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

[Florian Hahn via llvm-commits]

================
@@ -1372,13 +1365,14 @@ static void narrowToSingleScalarRecipes(VPlan &Plan) {
             RepOrWidenR->getUnderlyingInstr(), RepOrWidenR->operands(),
             true /*IsSingleScalar*/, nullptr /*Mask*/, *RepR /*Metadata*/);
         Clone->insertBefore(RepOrWidenR);
-        unsigned ExtractOpc =
-            vputils::isUniformAcrossVFsAndUFs(RepR->getOperand(1))
-                ? VPInstruction::ExtractLastElement
-                : VPInstruction::ExtractLastLanePerPart;
-        auto *Ext = new VPInstruction(ExtractOpc, {Clone->getOperand(0)});
-        Ext->insertBefore(Clone);
-        Clone->setOperand(0, Ext);
+        VPBuilder Builder(Clone);
----------------
fhahn wrote:

Yep, this requires adding support for creating VPReplicateRecipes in VPBuilder. Probably best done separately

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