on 2021/8/30 下午10:11, Bill Schmidt wrote: > On 8/30/21 8:04 AM, Florian Weimer wrote: >> There has been a discussion, both off-list and on the gcc-help mailing >> list (“Why vectorization didn't turn on by -O2”, spread across several >> months), about enabling the auto-vectorizer at -O2, similar to what >> Clang does. >> >> I think the review concluded that the very cheap cost model should be >> used for that. >> >> Are there any remaining blockers? > > Hi Florian, > > I don't think I'd characterize it as having blockers, but we are continuing > to investigate small performance issues that arise with very-cheap, including > some things that regressed in GCC 12. Kewen Lin is leading that effort. > Kewen, do you feel we have any major remaining concerns with this plan? >
Hi Florian & Bill, There are some small performance issues like PR101944 and PR102054, and still two degraded bmks (P9 520.omnetpp_r -2.41% and P8 526.blender_r -1.31%) to be investigated/clarified, but since their performance numbers with separated loop and slp vectorization options look neutral, they are very likely noises. IMHO I don't think they are/will be blockers. So I think it's good to turn this on by default for Power. BR, Kewen
