[MC] Pass through .code16/32/64 and .syntax unified for COFF

These flags should simply be passed through to the target, which will do
the right thing. Add an MC/X86 test that uses these directives with the
three primary object file formats and shows that they disassemble the
same everywhere.

There is a missing test for .code32 on Windows ARM, since I'm not sure
exactly how to construct one.

Fixes PR43203

llvm-svn: 370805

1 files changed, 13 insertions, 1 deletions

diff --git a/llvm/lib/MC/MCWinCOFFStreamer.cpp b/llvm/lib/MC/MCWinCOFFStreamer.cpp
index 04d5f100a2f..40470452686 100644
--- a/llvm/lib/MC/MCWinCOFFStreamer.cpp
+++ b/llvm/lib/MC/MCWinCOFFStreamer.cpp
@@ -88,7 +88,19 @@ void MCWinCOFFStreamer::EmitLabel(MCSymbol *S, SMLoc Loc) {
 }
 
 void MCWinCOFFStreamer::EmitAssemblerFlag(MCAssemblerFlag Flag) {
-  llvm_unreachable("not implemented");
+  // Let the target do whatever target specific stuff it needs to do.
+  getAssembler().getBackend().handleAssemblerFlag(Flag);
+
+  switch (Flag) {
+  // None of these require COFF specific handling.
+  case MCAF_SyntaxUnified:
+  case MCAF_Code16:
+  case MCAF_Code32:
+  case MCAF_Code64:
+    break;
+  case MCAF_SubsectionsViaSymbols:
+    llvm_unreachable("COFF doesn't support .subsections_via_symbols");
+  }
 }
 
 void MCWinCOFFStreamer::EmitThumbFunc(MCSymbol *Func) {