[llvm] [SampleFDO] Stale profile call-graph matching (PR #95135)

[via llvm-commits]

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@@ -127,8 +147,37 @@ void SampleProfileMatcher::findProfileAnchors(const FunctionSamples &FS,
   }
 }
 
-LocToLocMap SampleProfileMatcher::longestCommonSequence(
-    const AnchorList &AnchorList1, const AnchorList &AnchorList2) const {
+bool SampleProfileMatcher::functionMatchesProfile(
+    const FunctionId &IRFuncName, const FunctionId &ProfileFuncName,
+    bool FindMatchedProfileOnly) {
+  if (IRFuncName == ProfileFuncName)
+    return true;
+  if (!SalvageUnusedProfile)
+    return false;
+  // If IR function and profile function don't appear on either side, try
+  // matching the profile function.
+
+  // Check whether IR function appears in profile.
+  auto R = NewIRFunctions.find(IRFuncName);
+  if (R == NewIRFunctions.end() || !R->second)
+    return false;
+  Function &IRFunc = *R->second;
+  assert(FunctionId(IRFunc.getName()) != ProfileFuncName &&
+         "IR function should be different from profile function to match");
+
+  // Check whether profile function appears in IR.
+  auto F = SymbolMap->find(ProfileFuncName);
+  if (F != SymbolMap->end())
+    return false;
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WenleiHe wrote:

So this is because if the profile already matches a function with the same name, we don't want it to be matched to another function? If so, I understand the intention, but a match is match. Perhaps the logic can be split into `isProfileUnused`(hence cannot be matched to another function) + `functionMatchesProfile`? 



https://github.com/llvm/llvm-project/pull/95135