[llvm] [LoadStoreVectorizer] Support vectorization of mixed-type contiguous accesses (PR #177908)

[Anshil Gandhi via llvm-commits]

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@@ -160,7 +155,67 @@ struct ChainElem {
   ChainElem(Instruction *Inst, APInt OffsetFromLeader)
       : Inst(std::move(Inst)), OffsetFromLeader(std::move(OffsetFromLeader)) {}
 };
-using Chain = SmallVector<ChainElem, 1>;
+struct Chain : SmallVector<ChainElem, 1> {
+private:
+  Type *ElemTy = nullptr;
+
+public:
+  using SmallVector::SmallVector;
+
+  /// Return the GCD of the element sizes.
+  unsigned int computeGCDSize(const DataLayout &DL) const {
+    unsigned int GCDSize = 0;
+    for (const ChainElem &E : *this) {
+      Type *Ty = getLoadStoreType(E.Inst)->getScalarType();
+      unsigned Sz = DL.getTypeSizeInBits(Ty);
+      GCDSize = GCDSize == 0 ? Sz : std::gcd(GCDSize, Sz);
+    }
+    return GCDSize;
+  }
+
+  /// Gets the element type of the vector that the chain will load or store.
+  ///
+  /// The element type is determined by taking the GCD of the bitwidths of all
+  /// elements in the chain. Among types with this matching bitwidth, we prefer:
+  /// - A type that appears most frequently in the chain, to minimize casts.
+  /// - An integer type if the chain contains pointers, to avoid direct
+  ///   pointer-to-floating-point conversions.
+  ///
+  /// \param C The chain of instructions to be vectorized.
+  /// \returns The chosen element type for the vectorized load or store.
+  Type *computeAndCacheElemTy(LLVMContext &Ctx, const DataLayout &DL) {
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gandhi56 wrote:

Addressed in the latest revision.

https://github.com/llvm/llvm-project/pull/177908