[llvm] [SLP] Exit early if MaxVF < MinVF (NFCI). (PR #83283)

[via llvm-commits]

llvmbot wrote:


<!--LLVM PR SUMMARY COMMENT-->

@llvm/pr-subscribers-llvm-transforms

Author: Florian Hahn (fhahn)

<details>
<summary>Changes</summary>

Exit early if MaxVF < MinVF. In that case, the loop body below will never get entered. Note that this adjusts the condition from MaxVF <= MinVF. If MaxVF == MinVF, vectorization may still be feasible (and the loop below gets entered).

---
Full diff: https://github.com/llvm/llvm-project/pull/83283.diff


1 Files Affected:

- (modified) llvm/lib/Transforms/Vectorize/SLPVectorizer.cpp (+2-1) 


``````````diff
diff --git a/llvm/lib/Transforms/Vectorize/SLPVectorizer.cpp b/llvm/lib/Transforms/Vectorize/SLPVectorizer.cpp
index 2b7d518c1c1a78..e381cd2c5794b1 100644
--- a/llvm/lib/Transforms/Vectorize/SLPVectorizer.cpp
+++ b/llvm/lib/Transforms/Vectorize/SLPVectorizer.cpp
@@ -13912,10 +13912,11 @@ bool SLPVectorizerPass::vectorizeStores(ArrayRef<StoreInst *> Stores,
       unsigned MinVF = TTI->getStoreMinimumVF(
           R.getMinVF(DL->getTypeSizeInBits(ValueTy)), StoreTy, ValueTy);
 
-      if (MaxVF <= MinVF) {
+      if (MaxVF < MinVF) {
         LLVM_DEBUG(dbgs() << "SLP: Vectorization infeasible as MaxVF (" << MaxVF
                           << ") <= "
                           << "MinVF (" << MinVF << ")\n");
+        return;
       }
 
       // FIXME: Is division-by-2 the correct step? Should we assert that the

``````````

</details>


https://github.com/llvm/llvm-project/pull/83283