[llvm] [GlobalISel] support lowering of G_SHUFFLEVECTOR with pointer args (PR #141959)

[Michal Paszkowski via llvm-commits]

https://github.com/michalpaszkowski commented:

@stanleygambarin Thanks for working on this! LGTM! I can merge the PR if the patch is ready.

https://github.com/llvm/llvm-project/pull/141959