From: Josh Triplett <josh@joshtriplett.org>
To: Christopher Li <sparse@chrisli.org>
Cc: blp@cs.stanford.edu, linux-sparse@vger.kernel.org
Subject: Re: intended use of "safe"?
Date: Fri, 12 Aug 2011 10:58:35 -0700 [thread overview]
Message-ID: <20110812175835.GA1735@leaf> (raw)
In-Reply-To: <CANeU7Qn25EWmDFuQRhr2_txEhF9hguh=SMUJnNYjLPnCR2MDNg@mail.gmail.com>
On Fri, Aug 12, 2011 at 10:47:11AM -0700, Christopher Li wrote:
> On Thu, Aug 11, 2011 at 10:14 AM, Ben Pfaff <blp@cs.stanford.edu> wrote:
> > What is the intended use of the sparse "safe" attribute? I do
> > not see any uses of it in Linux (although there is a __safe macro
> > for it). I don't see any documentation for it either.
>
> I don't know much about the safe attribute either. I find out the
> commit which introduce the safe attribute by "git blame".
>
> If a pointer is never NULL, there is not need to test the pointer.
>
> Chris
>
> commit 98f14350c26518f0f5c45632d145a218d468d8b8
> Author: Linus Torvalds <torvalds@ppc970.osdl.org>
> Date: Fri Apr 16 18:19:30 2004 -0700
>
> Introduce "safe" pointer expressions.
>
> These are defined to never be NULL or nontrapping, and could
> help code generation, but right now only cause a warning if
> they are tested in a conditional.
That does actually seem useful. The Linux kernel has various structures
with pointers that should never be NULL, and documenting that in a
compiler-visible way seems like a feature.
- Josh Triplett
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prev parent reply other threads:[~2011-08-12 17:58 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-08-11 17:14 intended use of "safe"? Ben Pfaff
2011-08-12 17:47 ` Christopher Li
2011-08-12 17:58 ` Josh Triplett [this message]
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