To find the exiting VN of a LiveInterval from a block, use the previous slot
rather than the previous index. If a block has a single instruction, the
previous index may be in a different basic block.
I have no clue how this used to work on all of test-suite, because now this
failure is seen quite often when trying to compile code with -strong-phi-elim.
This fixes PR10252.
llvm-svn: 141812
diff --git a/llvm/lib/CodeGen/StrongPHIElimination.cpp b/llvm/lib/CodeGen/StrongPHIElimination.cpp
index 0fabd8e..76e6c99 100644
--- a/llvm/lib/CodeGen/StrongPHIElimination.cpp
+++ b/llvm/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.getPrevIndex());
+ VNInfo *SrcVNI = SrcInterval.getVNInfoAt(PredIndex.getPrevSlot());
assert(SrcVNI);
SrcVNI->setHasPHIKill(true);
continue;