From: Konstantin Khlebnikov <khlebnikov@openvz.org>
To: Cong Wang <xiyou.wangcong@gmail.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
"linux-arch@vger.kernel.org" <linux-arch@vger.kernel.org>,
Andrew Morton <akpm@linux-foundation.org>
Subject: Re: [PATCH 1/4] compiler.h: introduce unused_expression() macro
Date: Wed, 25 Apr 2012 15:54:31 +0400 [thread overview]
Message-ID: <4F97E5F7.9030305@openvz.org> (raw)
In-Reply-To: <4F97E550.4060208@gmail.com>
Cong Wang wrote:
> On 04/25/2012 07:26 PM, Konstantin Khlebnikov wrote:
>> Sometimes we want to check some expressions correctness in compile-time without
>> generating extra code. "(void)(e)" does not work if expression has side-effects.
>> This patch introduces macro unused_expression() which helps in this situation.
>>
>
> Interesting, I am wondering why gcc doesn't eliminate the code as we
> pass either -O2 or -Os to it.
It cannot do this if expression has some side-effects, for example if it contains BUG().
next prev parent reply other threads:[~2012-04-25 11:54 UTC|newest]
Thread overview: 30+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-04-25 11:26 [PATCH 1/4] compiler.h: introduce unused_expression() macro Konstantin Khlebnikov
2012-04-25 11:26 ` [PATCH 2/4] bug: completely remove code of disabled VM_BUG_ON() Konstantin Khlebnikov
2012-04-25 14:40 ` Geert Uytterhoeven
2012-04-26 22:32 ` Andrew Morton
2012-04-27 5:17 ` Geert Uytterhoeven
2012-04-27 7:07 ` Andrew Morton
2012-04-25 11:26 ` [PATCH 3/4] bug: completely remove code of disabled BUG_ON() Konstantin Khlebnikov
2012-04-25 11:26 ` Konstantin Khlebnikov
2012-04-25 11:26 ` [PATCH 4/4] bug: mark disabled BUG() as unreachable() code Konstantin Khlebnikov
2012-04-25 11:26 ` Konstantin Khlebnikov
2012-04-28 5:10 ` Konstantin Khlebnikov
2012-04-28 5:21 ` Linus Torvalds
2012-04-28 5:21 ` Linus Torvalds
2012-04-28 6:14 ` Andrew Morton
2012-04-25 11:51 ` [PATCH 1/4] compiler.h: introduce unused_expression() macro Cong Wang
2012-04-25 11:54 ` Konstantin Khlebnikov [this message]
2012-04-25 11:54 ` Konstantin Khlebnikov
2012-04-26 22:29 ` Andrew Morton
2012-04-27 9:55 ` Konstantin Khlebnikov
2012-04-27 21:53 ` Andrew Morton
2012-04-26 22:34 ` Andrew Morton
2012-04-26 22:34 ` Andrew Morton
2012-04-27 7:54 ` Konstantin Khlebnikov
2012-04-27 8:16 ` H. Peter Anvin
2012-04-28 3:50 ` Konstantin Khlebnikov
2012-04-28 3:50 ` Konstantin Khlebnikov
2012-04-28 7:06 ` [PATCH v2 1/2] bug: introduce BUILD_BUG_ON_INVALID() macro Konstantin Khlebnikov
2012-04-28 7:06 ` Konstantin Khlebnikov
2012-04-28 7:06 ` [PATCH v2 2/2] bug: completely remove code of disabled VM_BUG_ON() Konstantin Khlebnikov
2012-04-28 7:06 ` Konstantin Khlebnikov
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