[llvm] [AMDGPU] Fix GFX1250 hazard: S_SET_VGPR_MSB dropped (PR #184904)

[Stanislav Mekhanoshin via llvm-commits]

rampitec wrote:

> > It's a huge change and hazard recognizer mitigates the hazard for instruction which does not exist yet. Why not to insert nops in the VGPR lowering pass itself?
> 
> Why not swap the order of passes so that GCNHazardRcognizer runs after AMDGPULowerVGPREncoding? That's how I assumed it was already. That's why I suggested fixing it in the hazard recognizer.

Because contract with HW was that this MSB lowering does not create hazards in the first place.

https://github.com/llvm/llvm-project/pull/184904