On Thursday 28 September 2006 03:35, Paul de Vrieze <[EMAIL PROTECTED]> wrote about 'Re: [gentoo-amd64] First Impressions': > Boyd Stephen Smith Jr. wrote: > > On Wednesday 27 September 2006 11:11, "Hemmann, Volker Armin" > > <[EMAIL PROTECTED]> wrote about 'Re: [gentoo-amd64] > > > > First Impressions': > >> -O3 don't do it. > > -O3 breaking just doesn't happen anymore. > The thing is that besides compiler errors, there are many program errors > out there that are not caused by optimization levels, just exposed. From > the point of view of a user however it doesn't matter where the error > is. It is an error, and thus should be fixed.
Agreed, but the fix is not "don't use useful compiler features", it's "change the program source to not be erroneous". Of course, there's also the short-term solution of "filter/replace flags for the few programs known to have issues". It's wrong-headed to deride or discourage users for using the features of their compiler when those functions are not erroneous. Instead, you should be leaning on the developers to fix the erroneous code. > The main thing is that -O2 is the default at most places, and as such > gets the most testing. That means that things generally work for -O2 > where -O3 or -Os exposes bugs in the software. Again, there's no completely safe setting. -O2 breaks stuff; -O3 breaks stuff; -Os breaks stuff. None of them are due to a bad compiler. I therefore urge people to use whatever optimization level they think is best and then file bugs if the package is broken. (It is the package that's broken, not the compiler or the choice of CFLAGS.) Also, surveying existing ebuilds, there are evidently quite a few more than I originally thought that force an optimization lower than -O2... around 40. There's actually about 14 that *force* -Os. Well, drilling down I see that is just every postfix ebuild -- that could certainly be accumulated cruft. -- "If there's one thing we've established over the years, it's that the vast majority of our users don't have the slightest clue what's best for them in terms of package stability." -- Gentoo Developer Ciaran McCreesh
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