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From: "glisse at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug ipa/59948] Optimize std::function
Date: Thu, 26 Feb 2015 00:09:00 -0000
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https://gcc.gnu.org/bugzilla/show_bug.cgi?id=59948

--- Comment #7 from Marc Glisse <glisse at gcc dot gnu.org> ---
There has been huge progress in gcc-5:

int m() ()
{
  struct function h;

  <bb 2>:
  MEM[(int (*<T5c6a>) (int) *)&h] = f;
  h._M_invoker = _M_invoke;
  h.D.27699._M_manager = _M_manager;
  std::_Function_base::_Base_manager<int (*)(int)>::_M_manager (&MEM[(struct
_Function_base *)&h]._M_functor, &MEM[(struct _Function_base *)&h]._M_functor,
3);
  h ={v} {CLOBBER};
  return 0;

}

Apparently we managed to inline f! For this simple testcase, all that is
missing is inlining _M_manager to realize that when the last argument is 3 it
does nothing. Then we can go back to more complicated examples like the one
linked at the end of comment #0.