From: Dale Johannesen <dalej@apple.com>
To: Bernardo Innocenti <bernie@develer.com>
Cc: Dale Johannesen <dalej@apple.com>,
Richard Henderson <rth@twiddle.net>,
Andrea Arcangeli <andrea@suse.de>,
Linus Torvalds <torvalds@osdl.org>,
linux-kernel@vger.kernel.org,
Peter Chubb <peter@chubb.wattle.id.au>,
Andrew Morton <akpm@digeo.com>, Ian Molton <spyro@f2s.com>,
gcc@gcc.gnu.org
Subject: Re: [PATCH] Fix do_div() for all architectures
Date: Thu, 10 Jul 2003 12:53:44 -0700 [thread overview]
Message-ID: <3645F0F8-B310-11D7-890F-000393D76DAA@apple.com> (raw)
In-Reply-To: <200307102131.45474.bernie@develer.com>
On Thursday, July 10, 2003, at 12:31 PM, Bernardo Innocenti wrote:
>
> The compiler could easily tell what memory can be clobbered by a
> pointer
> by applying type-based aliasing rules. For example, a function taking a
> "char *" can't clobber memory objects declared as "long bar" or
> "struct foo".
No, for two reasons. First, anything can be aliased by a char. Second,
the restriction is on the type of the eventual memory reference,
not on the type of the pointer. Assuming an int* p, you can still do
*((char*)p) and
that may alias anything. So you must check each dereference; this
can't be
done easily at function entry.
next prev parent reply other threads:[~2003-07-10 19:40 UTC|newest]
Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top
2003-07-05 23:33 [PATCH] Fix do_div() for all architectures Bernardo Innocenti
2003-07-06 7:47 ` Russell King
2003-07-06 15:40 ` Ian Molton
2003-07-07 4:26 ` Bernardo Innocenti
2003-07-08 18:27 ` Bernardo Innocenti
2003-07-08 18:31 ` Andrew Morton
2003-07-08 20:56 ` Bernardo Innocenti
2003-07-10 15:40 ` Richard Henderson
2003-07-10 16:18 ` Andrea Arcangeli
2003-07-10 16:39 ` Richard Henderson
2003-07-10 19:31 ` Bernardo Innocenti
2003-07-10 19:53 ` Dale Johannesen [this message]
2003-07-10 20:19 ` Andrea Arcangeli
2003-07-10 22:58 ` Bernardo Innocenti
2003-07-10 22:04 ` Richard Henderson
2003-07-10 23:13 ` Bernardo Innocenti
-- strict thread matches above, loose matches on Subject: below --
2003-07-02 16:16 [PATCH] Kill div64.h dupes, parenthesize do_div() macro params Linus Torvalds
2003-07-03 10:43 ` [PATCH] Fix do_div() for all architectures Bernardo Innocenti
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