1 files changed, 3 insertions, 2 deletions
diff --git a/include/llvm/Bitcode/BitCodes.h b/include/llvm/Bitcode/BitCodes.h
index d9a5874966..2cf8b7b723 100644
--- a/include/llvm/Bitcode/BitCodes.h
+++ b/include/llvm/Bitcode/BitCodes.h
@@ -66,8 +66,9 @@ namespace bitc {
   /// BlockInfoCodes - The blockinfo block contains metadata about user-defined
   /// blocks.
   enum BlockInfoCodes {
-    BLOCKINFO_CODE_SETBID = 1,  // SETBID: [blockid#]
-    BLOCKINFO_CODE_ABBREV = 2   // ABBREV: [standard abbrev encoding]
+    BLOCKINFO_CODE_SETBID = 1  // SETBID: [blockid#]
+    // DEFINE_ABBREV has magic semantics here, applying to the current SETBID'd
+    // block, instead of the BlockInfo block.
     // BLOCKNAME: give string name to block, if desired.
   };