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From: Joern Rennecke <amylaar@cygnus.co.uk>
To: michaelh@ongaonga.chch.cri.nz (Michael P. Hayes)
Cc: law@cygnus.com, amylaar@cygnus.co.uk,
	michaelh@ongaonga.chch.cri.nz, gcc2@cygnus.com, egcs@cygnus.com
Subject: Re: Autoincrement addressing modes
Date: Wed, 11 Feb 1998 18:20:00 -0000	[thread overview]
Message-ID: <199802120020.AAA12058@phal.cygnus.co.uk> (raw)
In-Reply-To: <199802120014.NAA29645@ongaonga.chch.cri.nz>

> Does this asymmetry only apply to these update forms of addressing
> modes?
> 
> Any ideas how to describe this to GCC?  I suppose if there was a flag

One way would be to have

HAVE_PRE_DECREMENT_READ and HAVE_PRE_DECREMENT_WRITE to control the
two possible uses of PRE_DEC;
when HAVE_PRE_DECREMENT is defined, it can mean both of the above,
to maintain backward compatibility and make it easy for ports that
don't need to distinguish them.
Similarily for POST_DEC, PRE_INC, POST_INC.

> to differentiate memory reads from writes, then
> GO_IF_LEGITIMATE_ADDRESS could reject the invalid forms.

That would be goof too, but it doesn't help the code that doesn't
actually try to use the auto-increment, e.g. like move_by_pieces
in expr.c

  parent reply	other threads:[~1998-02-11 18:20 UTC|newest]

Thread overview: 16+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
1998-02-11 18:20 Michael P. Hayes
1998-02-11 16:33 ` Joern Rennecke
1998-02-11 17:22   ` Jeffrey A Law
1998-02-11 17:22     ` Michael P. Hayes
1998-02-11 16:33       ` Joern Rennecke
1998-02-11 18:20       ` Jeffrey A Law
1998-02-11 18:20       ` Joern Rennecke [this message]
1998-02-12  6:42 ` Richard Henderson
1998-02-14 15:24   ` Michael P. Hayes
1998-03-16 20:25   ` Joern Rennecke
1998-03-16 20:25     ` Richard Henderson
1998-03-16 20:25       ` Michael P. Hayes
1998-03-16 20:25         ` Joern Rennecke
1998-03-17  1:28           ` Richard Henderson
1998-03-17 13:29             ` Joern Rennecke
1998-03-16 20:44     ` Michael P. Hayes

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