Use an existing method.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@141855 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/CodeGen/StrongPHIElimination.cpp b/lib/CodeGen/StrongPHIElimination.cpp
index 76e6c99..260cc0e 100644
--- a/lib/CodeGen/StrongPHIElimination.cpp
+++ b/lib/CodeGen/StrongPHIElimination.cpp
@@ -674,7 +674,7 @@
     if (PHIColor && SrcColor == PHIColor) {
       LiveInterval &SrcInterval = LI->getInterval(SrcReg);
       SlotIndex PredIndex = LI->getMBBEndIdx(PredBB);
-      VNInfo *SrcVNI = SrcInterval.getVNInfoAt(PredIndex.getPrevSlot());
+      VNInfo *SrcVNI = SrcInterval.getVNInfoBefore(PredIndex);
       assert(SrcVNI);
       SrcVNI->setHasPHIKill(true);
       continue;