From: Toon Moene <toon@moene.indiv.nluug.nl>
To: Richard Henderson <rth@redhat.com>
Cc: gcc@gcc.gnu.org
Subject: Re: possible gcse failure: not able to eliminate redundant loads
Date: Mon, 16 Dec 2002 14:44:00 -0000 [thread overview]
Message-ID: <3DFE5562.6030608@moene.indiv.nluug.nl> (raw)
In-Reply-To: <20021216211245.F4851@redhat.com>
Richard Henderson wrote:
> On Mon, Dec 16, 2002 at 10:04:01PM +0100, Toon Moene wrote:
>
>>BTW, I wasn't aware it's legal to dereference NULL C pointers.
> It isn't, of course. But that's the whole point. You've
> got code that says
>
> x = (condition ? *p : 0);
>
> i.e. the dereference is protected by a conditional. Thus
> we can't hoist the dereference past the conditional (and
> thence out of the loop that started this thread).
Oh, Fortran is sooooo much easier in this respect than [some other
languages]. Of course you can [syntactically] express "dereferencing" a
invalid pointer in Fortran 90/95. That doesn't mean the resulting
program has to do something meaningful, however [could start WW III and
all that]
--
Toon Moene - mailto:toon@moene.indiv.nluug.nl - phoneto: +31 346 214290
Saturnushof 14, 3738 XG Maartensdijk, The Netherlands
Maintainer, GNU Fortran 77: http://gcc.gnu.org/onlinedocs/g77_news.html
Join GNU Fortran 95: http://g95.sourceforge.net/ (under construction)
next prev parent reply other threads:[~2002-12-16 22:39 UTC|newest]
Thread overview: 40+ messages / expand[flat|nested] mbox.gz Atom feed top
2002-12-13 0:39 Sanjiv Kumar Gupta, Noida
2002-12-13 2:42 ` Richard Henderson
2002-12-13 13:10 ` Toon Moene
2002-12-16 10:15 ` Richard Henderson
2002-12-16 11:32 ` Andrew Haley
2002-12-16 13:13 ` Toon Moene
2002-12-16 13:32 ` Richard Henderson
2002-12-16 14:44 ` Toon Moene [this message]
2002-12-16 14:48 ` Toon Moene
2002-12-16 15:29 ` Richard Henderson
2002-12-17 15:20 ` Toon Moene
2002-12-16 15:38 ` Jan Hubicka
2002-12-16 16:40 ` Alex Rosenberg
-- strict thread matches above, loose matches on Subject: below --
2002-12-21 20:36 Robert Dewar
2002-12-19 7:08 Richard Kenner
2002-12-18 18:39 Robert Dewar
2002-12-19 3:02 ` Richard Henderson
2002-12-21 19:49 ` Alexandre Oliva
2002-12-12 23:42 Sanjiv Kumar Gupta, Noida
2002-12-12 21:35 Sanjiv Kumar Gupta, Noida
2002-12-12 21:44 ` Dan Nicolaescu
2002-12-11 22:00 Sanjiv Kumar Gupta, Noida
2002-12-11 22:18 ` Daniel Berlin
2002-12-11 20:32 Sanjiv Kumar Gupta, Noida
2002-12-11 3:30 Sanjiv Kumar Gupta, Noida
2002-12-11 14:53 ` Dale Johannesen
2002-12-11 20:02 ` Daniel Berlin
2002-12-11 20:03 ` Daniel Berlin
2002-12-12 12:25 ` Richard Henderson
2002-12-12 12:28 ` Daniel Berlin
2002-12-12 13:03 ` Richard Henderson
2002-12-12 13:04 ` David Edelsohn
2002-12-12 14:32 ` Richard Henderson
2002-12-12 14:42 ` David Edelsohn
2002-12-12 14:58 ` Richard Henderson
2002-12-12 15:28 ` Daniel Berlin
2002-12-13 3:41 ` Richard Henderson
2002-12-12 20:30 ` David Edelsohn
2002-12-12 15:29 ` Geoff Keating
2002-12-11 3:27 Sanjiv Kumar Gupta, Noida
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