[llvm] [AMDGPU] Improved Lowering of abs(i16) and -abs(i16) (PR #165626)

[Juan Manuel Martinez Caamaño via llvm-commits]

jmmartinez wrote:

> Hi @jmmartinez, thanks for reviewing this PR. Normally I would not have a problem squashing the commits as you suggested, but, in this case, the commit history contains two failed implementation attempts that I would like to preserve during the review process in case a method of fixing one of them is discovered. Would it be acceptable if I posted the master/branch assemblies of the s_cmp_0.ll testcase instead to facilitate seeing the improvement?

No problem in keeping the previous cases, but at least seeing the difference in `s_abs_16` would be nice (and knowing what happens for gisel).

https://github.com/llvm/llvm-project/pull/165626