Re: [boost] [config] [chrono] consexpr workaround

Subject: Re: [boost] [config] [chrono] consexpr workaround
From: Krzysztof Czainski (1czajnik_at_[hidden])
Date: 2013-03-21 04:33:16

2013/3/20 Vicente J. Botet Escriba <vicente.botet_at_[hidden]>

> Le 20/03/13 18:57, Krzysztof Czainski a écrit :
>
>  2013/3/19 Vicente J. Botet Escriba <vicente.botet_at_[hidden]>
>>
>>  Le 19/03/13 22:25, Krzysztof Czainski a écrit :
>>>
>>>   2013/3/19 Vicente J. Botet Escriba <vicente.botet_at_[hidden]>
>>>
>>>>   Le 19/03/13 17:00, Krzysztof Czainski a écrit :
>>>>
>>>>> So now, narrowing the question to use of
>>>>>
>>>>>   BOOST_CONSTEXPR in Boost.Chrono:
>>>>>
>>>>>> 1. Could the functions marked BOOST_CONSTEXPR be also marked inline
>>>>>> (and
>>>>>> this question probably applies to other Boost libraries)?
>>>>>>
>>>>>
They already are inline, and I had missed that, sorry for the noise ;-)

>  2. This is probably related only to the TI compiler I use: marking
>>>>>> constructors inline doesn't work for me, they need to be marked
>>>>>> BOOST_FORCEINLINE (I've configured it), so could the constexpr
>>>>>> constructors
>>>>>> in Boost.Chrono be marked with BOOST_FORCEINLINE as well?
>>>>>>
>>>>>>    Hi,
>>>>>>
>>>>>>  could you point me to the cases that need to be inlined that the
>>>>> compiler
>>>>> doesn't inline by itself?
>>>>>
>>>>> Please create a ticket so that I don't forget it.
>>>>>
>>>>> Best,
>>>>> Vicente
>>>>>
>>>>>  Hi Vincente,
>>>>
>>>> Thanks for looking at this.
>>>>
>>>> I think this TI compiler doesn't inline anything not marked inline.
>>>> Additionally it doesn't seem to inline constructors, unless marked
>>>> BOOST_FORCEINLINE [1].
>>>>
>>>> So if there aren't any thoughts against this, I suggest all constexpr
>>>> functions in duration and time_point to be marked inline, and constexpr
>>>> constructors to be marked forceinline. Or should I just touch the cases,
>>>> that need to be inline in my example situation? I'd prefer the former
>>>> ;-)
>>>>
>>>> I'll create a ticket and supply a patch shortly.
>>>>
>>>> Cheers,
>>>> Kris
>>>>
>>>> [1] The TI compiler supports the GCC extension attribute forceinline.
>>>>
>>>>
>>>>   What makes the consexpr functions different from the other functions
>>>>
>>> that the compiler could inline and it doesn't?
>>> Are you proposing that all the boost libraries uses BOOST_FORCEINLINE on
>>> all the functions defined in the declaration?
>>>
>>> Vicente
>>>
>>>  I misread those files, all constexpr function are already inline ;-)
>>
>> So I'm only talking about constructors (3 constructors of class duration,
>> and 3 constructors of class time_point), and constexpr doesn't have much
>> to
>> do with this, sorry for the noise.
>>
>
> I don't understand the conditions that need to use BOOST_FORCEINLINE .

This problematic TI compiler doesn't inline any constructors, unless marked
BOOST_FORCEINLINE. I haven't identified any other conditions requiring
BOOST_FORCEINLINE yet ;-)

> There are a lot of functions that are not marked inline and I expect the
> compiler to inline as e.g.
>
>         BOOST_CONSTEXPR
>         duration time_since_epoch() const
>         {
>             return d_;
>         }
>
> Should I add BOOST_FORCEINLINE to this kind of code also?

FWIU so far, no. Only constructors need BOOST_FORCEINLINE.

>  Ticket #8318 created with a patch.
>>
>>  I will apply the patch soon.
>

Thanks,
Kris