Sender: nate AT cartsys DOT com
Message-ID: <35DF04B7.5F6BA508@cartsys.com>
Date: Sat, 22 Aug 1998 10:49:43 -0700
From: Nate Eldredge <nate AT cartsys DOT com>
MIME-Version: 1.0
To: arfa AT clara DOT net
CC: DJGPP Mailing List <djgpp AT delorie DOT com>, D DOT J DOT Eleveld AT anest DOT azg DOT nl
Subject: Re: How safe is the -march=pentium flag?
References: <000101bdc476$090d6620$244e08c3 AT arthur>
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Arthur wrote:

> > Doesn't -march=pentium make pentium optimized code?
> 
> AFAIK it only aligns the instructions for a Pentium.  Code using -march=pentium will
> still work on older machines.

You've got it backwards.  -march=xxx makes specific code (I think
-march=pentiumpro will use tge ficomp instructions (though wrongly-- it
has a bug)).  -mcpu=xxx just does alignment and instruction choice
(`enter' vs. `push ebp; mov ebp,esp' sort of thing), and maybe
scheduling as well, I'm not sure,
-- 

Nate Eldredge
nate AT cartsys DOT com