Annotate VirtRegRewriter debug output with slot indexes.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@123333 91177308-0d34-0410-b5e6-96231b3b80d8

include/llvm/CodeGen/LiveIntervalAnalysis.h

@@ -171,6 +171,10 @@ namespace llvm {
       r2iMap_.erase(I);
     }
 
+    SlotIndexes *getSlotIndexes() const {
+      return indexes_;
+    }
+
     SlotIndex getZeroIndex() const {
       return indexes_->getZeroIndex();
     }