[llvm] [CSSPGO] Compute and report profile matching recovered callsites and samples (PR #79090)

[via llvm-commits]

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@@ -2443,53 +2374,232 @@ void SampleProfileMatcher::runOnFunction(const Function &F) {
   std::map<LineLocation, std::unordered_set<FunctionId>> ProfileAnchors;
   findProfileAnchors(*FSFlattened, ProfileAnchors);
 
-  // Detect profile mismatch for profile staleness metrics report.
-  // Skip reporting the metrics for imported functions.
-  if (!GlobalValue::isAvailableExternallyLinkage(F.getLinkage()) &&
-      (ReportProfileStaleness || PersistProfileStaleness)) {
-    // Use top-level nested FS for counting profile mismatch metrics since
-    // currently once a callsite is mismatched, all its children profiles are
-    // dropped.
-    if (const auto *FS = Reader.getSamplesFor(F))
-      countProfileMismatches(F, *FS, IRAnchors, ProfileAnchors);
-  }
+  // Compute the callsite match states for profile staleness report.
+  if (ReportProfileStaleness || PersistProfileStaleness)
+    recordCallsiteMatchStates(F, IRAnchors, ProfileAnchors, nullptr);
 
   // Run profile matching for checksum mismatched profile, currently only
   // support for pseudo-probe.
   if (SalvageStaleProfile && FunctionSamples::ProfileIsProbeBased &&
       !ProbeManager->profileIsValid(F, *FSFlattened)) {
     // The matching result will be saved to IRToProfileLocationMap, create a new
     // map for each function.
+    auto &IRToProfileLocationMap = getIRToProfileLocationMap(F);
     runStaleProfileMatching(F, IRAnchors, ProfileAnchors,
-                            getIRToProfileLocationMap(F));
+                            IRToProfileLocationMap);
+    // Find and update callsite match states after matching.
+    if (ReportProfileStaleness || PersistProfileStaleness)
+      recordCallsiteMatchStates(F, IRAnchors, ProfileAnchors,
+                                &IRToProfileLocationMap);
   }
 }
 
-void SampleProfileMatcher::runOnModule() {
-  ProfileConverter::flattenProfile(Reader.getProfiles(), FlattenedProfiles,
-                                   FunctionSamples::ProfileIsCS);
-  for (auto &F : M) {
-    if (F.isDeclaration() || !F.hasFnAttribute("use-sample-profile"))
+void SampleProfileMatcher::recordCallsiteMatchStates(
+    const Function &F, const std::map<LineLocation, StringRef> &IRAnchors,
+    const std::map<LineLocation, std::unordered_set<FunctionId>>
+        &ProfileAnchors,
+    const LocToLocMap *IRToProfileLocationMap) {
+  bool IsPostMatch = IRToProfileLocationMap != nullptr;
+  auto &CallsiteMatchStates =
+      FuncCallsiteMatchStates[FunctionSamples::getCanonicalFnName(F.getName())];
+
+  auto MapIRLocToProfileLoc = [&](const LineLocation &IRLoc) {
+    // IRToProfileLocationMap is null in pre-match phrase.
+    if (!IRToProfileLocationMap)
+      return IRLoc;
+    const auto &ProfileLoc = IRToProfileLocationMap->find(IRLoc);
+    if (ProfileLoc != IRToProfileLocationMap->end())
+      return ProfileLoc->second;
+    else
+      return IRLoc;
+  };
+
+  for (const auto &I : IRAnchors) {
+    // In post-match, use the matching result to remap the current IR callsite.
+    const auto &ProfileLoc = MapIRLocToProfileLoc(I.first);
+    const auto &IRCalleeName = I.second;
+    const auto &It = ProfileAnchors.find(ProfileLoc);
+    if (It == ProfileAnchors.end())
       continue;
-    runOnFunction(F);
+    const auto &Callees = It->second;
+
+    bool IsCallsiteMatched = false;
+    // 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)
+      IsCallsiteMatched = true;
+    else if (Callees.size() == 1 && Callees.count(getRepInFormat(IRCalleeName)))
+      IsCallsiteMatched = true;
+
+    if (IsCallsiteMatched) {
+      auto R =
+          CallsiteMatchStates.emplace(ProfileLoc, MatchState::InitialMatch);
+      // When there is an existing state, we know it's in post-match phrase.
+      // Update the matching state accordingly.
+      if (!R.second && R.first->second == MatchState::InitialMismatch)
+        R.first->second = MatchState::RecoveredMismatch;
+    }
+  }
+
+  // Check if there are any callsites in the profile that does not match to any
+  // IR callsites.
+  for (const auto &I : ProfileAnchors) {
+    const auto &Loc = I.first;
+    [[maybe_unused]] const auto &Callees = I.second;
+    assert(!Callees.empty() && "Callees should not be empty");
+    auto It = CallsiteMatchStates.find(Loc);
+    if (It == CallsiteMatchStates.end())
+      CallsiteMatchStates.emplace(Loc, MatchState::InitialMismatch);
+    // The inital match is removed in post-match.
+    else if (IsPostMatch && It->second == MatchState::InitialMatch)
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WenleiHe wrote:

6 explicit state sounds ok with me, that should make things really clear? 

I'd add comment for each of the state. 

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