Support .code32 and .code64 in X86 assembler.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@136197 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/MC/MCELFStreamer.cpp b/lib/MC/MCELFStreamer.cpp
index 84eab9d..573b3e4 100644
--- a/lib/MC/MCELFStreamer.cpp
+++ b/lib/MC/MCELFStreamer.cpp
@@ -53,8 +53,9 @@
 void MCELFStreamer::EmitAssemblerFlag(MCAssemblerFlag Flag) {
   switch (Flag) {
   case MCAF_SyntaxUnified: return; // no-op here.
-  case MCAF_Code16: return; // no-op here.
-  case MCAF_Code32: return; // no-op here.
+  case MCAF_Code16: return; // Change parsing mode; no-op here.
+  case MCAF_Code32: return; // Change parsing mode; no-op here.
+  case MCAF_Code64: return; // Change parsing mode; no-op here.
   case MCAF_SubsectionsViaSymbols:
     getAssembler().setSubsectionsViaSymbols(true);
     return;