Re: [gentoo-dev] GCC 4.7 unmasking

[Luca Barbato <lu_zero@gentoo.org>]

On 25/02/13 22:32, Rich Freeman wrote:
> On Mon, Feb 25, 2013 at 4:18 PM, Tom Wijsman <TomWij@gentoo.org> wrote:
>> Though people that use -ffast-math / -fLTO / -fuse-linker-plugin should
>> be on their own, thus I drop -ffast-math because it breaks my browser;
>> but that doesn't mean that those ricer flags should stop stabilization.
> 
> If we're talking about for general use in CFLAGs clearly -ffast-math
> isn't something that even could be supported if we wanted to.  The
> flag is just not intended for general use.

And if you stop here everything would be agreeable.

> That isn't the same as saying that we can just break it in cases where
> it actually is appropriate.  Calculating scroll bar movement is
> exactly the sort of thing that this flag was actually designed for -
> you don't care if it is off by 1/100th of a pixel.

Please check your facts. using -ffast-math could do anything from
nothing to cause severe security issues.

> But, the way to track that sort of a thing is to log those as bugs
> against appropriate use within individual apps and make them blockers.

No.

>  I'd consider things like this valid bugs - but whether they hold
> things up should depend on real-world impact.  I'm not sure how bad
> the impact on chromium actually is.

Absolutely not. Some code is _designed_ to work w/out caring about ieee
corner cases and some is _designed_ to work leveraging them.

NOT bug.

To reinstate: if you use -ffast-math or other
known-to-alter-the-standard-behaviour or, even worst, experimental flags
you are on your own.

lu