[PATCH] D19392: Emit code16 in assembly in 16-bit mode

[Nirav Dave via llvm-commits]

niravd created this revision.
niravd added a reviewer: dwmw2.
niravd added a subscriber: llvm-commits.

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.

http://reviews.llvm.org/D19392

Files:
  lib/Target/X86/X86AsmPrinter.cpp
  test/CodeGen/X86/x86-16.ll

Index: test/CodeGen/X86/x86-16.ll
===================================================================
--- /dev/null
+++ test/CodeGen/X86/x86-16.ll
@@ -0,0 +1,20 @@
+; RUN: llc < %s | FileCheck %s
+target datalayout = "e-m:e-p:32:32-f64:32:64-f80:32-n8:16:32-S128"
+target triple = "i386-unknown-linux-code16"
+
+; Function Attrs: nounwind
+define i32 @main() #0 {
+  %retval = alloca i32, align 4
+  store i32 0, i32* %retval, align 4
+  ret i32 0
+}
+
+; CHECK: .code16
+; CHECK-LABEL: main
+
+
+attributes #0 = { nounwind }
+
+!llvm.ident = !{!0}
+
+!0 = !{!"clang version 3.9.0 (trunk 265439) (llvm/trunk 265567)"}
\ No newline at end of file
Index: lib/Target/X86/X86AsmPrinter.cpp
===================================================================
--- lib/Target/X86/X86AsmPrinter.cpp
+++ lib/Target/X86/X86AsmPrinter.cpp
@@ -535,6 +535,12 @@
     }
   }
   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


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