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

[via cfe-commits]

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@@ -2205,93 +2230,141 @@ void SampleProfileMatcher::countMismatchedSamples(const FunctionSamples &FS) {
       countMismatchedSamples(CS.second);
 }
 
-void SampleProfileMatcher::countProfileMismatches(
-    const Function &F, const FunctionSamples &FS,
-    const std::map<LineLocation, StringRef> &IRAnchors,
+void ProfileMatchStats::countMismatchedCallsites(
+    const Function &F, const std::map<LineLocation, StringRef> &IRAnchors,
+    const std::map<LineLocation, std::unordered_set<FunctionId>>
+        &ProfileAnchors,
+    const LocToLocMap &IRToProfileLocationMap) {
+  auto &MismatchedCallsites =
+      FuncMismatchedCallsites[FunctionSamples::getCanonicalFnName(F.getName())];
+
+  auto MapIRLocToProfileLoc = [&](const LineLocation &IRLoc) {
+    const auto &ProfileLoc = IRToProfileLocationMap.find(IRLoc);
+    if (ProfileLoc != IRToProfileLocationMap.end())
+      return ProfileLoc->second;
+    else
+      return IRLoc;
+  };
+
+  std::set<LineLocation> MatchedCallsites;
+  for (const auto &I : IRAnchors) {
+    // In post-match, use the matching result to remap the current IR callsite.
+    const auto &Loc = MapIRLocToProfileLoc(I.first);
+    const auto &IRCalleeName = I.second;
+    const auto &It = ProfileAnchors.find(Loc);
+    if (It == ProfileAnchors.end())
+      continue;
+    const auto &Callees = It->second;
+
+    // Since indirect call does not have CalleeName, check conservatively if
+    // callsite in the profile is a callsite location. This is to reduce num of
+    // false positive since otherwise all the indirect call samples will be
+    // reported as mismatching.
+    if (IRCalleeName == SampleProfileMatcher::UnknownIndirectCallee)
+      MatchedCallsites.insert(Loc);
+    else if (Callees.count(getRepInFormat(IRCalleeName)))
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WenleiHe wrote:

If there is potentially a bug and this is workaround, at least leave a TODO comment. Preferably we should not need a workaround.  

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