From: Nathan Sidwell <nathan@codesourcery.com>
To: Richard Kenner <kenner@vlsi1.ultra.nyu.edu>
Cc: gcc-patches@gcc.gnu.org, jsm@polyomino.org.uk
Subject: Re: Patch to allow Ada to work with tree-ssa
Date: Wed, 23 Jun 2004 11:42:00 -0000 [thread overview]
Message-ID: <40D93E0D.6090103@codesourcery.com> (raw)
In-Reply-To: <10406222111.AA11317@vlsi1.ultra.nyu.edu>
Richard Kenner wrote:
> so it's an accident then? why not just remove it?
>
> I'm not at all convinced it's an "accident".
I was using sarcasm.
> The GNU C extensions
> were never documented, but that doesn't mean that nobody used them.
> The code I showed is just a logical consequence of the existance of
> those extensions. I've certainly known that it will work for quite
> some time, perhaps as long as 20 years. There's no way to know how
> much code that depends on this is out there.
this is my point. What is the point of this extension?
* It's not documented, so users have no formal knowledge of its existance
* It's not documented, so users have no guarantee that it'll continue to work
* IMO, it's marginally useful to have a variable length array in the *middle*
of a C structure -- I notice PR2939' example is a structure with a trailing
array, which I consider to be significantly different, there being no
varying field offsets to consider (but it's still not documented to work).
Surely a more common need for variable length arrays is to support
multidimensional array parameters with something like,
void Foo (int n, int m, int ary[n][m]);
Heck, that's even been codified in C99 (with slightly different syntax IIRC).
That would have more uptake in the field and IMO would have been a better
use of GCC developer time.
> I'll repeat now what I said a few weeks ago: it's precisely because of
> these things already being in GCC that the GNAT project chose GCC to
> use as a backend.
Then you should take the opportunity to document it, as it's become an
undocumented requirement of GNAT.
> In any event, there's no reason to remove this since we can easily support it.
Then document it. And the fact that it didn't work properly, and you're having
such grief getting it working seems to imply 'easily support' is not actually
true.
I'd like to know how many real (not a testcase) GNU C programs out there use
this varray-in-middle idiom (really, I would).
nathan
--
Nathan Sidwell :: http://www.codesourcery.com :: CodeSourcery LLC
nathan@codesourcery.com :: http://www.planetfall.pwp.blueyonder.co.uk
next prev parent reply other threads:[~2004-06-23 8:23 UTC|newest]
Thread overview: 77+ messages / expand[flat|nested] mbox.gz Atom feed top
2004-06-22 23:05 Richard Kenner
2004-06-23 11:42 ` Nathan Sidwell [this message]
-- strict thread matches above, loose matches on Subject: below --
2004-07-29 19:02 Richard Kenner
2004-07-29 18:43 Richard Kenner
2004-07-29 17:12 Richard Kenner
2004-07-29 17:13 ` Diego Novillo
2004-07-29 17:57 ` Richard Henderson
2004-06-25 15:28 Richard Kenner
2004-06-28 15:09 ` Paolo Bonzini
2004-06-24 15:58 Richard Kenner
2004-06-24 16:04 ` Nathan Sidwell
2004-06-25 14:43 ` Joseph S. Myers
2004-06-23 5:54 Richard Kenner
2004-06-23 2:32 Richard Kenner
2004-06-23 4:54 ` Bryce McKinlay
2004-06-23 0:16 Richard Kenner
2004-06-22 22:18 Richard Kenner
2004-06-23 1:07 ` Richard Henderson
2004-06-22 21:30 Richard Kenner
2004-06-22 22:04 ` Paul Brook
2004-06-22 21:27 Richard Kenner
2004-06-22 21:29 ` Mark Mitchell
2004-06-22 21:10 Richard Kenner
2004-06-22 21:12 ` Mark Mitchell
2004-06-22 22:16 ` Daniel Berlin
2004-06-22 21:07 Richard Kenner
2004-06-22 21:12 ` Bryce McKinlay
2004-06-22 21:05 Richard Kenner
2004-06-22 21:01 Richard Kenner
2004-06-22 20:54 Richard Kenner
2004-06-22 21:06 ` Paul Brook
2004-06-22 21:37 ` Richard Henderson
2004-06-22 20:44 Richard Kenner
2004-06-22 21:03 ` Mark Mitchell
2004-06-23 20:58 ` Geoffrey Keating
2004-06-22 20:40 Richard Kenner
2004-06-22 22:02 ` Nathan Sidwell
2004-06-22 22:27 ` Joseph S. Myers
2004-06-22 20:23 Richard Kenner
2004-06-22 20:37 ` Joseph S. Myers
2004-06-23 20:47 ` Geoffrey Keating
2004-06-24 14:59 ` Joseph S. Myers
2004-06-24 16:26 ` Richard Earnshaw
2004-06-24 19:57 ` Laurent GUERBY
2004-06-24 20:06 ` Diego Novillo
2004-06-24 20:24 ` Andrew Pinski
2004-06-24 22:35 ` Laurent GUERBY
2004-06-24 21:33 ` Laurent GUERBY
2004-06-24 21:01 ` Joseph S. Myers
2004-06-25 14:51 ` Richard Earnshaw
2004-06-22 20:22 Richard Kenner
2004-06-22 20:30 ` Mark Mitchell
2004-06-22 19:05 Richard Kenner
2004-06-22 20:10 ` Joseph S. Myers
2004-06-22 20:27 ` Andrew Haley
[not found] <10406221359.AA05860@vlsi1.ultra.nyu.edu>
2004-06-22 18:47 ` Richard Henderson
2004-06-22 18:33 Richard Kenner
2004-06-22 18:19 Richard Kenner
2004-06-22 18:36 ` Nathan Sidwell
2004-06-22 18:37 ` Nathan Sidwell
2004-06-22 18:45 ` Mark Mitchell
2004-06-22 17:05 Richard Kenner
2004-06-22 17:21 ` Andrew Haley
2004-06-22 19:01 ` Richard Henderson
2004-06-22 16:34 Richard Kenner
2004-06-22 16:33 Richard Kenner
2004-06-22 17:46 ` Mark Mitchell
2004-06-22 18:17 ` Joseph S. Myers
2004-06-22 18:52 ` Richard Henderson
2004-06-22 19:37 ` Zack Weinberg
2004-06-22 7:05 Richard Kenner
2004-06-22 7:29 ` Mark Mitchell
2004-06-22 9:14 ` Andrew Pinski
2004-06-22 14:16 ` Andrew Haley
2004-06-22 11:00 ` Richard Henderson
2004-06-22 13:52 ` Ranjit Mathew
2004-07-29 17:02 ` Diego Novillo
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