[llvm] [VPlan] Replace ExtractLast(Elem|LanePerPart) with ExtractLast(Lane/Part) (PR #164124)

[via llvm-commits]

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@@ -4513,10 +4508,11 @@ void VPlanTransforms::addExitUsersForFirstOrderRecurrences(VPlan &Plan,
     // Now update VPIRInstructions modeling LCSSA phis in the exit block.
     // Extract the penultimate value of the recurrence and use it as operand for
     // the VPIRInstruction modeling the phi.
-    for (VPUser *U : FOR->users()) {
-      using namespace llvm::VPlanPatternMatch;
-      if (!match(U, m_ExtractLastElement(m_Specific(FOR))))
+    for (VPRecipeBase &R : make_early_inc_range(
+             make_range(MiddleVPBB->getFirstNonPhi(), MiddleVPBB->end()))) {
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ayalz wrote:

... as done above in adjustRecipesForReductions(). Matching this recipe-pair pattern going backwards from use to def is indeed simpler that going forward from def to use, hence the suggestion for (the abstract) ExtractFinalLane to represent both.

https://github.com/llvm/llvm-project/pull/164124