[IndVars] Pass the right loop to isLoopInvariantPredicate

The loop on IVOperand's incoming values assumes IVOperand to be an
induction variable on the loop over which `S Pred X` is invariant;
otherwise loop invariant incoming values to IVOperand are not guaranteed
to dominate the comparision.

This fixes PR26973.

llvm-svn: 263827

1 files changed, 2 insertions, 3 deletions

diff --git a/llvm/lib/Transforms/Utils/SimplifyIndVar.cpp b/llvm/lib/Transforms/Utils/SimplifyIndVar.cpp
index ddd8775..fe5d8e4 100644
--- a/llvm/lib/Transforms/Utils/SimplifyIndVar.cpp
+++ b/llvm/lib/Transforms/Utils/SimplifyIndVar.cpp
@@ -183,9 +183,8 @@ void SimplifyIndvar::eliminateIVComparison(ICmpInst *ICmp, Value *IVOperand) {
     DeadInsts.emplace_back(ICmp);
     DEBUG(dbgs() << "INDVARS: Eliminated comparison: " << *ICmp << '\n');
   } else if (isa<PHINode>(IVOperand) &&
-             SE->isLoopInvariantPredicate(Pred, S, X, ICmpLoop,
-                                          InvariantPredicate, InvariantLHS,
-                                          InvariantRHS)) {
+             SE->isLoopInvariantPredicate(Pred, S, X, L, InvariantPredicate,
+                                          InvariantLHS, InvariantRHS)) {
 
     // Rewrite the comparison to a loop invariant comparison if it can be done
     // cheaply, where cheaply means "we don't need to emit any new