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

[via llvm-commits]

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@@ -7590,6 +7412,7 @@ SCEV2ValueTy LoopVectorizationPlanner::executePlan(
     State.Builder.SetInsertPoint(OrigLoop->getLoopPreheader()->getTerminator());
     BestVPlan.getPreheader()->execute(&State);
   }
+  State.CFG.VPBB2IRBB[BestVPlan.getPreheader()] = OrigLoop->getLoopPreheader();
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ayalz wrote:

Is setting VPBB2IRBB for the preheader independent of this patch?
Worth updating inside the if, for non-empty preheaders only?
Note that multiple VPBB's may be associated with OrigLoop's preheader.

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