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Re: PATCH: Add ifunc attribute


On Wed, Jun 24, 2009 at 8:09 AM, Richard
Guenther<richard.guenther@gmail.com> wrote:
> On Wed, Jun 24, 2009 at 4:54 PM, Richard Henderson<rth@twiddle.net> wrote:
>> On 06/24/2009 03:22 AM, Paolo Bonzini wrote:
>>>
>>> Looks a bit too like DWIM and too little like a specification. I think I
>>> prefer option 1, in some cases you may want to call the trampoline and
>>> having it accessible can help. With
>>>
>>> __typeof (foo) *
>>> __attribute__ ((ifunc ("foo")))
>>> foo_ifunc (void)
>>> {
>>> <return address of foo_{1,2,3}>
>>> }
>>>
>>> you could call foo_ifunc if you wish in principle, and the header file
>>> only has the prototype of foo as expected.
>>
>> I think I have to agree with you, Paolo. ?This example is the sort of
>> thing I'd expect to actually be writing.
>
> You wouldn't call foo_ifunc but maybe one of foo_{1,2,3} directly. ?At
> least for non-trivial foo_ifunc implementations.
>
> I still fail to see why we need the ifunc argument here though.
>
> __typeof (foo) *
> __attribute__((ifunc))
> foo_ifunc (void) asm("foo")
> {
> ?<return address of foo_{1,2,3}>
> }
>
> works for me. ?Adding __attribute__((alias("foo_ifunc"))) should
> make an alias available that you could call directly if you really
> want to.
>

Is asm("foo") required for ifunc function?


-- 
H.J.


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