[llvm] [SLP][REVEC] Fix false assumption of the source for castToScalarTyElem. (PR #99424)

[via llvm-commits]

llvmbot wrote:


<!--LLVM PR SUMMARY COMMENT-->

@llvm/pr-subscribers-llvm-transforms

Author: Han-Kuan Chen (HanKuanChen)

<details>
<summary>Changes</summary>

The argument V may come from adjustExtracts, which is the vector operand of ExtractElementInst. In addition, it is not existed in getTreeEntry.

The vector operand of ExtractElementInst may have a type of <1 x Ty>, ensuring that the number of elements in ScalarTy and VecTy are equal.

reference: https://github.com/llvm/llvm-project/issues/99411

---
Full diff: https://github.com/llvm/llvm-project/pull/99424.diff


1 Files Affected:

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


``````````diff
diff --git a/llvm/lib/Transforms/Vectorize/SLPVectorizer.cpp b/llvm/lib/Transforms/Vectorize/SLPVectorizer.cpp
index ccb6734d5618c..a09bb00f3419e 100644
--- a/llvm/lib/Transforms/Vectorize/SLPVectorizer.cpp
+++ b/llvm/lib/Transforms/Vectorize/SLPVectorizer.cpp
@@ -11850,7 +11850,7 @@ class BoUpSLP::ShuffleInstructionBuilder final : public BaseShuffleAnalysis {
   Value *castToScalarTyElem(Value *V,
                             std::optional<bool> IsSigned = std::nullopt) {
     auto *VecTy = cast<VectorType>(V->getType());
-    assert(getNumElements(ScalarTy) < getNumElements(VecTy) &&
+    assert(getNumElements(ScalarTy) <= getNumElements(VecTy) &&
            (getNumElements(VecTy) % getNumElements(ScalarTy) == 0));
     if (VecTy->getElementType() == ScalarTy->getScalarType())
       return V;

``````````

</details>


https://github.com/llvm/llvm-project/pull/99424