[llvm] [SLP] Initial vectorization of non-power-of-2 ops. (PR #77790)

[Florian Hahn via llvm-commits]

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@@ -2891,9 +2898,13 @@ class BoUpSLP {
           ValueToGatherNodes.try_emplace(V).first->getSecond().insert(Last);
     }
 
-    if (UserTreeIdx.UserTE)
+    if (UserTreeIdx.UserTE) {
       Last->UserTreeIndices.push_back(UserTreeIdx);
-
+      if (!isPowerOf2_32(Last->Scalars.size())) {
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fhahn wrote:

Done, thanks! Also folded the `if` into the assert

https://github.com/llvm/llvm-project/pull/77790