Add "swi" which is an obsolete mnemonic for "svc".

llvm-svn: 127788
diff --git a/llvm/lib/Target/ARM/ARMInstrInfo.td b/llvm/lib/Target/ARM/ARMInstrInfo.td
index d7e3dc8..896549b 100644
--- a/llvm/lib/Target/ARM/ARMInstrInfo.td
+++ b/llvm/lib/Target/ARM/ARMInstrInfo.td
@@ -1531,6 +1531,7 @@
   let Inst{23-0} = svc;
 }
 }
+def : MnemonicAlias<"swi", "svc">;
 
 // Store Return State is a system instruction -- for disassembly only
 let isCodeGenOnly = 1 in {  // FIXME: This should not use submode!