From: Derek M Jones <derek@knosof.co.uk>
To: Morten Welinder <mwelinder@gmail.com>
Cc: Al Viro <viro@ftp.linux.org.uk>, linux-sparse@vger.kernel.org
Subject: Re: pointer arithmetics and casts
Date: Sat, 26 May 2007 04:32:47 +0100 [thread overview]
Message-ID: <4657AA5F.1020705@knosof.co.uk> (raw)
In-Reply-To: <118833cc0705251814h9fffa39xc4a0f3f9e61242b9@mail.gmail.com>
Morten,
>> BINOP[+]
>> <tree for p>
>> BINOP[*]
>> IMPLICIEDT_CAST[ptrdiff_t]
>> <tree for i>
>> VAL[sizeof(*p)]
>
> I don't think you want ptrdiff_t there. It isn't guaranteed to
> be big enough.
It is also a signed type.
> size_t should do, though.
This is an unsigned type, so the wrap around behavior is defined.
But do you really want to map a small negative index into a large
positive one?
You probably have to use intptr_t and uintptr_t.
On the other hand if sizeof(size_t) == sizeof(type_of(tree for i))
is an implicit cast needed?
--
Derek M. Jones tel: +44 (0) 1252 520 667
Knowledge Software Ltd mailto:derek@knosof.co.uk
Applications Standards Conformance Testing http://www.knosof.co.uk
next prev parent reply other threads:[~2007-05-26 3:32 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2007-05-25 21:23 pointer arithmetics and casts Al Viro
2007-05-25 22:00 ` Al Viro
2007-05-26 15:45 ` Al Viro
2007-05-26 1:14 ` Morten Welinder
2007-05-26 3:32 ` Derek M Jones [this message]
2007-05-26 4:16 ` Al Viro
2007-05-26 3:43 ` Al Viro
2007-05-26 3:44 ` Neil Booth
2007-05-26 4:22 ` Al Viro
2007-05-26 4:37 ` Neil Booth
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