------- Comment #10 from bonzini at gnu dot org 2009-01-02 16:33 ------- Subject: Re: [ira] error in start_allocno_priorities, at ira-color.c:1806
> I will test this patch, but we still need to resolve your issues with my > approach. The problem is that you're really doubling the cost of computing the live registers. I know that previously it was wrong, but at this point there's no difference with the full-blown pass... Despite the idea of DF_LR_RUN_DCE being that it was "free", now it would do the same work as a pass_fast_rtl_dce modulo some O(#bbs) work. At this point, if your patch costs say 0.3%, and removing all traces of DF_LR_RUN_DCE (instead scheduling a dozen more pass_fast_rtl_dce in passes.c) costs 0.5%, I'd rather see the latter, at least it's easier to look for opportunities to remove some useless DCE. If it wasn't for verification, we could just decide that DF_LR_RUN_DCE is only for passes that can tolerate a little inaccurate info... Paolo -- http://gcc.gnu.org/bugzilla/show_bug.cgi?id=35805
