBase &llvm::pgo::promoteIndirectCall(CallBase &CB, Function *DirectCallee,
 }
 
 // Promote indirect-call to conditional direct-call for one callsite.
-uint32_t IndirectCallPromoter::tryToPromote(
+bool IndirectCallPromoter::tryToPromoteWithFuncCmp(
     CallBase &CB, const std::vector<PromotionCandidate> &Candidates,
-    uint64_t &TotalCount) {
+    uint64_t TotalCount, ArrayRef<InstrProfValueData> ICallProfDataRef,
+    uint32_t NumCandidates) {
   uint32_t NumPromoted = 0;
 
   for (const auto &C : Candidates) {
@@ -287,7 +290,22 @@ uint32_t IndirectCallPromoter::tryToPromote(
     NumOfPGOICallPromotion++;
     NumPromoted++;
   }
-  return NumPromoted;
+
+  if (NumPromoted == 0)
+    return false;
+
+  // Adjust the MD.prof metadata. First delete the old one.
+  CB.setMetadata(LLVMContext::MD_prof, nullptr);
+
+  assert(NumPromoted <= ICallProfDataRef.size() &&
+         "Number of promoted functions should not be greater than the number "
+         "of values in profile metadata");
+  // Annotate the remaining value profiles if counter is not zero.
+  if (TotalCount != 0)
+    annotateValueSite(*F.getParent(), CB, ICallProfDataRef.slice(NumPromoted),
+                      TotalCount, IPVK_IndirectCallTarget, NumCandidates);
+
+  return true;
 }
 
 // Traverse all the indirect-call callsite and get the value profile
@@ -305,19 +323,8 @@ bool IndirectCallPromoter::processFunction(ProfileSummaryInfo *PSI) {
       continue;
     auto PromotionCandidates = getPromotionCandidatesForCallSite(
         *CB, ICallProfDataRef, TotalCount, NumCandidates);
-    uint32_t NumPromoted = tryToPromote(*CB, PromotionCandidates, TotalCount);
-    if (NumPromoted == 0)
-      continue;
-
-    Changed = true;
-    // Adjust the MD.prof metadata. First delete the old one.
-    CB->setMetadata(LLVMContext::MD_prof, nullptr);
-    // If all promoted, we don't need the MD.prof metadata.
-    if (TotalCount == 0 || NumPromoted == NumVals)
-      continue;
-    // Otherwise we need update with the un-promoted records back.
-    annotateValueSite(*F.getParent(), *CB, ICallProfDataRef.slice(NumPromoted),
-                      TotalCount, IPVK_IndirectCallTarget, NumCandidates);
+    Changed |= tryToPromoteWithFuncCmp(*CB, PromotionCandidates, TotalCount,
+                                       ICallProfDataRef, NumCandidates);
   }
   return Changed;
 }