[llvm] [VPlan] Model FOR extract of exit value in VPlan. (PR #93395)

[via llvm-commits]

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@@ -3657,7 +3672,8 @@ inline bool isUniformAfterVectorization(VPValue *VPV) {
   if (auto *GEP = dyn_cast<VPWidenGEPRecipe>(Def))
     return all_of(GEP->operands(), isUniformAfterVectorization);
   if (auto *VPI = dyn_cast<VPInstruction>(Def))
-    return VPI->getOpcode() == VPInstruction::ComputeReductionResult;
+    return VPI->getOpcode() == VPInstruction::ComputeReductionResult ||
+           VPI->getOpcode() == VPInstruction::ExtractFromEnd;
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ayalz wrote:

```suggestion
    return VPI->isVectorToScalar();
```
?

https://github.com/llvm/llvm-project/pull/93395