On Fri, Apr 22, 2016 at 11:17:35AM +0200, Didier Kryn wrote: > Le 21/04/2016 20:38, KatolaZ a écrit : > >The simple reason is that the very same gcc has compiled at least 90% > >of the software you are using in alpha4, and who knows how many other > >millions of packages. So if there were any such bug in gcc, it would > >have probably been hit by now, just out of pure probability... > Jaromil, I agree with one of your other posts in which you say > that changing optimisation options often reveals a bug in the > source. But for the argument above, well... I'm not sure 90% of the > millions of packages have been compiled with -O3. > > I remember, sometimes in the 80's, when Microware shipped their > OS9 with their new ANSI C compiler, I had found a bug in the > compiler, caused by some level of optimisation - it could be > demonstrated with an ~5 lines example. >
It was actually me who wrote that comment :) What I mean is that *normally* a bug that appears only when code is optimised might signal a problem in memory management/access. There are some cases in which -O3 might lead to problems, but they seem to be mostly related to multithreaded applications and to specific issues with floating-point optimisations, as also explained here: http://stackoverflow.com/questions/14850593/when-can-i-confidently-compile-program-with-o3/14853616#14853616 My2Cents KatolaZ -- [ Enzo Nicosia aka KatolaZ --- GLUG Catania -- Freaknet Medialab ] [ me [at] katolaz.homeunix.net -- http://katolaz.homeunix.net -- ] [ GNU/Linux User:#325780/ICQ UIN: #258332181/GPG key ID 0B5F062F ] [ Fingerprint: 8E59 D6AA 445E FDB4 A153 3D5A 5F20 B3AE 0B5F 062F ] _______________________________________________ Dng mailing list [email protected] https://mailinglists.dyne.org/cgi-bin/mailman/listinfo/dng
