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Re: Latest sources from CVS.

To: Thiemo Seufer <ica2_ts@csv.ica.uni-stuttgart.de>
Subject: Re: Latest sources from CVS.
From: Ralf Baechle <ralf@linux-mips.org>
Date: Sat, 7 Dec 2002 01:00:28 +0100
Cc: Dominic Sweetman <dom@algor.co.uk>, "Maciej W. Rozycki" <macro@ds2.pg.gda.pl>, Carsten Langgaard <carstenl@mips.com>, "Kevin D. Kissell" <kevink@mips.com>, linux-mips@linux-mips.org
In-reply-to: <20021206233337.GM23743@rembrandt.csv.ica.uni-stuttgart.de>; from ica2_ts@csv.ica.uni-stuttgart.de on Sat, Dec 07, 2002 at 12:33:37AM +0100
Original-recipient: rfc822;linux-mips@linux-mips.org
References: <20021206135110.GD23743@rembrandt.csv.ica.uni-stuttgart.de> <Pine.GSO.3.96.1021206165118.26674N-100000@delta.ds2.pg.gda.pl> <20021206164558.GH23743@rembrandt.csv.ica.uni-stuttgart.de> <20021206180241.A7492@linux-mips.org> <15856.59886.661994.493446@gladsmuir.algor.co.uk> <20021207001731.D12968@linux-mips.org> <20021206233337.GM23743@rembrandt.csv.ica.uni-stuttgart.de>
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On Sat, Dec 07, 2002 at 12:33:37AM +0100, Thiemo Seufer wrote:

> > I'd worry less if that was just 220kB of unused memory wasted.  But it's
> > actually inflated code, it's wasted i-cache and cycles.  220kB translates
> > to alost 7 times the size of today's typical 32kB i-cache.
> > 
> > Even if Thiemo was right this trick is probably the biggest micro-
> > optimization of the decade ...
> 
> Even if it was such a big win it would IMHO be better to use N64 and
> teach the assembler some optimization for such register loads.
> -Wa,--sign-extend-immediates shouldn't be that complicated to implement.

The entire situation will change anyway once gcc no longer emits macro
instructions such as la or dla.

  Ralf

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