On Thu, Oct 22, 2015 at 8:33 AM, Michael Niedermayer <mich...@niedermayer.cc> wrote: > On Thu, Oct 22, 2015 at 07:04:41AM -0400, Ganesh Ajjanagadde wrote: >> On Thu, Oct 22, 2015 at 5:49 AM, Carl Eugen Hoyos <ceho...@ag.or.at> wrote: >> > Ganesh Ajjanagadde <gajjanagadde <at> gmail.com> writes: >> > >> >> > This broke fate with -ftrapv >> > >> >> > The problem seems to be in av_gcd() and not the De-Bruijn version of >> >> > ff_ctzll since the gcc builtin is being used. >> >> >> >> Don't have the time to investigate right now - revert for now unless >> >> someone can fix it quickly. >> > >> > Ping? >> > >> > Please revert if nobody can fix this. >> >> "Fixing" this at the moment is highly dubious - read the thread. It >> does not even occur in a reproducible way, does not trigger on ubsan, >> I can't even see it on ftrapv. Show me why it is not a toolchain >> issue. > > IMO never just assume that a problem that appears after a change you do > is not caused by your code. > Because if you do and you are wrong the bug might never be fixed > while OTOH, if you assume its in your code you will sooner or later > by debuging find the bug or more details, and that may be a > code generation issue in the toolchain outside your code in case > you where wrong. > Its the safer default assumtation as the failure path if you are wrong > is less bad. > > either way, bug fixed > the reason for non reproduceablility likely was that the x86 asm > overrode the C code in which the bug was
Ok, go ahead and revert. I just did not see the hurry for reverting; since it does not break normal builds. > > > [...] > -- > Michael GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB > > I have often repented speaking, but never of holding my tongue. > -- Xenocrates > > _______________________________________________ > ffmpeg-devel mailing list > ffmpeg-devel@ffmpeg.org > http://ffmpeg.org/mailman/listinfo/ffmpeg-devel > _______________________________________________ ffmpeg-devel mailing list ffmpeg-devel@ffmpeg.org http://ffmpeg.org/mailman/listinfo/ffmpeg-devel
