[llvm] [AArch64][GlobalISel] Bitcast and Build Illegal G_CONCAT_VECTOR Instructions (PR #96492)

[David Green via llvm-commits]

davemgreen wrote:

Could you explain what you mean by "other more obvious approaches"?

The tests probably don't show the issues very well as they are all using arguments which are not really v4i8 but v4i16. The loads case is what we have seen come up a number of times, usually from SLP vectorization https://godbolt.org/z/6s3neP153.

https://github.com/llvm/llvm-project/pull/96492