SCEVExpander: Don't crash when trying to merge two constant phis.
Just constant fold them so they can't cause any trouble. Fixes PR12627.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@166286 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Analysis/ScalarEvolutionExpander.cpp b/lib/Analysis/ScalarEvolutionExpander.cpp
index 5c2a49e..f18c50e 100644
--- a/lib/Analysis/ScalarEvolutionExpander.cpp
+++ b/lib/Analysis/ScalarEvolutionExpander.cpp
@@ -1618,6 +1618,17 @@
PEnd = Phis.end(); PIter != PEnd; ++PIter) {
PHINode *Phi = *PIter;
+ // Fold constant phis. They may be congruent to other constant phis and
+ // would confuse the logic below that expects proper IVs.
+ if (Value *V = Phi->hasConstantValue()) {
+ Phi->replaceAllUsesWith(V);
+ DeadInsts.push_back(Phi);
+ ++NumElim;
+ DEBUG_WITH_TYPE(DebugType, dbgs()
+ << "INDVARS: Eliminated constant iv: " << *Phi << '\n');
+ continue;
+ }
+
if (!SE.isSCEVable(Phi->getType()))
continue;