Delete dead code after rematerializing.

LiveRangeEdit::eliminateDeadDefs() will eventually be used by coalescing,
splitting, and spilling for dead code elimination. It can delete chains of dead
instructions as long as there are no dependency loops.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@127287 91177308-0d34-0410-b5e6-96231b3b80d8

lib/CodeGen/SplitKit.h

@@ -272,6 +272,9 @@ class SplitEditor {
   void rewriteComponents(const SmallVectorImpl<LiveInterval*> &Intvs,
                          const ConnectedVNInfoEqClasses &ConEq);
 
+  /// deleteRematVictims - Delete defs that are dead after rematerializing.
+  void deleteRematVictims();
+
 public:
   /// Create a new SplitEditor for editing the LiveInterval analyzed by SA.
   /// Newly created intervals will be appended to newIntervals.