[Bug tree-optimization/122380] [15/16 regression] std::variant with std::vectors of differing types may lead to double frees since r15-5595

[jakub at gcc dot gnu.org via Gcc-bugs]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=122380

Jakub Jelinek <jakub at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |rguenth at gcc dot gnu.org

--- Comment #15 from Jakub Jelinek <jakub at gcc dot gnu.org> ---
-fno-tree-pre also works.
PRE actually has not changed the
  MEM[(struct _Vector_impl_data *)m_3(D) + 8B]._M_start = 0B;
  MEM[(struct _Vector_impl_data *)m_3(D) + 8B]._M_finish = 0B;
  MEM[(struct _Vector_impl_data *)m_3(D) + 8B]._M_end_of_storage = 0B;
stores, but merged the reads which were separate based on _M_index, for 0 (aka
A)
  _33 = MEM[(struct _Vector_base *)m_3(D) +
8B]._M_impl.D.36905._M_end_of_storage;
  _34 = MEM[(struct _Vector_base *)m_3(D) + 8B]._M_impl.D.36905._M_start;
and for 1 (aka B)
  _39 = MEM[(struct _Vector_base *)m_3(D) +
8B]._M_impl.D.38000._M_end_of_storage;
  _40 = MEM[(struct _Vector_base *)m_3(D) + 8B]._M_impl.D.38000._M_start;
into
  pretmp_62 = MEM[(struct _Vector_base *)m_3(D) +
8B]._M_impl.D.38000._M_end_of_storage;
  pretmp_48 = MEM[(struct _Vector_base *)m_3(D) + 8B]._M_impl.D.38000._M_start;
plus kept the _39/_40 as is.  So, I think aliasing-wise it used to read once
from std::vector<double> elts and once from std::vector<int> and now it reads
in both cases using the same.