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From: "pinskia at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug tree-optimization/110060] Adding optimizer hints to std::vector
 causes a new -Wstringop-overread false positive
Date: Wed, 31 May 2023 22:53:42 +0000
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X-Bugzilla-Component: tree-optimization
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https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D110060

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

           What    |Removed                     |Added
----------------------------------------------------------------------------
           Keywords|                            |missed-optimization

--- Comment #1 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
Hmm:
```
  MEM[(struct _Vector_base *)&w]._M_impl.D.25239._M_start =3D _73;
  _66 =3D _73 + 1;
  MEM[(struct _Vector_base *)&w]._M_impl.D.25239._M_end_of_storage =3D _66;
  MEM[(struct vector *)&w].D.25935._M_impl.D.25239._M_finish =3D _66;
  _486 =3D _63 + 2;
  v.D.25935._M_impl.D.25239._M_finish =3D _486;
  _154 =3D _63 + 3;
  v.D.25935._M_impl.D.25239._M_finish =3D _154;
  _138 =3D MEM[(struct X * const &)&v];
  _215 =3D v.D.25935._M_impl.D.25239._M_end_of_storage;
  _216 =3D v.D.25935._M_impl.D.25239._M_finish;
  if (_215 !=3D _216)
```

There is huge missed optimizations here.
I noticed that the last fre is not iterative and we have the case where man=
y of
the ifs are removed due to fre and forwprop at the end.=