[llvm] [VectorCombine] Fold Deinterleave/Interleave Pairs (PR #211022)

[Benjamin Maxwell via llvm-commits]

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MacDue wrote:

nit: Use `WideValue`
```suggestion
  ElementCount WideEC =
      cast<VectorType>(WideValue->getType())
          ->getElementCount();
```

https://github.com/llvm/llvm-project/pull/211022