From: Linus Torvalds <torvalds@linux-foundation.org>
To: Andi Kleen <andi@firstfloor.org>
Cc: Ingo Molnar <mingo@elte.hu>, Jeff Garzik <jeff@garzik.org>,
LKML <linux-kernel@vger.kernel.org>,
Thomas Gleixner <tglx@linutronix.de>,
Ingo Molnar <mingo@redhat.com>, "H. Peter Anvin" <hpa@zytor.com>,
x86@kernel.org
Subject: Re: [PATCH] X86-32: Let gcc decide whether to inline memcpy was Re: New x86 warning
Date: Wed, 22 Apr 2009 13:56:54 -0700 (PDT) [thread overview]
Message-ID: <alpine.LFD.2.00.0904221354320.3101@localhost.localdomain> (raw)
In-Reply-To: <8763gxoz50.fsf_-_@basil.nowhere.org>
On Wed, 22 Apr 2009, Andi Kleen wrote:
>
> Modern gcc (and that is all that is supported now) should be able to
> generate this code on its own already. So if you call __builtin_* it
> will just work (that is what 64bit does) without that explicit code.
Last time we tried that, it wasn't true. Gcc wouldn't inline even trivial
cases of constant sizes.
I do not recall what gcc version that was all about, and maybe the
versions we now require are all modern enough that it isn't an issue, but
I'd want somebody to actually _verify_ that the oldest version we support
does an ok job, and doesn't do stupid things for constant-sized memcpy's.
> IMHO it's long overdue to do this for 32bit too.
With actual testing, I'll happily merge this.
Linus
next prev parent reply other threads:[~2009-04-22 21:04 UTC|newest]
Thread overview: 19+ messages / expand[flat|nested] mbox.gz Atom feed top
2009-04-22 6:46 Jeff Garzik
2009-04-22 7:01 ` Ingo Molnar
2009-04-22 8:45 ` [PATCH] X86-32: Let gcc decide whether to inline memcpy was " Andi Kleen
2009-04-22 18:00 ` [tip:x86/asm] x86: use __builtin_memcpy() on 32 bits tip-bot for Andi Kleen
2009-04-22 20:56 ` Linus Torvalds [this message]
2009-04-22 21:15 ` [PATCH] X86-32: Let gcc decide whether to inline memcpy was Re: New x86 warning Andi Kleen
2009-04-22 21:19 ` Linus Torvalds
2009-04-22 22:04 ` Andi Kleen
2009-04-23 6:08 ` fresh data was " Andi Kleen
2009-04-23 6:36 ` Ingo Molnar
2009-04-23 7:37 ` Andi Kleen
2009-04-23 6:30 ` Ingo Molnar
2009-04-23 7:43 ` Andi Kleen
2009-04-22 23:49 ` Joe Damato
2009-04-23 1:48 ` H. Peter Anvin
2009-04-23 21:22 ` Joe Damato
2009-04-23 22:09 ` H. Peter Anvin
2009-04-24 8:44 ` Andi Kleen
2009-04-23 6:09 ` Andi Kleen
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