From: Al Viro <viro@ftp.linux.org.uk>
To: Alan Cox <alan@lxorguk.ukuu.org.uk>
Cc: Dave Jones <davej@redhat.com>, Keith Owens <kaos@ocs.com.au>,
linux-kernel@vger.kernel.org
Subject: Re: 2.6.14 assorted warnings
Date: Sun, 30 Oct 2005 22:25:43 +0000 [thread overview]
Message-ID: <20051030222543.GN7992@ftp.linux.org.uk> (raw)
In-Reply-To: <1130710531.32734.5.camel@localhost.localdomain>
On Sun, Oct 30, 2005 at 10:15:31PM +0000, Alan Cox wrote:
> gcc is a *LOT* smarter than you give it credit for. It will not warn for
> cases where it isn't able to tell how foo is used passed with &foo. It
> will warn for cases where it can
static inline __attribute__((always_inline)) int bar(int n, int *idx)
{
if (n != 1)
return 0;
*idx = 1;
return 1;
}
void baz(int *v, int n)
{
int idx;
int p = bar(n, &idx);
if (__builtin_expect(!p, 0))
return;
*v |= idx;
}
and try gcc -Wall on that. Watch it warn about idx being possibly
uninitialized. Replace __builtin_expect(!p, 0) with !p and see
the warning go away. That, BTW, is a trimmed-down source of bogus
warning in bio.c. And a lot of its analogs all over the tree.
next prev parent reply other threads:[~2005-10-30 22:25 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2005-10-28 7:21 2.6.14 assorted warnings Keith Owens
2005-10-28 7:28 ` Jens Axboe
2005-10-28 7:30 ` Dave Jones
2005-10-28 8:07 ` Arnd Bergmann
2005-10-28 8:29 ` Jens Axboe
2005-10-29 5:59 ` Richard Knutsson
2005-10-29 6:03 ` Al Viro
2005-10-28 8:10 ` Richard Knutsson
2005-10-30 22:15 ` Alan Cox
2005-10-30 22:25 ` Al Viro [this message]
2005-10-30 22:32 ` Al Viro
2005-10-30 22:29 ` Stephen Rothwell
2005-10-31 0:53 ` Paul Mackerras
2005-10-31 0:57 ` Al Viro
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