Implement cfi_restore. Patch by Brian Anderson!

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@147356 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/MC/MCDwarf.cpp b/lib/MC/MCDwarf.cpp
index 881fed4..986b8b6 100644
--- a/lib/MC/MCDwarf.cpp
+++ b/lib/MC/MCDwarf.cpp
@@ -987,6 +987,15 @@
     Streamer.EmitULEB128IntValue(Reg);
     return;
   }
+  case MCCFIInstruction::Restore: {
+    unsigned Reg = Instr.getDestination().getReg();
+    if (VerboseAsm) {
+      Streamer.AddComment("DW_CFA_restore");
+      Streamer.AddComment(Twine("Reg ") + Twine(Reg));
+    }
+    Streamer.EmitIntValue(dwarf::DW_CFA_restore | Reg, 1);
+    return;
+  }
   case MCCFIInstruction::Escape:
     if (VerboseAsm) Streamer.AddComment("Escape bytes");
     Streamer.EmitBytes(Instr.getValues(), 0);