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To: linux-kernel@vger.kernel.org
From: "H. Peter Anvin" <hpa@zytor.com>
Subject: Re: Where is it written?
Date: 10 Nov 2000 17:06:41 -0800
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In-Reply-To: <20001110184031.A2704@munchkin.spectacle-pond.org> <200011110011.eAB0BbF244111@saturn.cs.uml.edu>
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Copyright: Copyright 2000 H. Peter Anvin - All Rights Reserved
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Followup to:  <200011110011.eAB0BbF244111@saturn.cs.uml.edu>
By author:    "Albert D. Cahalan" <acahalan@cs.uml.edu>
In newsgroup: linux.dev.kernel
> 
> Gee that looks old. Might there be better calling conventions
> for the Pentium 4 or Athlon? Memory latency, vector registers,
> and more direct access to floating-point registers may mean
> we ought to change the calling conventions. One would start
> with the kernel of course, because it stands alone.
> 

The main win would be passing arguments in registers -- at least three
such registers could be used (%eax, %edx, %ecx) without increasing
register pressure.  Doing this for nonvaradic functions probably would
be a win.  Similarly, floating-point arguments and SSE arguments could
be passed in registers, and _Bool output (a C99 feature) could at
least theoretically be returned in a flag.

	-hpa
-- 
<hpa@transmeta.com> at work, <hpa@zytor.com> in private!
"Unix gives you enough rope to shoot yourself in the foot."
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