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From: "rguenth at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug tree-optimization/114647] missing DSE when looping over a VLA
Date: Tue, 09 Apr 2024 07:12:50 +0000
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https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D114647

Richard Biener <rguenth at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
           Assignee|unassigned at gcc dot gnu.org      |rguenth at gcc dot =
gnu.org
             Status|NEW                         |ASSIGNED

--- Comment #2 from Richard Biener <rguenth at gcc dot gnu.org> ---
                      /* If we visit this PHI by following a backedge then =
we
                         have to make sure ref->ref only refers to SSA names
                         that are invariant with respect to the loop
                         represented by this PHI node.  */
                      if (dominated_by_p (CDI_DOMINATORS, gimple_bb (stmt),
                                          gimple_bb (use_stmt))
                          && !for_each_index (ref->ref ? &ref->ref :
&ref->base,
                                              check_name, gimple_bb
(use_stmt)))
                        return DSE_STORE_LIVE;

we could make this bail-out "delayed" until we hit the next possible use in
the loop (of which there is none).=