[llvm] [SLP] Allow non-power-of-2 VF in tryToVectorizeList (PR #206259)

[Harrison Hao via llvm-commits]

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@@ -28601,7 +28605,8 @@ bool SLPVectorizerPass::tryToVectorizeList(ArrayRef<Value *> VL, BoUpSLP &R,
     for (unsigned I = NextInst; I < MaxInst; ++I) {
       unsigned ActualVF = std::min(MaxInst - I, VF);
 
-      if (!hasFullVectorsOrPowerOf2(*TTI, ScalarTy, ActualVF))
+      if (!hasFullVectorsOrPowerOf2(*TTI, ScalarTy, ActualVF) &&
+          !isAllowedNonPowerOf2VF(ActualVF))
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harrisonGPU wrote:

For <15 x half>, `hasFullVectorsOrPowerOf2()` returns false since 15 is not a power of two. Without checking `isAllowedNonPowerOf2VF()`, it still rejects vectorize.

https://github.com/llvm/llvm-project/pull/206259