[llvm] [VPlan] Add ReductionStartVector VPInstruction. (PR #142290)

[Florian Hahn via llvm-commits]

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@@ -3855,17 +3875,19 @@ void VPFirstOrderRecurrencePHIRecipe::print(raw_ostream &O, const Twine &Indent,
 #endif
 
 void VPReductionPHIRecipe::execute(VPTransformState &State) {
-  // If this phi is fed by a scaled reduction then it should output a
-  // vector with fewer elements than the VF.
-  ElementCount VF = State.VF.divideCoefficientBy(VFScaleFactor);
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fhahn wrote:

Nope, both the start value and the backedge value now are narrowed already.

https://github.com/llvm/llvm-project/pull/142290