Date: Sun, 10 Apr 2005 15:21:35 +0200 From: Ulrich Spoerlein <q@uni.de> To: Daniel Ellard <ellard@eecs.harvard.edu> Cc: freebsd-current@freebsd.org Subject: Re: smbfs bug introduced at smbfs_vnops.c:1.58 Message-ID: <20050410132135.GB774@galgenberg.net> In-Reply-To: <20050410074009.N66651@bowser.eecs.harvard.edu> References: <200504100251.j3A2pLEH055107@sana.init-main.com> <20050410092417.GA774@galgenberg.net> <20050410074009.N66651@bowser.eecs.harvard.edu>
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On Sun, 10.04.2005 at 07:45:50 -0400, Daniel Ellard wrote:
> Certainly this is undesireable, but from what I can tell this
> happens because "a" is a dead variable and removed. (Look at
> the asm output and you'll see what I mean.) So it's debatable
> whether this is a bug.
>=20
> If you change the -O to -g, then the code for "a" is not
> removed -- but there's still no warning. I think this is
> a bug, because if the expression wasn't an innocuous a+=3D1
> it could be a real problem if the variable wasn't removed.
> But people will also argue about this..
You are right, using something like this:
#include <stdio.h>
int main(void) {
int a,b;
a+=3D1;
b=3D1+a;
printf("%d\n", b);
return (0);
}
I get a warning:
% cc -O -W -Wall -Wuninitialized foo.c
foo.c: In function `main':
foo.c:3: warning: 'a' might be used uninitialized in this function
Sorry for the noise then. /me needs to learn asm some day.
Ulrich Sp=F6rlein
--=20
PGP Key ID: F0DB9F44 Encrypted mail welcome!
Fingerprint: F1CE D062 0CA9 ADE3 349B 2FE8 980A C6B5 F0DB 9F44
Ok, which part of "Ph'nglui mglw'nafh Cthulhu R'lyeh wgah'nagl fhtagn."
didn't you understand?
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