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Date: Tue, 23 Feb 2010 09:34:04 -0800
From: "H. Peter Anvin" <hpa@zytor.com>
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Subject: Re: [PATCH] x86: Add optimized popcnt variants
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To: Borislav Petkov <bp@amd64.org>
Cc: Michal Marek <mmarek@suse.cz>, linux-kbuild <linux-kbuild@vger.kernel.org>, Peter Zijlstra <peterz@infradead.org>, Andrew Morton <akpm@linux-foundation.org>, Wu Fengguang <fengguang.wu@intel.com>, LKML <linux-kernel@vger.kernel.org>, Jamie Lokier <jamie@shareable.org>, Roland Dreier <rdreier@cisco.com>, Al Viro <viro@ZenIV.linux.org.uk>, "linux-fsdevel@vger.kernel.org" <linux-fsdevel@vger.kernel.org>, Ingo Molnar <mingo@elte.hu>, Brian Gerst <brgerst@gmail.com>

On 02/23/2010 07:58 AM, Borislav Petkov wrote:
>
> Hmm, we cannot do that with the current design since __arch_hweight64
> is being inlined into every callsite and AFAICT we would have to build
> every callsite with "-fcall-saved-rdi" which is clearly too much. The
> explicit "=D" dummy constraint is straightforward, instead.
>

Uh... the -fcall-saved-rdi would go with all the other ones.  Assuming 
it can actually work and that gcc doesn't choke on an inbound argument 
being saved.

	-hpa