[llvm] [VectorCombine] foldBitcastShuffle - peek through any residual bitcasts before creating a new bitcast on top (PR #86119)

[Yingwei Zheng via llvm-commits]

dtcxzyw wrote:

> I'm assuming we can't safely put this inside IRBuilderBase.CreateBitCast?

FYI, folding bitcast of bitcast is always safe.

https://github.com/llvm/llvm-project/blob/857161c367a1cdca926dbe0d2601e3afc52f03f9/llvm/lib/IR/Instructions.cpp#L3504-L3569

https://github.com/llvm/llvm-project/pull/86119