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

[Florian Hahn via llvm-commits]

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@@ -495,9 +495,9 @@ Value *VPInstruction::generate(VPTransformState &State) {
   }
   case Instruction::ExtractElement: {
     assert(State.VF.isVector() && "Only extract elements from vectors");
-    Value *Vec = State.get(getOperand(0));
-    Value *Idx = State.get(getOperand(1), /*IsScalar=*/true);
-    return Builder.CreateExtractElement(Vec, Idx, Name);
+    unsigned IdxToExtract =
+        cast<ConstantInt>(getOperand(1)->getLiveInIRValue())->getZExtValue();
+    return State.get(getOperand(0), VPLane(IdxToExtract));
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fhahn wrote:

I had to update the code here; there is code that may construct ExtractElement with non-constant values (early-exit with forced interleaving, where it is the first active lane)

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