[memprof] Add another constructor to MemProfReader (llvm#88952)

This patch enables users of MemProfReader to directly supply mappings
from CallStackId to actual call stacks.

Once the users of the current constructor without CSIdMap switch to
the new constructor, we'll have fewer users of:

- IndexedAllocationInfo::CallStack
- IndexedMemProfRecord::CallSites

bringing us one step closer to the removal of these fields in favor
of:

- IndexedAllocationInfo::CSId
- IndexedMemProfRecord::CallSiteIds

llvm/include/llvm/ProfileData/MemProfReader.h

@@ -98,6 +98,15 @@ class MemProfReader {
       llvm::DenseMap<FrameId, Frame> FrameIdMap,
       llvm::MapVector<GlobalValue::GUID, IndexedMemProfRecord> ProfData);
 
+  // Initialize the MemProfReader with the frame mappings, call stack mappings,
+  // and profile contents.
+  MemProfReader(
+      llvm::DenseMap<FrameId, Frame> FrameIdMap,
+      llvm::DenseMap<CallStackId, llvm::SmallVector<FrameId>> CSIdMap,
+      llvm::MapVector<GlobalValue::GUID, IndexedMemProfRecord> ProfData)
+      : IdToFrame(std::move(FrameIdMap)), CSIdToCallStack(std::move(CSIdMap)),
+        FunctionProfileData(std::move(ProfData)) {}
+
 protected:
   // A helper method to extract the frame from the IdToFrame map.
   const Frame &idToFrame(const FrameId Id) const {

llvm/unittests/ProfileData/MemProfTest.cpp

@@ -436,6 +436,47 @@ TEST(MemProf, BaseMemProfReader) {
               FrameContains("bar", 10U, 2U, false));
 }
 
+TEST(MemProf, BaseMemProfReaderWithCSIdMap) {
+  llvm::DenseMap<FrameId, Frame> FrameIdMap;
+  Frame F1(/*Hash=*/IndexedMemProfRecord::getGUID("foo"), /*LineOffset=*/20,
+           /*Column=*/5, /*IsInlineFrame=*/true);
+  Frame F2(/*Hash=*/IndexedMemProfRecord::getGUID("bar"), /*LineOffset=*/10,
+           /*Column=*/2, /*IsInlineFrame=*/false);
+  FrameIdMap.insert({F1.hash(), F1});
+  FrameIdMap.insert({F2.hash(), F2});
+
+  llvm::DenseMap<CallStackId, llvm::SmallVector<FrameId>> CSIdMap;
+  llvm::SmallVector<FrameId> CallStack = {F1.hash(), F2.hash()};
+  CallStackId CSId = llvm::memprof::hashCallStack(CallStack);
+  CSIdMap.insert({CSId, CallStack});
+
+  llvm::MapVector<llvm::GlobalValue::GUID, IndexedMemProfRecord> ProfData;
+  IndexedMemProfRecord FakeRecord;
+  MemInfoBlock Block;
+  Block.AllocCount = 1U, Block.TotalAccessDensity = 4,
+  Block.TotalLifetime = 200001;
+  FakeRecord.AllocSites.emplace_back(
+      /*CS=*/llvm::SmallVector<FrameId>(),
+      /*CSId=*/llvm::memprof::hashCallStack(CallStack),
+      /*MB=*/Block);
+  ProfData.insert({F1.hash(), FakeRecord});
+
+  MemProfReader Reader(FrameIdMap, CSIdMap, ProfData);
+
+  llvm::SmallVector<MemProfRecord, 1> Records;
+  for (const auto &KeyRecordPair : Reader) {
+    Records.push_back(KeyRecordPair.second);
+  }
+
+  ASSERT_THAT(Records, SizeIs(1));
+  ASSERT_THAT(Records[0].AllocSites, SizeIs(1));
+  ASSERT_THAT(Records[0].AllocSites[0].CallStack, SizeIs(2));
+  EXPECT_THAT(Records[0].AllocSites[0].CallStack[0],
+              FrameContains("foo", 20U, 5U, true));
+  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.