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Date:      Sat, 8 Apr 2000 14:18:47 -0700 (PDT)
From:      Kris Kennaway <kris@FreeBSD.org>
To:        "Alexey N. Dokuchaev" <danfe@inet.ssc.nsu.ru>
Cc:        freebsd-hackers@freebsd.org
Subject:   Re: What are the best gcc optimization options for Pentium 200 MMX
Message-ID:  <Pine.BSF.4.21.0004081416110.70551-100000@freefall.freebsd.org>
In-Reply-To: <Pine.LNX.4.10.10004082114170.23805-100000@inet.ssc.nsu.ru>

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On Sat, 8 Apr 2000, Alexey N. Dokuchaev wrote:

> AFAIK, Linux Mandrake has it's kernel and userland highly optimized for
> Pentium architecture.  However, they have additional gcc optimization 
> flags turned on by default, including -O3 and -mfast_math.

Can you say "gimmick"? :-) gcc often produces demonstrably broken code for
optimisation levels higher than -O.

Probably the only useful and safe option apart from -O is the
-march=pentium/pentiumpro/pentiumii/etc option for using
processor-specific opcodes and instruction scheduling.

By all means, compile your own system the way you want, but be sure to
recompile with nothing but -O before submitting any bug reports.

Kris

----
In God we Trust -- all others must submit an X.509 certificate.
    -- Charles Forsythe <forsythe@alum.mit.edu>



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