From: Andreas Schwab <schwab@redhat.com>
To: "David Laight" <David.Laight@ACULAB.COM>
Cc: "David Daney" <ddaney@caviumnetworks.com>,
"Coly Li" <bosong.ly@taobao.com>,
Wang Cong <xiyou.wangcong@gmail.com>,
Jeremy Fitzhardinge <jeremy@goop.org>,
linuxppc-dev@lists.ozlabs.org, linux-kernel@vger.kernel.org,
Yong Zhang <yong.zhang0@gmail.com>
Subject: Re: [PATCH 2/7] PowerPC: add unlikely() to BUG_ON()
Date: Fri, 28 Jan 2011 11:14:16 +0100 [thread overview]
Message-ID: <m31v3xxrlz.fsf@redhat.com> (raw)
In-Reply-To: <AE90C24D6B3A694183C094C60CF0A2F6D8AC2D__37237.0892241181$1296205746$gmane$org@saturn3.aculab.com> (David Laight's message of "Fri, 28 Jan 2011 09:05:59 -0000")
"David Laight" <David.Laight@ACULAB.COM> writes:
> Also, as (I think) in some of the generated code quoted,
> use of __builtin_expect() with a boolean expression can
> force some versions of gcc to generate the integer
> value of the expression
That's more likely a side effect of the definition of likely/unlikely:
they expand to !!(x).
Andreas.
--
Andreas Schwab, schwab@redhat.com
GPG Key fingerprint = D4E8 DBE3 3813 BB5D FA84 5EC7 45C6 250E 6F00 984E
"And now for something completely different."
WARNING: multiple messages have this Message-ID (diff)
From: Andreas Schwab <schwab@redhat.com>
To: "David Laight" <David.Laight@ACULAB.COM>
Cc: Jeremy Fitzhardinge <jeremy@goop.org>,
Coly Li <bosong.ly@taobao.com>,
David Daney <ddaney@caviumnetworks.com>,
linux-kernel@vger.kernel.org, Yong Zhang <yong.zhang0@gmail.com>,
Wang Cong <xiyou.wangcong@gmail.com>,
linuxppc-dev@lists.ozlabs.org
Subject: Re: [PATCH 2/7] PowerPC: add unlikely() to BUG_ON()
Date: Fri, 28 Jan 2011 11:14:16 +0100 [thread overview]
Message-ID: <m31v3xxrlz.fsf@redhat.com> (raw)
In-Reply-To: <AE90C24D6B3A694183C094C60CF0A2F6D8AC2D__37237.0892241181$1296205746$gmane$org@saturn3.aculab.com> (David Laight's message of "Fri, 28 Jan 2011 09:05:59 -0000")
"David Laight" <David.Laight@ACULAB.COM> writes:
> Also, as (I think) in some of the generated code quoted,
> use of __builtin_expect() with a boolean expression can
> force some versions of gcc to generate the integer
> value of the expression
That's more likely a side effect of the definition of likely/unlikely:
they expand to !!(x).
Andreas.
--
Andreas Schwab, schwab@redhat.com
GPG Key fingerprint = D4E8 DBE3 3813 BB5D FA84 5EC7 45C6 250E 6F00 984E
"And now for something completely different."
next prev parent reply other threads:[~2011-01-28 10:14 UTC|newest]
Thread overview: 22+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-01-27 12:12 [PATCH 0/6] use BUG_ON correctly, v2 Coly Li
2011-01-27 12:12 ` [PATCH 1/7] MIPS: add unlikely() to BUG_ON() Coly Li
2011-01-27 17:50 ` David Daney
2011-01-28 10:41 ` Coly Li
2011-01-27 12:12 ` [PATCH 2/7] PowerPC: " Coly Li
2011-01-27 17:57 ` David Daney
2011-01-27 17:57 ` David Daney
2011-01-27 20:04 ` Scott Wood
2011-01-27 20:04 ` Scott Wood
2011-01-27 20:32 ` David Daney
2011-01-27 20:32 ` David Daney
2011-01-28 9:05 ` David Laight
2011-01-28 9:05 ` David Laight
[not found] ` <AE90C24D6B3A694183C094C60CF0A2F6D8AC2D__37237.0892241181$1296205746$gmane$org@saturn3.aculab.com>
2011-01-28 10:14 ` Andreas Schwab [this message]
2011-01-28 10:14 ` Andreas Schwab
2011-01-28 11:02 ` Coly Li
2011-01-28 11:02 ` Coly Li
2011-01-27 12:12 ` [PATCH 3/7] dma: use BUG_ON correctly in iop-adma.c Coly Li
2011-01-27 12:12 ` [PATCH 4/7] dma: use BUG_ON correctly in mv_xor.c Coly Li
2011-01-27 12:12 ` [PATCH 5/7] dma: use BUG_ON correctly in ppc4xx/adam.c Coly Li
2011-01-27 12:12 ` [PATCH 6/7] wl_cfg80211.c: use BUG_ON correctly Coly Li
2011-01-27 12:12 ` [PATCH 7/7] scsi_lib.c: " Coly Li
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