From: Robert Hancock <hancockr@shaw.ca>
To: linux-kernel <linux-kernel@vger.kernel.org>
Subject: Re: Big GCC bug!!! [Was: Re: Do not misuse Coverity please]
Date: Wed, 30 Mar 2005 17:57:49 -0600 [thread overview]
Message-ID: <424B3CFD.5050402@shaw.ca> (raw)
In-Reply-To: <3NUDL-DU-13@gated-at.bofh.it>
Kyle Moffett wrote:
> Dereferencing null pointers is relied upon by a number of various
> emulators and such, and is "platform-defined" in the standard, so
> since Linux allows mmap at NULL, GCC shouldn't optimize that case
> any differently.
From the GCC manual: "The compiler assumes that dereferencing a null
pointer would have halted the program. If a pointer is checked after it
has already been dereferenced, it cannot be null. In some environments,
this assumption is not true, and programs can safely dereference null
pointers. Use -fno-delete-null-pointer-checks to disable this
optimization for programs which depend on that behavior. "
--
Robert Hancock Saskatoon, SK, Canada
To email, remove "nospam" from hancockr@nospamshaw.ca
Home Page: http://www.roberthancock.com/
next parent reply other threads:[~2005-03-30 23:58 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <3NC4e-1X1-21@gated-at.bofh.it>
[not found] ` <3NGrd-5rX-21@gated-at.bofh.it>
[not found] ` <3NQgW-5h6-41@gated-at.bofh.it>
[not found] ` <3NR3q-5YI-59@gated-at.bofh.it>
[not found] ` <3NUDL-DU-13@gated-at.bofh.it>
2005-03-30 23:57 ` Robert Hancock [this message]
2005-03-30 1:25 Do not misuse Coverity please (Was: sound/oss/cs46xx.c: fix a check after use) Horst von Brand
2005-03-30 7:53 ` Do not misuse Coverity please Jean Delvare
2005-03-30 18:29 ` Shankar Unni
2005-03-30 19:14 ` Paulo Marques
2005-03-30 23:11 ` Big GCC bug!!! [Was: Re: Do not misuse Coverity please] Kyle Moffett
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