[llvm] [LoopPeel] Use loop guards when checking if last iter can be peeled. (PR #142605)

[Nikita Popov via llvm-commits]

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@@ -374,6 +374,9 @@ static bool shouldPeelLastIteration(Loop &L, CmpPredicate Pred,
                                    L.getLoopPredecessor()->getTerminator()))
     return false;
 
+  auto Guards = ScalarEvolution::LoopGuards::collect(&L, SE);
+  BTC = SE.applyLoopGuards(BTC, Guards);
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nikic wrote:

FWIW, I do think using loop guards for the isKnownNonZero(BTC) check makes sense, I was just saying it shouldn't be used for the high cost expansion check.

https://github.com/llvm/llvm-project/pull/142605