[libcxxabi] [clang] [compiler-rt] [lld] [llvm] [libc] [libcxx] [clang-tools-extra] [flang] [CSSPGO] Compute and report post-match profile staleness (PR #79090)

[via cfe-commits]

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@@ -2422,59 +2342,226 @@ void SampleProfileMatcher::runStaleProfileMatching(
   }
 }
 
-void SampleProfileMatcher::runOnFunction(const Function &F) {
-  // We need to use flattened function samples for matching.
-  // Unlike IR, which includes all callsites from the source code, the callsites
-  // in profile only show up when they are hit by samples, i,e. the profile
-  // callsites in one context may differ from those in another context. To get
-  // the maximum number of callsites, we merge the function profiles from all
-  // contexts, aka, the flattened profile to find profile anchors.
-  const auto *FSFlattened = getFlattenedSamplesFor(F);
-  if (!FSFlattened)
-    return;
+void SampleProfileMatcher::runStaleProfileMatching() {
+  for (const auto &F : M) {
+    if (F.isDeclaration() || !F.hasFnAttribute("use-sample-profile"))
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WenleiHe wrote:

This particular check is duplicated now because we turned `runOnFunction` into `runOnModule`. Maybe make a small helper to centralize this check and keep them always in sync for the different function loops. 

https://github.com/llvm/llvm-project/pull/79090