[LLVMdev] specializing hybrid_ls_rr_sort (was: Re: Bottom-Up Scheduling?)

Hal Finkel hfinkel at anl.gov
Mon Dec 19 06:51:52 PST 2011

On Tue, 2011-10-25 at 21:00 -0700, Andrew Trick wrote:
Now, to generate the best PPC schedules, there is one thing you may
> want to override. The scheduler's priority function has a
> HasReadyFilter attribute (enum). It can be overriden by specializing
> hybrid_ls_rr_sort. Setting this to "true" enables proper ILP
> scheduling, and maximizes the instructions that can issue in one
> group, regardless of register pressure. We still care about register
> pressure enough in ARM to avoid enabling this. I'm really not sure how
> much it will help on modern PPC implementations though.
> hybrid_ls_rr_sort

Can this be done without modifying common code? It looks like
hybrid_ls_rr_sort is local to ScheduleDAGRRList.cpp.

Thanks again,

Hal Finkel
Postdoctoral Appointee
Leadership Computing Facility
Argonne National Laboratory

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