[llvm] [VPlan] Construct VPlan1 once, share across buildVPlans calls. (NFC) (PR #197276)

[Florian Hahn via llvm-commits]

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@@ -5599,12 +5599,17 @@ void LoopVectorizationPlanner::plan(ElementCount UserVF, unsigned UserIC) {
   if (!MaxFactors) // Cases that should not to be vectorized nor interleaved.
     return;
 
+  Config.collectInLoopReductions();
+
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fhahn wrote:

We could do that - they are coming from the VF-independent `isConsecutivePtr` calls used. We would need to  walk all memory instructions in the loop and call `isConsecutivePtr` on their pointers to populate the predicates. Not sure if that's preferred?

https://github.com/llvm/llvm-project/pull/197276