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From: "fxue at os dot amperecomputing.com" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug tree-optimization/107828] New: tree-inlining would generate SSA
 with incorrect def stmt
Date: Wed, 23 Nov 2022 01:42:25 +0000
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X-Bugzilla-Component: tree-optimization
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https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D107828

            Bug ID: 107828
           Summary: tree-inlining would generate SSA with incorrect def
                    stmt
           Product: gcc
           Version: unknown
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: tree-optimization
          Assignee: unassigned at gcc dot gnu.org
          Reporter: fxue at os dot amperecomputing.com
  Target Milestone: ---

In the function "remap_gimple_op_r" of tree-inlining.cc:

  ...

  if (TREE_CODE (*tp) =3D=3D SSA_NAME)
    {
      *tp =3D remap_ssa_name (*tp, id);
      *walk_subtrees =3D 0;
      if (is_lhs)
         SSA_NAME_DEF_STMT (*tp) =3D wi_p->stmt;
      return NULL;
    }

The definition statement of original "*tp" may be same as wi_p->stmt. So, we
will end up with a statement that it is pointed by both old and new SSA nam=
e,
while the old one should have been reclaimed.

And this happens when some parameter needs to be adjusted during inline
versioning as:

remap_gimple_stmt()

{
  ...
  if (id->param_body_adjs)
    {
      ...
      if (!gimple_seq_empty_p (extra_stmts))
        {
          memset (&wi, 0, sizeof (wi));
          wi.info =3D id;
          for (gimple_stmt_iterator egsi =3D gsi_start (extra_stmts);
               !gsi_end_p (egsi);
               gsi_next (&egsi))
            walk_gimple_op (gsi_stmt (egsi), remap_gimple_op_r, &wi);
                                             ^^^^^^^^^^^^^^^^^

            ...
        }
    }
   ...
}=