[llvm] [MISched] Extend overridePostRASchedPolicy to support per-function scheduling direction (PR #149297)

[Harrison Hao via llvm-commits]

harrisonGPU wrote:

> I still think we should pass `SchedRegion`. The signature will be:
> 
> ```
> void overridePostRASchedPolicy(MachineSchedPolicy &Policy,
>                                const SchedRegion &Region) const
> ```
> 
> The parameters are less and it is more straightforward since the scheduler is region-based, `MachineBasicBlock` != `SchedRegion` conceptively.

Thanks, I need to change `overrideSchedPolicy` as well?

https://github.com/llvm/llvm-project/pull/149297