[Date Prev][Date Next]   [Thread Prev][Thread Next]   [Thread Index] [Date Index] [Author Index]

Re: using non-standard optflags (-O3, in particular)



On Fri, 2007-02-09 at 10:59 -0500, Simon Perreault wrote:
> Ralf Corsepius wrote:
> > So, the only results of recommendations to trust when it comes to
> > packaging binaries for a distro is those who are deeply familiar with
> > the guts of the OS, in case of Fedora, RH's GCC, glibc and kernel
> > developers.
> 
> This is BS.
Beg your pardon? 

>  Sure, people have thought about the defaults, but it doesn't 
> mean that the packager doesn't know what he's doing either.
Rest assured: In 99% of all cases they don't know.

They test on their "Pentium IV" and claim something - They can't have
any clues about what happens on a sparc, an i586 and 
AMD X2 <what the heck>, or a ppc something.

>  Some 
> software, particularly numerical computation stuff, is built for being 
> optimized properly. There are some extreme cases where using -O2 instead 
> of -O3 simply makes a piece of software useless (take Blitz++ for example).
In other words: Crappy non-portable SW,

> Using -O3 in specific cases isn't that big of a deal.
It is - It renders debugging impossible on many systems, strict-aliasing
silently kills SW on some targets, it might trigger exotic
target-specific bugs etc. etc. 

As part of the distro you can't to compromise between different
trade-offs.

Ralf





[Date Prev][Date Next]   [Thread Prev][Thread Next]   [Thread Index] [Date Index] [Author Index]