[ARM] In thumb mode, emit directive ".code 16" before file level inline

assembly instructions.

This is necessary to ensure ARM assembler switches to Thumb mode before it
starts assembling the file level inline assembly instructions at the beginning
of a .s file.

<rdar://problem/17757232>

llvm-svn: 213924

2 files changed, 16 insertions, 0 deletions

diff --git a/llvm/lib/Target/ARM/ARMAsmPrinter.cpp b/llvm/lib/Target/ARM/ARMAsmPrinter.cpp
index 28d2610c390..9ad808c00e7 100644
--- a/llvm/lib/Target/ARM/ARMAsmPrinter.cpp
+++ b/llvm/lib/Target/ARM/ARMAsmPrinter.cpp
@@ -478,6 +478,9 @@ void ARMAsmPrinter::EmitStartOfAsmFile(Module &M) {
   // Emit ARM Build Attributes
   if (Subtarget->isTargetELF())
     emitAttributes();
+
+  if (!M.getModuleInlineAsm().empty() && Subtarget->isThumb())
+    OutStreamer.EmitAssemblerFlag(MCAF_Code16);
 }
 
 static void
diff --git a/llvm/test/CodeGen/ARM/inlineasm-global.ll b/llvm/test/CodeGen/ARM/inlineasm-global.ll
new file mode 100644
index 00000000000..d1a15e393a1
--- /dev/null
+++ b/llvm/test/CodeGen/ARM/inlineasm-global.ll
@@ -0,0 +1,13 @@
+; RUN: llc -march thumb -no-integrated-as %s -o - | FileCheck %s --check-prefix=THUMB
+; RUN: llc -march arm -no-integrated-as %s -o - | FileCheck %s --check-prefix=ARM
+
+; In thumb mode, emit ".code 16" before global inline-asm instructions.
+
+; THUMB: .code 16
+; THUMB: stmib
+; THUMB: .code 16
+
+; ARM-NOT: .code 16
+; ARM:     stmib
+
+module asm "stmib sp, {r0-r14};"