[llvm] [SampleFDO] Stale profile renaming matching (PR #92151)

[via llvm-commits]

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@@ -590,13 +609,260 @@ void SampleProfileMatcher::computeAndReportProfileStaleness() {
   }
 }
 
-void SampleProfileMatcher::runOnModule() {
+// Find functions that don't show in the profile or profile symbol list, which
+// are supposed to be new functions. We use them as the targets for renaming
+// matching.
+void SampleProfileMatcher::findIRNewFunctions(
+    StringMap<Function *> &IRNewFunctions) {
+  // TODO: Support MD5 profile.
+  if (FunctionSamples::UseMD5)
+    return;
+  StringSet<> NamesInProfile;
+  if (auto NameTable = Reader.getNameTable()) {
+    for (auto Name : *NameTable)
+      NamesInProfile.insert(Name.stringRef());
+  }
+
+  for (auto &F : M) {
+    // Skip declarations, as even if the function can be recognized renamed, we
+    // have nothing to do with it.
+    if (F.isDeclaration())
+      continue;
+
+    StringRef CanonFName = FunctionSamples::getCanonicalFnName(F.getName());
+    const auto *FS = getFlattenedSamplesFor(F);
+    if (FS)
+      continue;
+
+    // For extended binary, the full function name symbols exits in the profile
+    // symbol list table.
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WenleiHe wrote:

comment belong to the next if? 

https://github.com/llvm/llvm-project/pull/92151