[llvm] AMDGPU: Delete seemingly dead s_fmaak_f32/s_fmamk_f32 folding code (PR #140580)

[Mirko Brkušanin via llvm-commits]

mbrkusanin wrote:

> Cases that this was supposed to cover can no longer happen in this part of the code due to #127563 and #127626.

We used to prefer s_fmamk and s_fmamk over s_fmac with inlinable constants because they had untied src2 from dst.
This code was working with cases where inlinable constant was in the literal slot of fmamk or fmaak and we wanted to fold another noninlinable one.

Either way due to other changes this can no longer be used in the same way.


https://github.com/llvm/llvm-project/pull/140580