[clang] [CIR][AArch64] Lower NEON vzip intrinsics (PR #193658)

[Andrzej Warzyński via cfe-commits]

https://github.com/banach-space commented:

All in all looks good, but I have two high-level suggestions (should be easy to incorporate).

* Move the new tests to a dedicated file, e..g "test/CodeGen/AArch64/neon/perm.c" - "intrinsics.c" is already becoming too large and the zip-unzip group is large enough to deserve a dedicated file.
* Add `instcombine` to `opt -S -passes=mem2reg,sroa` so that we avoid the additional `extractvalue`/`insertvalue` and the so that you can restore `ret` statements without bloating the tests with IR.

Hopefully this makes sense - thanks again for working on this!

https://github.com/llvm/llvm-project/pull/193658