[SampleFDO] Read call-graph matching recovered top-level function profile

llvm/include/llvm/ProfileData/SampleProfReader.h

@@ -380,6 +380,22 @@ class SampleProfileReader {
     return sampleprof_error::success;
   }
 
+  /// Read sample profiles for the given functions. Currently it's only used for
+  /// extended binary format to load the profiles on-demand.
+  std::error_code read(const DenseSet<StringRef> &FuncsToUse) {
+    if (std::error_code EC = read(FuncsToUse, Profiles))
+      return EC;
+    return sampleprof_error::success;
+  };
+
+  /// Read sample profiles for the given functions and write them to the given
+  /// profile map. Currently it's only used for extended binary format to load
+  /// the profiles on-demand.
+  virtual std::error_code read(const DenseSet<StringRef> &FuncsToUse,
+                               SampleProfileMap &Profiles) {
+    return sampleprof_error::not_implemented;
+  };
+
   /// The implementaion to read sample profiles from the associated file.
   virtual std::error_code readImpl() = 0;
 
@@ -413,6 +429,16 @@ class SampleProfileReader {
     if (It != Profiles.end())
       return &It->second;
 
+    if (FuncNameToProfNameMap && !FuncNameToProfNameMap->empty()) {
+      auto R = FuncNameToProfNameMap->find(FunctionId(Fname));
+      if (R != FuncNameToProfNameMap->end()) {
+        Fname = R->second.stringRef();
+        auto It = Profiles.find(FunctionId(Fname));
+        if (It != Profiles.end())
+          return &It->second;
+      }
+    }
+
     if (Remapper) {
       if (auto NameInProfile = Remapper->lookUpNameInProfile(Fname)) {
         auto It = Profiles.find(FunctionId(*NameInProfile));
@@ -494,6 +520,11 @@ class SampleProfileReader {
 
   void setModule(const Module *Mod) { M = Mod; }
 
+  void setFuncNameToProfNameMap(
+      const HashKeyMap<std::unordered_map, FunctionId, FunctionId> &FPMap) {
+    FuncNameToProfNameMap = &FPMap;
+  }
+
 protected:
   /// Map every function to its associated profile.
   ///
@@ -522,6 +553,22 @@ class SampleProfileReader {
 
   std::unique_ptr<SampleProfileReaderItaniumRemapper> Remapper;
 
+  // A map pointer to the FuncNameToProfNameMap in SampleProfileLoader,
+  // which maps the function name to the matched profile name. This is used
+  // for sample loader to look up profile using the new name.
+  const HashKeyMap<std::unordered_map, FunctionId, FunctionId>
+      *FuncNameToProfNameMap = nullptr;
+
+  // A map from a function's context hash to its meta data section range, used
+  // for on-demand read function profile metadata.
+  std::unordered_map<uint64_t, std::pair<const uint8_t *, const uint8_t *>>
+      FuncMetadataIndex;
+
+  std::pair<const uint8_t *, const uint8_t *> LBRProfileSecRange;
+
+  /// Whether the profile has attribute metadata.
+  bool ProfileHasAttribute = false;
+
   /// \brief Whether samples are collected based on pseudo probes.
   bool ProfileIsProbeBased = false;
 
@@ -621,6 +668,8 @@ class SampleProfileReaderBinary : public SampleProfileReader {
 
   /// Read the next function profile instance.
   std::error_code readFuncProfile(const uint8_t *Start);
+  std::error_code readFuncProfile(const uint8_t *Start,
+                                  SampleProfileMap &Profiles);
 
   /// Read the contents of the given profile instance.
   std::error_code readProfile(FunctionSamples &FProfile);
@@ -720,11 +769,15 @@ class SampleProfileReaderExtBinaryBase : public SampleProfileReaderBinary {
   std::error_code readSecHdrTableEntry(uint64_t Idx);
   std::error_code readSecHdrTable();
 
+  std::error_code readFuncMetadata(bool ProfileHasAttribute,
+                                   SampleProfileMap &Profiles);
   std::error_code readFuncMetadata(bool ProfileHasAttribute);
   std::error_code readFuncMetadata(bool ProfileHasAttribute,
                                    FunctionSamples *FProfile);
   std::error_code readFuncOffsetTable();
   std::error_code readFuncProfiles();
+  std::error_code readFuncProfiles(const DenseSet<StringRef> &FuncsToUse,
+                                   SampleProfileMap &Profiles);
   std::error_code readNameTableSec(bool IsMD5, bool FixedLengthMD5);
   std::error_code readCSNameTableSec();
   std::error_code readProfileSymbolList();
@@ -776,6 +829,13 @@ class SampleProfileReaderExtBinaryBase : public SampleProfileReaderBinary {
   /// the reader has been given a module.
   bool collectFuncsFromModule() override;
 
+  /// Read the profiles on-demand for the given functions. This is used after
+  /// stale call graph matching finds new functions whose profiles aren't loaded
+  /// at the beginning and we need to loaded the profiles explicitly for
+  /// potential matching.
+  std::error_code read(const DenseSet<StringRef> &FuncsToUse,
+                       SampleProfileMap &Profiles) override;
+
   std::unique_ptr<ProfileSymbolList> getProfileSymbolList() override {
     return std::move(ProfSymList);
   };

llvm/include/llvm/Transforms/IPO/SampleProfileMatcher.h

@@ -198,6 +198,7 @@ class SampleProfileMatcher {
   // function and all inlinees.
   void countMismatchedCallsiteSamples(const FunctionSamples &FS);
   void computeAndReportProfileStaleness();
+  void UpdateWithSalvagedProfiles();
 
   LocToLocMap &getIRToProfileLocationMap(const Function &F) {
     auto Ret = FuncMappings.try_emplace(