[Bug c/40528] Add a new ifunc attribute

["hjl dot tools at gmail dot com" <gcc-bugzilla at gcc dot gnu dot org>]

------- Comment #4 from hjl dot tools at gmail dot com  2009-06-24 16:07 -------
(In reply to comment #3)
> Option 2) is certainly the least intrusive in the compiler and you can use it
> even with foo's prototype and calling it from the same CU, just use asm.
> __typeof (foo) *
> __attribute__ ((ifunc))
> foo_ifunc (void) __asm ("foo")
> {
>   <return address of foo_{1,2,3}>
> }
> If you don't have a prototype, you can use the variant originally mentioned in
> option 2).  Most users will wrap this stuff in a macro anyway and in that case
> whether they use just an attribute or attribute and __asm is not a big deal.

I think we enforce type check on return value of ifunc function.
This is a user feature. Option 3 is the most user friendly. We
only need to change the return type to a pointer to function
prototype inside ifunc function body. I have a patch for option 3.
It isn't too bad.


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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=40528