Re: [2.6 patch] offer CC_OPTIMIZE_FOR_SIZE only if EXPERIMENTAL

[Dave Jones]

On Wed, Dec 14, 2005 at 11:28:13PM +0100, Jesper Juhl wrote:

 > I should probably back this up with *why* it boggles my mind.
 > 
 > -Os has been in EMBEDDED for ages, so it's not been tested by the
 > majority of users with the wide range of compilers etc that people
 > use.

Fedora has had this enabled most of the time for x86, x86-64, ia64,
s390, s390x, ppc32 and ppc64 for a long time.  From time to time
when a gcc bug has been tickled it's been disabled again until its
been worked out, but for the most part, it's been a complete non-event
wrt regressions.  In the ~2 years that we've had it enabled I recall
2-3 occasions where it broke something badly (and it was really noticable,
like "networking doesn't work any more", or "x86-64 stopped booting"[1]),
and once or twice when moving to a newer gcc point release, it tripped an ICE.

The RHEL4 kernel has also been built this way since day 1.

		Dave

[1] In that particular case, it was broken asm-x86-64/ macros that 
    just happened to work at -O2 by chance, so it actually found latent bugs.

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