------- Comment #18 from hjl dot tools at gmail dot com 2009-01-04 18:23 ------- Subject: Re: [ira] error in start_allocno_priorities, at ira-color.c:1806
On Fri, Jan 2, 2009 at 4:34 PM, Kenneth Zadeck <zad...@naturalbridge.com> wrote: > Kenneth Zadeck wrote: >> Steven Bosscher wrote: >> >>> On Fri, Jan 2, 2009 at 7:37 PM, Paolo Bonzini <bonz...@gnu.org> wrote: >>> >>> >>>>>> At this point, if your patch costs say 0.3%, and removing all traces >>>>>> 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. >>>>>> >>>>>> >>>> I'll try to do this for 4.5. >>>> >>>> >>> It might be more worthwhile to just "fix" IRA to use DF_LIVE (which >>> Vlad should have done in the first place). Then we wouldn't need >>> Kenny's patch and DF_LR_RUN_DCE would still be essentially free. >>> >>> Gr. >>> Steven >>> >> There is the issue of correctness vs rot. I actually think that one of >> the reasons that flow was so bad was that people went down this long >> slippery slope of well it is good enough here ... and we really can get >> away with it not being right here ... and after a while, all you have is >> garbage. >> >> The problem with this game is that it is not maintainable. Those kinds >> of decisions tend to get forgotten and lost as the personnel supporting >> the compiler changes. Even if it is a fractional percentage slower, >> the fact that you do not have to reason about it as the compiler evolves >> is actually quite important. >> >> Thus, I plan to both fix this bug and add another one for vlad to fix >> the sets that he uses. >> >> Kenny >> > 2009-01-02 Kenneth Zadeck <zad...@naturalbridge.com> > > PR rtl-optimization/35805 > * df-problems.c (df_lr_finalize): Add recursive call to resolve lr > problem if fast dce is able to remove any instructions. > * dce.c (dce_process_block): Fix dump message. > > Rebootstrapped and regression tested on x86*. > > Committed as revision 143027. > Hi, This caused: http://gcc.gnu.org/bugzilla/show_bug.cgi?id=38722 -- http://gcc.gnu.org/bugzilla/show_bug.cgi?id=35805
