[llvm] [AArch64][SelectionDAG] Implement vector splitting for histogram intrinsic (PR #103037)

[Max Beck-Jones via llvm-commits]

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@@ -25434,6 +25436,41 @@ performScalarToVectorCombine(SDNode *N, TargetLowering::DAGCombinerInfo &DCI,
   return NVCAST;
 }
 
+static SDValue performHistogramCombine(SDNode *N,
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DevM-uk wrote:

You're right. I've moved the splitting to `DAGTypeLegalizer::SplitVecOp_VECTOR_HISTOGRAM` and added/moved the `INC` operand promotion to `DAGTypeLegalizer::PromoteIntOp_VECTOR_HISTOGRAM`.

https://github.com/llvm/llvm-project/pull/103037