[llvm] [AArch64][GlobalISel] Combine G_EXTRACT_VECTOR_ELT and G_BUILD_VECTOR sequences into G_SHUFFLE_VECTOR (PR #110545)

[Matt Arsenault via llvm-commits]

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@@ -772,8 +772,6 @@ MachineInstrBuilder MachineIRBuilder::buildShuffleVector(const DstOp &Res,
   LLT DstTy = Res.getLLTTy(*getMRI());
   LLT Src1Ty = Src1.getLLTTy(*getMRI());
   LLT Src2Ty = Src2.getLLTTy(*getMRI());
-  assert((size_t)(Src1Ty.getNumElements() + Src2Ty.getNumElements()) >=
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arsenm wrote:

The source vectors each must be the same size, and the result number of elements must exactly match the number of elements in the mask. The assert doesn't quite match the machine verifier's rules for G_SHUFFLE_VECTOR 

https://github.com/llvm/llvm-project/pull/110545