Ignore register mask operands when lowering instructions to MC.

This is similar to implicit register operands.  MC doesn't understand
register liveness and call clobbers.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@148437 91177308-0d34-0410-b5e6-96231b3b80d8

lib/Target/ARM/ARMMCInstLower.cpp

@@ -107,6 +107,9 @@ bool ARMAsmPrinter::lowerOperand(const MachineOperand &MO,
     MCOp = MCOperand::CreateFPImm(Val.convertToDouble());
     break;
   }
+  case MachineOperand::MO_RegisterMask:
+    // Ignore call clobbers.
+    return false;
   }
   return true;
 }