[Bug rtl-optimization/105577] [12/13 Regression] ICE in delete_unmarked_insns, at dce.cc:653 since r12-248-gb58dc0b803057c0e

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

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=105577

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 #9 from Richard Biener <rguenth at gcc dot gnu.org> ---
So DSE does

  /* DSE can eliminate potentially-trapping MEMs.
     Remove any EH edges associated with them.  */
  if ((locally_deleted || globally_deleted)
      && cfun->can_throw_non_call_exceptions
      && purge_all_dead_edges ())
    {
      free_dominance_info (CDI_DOMINATORS);
      cleanup_cfg (0);

which should do the trick, but the fast-DCE is invoked via

  dse_step0 ();
  dse_step1 ();
  dse_step2_init ();
  if (dse_step2 ())
    {
      df_set_flags (DF_LR_RUN_DCE);
      df_analyze ();

and dse_step0/1 already removed the stores, exposing the bad IL.  One
way to fix this might be to run cleanup_cfg after dse_step1 already,
or just remove_unreachable_blocks.

I'm going to test

diff --git a/gcc/dse.cc b/gcc/dse.cc
index b8914a3ae24..bb658a85959 100644
--- a/gcc/dse.cc
+++ b/gcc/dse.cc
@@ -3682,6 +3682,16 @@ rest_of_handle_dse (void)

   dse_step0 ();
   dse_step1 ();
+  /* DSE can eliminate potentially-trapping MEMs.
+     Remove any EH edges associated with them, since otherwise
+     DF_LR_RUN_DCE will complain later.  */
+  if ((locally_deleted || globally_deleted)
+      && cfun->can_throw_non_call_exceptions
+      && purge_all_dead_edges ())
+    {
+      free_dominance_info (CDI_DOMINATORS);
+      delete_unreachable_blocks ();
+    }
   dse_step2_init ();
   if (dse_step2 ())
     {