Re: User directed Function Multiversioning via Function Overloading (issue5752064)

[Sriraman Tallam <tmsriram at google dot com>]

Hi Jason,

   I have made all the changes you mentioned and attached the new
patch.  Summary of the important things changed:

* The versions are collected at declaration time itself now.
* extern "C" functions are disallowed from being versions for now.
extern "C" functions have to be handled exactly like how the C
front-end would handle versioned functions. I will do this when I get
to the C front-end.
* Finalizing cgraph nodes is removed from front-end code.


Thanks,
-Sri.


On Wed, Oct 31, 2012 at 7:02 AM, Jason Merrill <jason@redhat.com> wrote:
> On 10/30/2012 05:49 PM, Sriraman Tallam wrote:
>>
>> AFAIU, this should not be a problem. For duplicate declarations,
>> duplicate_decls should merge them and they should never be seen here.
>> Did I miss something?
>
>
> With extern "C" functions you can have multiple declarations of the same
> function in different namespaces that are not duplicates, but still match.
> And I can't think what that test is supposed to be catching, anyway.
>
>
>> No, I thought about this but I did not want to handle this case in
>> this iteration. The dispatcher is created only once and if more
>> functions are declared later, they will not be dispatched atleast in
>> this iteration.
>
>
> I still think that instead of collecting the set of functions in overload
> resolution, they should be collected at declaration time and added to a
> vector in the cgraph information for use when generating the body of the
> dispatcher.
>
>
>> You talked about doing the dispatcher
>> building later, but I did it here since I am doing it only once.
>
>
> I still don't think this is the right place for it.
>
>
>> dispatcher_node does not have a body  until it is generated in
>> cgraphunit.c, so cgraph does not mark this field before this is
>> processed in cgraph_analyze_function.
>
>
> That seems like something to address in your cgraph changes.
>
> Jason
>

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