Mark IMPLICIT_DEF as being rematerializable and cheap-as-a-move.

It's already special-cased and treated as rematerializable within
LiveIntervals; this allows it to be handled by other passes
such as TwoAddressInstrctionPass.

llvm-svn: 55999

llvm/lib/Target/Target.td

@@ -390,6 +390,8 @@ def IMPLICIT_DEF : Instruction {
   let AsmString = "";
   let Namespace = "TargetInstrInfo";
   let neverHasSideEffects = 1;
+  let isReMaterializable = 1;
+  let isAsCheapAsAMove = 1;
 }
 def SUBREG_TO_REG : Instruction {
   let OutOperandList = (ops unknown:$dst);