[llvm] [TypeProf][PGO]Skip vtable-based ICP for which type profiles are known to be unrepresentative (PR #110575)

[Snehasish Kumar via llvm-commits]

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@@ -851,8 +859,27 @@ bool IndirectCallPromoter::isProfitableToCompareVTables(
     LLVM_DEBUG(dbgs() << "\n");
 
     uint64_t CandidateVTableCount = 0;
-    for (auto &[GUID, Count] : VTableGUIDAndCounts)
+    SmallVector<MDNode *, 2> Types;
+    for (auto &[GUID, Count] : VTableGUIDAndCounts) {
       CandidateVTableCount += Count;
+      auto *VTableVar = Symtab->getGlobalVariable(GUID);
+
+      assert(VTableVar &&
+             "VTableVar must exist for GUID in VTableGUIDAndCounts");
+
+      Types.clear();
+      VTableVar->getMetadata(LLVMContext::MD_type, Types);
+
+      const DenseSet<StringRef> &VTableSet = ICPIgnoredBaseTypes.getValue();
+      for (auto *Type : Types)
+        if (auto *TypeId = dyn_cast<MDString>(Type->getOperand(1).get()))
+          if (VTableSet.contains(TypeId->getString().str())) {
+            LLVM_DEBUG(dbgs()
+                       << "    vtable profiles are known to be "
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snehasish wrote:

Update the comment? s/known to be unrepresentative/ignored by option ..../

https://github.com/llvm/llvm-project/pull/110575