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From: "jamborm at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>
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Subject: [Bug tree-optimization/45791] Missed devirtualization
Date: Thu, 07 Jan 2021 17:38:56 +0000
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https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D45791

Martin Jambor <jamborm at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
         Resolution|---                         |FIXED
             Status|NEW                         |RESOLVED

--- Comment #18 from Martin Jambor <jamborm at gcc dot gnu.org> ---
The release_ssa dump of function main in the testcase from bug
description is just "return 0;"

The release_ssa dump of function main the testcase from comment #15
is:

int main ()
{
  <bb 2> [local count: 1073741824]:
  Sub::bar (&foo);
  Sub::bar (&foo);
  return 0;

}
...so devirtualized in my book (main is cold, so they are not inlined,
of course).


The release_ssa dump of function foo in the testcase from comment #5
is:

void foo ()
{
  void * _3;

  <bb 2> [local count: 1073741824]:
  _3 =3D operator new (8);
  MEM[(struct X *)_3]._vptr.X =3D &MEM <int (*) ()[4]> [(void *)&_ZTV1X + 1=
6B];
  X::~X (_3);
  return;

}
...so also devirtualzied before IPA.

Therefore I am going to close this old bug as done.  If anyone finds a
different testcase where the early optimizers should do a better job
to help devirtualziation, please file a new bug.=