Add a comment explaining why this code doesn't just call
ParseMetadataValue.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@111914 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/AsmParser/LLParser.cpp b/lib/AsmParser/LLParser.cpp
index 0eb1b70..7766ad6 100644
--- a/lib/AsmParser/LLParser.cpp
+++ b/lib/AsmParser/LLParser.cpp
@@ -1134,6 +1134,10 @@
     if (ParseToken(lltok::exclaim, "expected '!' here"))
       return true;
 
+    // This code is similar to that of ParseMetadataValue, however it needs to
+    // have special-case code for a forward reference; see the comments on
+    // ForwardRefInstMetadata for details. Also, MDStrings are not supported
+    // at the top level here.
     if (Lex.getKind() == lltok::lbrace) {
       ValID ID;
       if (ParseMetadataListValue(ID, PFS))