Re: [Qemu-devel] [PATCH for-2.5 08/30] m68k: update CPU flags management

[Laurent Vivier]

Le 12/08/2015 23:19, Richard Henderson a écrit :
> On 08/12/2015 01:56 PM, Laurent Vivier wrote:
>>>> -DEF_HELPER_2(flush_flags, void, env, i32)
>>>> +DEF_HELPER_2(flush_flags, i32, env, i32)
>>>
>>> Modify to use DEF_HELPER_FLAGS while you're at it.  At the moment it
>>> reads some globals, but doesn't write any, or have any other side
>>> effects.
>>
>> It writes "env->cc_x", so I guess I can't use DEF_HELPER_FLAGS ?
> 
> Ah, missed that.  So, no, not usefully.
> 
>>> That const needs to be freed.
>>
>> perhaps I'm wrong, what I had understood is:
>>
>> tcg_const_i32() creates a tcg_temp_new_i32(), and tcg_temp_new_i32() are
>> automatically freed at end of tcg block (whereas tcg_const_local adn
>> tcg_temp_local are not).
> 
> They are freed at the end of a basic block.  But the total number of
> temps affects the speed of the tcg code generator.  So you can improve
> the speed of qemu by freeing temporaries that are no longer needed.

OK, thank you. I was wondering if it is useful to free temp or not...

Laurent