From: Michael Meissner <meissner@cygnus.com>
To: jcardoso@inescn.pt, tv@pobox.com
Cc: egcs@cygnus.com
Subject: Re: egcs-1.0.2 wrongly detect a Pentium II as a i386 on SCO5 - patch included
Date: Wed, 29 Apr 1998 07:57:00 -0000 [thread overview]
Message-ID: <199804291457.KAA14091@tiktok.cygnus.com> (raw)
| On Mon, 27 Apr 1998, Joao Cardoso wrote:
|
| : On sco-3.2v5.0.4 `configure' wrongly detect a Pentium II as a i386.
|
| This is actually half correct.
Well if you look at config.guess, you will see that it gets the information
from /usr/options/cb.name if it exists, and /bin/uname -X if it does not.
Somebody who has a SCO system with a Pentium-II will have to supply us with the
appropriate lines to use, since there is no telling what an OS might choose to
report.
| : I don't know if this has any implications on code generation. A simple
| : `gcc -S foo.c' report `-mcpu=i386 -march=pentium'
|
| The -march= is what really matters. All i[3456]86 based chips are, at their
| base, considered `i386' processors, but the architecture can be set for code
| generation as gcc does above. The actual architecture name is i386, not
| i586 or i686.
|
| When it comes down to it, a machine name such as `i586-pc-linux' is
| incorrect. `configure' just happily accepts it and treats it as
| `i386-pc-linux'. Same goes for SCO.
Wrong. If you configure for i386-pc-linux, it will default the scheduling
parameters to be an i386. If you configure for i585-pc-linux, it will default
the scheduling parameters to be a Pentium classic. Similarly for
i686-pc-linux, it will default for a Pentium-{Pro,II}. For example, when
compiling for a i386, the compiler believes the fastest way to push a value in
memory is to execute a single push instruction, while for all machines higher
than a i386, it loads the value into a register and then does a push.
--
Michael Meissner, Cygnus Solutions (Massachusetts office)
4th floor, 955 Massachusetts Avenue, Cambridge, MA 02139, USA
meissner@cygnus.com, 617-354-5416 (office), 617-354-7161 (fax)
next reply other threads:[~1998-04-29 7:57 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
1998-04-29 7:57 Michael Meissner [this message]
-- strict thread matches above, loose matches on Subject: below --
1998-04-27 14:44 Joao Cardoso
1998-04-28 15:33 ` Richard Henderson
1998-04-28 19:49 ` Todd Vierling
1998-05-03 22:02 ` Jim Wilson
1998-04-30 20:03 ` Joao Cardoso
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