On Fri, Aug 26, 2011 at 10:37 AM, Sriraman Tallam <tmsri...@google.com> wrote:
> On Fri, Aug 26, 2011 at 10:24 AM, H.J. Lu <hjl.to...@gmail.com> wrote:
>> On Fri, Aug 26, 2011 at 10:17 AM, Sriraman Tallam <tmsri...@google.com>
>> wrote:
>>> On Fri, Aug 26, 2011 at 10:10 AM, H.J. Lu <hjl.to...@gmail.com> wrote:
>>>> On Fri, Aug 26, 2011 at 10:06 AM, Sriraman Tallam <tmsri...@google.com>
>>>> wrote:
>>>>> On Thu, Aug 25, 2011 at 6:02 PM, H.J. Lu <hjl.to...@gmail.com> wrote:
>>>>>> On Thu, Aug 25, 2011 at 5:37 PM, Sriraman Tallam <tmsri...@google.com>
>>>>>> wrote:
>>>>>>> Hi,
>>>>>>>
>>>>>>> Thanks for all the comments. I am attaching a new patch
>>>>>>> incorporating all of the changes mentioned, mainly :
>>>>>>>
>>>>>>> 1) Make __cpu_indicator_init a constructor in libgcc and guard to call
>>>>>>> it only once.
>>>>>>
>>>>>> This is unreliable and you don't need 3 symbols from libgcc. You can use
>>>>>
>>>>> Do you mean it is unreliable because of the constructor ordering problem?
>>>>>
>>>>
>>>> You do not have total control when __cpu_indicator_init is called.
>>>
>>> Like discussed before, for non-ctor functions, which in my opinion is
>>> the common use case, it works out great because __cpu_indicator_init
>>> is guaranteed to be called and I save doing an extra check. It is only
>>>> for other ctors where this is a problem. So other ctors call this
>>> explicitly. What did I miss?
>>>
>>
>> I have
>>
>> static void foo ( void ) __attribute__((constructor));
>>
>> static void foo ( void )
>> {
>> ...
>> call bar ();
>> ...
>> }
>>
>> in my application. bar () uses those cpu specific functions.
>> foo () is called before __cpu_indicator_init. Since IFUNC
>> returns the cpu specific function address only for the
>> first call, the proper cpu specific functions will never be used.
>
> Please correct me if I am wrong since I did not follow the IFUNC part
> you mentioned. However, it looks like this could be solved with
> adding an explicit call to __cpu_indicator_init from within the ctor
> foo. To me, it seems like the pain of adding this call explicitly in
> other ctors is worth it because it works cleanly for non-ctors.
>
> static void foo ( void ) __attribute__((constructor));
>
> static void foo ( void )
> {
> ...
> __cpu_indicator_init ();
> call bar ();
> ...
> }
>
> Will this work?
>
>
Do I have to do that in every constructor, including
C++ global constructors? It is ridiculous.
--
H.J.
