> On Jan 11, 2016, at 3:07 PM, Richard Purdie > <[email protected]> wrote: > > On Mon, 2016-01-11 at 14:58 -0800, Khem Raj wrote: >>> On Jan 7, 2016, at 3:40 PM, Phil Blundell <[email protected]> wrote: >>> >>> On Thu, 2016-01-07 at 14:29 -0800, Andre McCurdy wrote: >>>> FULL_OPTIMIZATION_armv7a = "-fexpensive-optimizations -fomit >>>> -frame-pointer -O4 -ffast-math" >>>> +FULL_OPTIMIZATION_armv7ve = "-fexpensive-optimizations -fomit >>>> -frame-pointer -O4 -ffast-math" >>> >> >> O4 ? may be just replace this whole thing with -Ofast now a days >> -fexpensive-optimizations is enabled at -O2,-O3 anyway same for fomit >> -frame-pointer and -Ofast turns on >> feast-match on top of -O3 >> >>> I wonder if this would be better as just FULL_OPTIMIZATION_arm. >>> That >>> said, the OPTIMIZATION variables are primarily distro knobs and >>> it's not >>> entirely clear that individual packages ought to be overriding them >>> at >>> all. >>> >>> Does anybody know whether there is any actual science behind the >>> use of >>> those flags on armv7a specifically? >> >> it came into ffmpeg circa 2008 and proliferated into related >> components primarily to support vectorization and neon >> which was quite nascent for ARM architecture in those days in gcc. >> Today if you were to configure libav with default options >> then it uses mainly -fomit-frame-pointer-O3 -fno-math-errno -fno >> -signed-zeros -fno-tree-vectorize >> >> which is primarily -Ofast -fno-tree-vectorize > > I have to admit that my personal instinct on these is simply to remove > them. I doubt they're buying much now and if people really want to tune > specific recipes by hand they still can do so from their local/distro > config.
Thats ok, however the most tested option combination seems to use -O3 since thats configure’s default for libav If we start using -O2 .. as we use that for global optimizations in OE then we are odd man out. > > Cheers, > > Richard >
signature.asc
Description: Message signed with OpenPGP using GPGMail
-- _______________________________________________ Openembedded-core mailing list [email protected] http://lists.openembedded.org/mailman/listinfo/openembedded-core
