From: Serge Belyshev <belyshev@depni.sinp.msu.ru>
To: Andi Kleen <andi@firstfloor.org>
Cc: Andi Kleen <ak@suse.de>,
patches@x86-64.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH]: x86_64: Remove unnecessary cast in prefetch()
Date: Sun, 16 Sep 2007 01:16:18 +0400 [thread overview]
Message-ID: <87ejgziq8t.fsf@depni.sinp.msu.ru> (raw)
In-Reply-To: <20070915200117.GC14501@one.firstfloor.org> (Andi Kleen's message of "Sat\, 15 Sep 2007 22\:01\:17 +0200")
Andi Kleen <andi@firstfloor.org> writes:
...
>> to make kernel work with GCC 4.3 and above. (Also note that gcc 4.2 already
>> smart enough to break that code, but kernel is just lucky currently).
>
> How would it break the code exactly? It more sounded like an optimization
> to me. Would it generate incorrect code without it?
See http://gcc.gnu.org/PR33294 for testcase which fails if compiled with gcc 4.2
and above. Yes, incorrect code can be generated without the patch as demonstrated by
testcase, but i didn't analyze why kernel appears to work with 4.2 currently.
prev parent reply other threads:[~2007-09-15 21:16 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2007-09-06 21:27 Serge Belyshev
2007-09-07 7:18 ` Andi Kleen
2007-09-15 6:40 ` Serge Belyshev
2007-09-15 20:01 ` Andi Kleen
2007-09-15 21:16 ` Serge Belyshev [this message]
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