[llvm] AMDGPU/GlobalISel: Lower G_EXTRACT in legalizer (PR #181036)

[Petar Avramovic via llvm-commits]

https://github.com/petar-avramovic commented:

Unfortunately mir test have significant regressions (should not do shift trunc in easy cases), think we have to fix them first.
Now not sure if those cases are relevant since we don't have appropriate ll tests.

https://github.com/llvm/llvm-project/pull/181036