From: Andrew Morton <akpm@linux-foundation.org>
To: Randy Dunlap <rdunlap@xenotime.net>
Cc: Alexey Dobriyan <adobriyan@gmail.com>,
linux-kernel@vger.kernel.org, behlendorf1@llnl.gov,
oleg@redhat.com
Subject: Re: [PATCH] remove abs64()
Date: Tue, 12 Apr 2011 14:10:40 -0700 [thread overview]
Message-ID: <20110412141040.a5706346.akpm@linux-foundation.org> (raw)
In-Reply-To: <20110412140726.3f4f2a7b.rdunlap@xenotime.net>
On Tue, 12 Apr 2011 14:07:26 -0700
Randy Dunlap <rdunlap@xenotime.net> wrote:
> > --- a/include/linux/kernel.h
> > +++ b/include/linux/kernel.h
> > @@ -143,28 +143,27 @@ extern int _cond_resched(void);
> >
> > #define might_sleep_if(cond) do { if (cond) might_sleep(); } while (0)
> >
> > -/*
> > - * abs() handles unsigned and signed longs, ints, shorts and chars. For all
> > - * input types abs() returns a signed long.
> > - * abs() should not be used for 64-bit types (s64, u64, long long) - use abs64()
> > - * for those.
> > - */
> > -#define abs(x) ({ \
> > - long ret; \
> > - if (sizeof(x) == sizeof(long)) { \
> > - long __x = (x); \
> > - ret = (__x < 0) ? -__x : __x; \
> > - } else { \
> > - int __x = (x); \
> > - ret = (__x < 0) ? -__x : __x; \
> > - } \
> > - ret; \
> > - })
> > -
> > -#define abs64(x) ({ \
> > - s64 __x = (x); \
> > - (__x < 0) ? -__x : __x; \
> > - })
> > +#define abs(x) \
> > +({ \
> > + typeof(x) _x = (x); \
> > + \
> > + __builtin_choose_expr( \
> > + __builtin_types_compatible_p(typeof(_x), signed char), \
> > + (unsigned char)({ _x < 0 ? -_x : _x; }), \
> > + __builtin_choose_expr( \
> > + __builtin_types_compatible_p(typeof(_x), short), \
> > + (unsigned short)({ _x < 0 ? -_x : _x; }), \
> > + __builtin_choose_expr( \
> > + __builtin_types_compatible_p(typeof(_x), int), \
> > + (unsigned int)({ _x < 0 ? -_x : _x; }), \
> > + __builtin_choose_expr( \
> > + __builtin_types_compatible_p(typeof(_x), long), \
> > + (unsigned long)({ _x < 0 ? -_x : _x; }), \
> > + __builtin_choose_expr( \
> > + __builtin_types_compatible_p(typeof(_x), long long), \
> > + (unsigned long long)({ _x < 0 ? -_x : _x; }), \
> > + _x))))); \
> > +})
>
> that is better?
I think so.
It's a bit concerning that it changes the return type of abs().
next prev parent reply other threads:[~2011-04-12 21:11 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-04-12 21:00 [PATCH] remove abs64() Alexey Dobriyan
2011-04-12 21:07 ` Randy Dunlap
2011-04-12 21:10 ` Andrew Morton [this message]
2011-04-12 21:16 ` Alexey Dobriyan
2011-04-12 21:33 ` Andrew Morton
2011-04-12 21:40 ` Randy Dunlap
2011-04-12 21:14 ` Alexey Dobriyan
2011-04-13 14:27 ` Oleg Nesterov
2011-04-13 18:48 ` Andrew Morton
2011-04-13 20:20 ` Oleg Nesterov
2011-04-13 20:26 ` Andrew Morton
2011-04-13 20:36 ` Alexey Dobriyan
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20110412141040.a5706346.akpm@linux-foundation.org \
--to=akpm@linux-foundation.org \
--cc=adobriyan@gmail.com \
--cc=behlendorf1@llnl.gov \
--cc=linux-kernel@vger.kernel.org \
--cc=oleg@redhat.com \
--cc=rdunlap@xenotime.net \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).