On Wed, Nov 25, 2015 at 6:19 PM, Ronald S. Bultje <rsbul...@gmail.com> wrote: > Hi, > > On Wed, Nov 25, 2015 at 5:17 PM, Ganesh Ajjanagadde <gajjanaga...@gmail.com> > wrote: >> >> On systems having cbrt, there is no reason to use the slow pow function. >> >> Sample benchmark (x86-64, Haswell, GNU/Linux): >> new: >> 5124920 decicycles in cbrt_tableinit, 1 runs, 0 skips >> >> old: >> 12321680 decicycles in cbrt_tableinit, 1 runs, 0 skips >> >> Signed-off-by: Ganesh Ajjanagadde <gajjanaga...@gmail.com> >> >> ------------------------------------------------------------------------------- >> What I wonder about is why --enable-hardcoded-tables is not the default >> for >> FFmpeg. Unless I am missing something, static storage is anyway allocated >> even >> if hardcoded tables are not used, and the cost is deferred to runtime >> instead of >> build time. Thus binary size should not be affected, but users burn cycles >> unnecessarily for every codec having these kinds of tables. I have these >> patches, >> simply because at the moment users are paying a price for the typical >> default. >> --- >> libavcodec/cbrt_tablegen.h | 6 +++--- >> 1 file changed, 3 insertions(+), 3 deletions(-) > > > This has been discussed extensively in the past...
Can you please give a link and/or timeframe to search for? > > As for the patch, don't forget that tablegen runs on the host (build), not > target (runtime), whereas libm.h is for target (runtime) and may not be > compatible. I believe that's why we don't use libm.h in tablegen files. I don't understand this, it seems to me like any other code (at least in the default configure), it gets called, and like all other such things, we use libavutil/libm for hackery. This host/target business affects other things as well. What is the issue? > > It's fine to use pow or a compat wrapper, but then you need a build/host > libm.h instead of using the target/runtime one. > > Ronald _______________________________________________ ffmpeg-devel mailing list ffmpeg-devel@ffmpeg.org http://ffmpeg.org/mailman/listinfo/ffmpeg-devel
