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Re: Patch: speed up compiler a little bit by optimizing lookup_attribute() and is_attribute_p()
On Tue, Jun 21, 2011 at 2:20 PM, Dimitrios Apostolou <jimis@gmx.net> wrote:
> FWIW I think that most of the speedup is due to inlining lookup_attribute().
> I got almost the same by applying only the attached very simple patch, since
> strlen() was called too often (according to the profile at [1]). I used the
> always_inline attribute to avoid using a macro.
>
> I was going to send it together with some other changes I'm trying and after
> proper measurements. Anyway, better late than ever. Thanks to Christophe
> Jaillet (CC'd) for pointing it to me.
Don't use always_inline, and also inline the check for no present attributes.
Richard.
>
> Thanks,
> Dimitris
>
>
> [1] http://gcc.gnu.org/wiki/OptimisingGCC
>
>
>
>
> On Tue, 21 Jun 2011, Richard Guenther wrote:
>
>> On Tue, Jun 21, 2011 at 12:17 PM, Nicola Pero
>> <nicola.pero@meta-innovation.com> wrote:
>>>>>
>>>>> This patch speeds up the C/C++/ObjC/ObjC++ compiler a little bit by
>>>>> optimizing
>>>>> lookup_attribute() and is_attribute_p(). ?The main change is that these
>>>>> functions
>>>>> are now inline.
>>>>
>>>> I don't think this is a good idea.
>>>
>>> Can you explain why ? ?You never do in your response :-)
>>>
>>> I'm guessing it's because you think the inline functions are too big and
>>> that's
>>> counter-productive ?
>>
>> Yes.
>>
>>>> For this case I'd factor out the NULL attribute list check into an
>>>> inline function and keeping the non-NULL attribute list pieces
>>>> out-of-line.
>>>
>>> Ok ... so is this what you'd like - the common, hot case in the inline
>>> function,
>>> and the less common, cold case in the out-of-line one ? :-)
>>
>> Right.
>>
>>> That makes sense - I'll try that out tonight (it takes a few hours to run
>>> all
>>> the benchmarks). ;-)
>>
>> Thanks.
>>
>>>
>>>> Does it work for all languages? ?And yes, I agree it would be nice to
>>>> canonicalize to the form without _s even in the attribute lists itself.
>>>> Or go one step further - do not store an identifier but an enum as we
>>>> in fact only ever insert known attributes into the list (which should
>>>> be a VEC instead, possibly even sorted to allow binary search).
>>>
>>> Sure ... one step at a time. :-)
>>
>> Of course ;)
>>
>> Richard.
>>
>>> Thanks
>>>
>>>
>