[llvm-branch-commits] [llvm] [LoopInterchange] Reject if inner loop IV has outer-variant step (PR #202751)

[Ryotaro Kasuga via llvm-branch-commits]

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@@ -1251,8 +1251,14 @@ bool LoopInterchangeLegality::checkInductionsAndReductions(Loop *OuterLoop) {
     for (PHINode &PHI : CurLoop->getHeader()->phis()) {
       InductionDescriptor ID;
       if (InductionDescriptor::isInductionPHI(&PHI, CurLoop, SE, ID)) {
-        if (CurLoop == InnerLoop)
+        if (CurLoop == InnerLoop) {
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kasuga-fj wrote:

Yes, I believe so. I think the miscompilation we're seeing now is caused by the inner loop's IV depending on the outer loop's IV in the very loops we are actually attempting to interchange. Deeper nested loops shouldn’t be involved in this issue...

https://github.com/llvm/llvm-project/pull/202751