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/X86/X86MCInstLower.cpp

@@ -335,6 +335,9 @@ void X86MCInstLower::Lower(const MachineInstr *MI, MCInst &OutMI) const {
       MCOp = LowerSymbolOperand(MO,
                      AsmPrinter.GetBlockAddressSymbol(MO.getBlockAddress()));
       break;
+    case MachineOperand::MO_RegisterMask:
+      // Ignore call clobbers.
+      continue;
     }
     
     OutMI.addOperand(MCOp);