[clang] [llvm] [LLVM][SROA] Teach SROA how to "bitcast" between fixed and scalable vectors. (PR #130973)

[Nikita Popov via llvm-commits]

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@@ -554,6 +554,22 @@ class VectorType : public Type {
     return VectorType::get(VTy->getElementType(), EltCnt * 2);
   }
 
+  /// This static method returns a VectorType with the same size-in-bits as
+  /// SizeTy but with an element type that matches the scalar type of EltTy.
+  static VectorType *getWithSizeAndScalar(VectorType *SizeTy, Type *EltTy) {
+    if (SizeTy->getScalarType() == EltTy->getScalarType())
+      return SizeTy;
+
+    unsigned EltSize = EltTy->getScalarSizeInBits();
+    if (!SizeTy->getPrimitiveSizeInBits().isKnownMultipleOf(EltSize))
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nikic wrote:

This should really be using DataLayout, not getPrimitiveSizeInBits.

https://github.com/llvm/llvm-project/pull/130973