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Date: Wed, 02 Dec 2009 14:59:42 +0000
From: "Jan Beulich" <JBeulich@novell.com>
To: "Avi Kivity" <avi@redhat.com>
Cc: <a.p.zijlstra@chello.nl>, "Ingo Molnar" <mingo@elte.hu>,
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Subject: Re: [tip:core/locking] locking, x86: Slightly shorten	
	 __ticket_spin_trylock()
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>>> Avi Kivity <avi@redhat.com> 02.12.09 15:36 >>>
>On 12/02/2009 04:25 PM, Jan Beulich wrote:
>>>>> Avi Kivity<avi@redhat.com>  02.12.09 15:12>>>
>>>>>          
>>> Wouldn't 'u8 ret', as an additional argument be sufficient? gcc still
>>> ought to be able to use the same register for new and ret if we remove
>>> the early clobber.
>>>      
>> We can't (validly) remove the early-clobber, otherwise the compiler
>> would be permitted to use a register also used for addressing the lock
>> structure for "new".
>>    
>
>I meant for 'ret'.

But unless you drop the early-clobber on new, the compiler will have
to allocate another register, which I think is not desirable here.

Jan