[Bug rtl-optimization/56957] [4.9 regression] ICE in add_insn_after, at emit-rtl.c:3783

["steven at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=56957

Steven Bosscher <steven at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|ASSIGNED                    |NEW
                 CC|                            |abel at gcc dot gnu.org
         AssignedTo|steven at gcc dot gnu.org   |unassigned at gcc dot
                   |                            |gnu.org

--- Comment #2 from Steven Bosscher <steven at gcc dot gnu.org> 2013-04-16 20:54:17 UTC ---
Breakpoint 5, sel_remove_insn (insn=0x3fffb5da4e78, only_disconnect=false,
full_tidying=false) at ../../trunk/gcc/sel-sched-ir.c:3938
3938          delete_insn (insn);
1: debug_rtx(insn) = (insn 303 190 191 10 (set (reg:DF 165 f37 [421])
        (unspec:DF [
                (mem:DF (reg/f:DI 18 r18 [420]) [2 *a_7(D) S8 A64])
            ] UNSPEC_LDA)) 13 {movdf_advanced}
     (nil))
void
(gdb) up
#1  0x0000000010843984 in remove_insn_from_stream (insn=0x3fffb5da4e78,
only_disconnect=false) at ../../trunk/gcc/sel-sched.c:6042
6042      sel_remove_insn (insn, only_disconnect, false);
(gdb) up
#2  0x0000000010843af0 in move_op_orig_expr_found (insn=0x3fffb5da4e78,
expr=0x115f9fd8, lparams=0x3fffffffda78, static_params=0x3fffffffdaa8) at
../../trunk/gcc/sel-sched.c:6066
6066      remove_insn_from_stream (insn, only_disconnect);
gdb) p only_disconnect
$19 = false
(gdb) l 6060
6055      moveop_static_params_p params = (moveop_static_params_p)
static_params;
6056
6057      copy_expr_onside (params->c_expr, INSN_EXPR (insn));
6058      track_scheduled_insns_and_blocks (insn);
6059      insn_emitted = handle_emitting_transformations (insn, expr, params);
6060      only_disconnect = (params->uid == INSN_UID (insn)
6061                         && ! insn_emitted  && ! EXPR_WAS_CHANGED (expr));
6062
6063      /* Mark that we've disconnected an insn.  */
6064      if (only_disconnect)
(gdb) p params->uid
$20 = 303
(gdb) p insn_emitted
$21 = false
(gdb) p EXPR_WAS_CHANGED(expr)
$22 = true

No idea what to make of this. sel-sched deliberately chooses to discard
the insn instead of only disconnecting it, but it re-emits the insn
later anyway.  That's wrong.

CC sel-sched guru.