[llvm] [LoopVectorize] Add an option to test potential issues with VPlan (PR #121154)

[Danila Malyutin via llvm-commits]

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@@ -3448,8 +3453,9 @@ bool LoopVectorizationCostModel::isPredicatedInst(Instruction *I) const {
   // If predication is not needed, avoid it.
   // TODO: We can use the loop-preheader as context point here and get
   // context sensitive reasoning for isSafeToSpeculativelyExecute.
+  Instruction *CtxI = CheckSpeculatabilityAtUse ? I->getNextNode() : nullptr;
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danilaml wrote:

If it was a refinement/TODO implementation, then yes. But this is an option strictly for testing to allow the problematic codegen so that it can be tested against. More "ideologically pure" alternatives would be less clean to implement (at least I haven't come up with a way to), like special-casing loads from specific address space (the AS value could be an option, but not sure how to name it).

https://github.com/llvm/llvm-project/pull/121154