Add support for .cfi_signal_frame. Fixes pr11762.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@148733 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/MC/MCAsmStreamer.cpp b/lib/MC/MCAsmStreamer.cpp
index 87516e0..a2fb7a4 100644
--- a/lib/MC/MCAsmStreamer.cpp
+++ b/lib/MC/MCAsmStreamer.cpp
@@ -222,6 +222,7 @@
   virtual void EmitCFISameValue(int64_t Register);
   virtual void EmitCFIRelOffset(int64_t Register, int64_t Offset);
   virtual void EmitCFIAdjustCfaOffset(int64_t Adjustment);
+  virtual void EmitCFISignalFrame();
 
   virtual void EmitWin64EHStartProc(const MCSymbol *Symbol);
   virtual void EmitWin64EHEndProc();
@@ -993,6 +994,16 @@
   EmitEOL();
 }
 
+void MCAsmStreamer::EmitCFISignalFrame() {
+  MCStreamer::EmitCFISignalFrame();
+
+  if (!UseCFI)
+    return;
+
+  OS << "\t.cif_signal_frame";
+  EmitEOL();
+}
+
 void MCAsmStreamer::EmitWin64EHStartProc(const MCSymbol *Symbol) {
   MCStreamer::EmitWin64EHStartProc(Symbol);