[llvm] [VPlan] Introduce ComputeReductionResult VPInstruction opcode. (PR #70253)

[via llvm-commits]

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@@ -8973,7 +8821,8 @@ VPlanPtr LoopVectorizationPlanner::buildVPlan(VFRange &Range) {
 void LoopVectorizationPlanner::adjustRecipesForReductions(
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ayalz wrote:

Documentation should expand, e.g., to explain something like:
`// A ComputeReductionResult recipe is added to the middle block, also for in-loop reductions which conmpute their result in-loop, because this recipe currently takes care of generating the subsequent bc.merge.rdx phi which applies to all reductions.`

https://github.com/llvm/llvm-project/pull/70253