[llvm] [VPlan] Unroll VPReplicateRecipe by VF. (PR #142433)

[via llvm-commits]

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@@ -261,6 +261,14 @@ Value *VPTransformState::get(const VPValue *Def, const VPLane &Lane) {
     return Data.VPV2Scalars[Def][0];
   }
 
+  // Look through BuildVector to avoid redundant extracts.
+  // TODO: Remove once replicate regions are unrolled explicitly.
+  auto *BV = dyn_cast<VPInstruction>(Def);
+  if (Lane.getKind() == VPLane::Kind::First && BV &&
+      BV->getOpcode() == VPInstruction::BuildVector) {
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ayalz wrote:

Worth `match`ing?

https://github.com/llvm/llvm-project/pull/142433