[PATCH] D152366: [LoopVectorize] Allow inner loop runtime checks to be hoisted above an outer loop

[Florian Hahn via Phabricator via llvm-commits]

fhahn added inline comments.


================
Comment at: llvm/lib/Transforms/Utils/LoopUtils.cpp:1669
+        OuterExitCount->getType()->isIntegerTy()) {
+      const SCEV *NewHigh = cast<SCEVAddRecExpr>(High)->evaluateAtIteration(
+          OuterExitCount, *Exp.getSE());
----------------
Do we need to check if the AddRecs here don't wrap? If it would wrap, could NewHigh < NewLow?


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Comment at: llvm/lib/Transforms/Utils/LoopUtils.cpp:1650
+      isa<SCEVAddRecExpr>(High) && isa<SCEVAddRecExpr>(Low) &&
+      cast<SCEVAddRecExpr>(Low)->getLoop() == TheLoop->getParentLoop()) {
+    const Loop *OuterLoop = TheLoop->getParentLoop();
----------------
paulwalker-arm wrote:
> Given you evaluate `High` using the outer loop's exit count shouldn't you also check the following?
> ```
> cast<SCEVAddRecExpr>(High)->getLoop() == TheLoop->getParentLoop()
> ```
Could you add a test case for this case?


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https://reviews.llvm.org/D152366