http://gcc.gnu.org/bugzilla/show_bug.cgi?id=39423
--- Comment #18 from Oleg Endo <olegendo at gcc dot gnu.org> 2012-07-11 15:09:02 UTC --- (In reply to comment #17) > Created attachment 27775 [details] > plus add combine > > Here is the patch that I've been running since some time, it also use the same > combine pattern matcher, but the goal of this patch was originally to fix up > chains of multiple mult-add instructions. > Optimizing the cst+reg addressing mode appears as a nice effects. Out of range > indexes seems to be handled as afar as I can see. > > This brings a EEMBC telecom speedup of 10%.FFMPEG code size reduced to 30% on > a > few objects. > Validated on whole linux distribution, with only improvements (few regression > only bellow noise). Interesting. BTW, do you happen to have any (runtime) numbers for GCC 4.7.x vs current GCC 4.8? > This patch is only for comments/illustration. Need a few polishing before > proposing. I'm having a look at your implementation to see how they compare > and > possibly combined together. Both approaches look interesting. I guess folding the mul-add sequences like you did should be more useful than just handling one mem:SI pattern. In any case, if you find my impl useful please let me know, because then I'd also pop in patterns for mem:QI and mem:HI patterns.
