[memprof] Use CSId to construct MemProfRecord (#88362)

We are in the process of referring to call stacks with CallStackId in
IndexedMemProfRecord and IndexedAllocationInfo instead of holding call
stacks inline (both in memory and the serialized format).  Doing so
deduplicates call stacks and reduces the MemProf profile file size.

Before we can eliminate the two fields holding call stacks inline:

- IndexedAllocationInfo::CallStack
- IndexedMemProfRecord::CallSites

we need to eliminate all the read operations on them.

This patch is a step toward that direction.  Specifically, we
eliminate the read operations in the context of MemProfReader and
RawMemProfReader.  A subsequent patch will eliminate the read
operations during the serialization.

llvm/include/llvm/ProfileData/MemProf.h

@@ -16,6 +16,8 @@
 namespace llvm {
 namespace memprof {
 
+struct MemProfRecord;
+
 // The versions of the indexed MemProf format
 enum IndexedVersion : uint64_t {
   // Version 0: This version didn't have a version field.
@@ -392,6 +394,12 @@ struct IndexedMemProfRecord {
                                           const unsigned char *Buffer,
                                           IndexedVersion Version);
 
+  // Convert IndexedMemProfRecord to MemProfRecord.  Callback is used to
+  // translate CallStackId to call stacks with frames inline.
+  MemProfRecord toMemProfRecord(
+      std::function<const llvm::SmallVector<Frame>(const CallStackId)> Callback)
+      const;
+
   // Returns the GUID for the function name after canonicalization. For
   // memprof, we remove any .llvm suffix added by LTO. MemProfRecords are
   // mapped to functions using this GUID.

llvm/include/llvm/ProfileData/MemProfReader.h

@@ -70,8 +70,20 @@ class MemProfReader {
       Callback =
           std::bind(&MemProfReader::idToFrame, this, std::placeholders::_1);
 
+    auto CallStackCallback = [&](CallStackId CSId) {
+      llvm::SmallVector<Frame> CallStack;
+      auto Iter = CSIdToCallStack.find(CSId);
+      assert(Iter != CSIdToCallStack.end());
+      for (FrameId Id : Iter->second)
+        CallStack.push_back(Callback(Id));
+      return CallStack;
+    };
+
     const IndexedMemProfRecord &IndexedRecord = Iter->second;
-    GuidRecord = {Iter->first, MemProfRecord(IndexedRecord, Callback)};
+    GuidRecord = {
+        Iter->first,
+        IndexedRecord.toMemProfRecord(CallStackCallback),
+    };
     Iter++;
     return Error::success();
   }
@@ -84,9 +96,7 @@ class MemProfReader {
   // Initialize the MemProfReader with the frame mappings and profile contents.
   MemProfReader(
       llvm::DenseMap<FrameId, Frame> FrameIdMap,
-      llvm::MapVector<GlobalValue::GUID, IndexedMemProfRecord> ProfData)
-      : IdToFrame(std::move(FrameIdMap)),
-        FunctionProfileData(std::move(ProfData)) {}
+      llvm::MapVector<GlobalValue::GUID, IndexedMemProfRecord> ProfData);
 
 protected:
   // A helper method to extract the frame from the IdToFrame map.
@@ -97,6 +107,8 @@ class MemProfReader {
   }
   // A mapping from FrameId (a hash of the contents) to the frame.
   llvm::DenseMap<FrameId, Frame> IdToFrame;
+  // A mapping from CallStackId to the call stack.
+  llvm::DenseMap<CallStackId, llvm::SmallVector<FrameId>> CSIdToCallStack;
   // A mapping from function GUID, hash of the canonical function symbol to the
   // memprof profile data for that function, i.e allocation and callsite info.
   llvm::MapVector<GlobalValue::GUID, IndexedMemProfRecord> FunctionProfileData;

llvm/lib/ProfileData/MemProf.cpp

@@ -224,6 +224,24 @@ IndexedMemProfRecord::deserialize(const MemProfSchema &Schema,
   llvm_unreachable("unsupported MemProf version");
 }
 
+MemProfRecord IndexedMemProfRecord::toMemProfRecord(
+    std::function<const llvm::SmallVector<Frame>(const CallStackId)> Callback)
+    const {
+  MemProfRecord Record;
+
+  for (const memprof::IndexedAllocationInfo &IndexedAI : AllocSites) {
+    memprof::AllocationInfo AI;
+    AI.Info = IndexedAI.Info;
+    AI.CallStack = Callback(IndexedAI.CSId);
+    Record.AllocSites.push_back(AI);
+  }
+
+  for (memprof::CallStackId CSId : CallSiteIds)
+    Record.CallSites.push_back(Callback(CSId));
+
+  return Record;
+}
+
 GlobalValue::GUID IndexedMemProfRecord::getGUID(const StringRef FunctionName) {
   // Canonicalize the function name to drop suffixes such as ".llvm.". Note
   // we do not drop any ".__uniq." suffixes, as getCanonicalFnName does not drop

llvm/lib/ProfileData/MemProfReader.cpp

@@ -183,6 +183,28 @@ std::string getBuildIdString(const SegmentEntry &Entry) {
 }
 } // namespace
 
+MemProfReader::MemProfReader(
+    llvm::DenseMap<FrameId, Frame> FrameIdMap,
+    llvm::MapVector<GlobalValue::GUID, IndexedMemProfRecord> ProfData)
+    : IdToFrame(std::move(FrameIdMap)),
+      FunctionProfileData(std::move(ProfData)) {
+  // Populate CSId in each IndexedAllocationInfo and IndexedMemProfRecord
+  // while storing CallStack in CSIdToCallStack.
+  for (auto &KV : FunctionProfileData) {
+    IndexedMemProfRecord &Record = KV.second;
+    for (auto &AS : Record.AllocSites) {
+      CallStackId CSId = hashCallStack(AS.CallStack);
+      AS.CSId = CSId;
+      CSIdToCallStack.insert({CSId, AS.CallStack});
+    }
+    for (auto &CS : Record.CallSites) {
+      CallStackId CSId = hashCallStack(CS);
+      Record.CallSiteIds.push_back(CSId);
+      CSIdToCallStack.insert({CSId, CS});
+    }
+  }
+}
+
 Expected<std::unique_ptr<RawMemProfReader>>
 RawMemProfReader::create(const Twine &Path, const StringRef ProfiledBinary,
                          bool KeepName) {
@@ -445,6 +467,7 @@ Error RawMemProfReader::mapRawProfileToRecords() {
     }
 
     CallStackId CSId = hashCallStack(Callstack);
+    CSIdToCallStack.insert({CSId, Callstack});
 
     // We attach the memprof record to each function bottom-up including the
     // first non-inline frame.
@@ -467,7 +490,10 @@ Error RawMemProfReader::mapRawProfileToRecords() {
     auto Result = FunctionProfileData.insert({Id, IndexedMemProfRecord()});
     IndexedMemProfRecord &Record = Result.first->second;
     for (LocationPtr Loc : Locs) {
+      CallStackId CSId = hashCallStack(*Loc);
+      CSIdToCallStack.insert({CSId, *Loc});
       Record.CallSites.push_back(*Loc);
+      Record.CallSiteIds.push_back(CSId);
     }
   }
 

llvm/unittests/ProfileData/MemProfTest.cpp

@@ -21,9 +21,11 @@ using ::llvm::DILineInfo;
 using ::llvm::DILineInfoSpecifier;
 using ::llvm::DILocal;
 using ::llvm::StringRef;
+using ::llvm::memprof::CallStackId;
 using ::llvm::memprof::CallStackMap;
 using ::llvm::memprof::Frame;
 using ::llvm::memprof::FrameId;
+using ::llvm::memprof::IndexedAllocationInfo;
 using ::llvm::memprof::IndexedMemProfRecord;
 using ::llvm::memprof::MemInfoBlock;
 using ::llvm::memprof::MemProfReader;
@@ -36,6 +38,7 @@ using ::llvm::memprof::SegmentEntry;
 using ::llvm::object::SectionedAddress;
 using ::llvm::symbolize::SymbolizableModule;
 using ::testing::Return;
+using ::testing::SizeIs;
 
 class MockSymbolizer : public SymbolizableModule {
 public:
@@ -432,4 +435,86 @@ TEST(MemProf, BaseMemProfReader) {
   EXPECT_THAT(Records[0].AllocSites[0].CallStack[1],
               FrameContains("bar", 10U, 2U, false));
 }
+
+TEST(MemProf, IndexedMemProfRecordToMemProfRecord) {
+  // Verify that MemProfRecord can be constructed from IndexedMemProfRecord with
+  // CallStackIds only.
+
+  llvm::DenseMap<FrameId, Frame> FrameIdMap;
+  Frame F1(1, 0, 0, false);
+  Frame F2(2, 0, 0, false);
+  Frame F3(3, 0, 0, false);
+  Frame F4(4, 0, 0, false);
+  FrameIdMap.insert({F1.hash(), F1});
+  FrameIdMap.insert({F2.hash(), F2});
+  FrameIdMap.insert({F3.hash(), F3});
+  FrameIdMap.insert({F4.hash(), F4});
+
+  llvm::DenseMap<CallStackId, llvm::SmallVector<FrameId>> CallStackIdMap;
+  llvm::SmallVector<FrameId> CS1 = {F1.hash(), F2.hash()};
+  llvm::SmallVector<FrameId> CS2 = {F1.hash(), F3.hash()};
+  llvm::SmallVector<FrameId> CS3 = {F2.hash(), F3.hash()};
+  llvm::SmallVector<FrameId> CS4 = {F2.hash(), F4.hash()};
+  CallStackIdMap.insert({llvm::memprof::hashCallStack(CS1), CS1});
+  CallStackIdMap.insert({llvm::memprof::hashCallStack(CS2), CS2});
+  CallStackIdMap.insert({llvm::memprof::hashCallStack(CS3), CS3});
+  CallStackIdMap.insert({llvm::memprof::hashCallStack(CS4), CS4});
+
+  IndexedMemProfRecord IndexedRecord;
+  IndexedAllocationInfo AI;
+  AI.CSId = llvm::memprof::hashCallStack(CS1);
+  IndexedRecord.AllocSites.push_back(AI);
+  AI.CSId = llvm::memprof::hashCallStack(CS2);
+  IndexedRecord.AllocSites.push_back(AI);
+  IndexedRecord.CallSiteIds.push_back(llvm::memprof::hashCallStack(CS3));
+  IndexedRecord.CallSiteIds.push_back(llvm::memprof::hashCallStack(CS4));
+
+  bool CSIdMissing = false;
+  bool FrameIdMissing = false;
+
+  auto Callback = [&](CallStackId CSId) -> llvm::SmallVector<Frame> {
+    llvm::SmallVector<Frame> CallStack;
+    llvm::SmallVector<FrameId> FrameIds;
+
+    auto Iter = CallStackIdMap.find(CSId);
+    if (Iter == CallStackIdMap.end())
+      CSIdMissing = true;
+    else
+      FrameIds = Iter->second;
+
+    for (FrameId Id : FrameIds) {
+      Frame F(0, 0, 0, false);
+      auto Iter = FrameIdMap.find(Id);
+      if (Iter == FrameIdMap.end())
+        FrameIdMissing = true;
+      else
+        F = Iter->second;
+      CallStack.push_back(F);
+    }
+
+    return CallStack;
+  };
+
+  MemProfRecord Record = IndexedRecord.toMemProfRecord(Callback);
+
+  // Make sure that all lookups are successful.
+  ASSERT_FALSE(CSIdMissing);
+  ASSERT_FALSE(FrameIdMissing);
+
+  // Verify the contents of Record.
+  ASSERT_THAT(Record.AllocSites, SizeIs(2));
+  ASSERT_THAT(Record.AllocSites[0].CallStack, SizeIs(2));
+  EXPECT_EQ(Record.AllocSites[0].CallStack[0].hash(), F1.hash());
+  EXPECT_EQ(Record.AllocSites[0].CallStack[1].hash(), F2.hash());
+  ASSERT_THAT(Record.AllocSites[1].CallStack, SizeIs(2));
+  EXPECT_EQ(Record.AllocSites[1].CallStack[0].hash(), F1.hash());
+  EXPECT_EQ(Record.AllocSites[1].CallStack[1].hash(), F3.hash());
+  ASSERT_THAT(Record.CallSites, SizeIs(2));
+  ASSERT_THAT(Record.CallSites[0], SizeIs(2));
+  EXPECT_EQ(Record.CallSites[0][0].hash(), F2.hash());
+  EXPECT_EQ(Record.CallSites[0][1].hash(), F3.hash());
+  ASSERT_THAT(Record.CallSites[1], SizeIs(2));
+  EXPECT_EQ(Record.CallSites[1][0].hash(), F2.hash());
+  EXPECT_EQ(Record.CallSites[1][1].hash(), F4.hash());
+}
 } // namespace