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Re: [patch] alias.c: Replace "return NULL_RTX" with "return 0".

From: Alexandre Oliva <aoliva at redhat dot com>
To: "Kaveh R. Ghazi" <ghazi at caip dot rutgers dot edu>
Cc: zack at codesourcery dot com, fjh at cs dot mu dot oz dot au, gcc-patches at gcc dot gnu dot org, jason at redhat dot com, kazu at cs dot umass dot edu
Date: 12 Jun 2003 18:51:46 -0300
Subject: Re: [patch] alias.c: Replace "return NULL_RTX" with "return 0".
Organization: GCC Team, Red Hat
References: <20030612.141353.55502198.kazu@cs.umass.edu><20030612184112.GD8506@mars.cs.mu.oz.au><87of133zoz.fsf@egil.codesourcery.com><20030612185541.GE8506@mars.cs.mu.oz.au><wvlel1zcb5t.fsf@prospero.boston.redhat.com><87k7br3vem.fsf@egil.codesourcery.com><wvl65nbcabr.fsf@prospero.boston.redhat.com><87fzmf3t2h.fsf@egil.codesourcery.com><200306122138.RAA22263@caip.rutgers.edu>

On Jun 12, 2003, "Kaveh R. Ghazi" <ghazi@caip.rutgers.edu> wrote:

> I thought variadic function introduce extra overhead to avoid this
> issue.

Good ABIs generally try to get things to work, even if at some
overhead.  Such ABIs are not mandated by the Standard.

> Otherwise how would va_arg know where to get the data from?

It would look at the type of the argument and choose the appropriate
register.  We already do this in ABIs that pass floating-point values
in floating-point registers, for example, even in varargs.

-- 
Alexandre Oliva   Enjoy Guarana', see http://www.ic.unicamp.br/~oliva/
Red Hat GCC Developer                 aoliva@{redhat.com, gcc.gnu.org}
CS PhD student at IC-Unicamp        oliva@{lsd.ic.unicamp.br, gnu.org}
Free Software Evangelist                Professional serial bug killer

References:
- [patch] alias.c: Replace "return NULL_RTX" with "return 0".
  - From: Kazu Hirata
- Re: [patch] alias.c: Replace "return NULL_RTX" with "return 0".
  - From: Fergus Henderson
- Re: [patch] alias.c: Replace "return NULL_RTX" with "return 0".
  - From: Zack Weinberg
- Re: [patch] alias.c: Replace "return NULL_RTX" with "return 0".
  - From: Fergus Henderson
- Re: [patch] alias.c: Replace "return NULL_RTX" with "return 0".
  - From: Jason Merrill
- Re: [patch] alias.c: Replace "return NULL_RTX" with "return 0".
  - From: Zack Weinberg
- Re: [patch] alias.c: Replace "return NULL_RTX" with "return 0".
  - From: Jason Merrill
- Re: [patch] alias.c: Replace "return NULL_RTX" with "return 0".
  - From: Zack Weinberg
- Re: [patch] alias.c: Replace "return NULL_RTX" with "return 0".
  - From: Kaveh R. Ghazi

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