1 files changed, 44 insertions, 0 deletions
diff --git a/llvm/tools/llvm-profgen/ProfileGenerator.cpp b/llvm/tools/llvm-profgen/ProfileGenerator.cpp
index c4028e6..5aa4410 100644
--- a/llvm/tools/llvm-profgen/ProfileGenerator.cpp
+++ b/llvm/tools/llvm-profgen/ProfileGenerator.cpp
@@ -196,6 +196,48 @@ void ProfileGeneratorBase::showDensitySuggestion(double Density) {
            << "% total samples: " << format("%.1f", Density) << "\n";
 }
 
+bool ProfileGeneratorBase::filterAmbiguousProfile(FunctionSamples &FS) {
+  for (const auto &Prefix : FuncPrefixsToFilter) {
+    if (FS.getFuncName().starts_with(Prefix))
+      return true;
+  }
+
+  // Filter the function profiles for the inlinees. It's useful for fuzzy
+  // profile matching which flattens the profile and inlinees' samples are
+  // merged into top-level function.
+  for (auto &Callees :
+       const_cast<CallsiteSampleMap &>(FS.getCallsiteSamples())) {
+    auto &CalleesMap = Callees.second;
+    for (auto I = CalleesMap.begin(); I != CalleesMap.end();) {
+      auto FS = I++;
+      if (filterAmbiguousProfile(FS->second))
+        CalleesMap.erase(FS);
+    }
+  }
+  return false;
+}
+
+// For built-in local initialization function such as __cxx_global_var_init,
+// __tls_init prefix function, there could be multiple versions of the functions
+// in the final binary. However, in the profile generation, we call
+// getCanonicalFnName to canonicalize the names which strips the suffixes.
+// Therefore, samples from different functions queries the same profile and the
+// samples are merged. As the functions are essentially different, entries of
+// the merged profile are ambiguous. In sample loader, the IR from one version
+// would be attributed towards a merged entries, which is inaccurate. Especially
+// for fuzzy profile matching, it gets multiple callsites(from different
+// function) but used to match one callsite, which misleads the matching and
+// causes a lot of false positives report. Hence, we want to filter them out
+// from the profile map during the profile generation time. The profiles are all
+// cold functions, it won't have perf impact.
+void ProfileGeneratorBase::filterAmbiguousProfile(SampleProfileMap &Profiles) {
+  for (auto I = ProfileMap.begin(); I != ProfileMap.end();) {
+    auto FS = I++;
+    if (filterAmbiguousProfile(FS->second))
+      ProfileMap.erase(FS);
+  }
+}
+
 double ProfileGeneratorBase::calculateDensity(const SampleProfileMap &Profiles,
                                               uint64_t HotCntThreshold) {
   double Density = DBL_MAX;
@@ -491,6 +533,7 @@ void ProfileGenerator::generateProfile() {
 void ProfileGenerator::postProcessProfiles() {
   computeSummaryAndThreshold(ProfileMap);
   trimColdProfiles(ProfileMap, ColdCountThreshold);
+  filterAmbiguousProfile(ProfileMap);
   calculateAndShowDensity(ProfileMap);
 }
 
@@ -1024,6 +1067,7 @@ void CSProfileGenerator::postProcessProfiles() {
     CSConverter.convertCSProfiles();
     FunctionSamples::ProfileIsCS = false;
   }
+  filterAmbiguousProfile(ProfileMap);
 }
 
 void ProfileGeneratorBase::computeSummaryAndThreshold(