1 files changed, 8 insertions, 0 deletions
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();