[llvm] [LV] Vectorize uncountable early exit store loops with combined conditions (PR #205109)

[Florian Hahn via llvm-commits]

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@@ -6579,6 +6596,10 @@ VPlanPtr LoopVectorizationPlanner::tryToBuildVPlan1() {
 
   RUN_VPLAN_PASS(VPlanTransforms::addMiddleCheck, *VPlan0);
 
+  if (!RUN_VPLAN_PASS(VPlanTransforms::splitCombinedExits, *VPlan0, PSE,
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fhahn wrote:

I think we should guard this behind the uncountable early-exit check; there are some edge cases where SCEV can determine a exact trip count even for conditions feeding loads (e.g. from constant), e.g. something like https://llvm.godbolt.org/z/5TjTsofbE

If `splitCombinedExits` fails, we fail to vectorize and/or we split unnecessaryily 

https://github.com/llvm/llvm-project/pull/205109