[llvm] [memprof] Add Version2 of the indexed MemProf format (PR #89100)

[Teresa Johnson via llvm-commits]

================
@@ -1502,14 +1524,44 @@ IndexedInstrProfReader::getMemProfRecord(const uint64_t FuncNameHash) {
     return *FrIter;
   };
 
-  memprof::MemProfRecord Record(*Iter, IdToFrameCallback);
+  // Setup a callback to convert call stack ids to call stacks using the on-disk
+  // hash table.
+  std::optional<memprof::CallStackId> LastUnmappedCSId;
+  auto CSIdToCallStackCallback = [&](memprof::CallStackId CSId) {
+    llvm::SmallVector<memprof::Frame> Frames;
+    auto CSIter = MemProfCallStackTable->find(CSId);
+    if (CSIter == MemProfCallStackTable->end()) {
+      LastUnmappedFrameId = CSId;
----------------
teresajohnson wrote:

Oh, looks like you meant to set LastUnmappedCSId?

https://github.com/llvm/llvm-project/pull/89100