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 13:13:00 -0000 [thread overview]
Message-ID: <3DFE3FC1.9020802@moene.indiv.nluug.nl> (raw)
In-Reply-To: <20021216180441.C3953@redhat.com>
Richard Henderson wrote:
> On Fri, Dec 13, 2002 at 09:25:54PM +0100, Toon Moene wrote:
>>I cannot imagine a valid Fortran program that contains an access to
>>memory that "might trap".
> Yeah, I guess there's really no concept of a null pointer is there...
Well, certainly not in the language that g77 compiles (a superset of
Fortran 77), because there is no concept of "pointer" in that language.
However, Fortran 90/95 *do* have pointers, but also there it's not
legally possible to "dereference" (to use the C-term) pointers that
point to storage that has not been "defined" (given a value) - to say
nothing of to point to something that isn't there (i.e., a pointer that
hasn't been initialised to point to an existing object).
BTW, I wasn't aware it's legal to dereference NULL C pointers.
--
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 21:03 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 [this message]
2002-12-16 13:32 ` Richard Henderson
2002-12-16 14:44 ` Toon Moene
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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