[llvm] [VPlan] Split out optimizeEVLMasks. NFC (PR #174925)

[Luke Lau via llvm-commits]

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@@ -3083,43 +3099,6 @@ static void transformRecipestoEVLRecipes(VPlan &Plan, VPValue &EVL) {
       CmpInst::ICMP_ULT,
       Builder.createNaryOp(VPInstruction::StepVector, {}, EVLType), &EVL);
   HeaderMask->replaceAllUsesWith(EVLMask);
-  ToErase.push_back(HeaderMask->getDefiningRecipe());
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lukel97 wrote:

zip_equals asserts the number of defined values are the same now so the old assert is now redundant

https://github.com/llvm/llvm-project/pull/174925