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Re: r4600 flag

To: linux-mips@oss.sgi.com
Subject: Re: r4600 flag
From: Thiemo Seufer <ica2_ts@csv.ica.uni-stuttgart.de>
Date: Tue, 31 Jul 2001 15:08:29 +0200
In-reply-to: <006901c119b5$ac8ecfe0$0deca8c0@Ulysses>
Sender: owner-linux-mips@oss.sgi.com
User-agent: Mutt/1.3.18i
Kevin D. Kissell wrote:
[snip]
> > `-mcpu=CPU TYPE'
> >      Assume the defaults for the machine type CPU TYPE when scheduling
> >      instructions.  The choices for CPU TYPE are `r2000', `r3000',
> >      `r3900', `r4000', `r4100', `r4300', `r4400', `r4600', `r4650',
> >      `r5000', `r6000', `r8000', and `orion'.  Additionally, the
> >      `r2000', `r3000', `r4000', `r5000', and `r6000' can be abbreviated
> >      as `r2k' (or `r2K'), `r3k', etc.  While picking a specific CPU
> >      TYPE will schedule things appropriately for that particular chip,
> >      the compiler will not generate any code that does not meet level 1
> >      of the MIPS ISA (instruction set architecture) without a `-mipsX'
> >      or `-mabi' switch being used.
> 
> In that case, the tools that I've been using are technically
> broken.  Surprise surprise.   Because -mcpu=4600 is
> most assuredly setting the ISA level, even if it doesn't
> override one explicitly set!

gas and gcc have different meanings for this option, gas uses the
cpu's default ISA (if none specified) while gcc uses MIPS I.
In current binutils/gcc CVS, there was -march and -mtune introduced
as a replacement for -mcpu and -m<cpu>, which were kept for backward
compatibility only.

[snip]
> > No MAD on R4600.  Again it would be in contradiction with above document-
> > ation.  Mad you get with:
> 
> Right.  Sorry.  I got the 4600 and 4650 confused.  I no longer
> understand why "4600" and not "4650" is the model for MIPS32.

At least for the CVS binutils gas it is Generic-MIPS32, not 4600.


Thiemo

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