[Bug middle-end/45854] [4.5 Regression] ICE in redirect_eh_edge_1, at tree-eh.c:2131

[rguenth at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=45854

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

           What    |Removed                     |Added
----------------------------------------------------------------------------
           Priority|P3                          |P2
             Status|UNCONFIRMED                 |ASSIGNED
   Last reconfirmed|                            |2010.10.01 10:38:16
         AssignedTo|unassigned at gcc dot       |rguenth at gcc dot gnu.org
                   |gnu.org                     |
   Target Milestone|---                         |4.5.2
            Summary|ICE in redirect_eh_edge_1,  |[4.5 Regression] ICE in
                   |at tree-eh.c:2131           |redirect_eh_edge_1, at
                   |                            |tree-eh.c:2131
     Ever Confirmed|0                           |1

--- Comment #1 from Richard Guenther <rguenth at gcc dot gnu.org> 2010-10-01 
10:38:16 UTC ---
Confirmed.

#1  0x0000000000c55d81 in redirect_eh_edge_1 (edge_in=0x7ffff5b4bb00, 
    new_bb=0x7ffff5b596e8, change_region=0 '\000')
    at /space/rguenther/src/svn/gcc-4_5-branch/gcc/tree-eh.c:2131
#2  0x0000000000c5bc01 in cleanup_empty_eh_merge_phis (new_bb=0x7ffff5b596e8, 
    old_bb=0x7ffff5b596e8, old_bb_out=0x7ffff5b4bd80, change_region=0 '\000')
    at /space/rguenther/src/svn/gcc-4_5-branch/gcc/tree-eh.c:3594
#3  0x0000000000c5bfe8 in cleanup_empty_eh_unsplit (bb=0x7ffff5b596e8, 
    e_out=0x7ffff5b4bd80, lp=0x7ffff5b50a78)
    at /space/rguenther/src/svn/gcc-4_5-branch/gcc/tree-eh.c:3673
#4  0x0000000000c5c1de in cleanup_empty_eh (lp=0x7ffff5b50a78)
    at /space/rguenther/src/svn/gcc-4_5-branch/gcc/tree-eh.c:3723
#5  0x0000000000c5c523 in cleanup_all_empty_eh ()
    at /space/rguenther/src/svn/gcc-4_5-branch/gcc/tree-eh.c:3825
#6  0x0000000000c5c5b3 in execute_cleanup_eh ()
    at /space/rguenther/src/svn/gcc-4_5-branch/gcc/tree-eh.c:3854
#7  0x0000000000b15380 in execute_one_pass (pass=0x18ca7a0)
    at /space/rguenther/src/svn/gcc-4_5-branch/gcc/passes.c:1568
(gdb) p *pass
$1 = {type = GIMPLE_PASS, name = 0x13b7692 "ehcleanup", 
  gate = 0xc5c5ef <gate_cleanup_eh>, execute = 0xc5c579 <execute_cleanup_eh>, 
  sub = 0x0, next = 0x18c90e0, static_pass_number = 41, tv_id = TV_TREE_EH, 
  properties_required = 2, properties_provided = 0, properties_destroyed = 0, 
  todo_flags_start = 524288, todo_flags_finish = 1}
(gdb) call debug_function (cfun->decl, 1<<19 | 1<<5)
<anonymous struct>::._0() (struct ._0 * const this)
Eh tree:
   1 cleanup
{
  struct Y * D.2249;
  struct S * D.2248;
  struct X D.2247;

  # BLOCK 2
  # PRED: ENTRY (fallthru,exec)
  D.2247 = {};
  D.2248_2 = &this_1(D)->s;
  S::S (D.2248_2, D.2247);
  D.2249_3 = &this_1(D)->y;
  [LP 1] Y::Y (D.2249_3);
  # SUCC: 5 (eh,exec) 3 (fallthru,exec)

  # BLOCK 3
  # PRED: 2 (fallthru,exec)
  return;
  # SUCC: EXIT

  # BLOCK 4
  # PRED:
<L0>:
  # SUCC:

  # BLOCK 5 freq:10000
  # PRED: 5 [100.0%]  (fallthru,dfs_back) 2 (eh,exec)
<L1>:
  goto <bb 5> (<L1>);
  # SUCC: 5 [100.0%]  (fallthru,dfs_back)

}
(gdb) p edge_in->dest->index
$4 = 5
(gdb) p new_bb->index
$5 = 5

so we're trying to re-direct an EH edge from BB 5 to BB 5 ...

And the following fixes it.

Index: gcc/tree-eh.c
===================================================================
--- gcc/tree-eh.c       (revision 164873)
+++ gcc/tree-eh.c       (working copy)
@@ -3720,7 +3720,13 @@ cleanup_empty_eh (eh_landing_pad lp)

   /* If the block is totally empty, look for more unsplitting cases.  */
   if (gsi_end_p (gsi))
-    return cleanup_empty_eh_unsplit (bb, e_out, lp);
+    {
+      /* For the degenerate case of an infinite loop bail out.  */
+      if (e_out->dest == bb)
+       return false;
+
+      return cleanup_empty_eh_unsplit (bb, e_out, lp);
+    }

   /* The block should consist only of a single RESX statement.  */
   resx = gsi_stmt (gsi);