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Re: Possible IRA bug in assign_hard_reg


Ian Bolton wrote:
Thanks for the detailed answer.

While we're on the subject of assign_hard_reg, I notice the costs and
min_cost variable are set but never used (decisions are being made with
the full_costs array and min_full_cost). Should they be referenced
somehow or are they just redundant?
Yes, they are redundant. I worked a lot of time on IRA tuning which resulted in many (small or big) code modifications. I tried to remove all experimental code before submitting IRA but some redundant code went through. As you understand in some experiments min_cost was used instead of min_full_cost. Min_cost might work for some targets because I mostly focused on tuning for mainstream targets x86/x86_64 and powerpc.

By the way, I am still working on graph coloring based RA without cover classes. Finally, it might help with your target problems. Unfortunately, I have a performance degradation on mainstream targets for this code in comparison with code using the cover classes. It is a long way to fix the degradations. If I fix it, the code will be part of gcc 4.6.



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