Make SpillIs an optional pointer. Avoid creating a bunch of temporary SmallVectors.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@127388 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/CodeGen/Spiller.h b/lib/CodeGen/Spiller.h
index f017583..fc35075 100644
--- a/lib/CodeGen/Spiller.h
+++ b/lib/CodeGen/Spiller.h
@@ -36,7 +36,7 @@
     /// @param newIntervals  The newly created intervals will be appended here.
     virtual void spill(LiveInterval *li,
                        SmallVectorImpl<LiveInterval*> &newIntervals,
-                       const SmallVectorImpl<LiveInterval*> &spillIs) = 0;
+                       const SmallVectorImpl<LiveInterval*> *spillIs) = 0;
 
   };