Emit code16 in assembly in 16-bit mode

Summary:
When generating assembly using -m16 we must explicitly mark it as
16-bit. Emit .code16 at beginning of file. Fixes wrong results when
using -fno-integrated-as.

Reviewers: dwmw2

Subscribers: llvm-commits

Differential Revision: http://reviews.llvm.org/D19392

llvm-svn: 267152

1 files changed, 6 insertions, 0 deletions

diff --git a/llvm/lib/Target/X86/X86AsmPrinter.cpp b/llvm/lib/Target/X86/X86AsmPrinter.cpp
index 9d0ac319859..0a00463f8bf 100644
--- a/llvm/lib/Target/X86/X86AsmPrinter.cpp
+++ b/llvm/lib/Target/X86/X86AsmPrinter.cpp
@@ -538,6 +538,12 @@ void X86AsmPrinter::EmitStartOfAsmFile(Module &M) {
     }
   }
   OutStreamer->EmitSyntaxDirective();
+
+  // If this is not inline asm and we're in 16-bit
+  // mode prefix assembly with .code16.
+  bool is16 = TT.getEnvironment() == Triple::CODE16;
+  if (M.getModuleInlineAsm().empty() && is16)
+    OutStreamer->EmitAssemblerFlag(MCAF_Code16);
 }
 
 static void