[llvm] [LV] Check early for supported interleave factors with scalable types [nfc] (PR #111592)

[Mel Chen via llvm-commits]

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@@ -3414,9 +3415,14 @@ bool LoopVectorizationCostModel::interleavedAccessCanBeWidened(
   if (hasIrregularType(ScalarTy, DL))
     return false;
 
+  // We currently only know how to emit interleave/deinterleave with
+  // Factor=2 for scalable vectors.  This is purely an implementation
+  // limit.
+  if (VF.isScalable() && InterleaveFactor != 2)
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Mel-Chen wrote:

SVE also has a similar check in interleavedAccessCanBeWidened. 
Indeed, it would be better to clean them up together if possible. 


https://github.com/llvm/llvm-project/pull/111592