Allow LiveRangeEdit to be created with a NULL parent.

The dead code elimination with callbacks is still useful.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@157100 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/CodeGen/RegAllocBasic.cpp b/lib/CodeGen/RegAllocBasic.cpp
index 77ee314..6b01ccb 100644
--- a/lib/CodeGen/RegAllocBasic.cpp
+++ b/lib/CodeGen/RegAllocBasic.cpp
@@ -187,7 +187,7 @@
     unassign(SpilledVReg, PhysReg);
 
     // Spill the extracted interval.
-    LiveRangeEdit LRE(SpilledVReg, SplitVRegs, *MF, *LIS, VRM);
+    LiveRangeEdit LRE(&SpilledVReg, SplitVRegs, *MF, *LIS, VRM);
     spiller().spill(LRE);
   }
   // After extracting segments, the query's results are invalid. But keep the
@@ -287,7 +287,7 @@
   DEBUG(dbgs() << "spilling: " << VirtReg << '\n');
   if (!VirtReg.isSpillable())
     return ~0u;
-  LiveRangeEdit LRE(VirtReg, SplitVRegs, *MF, *LIS, VRM);
+  LiveRangeEdit LRE(&VirtReg, SplitVRegs, *MF, *LIS, VRM);
   spiller().spill(LRE);
 
   // The live virtual register requesting allocation was spilled, so tell