On Thursday 28 September 2006 16:17, Barry.SCHWARTZ@... wrote
about 'Optimizations (was Re: [gentoo-amd64] First Impressions)':
> "Boyd Stephen Smith Jr." <bss03@...> skribis:
> > Now, I have to problem with developers closing some bug opened by a
> > ricer out there that's added -ffast-math to their CFLAGS as
> > WONTFIX/INVALID since it's not really a problem. All the parts
> > provided by Gentoo (ebuild, source, compiler, portage, etc.) all
> > behaving properly. It's just that, just like the warning says,
> > programs WILL break
> > under -ffast-math.
> I have to disagree with this strongly, because -ffast-math means you
> want code that violates the IEEE floating point standard.
Sorry, I mistyped "no" as "to" in the first sentence which completely
changed my meaning. I agree that -ffast-math ricers could have their bugs
closed with prejudice. -ffast-math is basically something that should
only be allowed on a per-package basis, after consulting with upstream.
> > > Indeed, there aren’t many fields of ‘production’ in which end users
> > > ought to be encouraged to try things that expose flaws in design or
> > > manufacture.
> > I disagree. I want to know about those flaws, and I want the
> > manufactures to fix them -- which is why I like Consumer Reports so
> > much. :)
> It’s one thing to read Consumer Reports and have it say your SUV rolls
> over easily, and another to drive in a manner likely to roll your SUV
> over. It’s even worse to sort of hold SUV drivers hostage by
> encouraging them to roll over their SUVs unless and until the
> manufacturer fixes the SUV. People should be encouraged to drive their
> dangerous vehicles safely, and so should users be encouraged to set
> their CFLAGS safely.
I encourage users to try to roll their SUVs safely. :)
If you are running a nuclear power plant off of Gentoo, then I hope you are
going quite a bit further than just not using -O3.
However, using -O3 is usually dangerous to only the user themselves (at
most) so I see no problem encouraging it.
That said, once somebody figures out (and publishes) that when you do X, Y,
and Z to brand A SUV it rolls over. I'd discourage doing X, Y, and Z to
brand A SUVs (it'll cost you an SUV and really doesn't provide much
benefit). I'd encourage to X, Y, and Z to brand B, C, and D SUVs
(*safely*) so that we can determine if the manufacturing flaw affects them
"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