[llvm] [VPlan] Model FOR extract of exit value in VPlan. (PR #93395)

[via llvm-commits]

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@@ -598,6 +621,7 @@ void VPInstruction::execute(VPTransformState &State) {
   bool GeneratesPerFirstLaneOnly =
       canGenerateScalarForFirstLane() &&
       (vputils::onlyFirstLaneUsed(this) ||
+       getOpcode() == VPInstruction::ExtractRecurrenceResult ||
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ayalz wrote:

Perhaps worth introducing an `isReduction` trait to classify vector-to-scalar recipes including `ComputeReductionResult` and Extract*'s.

https://github.com/llvm/llvm-project/pull/93395