2 files changed, 22 insertions, 1 deletions
diff --git a/llvm/lib/Bitcode/Reader/BitcodeReader.cpp b/llvm/lib/Bitcode/Reader/BitcodeReader.cpp
index cbacf8127d4..8b583fe4995 100644
--- a/llvm/lib/Bitcode/Reader/BitcodeReader.cpp
+++ b/llvm/lib/Bitcode/Reader/BitcodeReader.cpp
@@ -5995,8 +5995,21 @@ std::error_code ModuleSummaryIndexBitcodeReader::parseModule() {
 std::error_code ModuleSummaryIndexBitcodeReader::parseEntireSummary() {
   if (Stream.EnterSubBlock(bitc::GLOBALVAL_SUMMARY_BLOCK_ID))
     return error("Invalid record");
-
   SmallVector<uint64_t, 64> Record;
+
+  // Parse version
+  {
+    BitstreamEntry Entry = Stream.advanceSkippingSubblocks();
+    if (Entry.Kind != BitstreamEntry::Record)
+      return error("Invalid Summary Block: record for version expected");
+    if (Stream.readRecord(Entry.ID, Record) != bitc::FS_VERSION)
+      return error("Invalid Summary Block: version expected");
+  }
+  const uint64_t Version = Record[0];
+  if (Version != 1)
+    return error("Invalid summary version " + Twine(Version) + ", 1 expected");
+  Record.clear();
+
   // Keep around the last seen summary to be used when we see an optional
   // "OriginalName" attachement.
   GlobalValueSummary *LastSeenSummary = nullptr;
diff --git a/llvm/lib/Bitcode/Writer/BitcodeWriter.cpp b/llvm/lib/Bitcode/Writer/BitcodeWriter.cpp
index 302629b9176..d0f87e7d9d0 100644
--- a/llvm/lib/Bitcode/Writer/BitcodeWriter.cpp
+++ b/llvm/lib/Bitcode/Writer/BitcodeWriter.cpp
@@ -3067,6 +3067,11 @@ void ModuleBitcodeWriter::writeModuleLevelReferences(
   NameVals.clear();
 }
 
+// Current version for the summary.
+// This is bumped whenever we introduce changes in the way some record are
+// interpreted, like flags for instance.
+static const uint64_t INDEX_VERSION = 1;
+
 /// Emit the per-module summary section alongside the rest of
 /// the module's bitcode.
 void ModuleBitcodeWriter::writePerModuleGlobalValueSummary() {
@@ -3078,6 +3083,8 @@ void ModuleBitcodeWriter::writePerModuleGlobalValueSummary() {
 
   Stream.EnterSubblock(bitc::GLOBALVAL_SUMMARY_BLOCK_ID, 3);
 
+  Stream.EmitRecord(bitc::FS_VERSION, ArrayRef<uint64_t>{INDEX_VERSION});
+
   // Abbrev for FS_PERMODULE.
   BitCodeAbbrev *Abbv = new BitCodeAbbrev();
   Abbv->Add(BitCodeAbbrevOp(bitc::FS_PERMODULE));
@@ -3162,6 +3169,7 @@ void ModuleBitcodeWriter::writePerModuleGlobalValueSummary() {
 /// Emit the combined summary section into the combined index file.
 void IndexBitcodeWriter::writeCombinedGlobalValueSummary() {
   Stream.EnterSubblock(bitc::GLOBALVAL_SUMMARY_BLOCK_ID, 3);
+  Stream.EmitRecord(bitc::FS_VERSION, ArrayRef<uint64_t>{INDEX_VERSION});
 
   // Abbrev for FS_COMBINED.
   BitCodeAbbrev *Abbv = new BitCodeAbbrev();