[fpc-devel] Patch for rtl/inc/rtti.inc

[Florian Klaempfl]

Daniël Mantione schrieb:
> 
> 
> Op Sun, 14 Sep 2008, schreef Florian Klaempfl:
> 
>> Daniël Mantione schrieb:
>>>
>>>
>>> Op Sun, 14 Sep 2008, schreef Jonas Maebe:
>>>
>>>>
>>>> On 14 Sep 2008, at 14:49, Markus Beth wrote:
>>>>
>>>>> this patch rewrites code of ArrayRTTI and fpc_Copy to allow the 
>>>>> compiler to generate faster code (at least on i386).
>>>>> The change in ArrayRTTI yields a performance gain of ~4% for our 
>>>>> real world application on a 3 GHz Intel Xeon.
>>>>> The change in fpc_Copy is completely untestet because I don't know 
>>>>> when this compilerproc is called. Maybe someone who knows can hack 
>>>>> a quick benchmark...
>>>>
>>>> I don't think it's a good idea to start manually adding loop 
>>>> induction variables to many routines in the rtl. It makes the code 
>>>> less maintainable, and at one point the compilation process itself 
>>>> will/should do that by itself.
>>>
>>> This patch should get applied. It's debatable wether additions are 
>>> hard to maintain than multiplications and it may take years before 
>>> the compiler can do that optimization. That doesn't mean we should 
>>> optimize anything manually, but fpc_copy is definately speed critical 
>>> code for things like widestrings.
>>
>> Shall I implement automatic simple loop induction variable tonight :)?
> 
> No, do it in a proper and maintainable way :)

I think this could be done already. DFA generates the necessary 
definition information. Expressions being candidates must be search anyways.