[llvm] [LoopVectorize] Vectorize fixed-order recurrence with vscale x 1. (PR #142772)

[via llvm-commits]

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@@ -6139,11 +6139,6 @@ LoopVectorizationCostModel::getInstructionCost(Instruction *I,
 
     // First-order recurrences are replaced by vector shuffles inside the loop.
     if (VF.isVector() && Legal->isFixedOrderRecurrence(Phi)) {
-      // For <vscale x 1 x i64>, if vscale = 1 we are unable to extract the
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ayalz wrote:

Does this imply that `VF.isVector()` returns true for single-element non-vector VF's when VF.isScalable() && VF.getKnownMinValue() == 1 and vscale == 1? The TODO is erased w/o considering vscale_range info?

https://github.com/llvm/llvm-project/pull/142772