[llvm] [AMDGPU] Remove s_delay_alu for VALU->SGPR->SALU (PR #127212)

[Jay Foad via llvm-commits]

jayfoad wrote:

> SALU will not issue until VA_SDST is zero, that is when VALU is finished writing. Therefore, delays added by s_delay_alu are not needed in this situation.

Right, good point! That is similar to the way that certain instructions wait for VA_VDST==0, which is handled here:
https://github.com/llvm/llvm-project/blob/1435c8ed95fa10a55c2f924984141e427b89c330/llvm/lib/Target/AMDGPU/AMDGPUInsertDelayAlu.cpp#L358

So I think the SALU wait for VA_SDST==0 should be handled in a similar way.

https://github.com/llvm/llvm-project/pull/127212