[llvm] [AArch64][ARM] Move ARM-specific InstCombine transforms to new module (PR #169589)

[David Green via llvm-commits]

https://github.com/davemgreen commented:

Hi. I just read https://discourse.llvm.org/t/should-there-be-an-architecture-agnostic-variable-vector-shuffle-operation/88936. (I like the idea). If that goes forward would this still be required?

Can the new file go into Transforms/Utils or somewhere like it? That would avoid the need for a new module, and the code in it doesn't look like it is using anything specific to the architectures (it doesn't use intrinsic definitions, etc, just checks for constants).

https://github.com/llvm/llvm-project/pull/169589