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From: "pinskia at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>
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Subject: [Bug tree-optimization/17217] not removing removal of nested structs
Date: Fri, 03 Sep 2021 06:13:20 +0000
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https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D17217

Andrew Pinski <pinskia at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|UNCONFIRMED                 |NEW
   Last reconfirmed|2005-01-25 03:37:17         |2021-09-03
     Ever confirmed|0                           |1

--- Comment #8 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
So where is a better testcase (which is not depedent on how gimplifier work=
s):
int h(int *a);
int f(int i, int j)
{
  int t =3D i;
  int t1 =3D j;
  int g()
  {
    int t11 =3D t1;
    int t2 =3D h(&t);
    return t2 + t11;
  }
  int t3 =3D g();
  return t3 + t1;
}

---- CUT ---
On the gimple level we get:
  _3 =3D __builtin_dwarf_cfa (0);
  FRAME.1.FRAME_BASE.PARENT =3D _3;
  FRAME.1.t =3D i_5(D);
  FRAME.1.t1 =3D j_7(D);
  t2_11 =3D h (&FRAME.1.t);
  _12 =3D j_7(D) + t2_11;
  _9 =3D FRAME.1.t1;
  _10 =3D _9 + _12;

We should know that FRAME.1 is special in that h can only escape t field of
FRAME.1 and not the other fields of FRAME.1 too.=