[memprof] Refactor getMemProfRecord (NFC) (#93138)

This patch refactors getMemProfRecord for readability while adding
consistency checks.

- This patch adds a switch statement on the MemProf version just like
  most places dealing with MemProf serialization/deserialization.

- This patch adds asserts to ensure that the exact set of data
  structures are available while ones we do not use are not present.
  That is, getMemProfRecord no longer determines the version based on
  the availability of MemProfCallStackTable.

Author: kazutakahirata

llvm/include/llvm/ProfileData/InstrProfReader.h

@@ -649,6 +649,8 @@ class InstrProfReaderRemapper {
 
 class IndexedMemProfReader {
 private:
+  /// The MemProf version.
+  memprof::IndexedVersion Version = memprof::Version0;
   /// MemProf profile schema (if available).
   memprof::MemProfSchema Schema;
   /// MemProf record profile data on-disk indexed via llvm::md5(FunctionName).

llvm/lib/ProfileData/InstrProfReader.cpp

@@ -1212,7 +1212,6 @@ Error IndexedMemProfReader::deserialize(const unsigned char *Start,
   const uint64_t FirstWord =
       support::endian::readNext<uint64_t, llvm::endianness::little>(Ptr);
 
-  memprof::IndexedVersion Version = memprof::Version0;
   if (FirstWord == memprof::Version1 || FirstWord == memprof::Version2) {
     // Everything is good.  We can proceed to deserialize the rest.
     Version = static_cast<memprof::IndexedVersion>(FirstWord);
@@ -1490,6 +1489,55 @@ Expected<InstrProfRecord> IndexedInstrProfReader::getInstrProfRecord(
   return error(instrprof_error::unknown_function);
 }
 
+static Expected<memprof::MemProfRecord>
+getMemProfRecordV0(const memprof::IndexedMemProfRecord &IndexedRecord,
+                   MemProfFrameHashTable &MemProfFrameTable) {
+  memprof::FrameIdConverter<MemProfFrameHashTable> FrameIdConv(
+      MemProfFrameTable);
+
+  memprof::MemProfRecord Record =
+      memprof::MemProfRecord(IndexedRecord, FrameIdConv);
+
+  // Check that all frame ids were successfully converted to frames.
+  if (FrameIdConv.LastUnmappedId) {
+    return make_error<InstrProfError>(instrprof_error::hash_mismatch,
+                                      "memprof frame not found for frame id " +
+                                          Twine(*FrameIdConv.LastUnmappedId));
+  }
+
+  return Record;
+}
+
+static Expected<memprof::MemProfRecord>
+getMemProfRecordV2(const memprof::IndexedMemProfRecord &IndexedRecord,
+                   MemProfFrameHashTable &MemProfFrameTable,
+                   MemProfCallStackHashTable &MemProfCallStackTable) {
+  memprof::FrameIdConverter<MemProfFrameHashTable> FrameIdConv(
+      MemProfFrameTable);
+
+  memprof::CallStackIdConverter<MemProfCallStackHashTable> CSIdConv(
+      MemProfCallStackTable, FrameIdConv);
+
+  memprof::MemProfRecord Record = IndexedRecord.toMemProfRecord(CSIdConv);
+
+  // Check that all call stack ids were successfully converted to call stacks.
+  if (CSIdConv.LastUnmappedId) {
+    return make_error<InstrProfError>(
+        instrprof_error::hash_mismatch,
+        "memprof call stack not found for call stack id " +
+            Twine(*CSIdConv.LastUnmappedId));
+  }
+
+  // Check that all frame ids were successfully converted to frames.
+  if (FrameIdConv.LastUnmappedId) {
+    return make_error<InstrProfError>(instrprof_error::hash_mismatch,
+                                      "memprof frame not found for frame id " +
+                                          Twine(*FrameIdConv.LastUnmappedId));
+  }
+
+  return Record;
+}
+
 Expected<memprof::MemProfRecord>
 IndexedMemProfReader::getMemProfRecord(const uint64_t FuncNameHash) const {
   // TODO: Add memprof specific errors.
@@ -1502,41 +1550,27 @@ IndexedMemProfReader::getMemProfRecord(const uint64_t FuncNameHash) const {
         instrprof_error::unknown_function,
         "memprof record not found for function hash " + Twine(FuncNameHash));
 
-  // Setup a callback to convert from frame ids to frame using the on-disk
-  // FrameData hash table.
-  memprof::FrameIdConverter<MemProfFrameHashTable> FrameIdConv(
-      *MemProfFrameTable.get());
-
   const memprof::IndexedMemProfRecord IndexedRecord = *Iter;
-  memprof::MemProfRecord Record;
-  if (MemProfCallStackTable) {
-    // Setup a callback to convert call stack ids to call stacks using the
-    // on-disk hash table.
-    memprof::CallStackIdConverter<MemProfCallStackHashTable> CSIdConv(
-        *MemProfCallStackTable.get(), FrameIdConv);
-
-    Record = IndexedRecord.toMemProfRecord(CSIdConv);
-
-    // Check that all call stack ids were successfully converted to call stacks.
-    if (CSIdConv.LastUnmappedId) {
-      return make_error<InstrProfError>(
-          instrprof_error::hash_mismatch,
-          "memprof call stack not found for call stack id " +
-              Twine(*CSIdConv.LastUnmappedId));
-    }
-  } else {
-    Record = memprof::MemProfRecord(IndexedRecord, FrameIdConv);
+  switch (Version) {
+  case memprof::Version0:
+  case memprof::Version1:
+    assert(MemProfFrameTable && "MemProfFrameTable must be available");
+    assert(!MemProfCallStackTable &&
+           "MemProfCallStackTable must not be available");
+    return getMemProfRecordV0(IndexedRecord, *MemProfFrameTable);
+  case memprof::Version2:
+    assert(MemProfFrameTable && "MemProfFrameTable must be available");
+    assert(MemProfCallStackTable && "MemProfCallStackTable must be available");
+    return getMemProfRecordV2(IndexedRecord, *MemProfFrameTable,
+                              *MemProfCallStackTable);
   }
 
-  // Check that all frame ids were successfully converted to frames.
-  if (FrameIdConv.LastUnmappedId) {
-    return make_error<InstrProfError>(
-        instrprof_error::hash_mismatch,
-        "memprof frame not found for frame id " +
-            Twine(*FrameIdConv.LastUnmappedId));
-  }
-
-  return Record;
+  return make_error<InstrProfError>(
+      instrprof_error::unsupported_version,
+      formatv("MemProf version {} not supported; "
+              "requires version between {} and {}, inclusive",
+              Version, memprof::MinimumSupportedVersion,
+              memprof::MaximumSupportedVersion));
 }
 
 Error IndexedInstrProfReader::getFunctionCounts(StringRef FuncName,