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Date:      Tue, 13 Mar 2001 16:41:38 -0300 (BRST)
From:      Rik van Riel <riel@conectiva.com.br>
To:        Charles Randall <crandall@matchlogic.com>
Cc:        "'freebsd-hackers@FreeBSD.ORG'" <freebsd-hackers@FreeBSD.ORG>
Subject:   Re: gcc optimization problems (RE: optimizing apache with php and nfs  mounts)
Message-ID:  <Pine.LNX.4.21.0103131639150.2056-100000@imladris.rielhome.conectiva>
In-Reply-To: <5FE9B713CCCDD311A03400508B8B30130828E8F7@bdr-xcln.corp.matchlogic.com>

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On Tue, 13 Mar 2001, Charles Randall wrote:
> From: David O'Brien [mailto:obrien@FreeBSD.ORG]
> >2.  The base, system C compiler is known to produce bad code with -O2.
> >    We have been proclaiming this since as long as I have been with the
> >    Project.
> 
> Is this an issue with FreeBSD's gcc's or gcc in general? If gcc in
> general, are there open PRs on this issue?

It's a gcc thing. Linux is having the same problems every once
in a while (currently there only seem to be _2_ gcc versions
which generate correct code for the Linux kernel ...).

OTOH, it is possible to work around gcc problems in the code
and code which was initially written for older gcc versions
often rely on things which were true in older gcc versions
but are no longer true currently ...

(especially things depending on certain ordering of instructions
and the (non-)presence of memory barriers)

regards,

Rik
--
Virtual memory is like a game you can't win;
However, without VM there's truly nothing to lose...

		http://www.surriel.com/
http://www.conectiva.com/	http://distro.conectiva.com.br/


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