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Re: Support for newer gcc/gas options

To: Dimitri Torfs <dimitri@sonycom.com>
Subject: Re: Support for newer gcc/gas options
From: "Maciej W. Rozycki" <macro@ds2.pg.gda.pl>
Date: Wed, 21 Jan 2004 15:09:12 +0100 (CET)
Cc: linux-mips@linux-mips.org
In-reply-to: <20040120204026.GA9470@sonycom.com>
Organization: Technical University of Gdansk
Original-recipient: rfc822;linux-mips@linux-mips.org
References: <20031223114644.GA5458@sonycom.com> <Pine.LNX.4.55.0312231303030.27594@jurand.ds.pg.gda.pl> <Pine.LNX.4.55.0401201332080.12841@jurand.ds.pg.gda.pl> <20040120204026.GA9470@sonycom.com>
Sender: linux-mips-bounce@linux-mips.org
On Tue, 20 Jan 2004, Dimitri Torfs wrote:

> >  It took a bit longer than I planned, sorry.  Anyway, here are two
> > functionally equivalent patches, for 2.4 and the head, that remove an ISA
> > specification if a tool supports "-march=" and "-mabi=" at the same time.  
> > Please try the appropriate one.
> 
> Tried the head one, it had some typos (patch follows). Unfortunately, as I 
> wrote

 Oops, thanks for the correction -- as I still have only gcc 2.95.4, I
wasn't able to see the typos immediately.

> earlier, gcc-3.2 doesn't set the ISA correctly when using -march=, so
> it doesn't work for 3.2. 

 But do we care of the ISA?  I don't think so -- it's just a leftover from
the days the MIPS world was less complicated.  If gcc 3.2 correctly emits
code for the selected processor and obeys the selected ABI, then
everything is fine.  Are the binaries correct?  If so, I'd like to apply
the patch.

 The few remaining bits in <asm/asm.h> that still depend on _MIPS_ISA
should be rewritten to make use of appropriate CONFIG_CPU_HAS_* settings.  
Or perhaps we can just scrap them -- nothing uses them at all (and current
gcc is able to emit conditional move instructions itself).  OTOH, for
hand-coded assembly it might be a good idea to put them into gas as macros
-- similarly to what gas does for the Alpha for certain instructions that
are only available with later architecture revisions.  I'll work on it in
some spare time.

  Maciej

-- 
+  Maciej W. Rozycki, Technical University of Gdansk, Poland   +
+--------------------------------------------------------------+
+        e-mail: macro@ds2.pg.gda.pl, PGP key available        +

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