[llvm] [AMDGPU] Schedule independent instructions between s_barrier_signal and s_barrier_wait (PR #172057)

[Carl Ritson via llvm-commits]

https://github.com/perlfu approved this pull request.

LGTM - thanks for looking at this.  I had also wondered about filling these gaps.

Wait a day or so before merging in case there are any further comments.

https://github.com/llvm/llvm-project/pull/172057