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From: David Howells <dhowells@redhat.com>
To: Josh Triplett <josh@joshtriplett.org>
Cc: dhowells@redhat.com, Arnd Bergmann <arnd@arndb.de>,
	Andrew Morton <akpm@linux-foundation.org>,
	linux-arch@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH RESEND] bug: When !CONFIG_BUG, simplify WARN_ON_ONCE and family
Date: Mon, 24 Feb 2014 12:09:11 +0000	[thread overview]
Message-ID: <10646.1393243751@warthog.procyon.org.uk> (raw)
In-Reply-To: <20140224084437.GG20680@thin>

Josh Triplett <josh@joshtriplett.org> wrote:

> > This means we actually want BUG() to end with __builtin_unreachable()
> > as in the CONFIG_BUG=y case, and also ensure it actually is
> > unreachable. As I have shown in [1], the there is a small overhead
> > of doing this in terms of code size.
> 
> I agree that allowing BUG() to become a no-op seems suboptimal, if only
> because of the resulting warnings and mis-optimizations.  However, I
> think the overhead could be cut down massively, such that BUG() just
> compiles down to a one-byte undefined instruction.  (__builtin_trap()
> might do the right thing here; worth checking.)

Is it possible to use an inline function with an empty body in this?  Let the
compiler prune away all the arguments?

David

  parent reply	other threads:[~2014-02-24 12:09 UTC|newest]

Thread overview: 13+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2014-02-22 19:23 Josh Triplett
2014-02-22 21:54 ` Randy Dunlap
2014-02-22 22:31   ` Josh Triplett
2014-02-22 22:36     ` Josh Triplett
2014-02-24  8:02 ` Arnd Bergmann
2014-02-24  8:44   ` Josh Triplett
2014-02-24  9:35     ` Arnd Bergmann
2014-02-24 12:09   ` David Howells [this message]
2014-02-24 12:42     ` Arnd Bergmann
2014-02-24 13:16       ` One Thousand Gnomes
2014-02-24 13:39         ` Arnd Bergmann
2014-02-24 23:17   ` Andrew Morton
2014-02-25  3:06     ` Josh Triplett

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