[Bug rtl-optimization/63384] New: ICE in moveup_expr_chached->sel_bb_head->bb_node with special options

[Bug rtl-optimization/63384] New: ICE in moveup_expr_chached->sel_bb_head->bb_node with special options

[andi-gcc at firstfloor dot org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=63384

            Bug ID: 63384
           Summary: ICE in moveup_expr_chached->sel_bb_head->bb_node with
                    special options
           Product: gcc
           Version: 5.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: rtl-optimization
          Assignee: unassigned at gcc dot gnu.org
          Reporter: andi-gcc at firstfloor dot org

Created attachment 33585
  --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=33585&action=edit
test case (non minimized)

The following combination of options causes an ICE with the attached test case:

g++50 matrix.i -o outfile -O2  -fsel-sched-pipelining-outer-loops
-fsel-sched-reschedule-pipelined -fvar-tracking-assignments-toggle
-ftree-vectorize -fselective-scheduling2

gcc version 4.9.0 20130617 (experimental) (GCC) 

apps/matrixmultiply.cpp: In function 'T** make_test_matrix() [with T = float]':
apps/matrixmultiply.cpp:22:1: internal compiler error: Segmentation fault
 }
 ^
0x8cde37 crash_signal
        ../../gcc/gcc/toplev.c:333
0x6764e1 bb_note(basic_block_def*)
        ../../gcc/gcc/cfgrtl.c:647
0x89c1a1 sel_bb_head(basic_block_def*)
        ../../gcc/gcc/sel-sched-ir.c:4536
0x8a6fa5 moveup_expr_cached
        ../../gcc/gcc/sel-sched.c:2563
0x8ac506 move_op_ascend
        ../../gcc/gcc/sel-sched.c:6217
0x8aabc7 code_motion_path_driver
        ../../gcc/gcc/sel-sched.c:6706
0x8aca54 move_op
        ../../gcc/gcc/sel-sched.c:6758
0x8aca54 move_exprs_to_boundary
        ../../gcc/gcc/sel-sched.c:5292
0x8aca54 schedule_expr_on_boundary
        ../../gcc/gcc/sel-sched.c:5504
0x8af552 fill_insns
        ../../gcc/gcc/sel-sched.c:5646
0x8af552 schedule_on_fences
        ../../gcc/gcc/sel-sched.c:7410
0x8af552 sel_sched_region_2
        ../../gcc/gcc/sel-sched.c:7544
0x8b14bf sel_sched_region_1
        ../../gcc/gcc/sel-sched.c:7583
0x8b14bf sel_sched_region(int)
        ../../gcc/gcc/sel-sched.c:7684
0x8b1fc1 run_selective_scheduling()
        ../../gcc/gcc/sel-sched.c:7760
0x895b56 rest_of_handle_sched2
        ../../gcc/gcc/sched-rgn.c:3606

[Bug rtl-optimization/63384] ICE in moveup_expr_chached->sel_bb_head->bb_node with special options

[andi-gcc at firstfloor dot org]

[-- Warning: decoded text below may be mangled, UTF-8 assumed --]
[-- Attachment #1: Type: text/plain; charset="UTF-8", Size: 5288 bytes --]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=63384

--- Comment #1 from Andi Kleen <andi-gcc at firstfloor dot org> ---
With a newer compiler version

gcc version 5.0.0 20140926 (experimental) (GCC) 


the test case doesn't crash anymore, but just runs very very long. I killed it
after 20s. This happens with the following two options:


g++50 matrix.i -o outfile -O2  -fvar-tracking-assignments-toggle 
-fselective-scheduling2

The overhead is mostly in the scheduler:

  - sched_analyze_insn(deps_desc*, rtx_def*, rtx_insn*)                     â–’
      - 99.39% deps_analyze_insn(deps_desc*, rtx_insn*)                      â–’
           tick_check_p(_expr*, deps_desc*, _fence*)                         â–’
           fill_insns(_fence*, int, _list_node***)                           â–’
           sel_sched_region_2(int)                                           â–’
           sel_sched_region(int)                                             â–’
           run_selective_scheduling()                                        â–’
           (anonymous namespace)::pass_sched2::execute(function*)            â–’
           execute_one_pass(opt_pass*)                                       â–’
           execute_pass_list_1(opt_pass*)                                    â–’
           execute_pass_list_1(opt_pass*)                                    â–’
           execute_pass_list_1(opt_pass*)                                    â–’
           execute_pass_list(function*, opt_pass*)                           â–’
           cgraph_node::expand()                                             â–’
           symbol_table::compile()                                           â–’
           symbol_table::finalize_compilation_unit()                         â–’
           cp_write_global_declarations()                                    â–’
           compile_file()                                                    â–’
           toplev_main(int, char**)                                          â–’
           __libc_start_main                                                 â–’
      + 0.61% tick_check_p(_expr*, deps_desc*, _fence*)         


sched_analyze_insn(deps_desc*, rtx_def*, rtx_insn*)                             


       │
       │            for (i = 0; i < FIRST_PSEUDO_REGISTER; i++)
 12.84 │ 748:   add    $0x1,%r13d
  0.07 │        add    $0x30,%r14
       │        cmp    $0x4d,%r13d
       │      ↓ je     7e5
       │              if (TEST_HARD_REG_BIT (implicit_reg_pending_uses, i))
  0.06 │ 75a:   mov    %r13d,%eax
 12.45 │        shr    $0x6,%eax
  0.17 │        mov    0x1828100(,%rax,8),%rax
  6.06 │        bt     %r13,%rax
  6.21 │      ↑ jae    748
       │                {
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From: "andi-gcc at firstfloor dot org" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug rtl-optimization/63384] selective scheduling on x86 takes very long
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https://gcc.gnu.org/bugzilla/show_bug.cgi?idc384

Andi Kleen <andi-gcc at firstfloor dot org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
  Attachment #33585|0                           |1
        is obsolete|                            |

--- Comment #2 from Andi Kleen <andi-gcc at firstfloor dot org> ---
Created attachment 33600
  --> https://gcc.gnu.org/bugzilla/attachment.cgi?id3600&actioníit
Reduced test case for long compile time

Oddly the problem goes away when the variable allocation that is not used is
commented out.

[Bug rtl-optimization/63384] selective scheduling on x86 takes very long

[andi-gcc at firstfloor dot org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=63384

--- Comment #3 from Andi Kleen <andi-gcc at firstfloor dot org> ---
It loops (forever?) on this in sched2:


Scheduling on fences: (uid:28;seqno:7;) 
Fence 28[2] has not changed

Scheduling on fences: (uid:28;seqno:7;) 
Fence 28[2] has not changed

Scheduling on fences: (uid:28;seqno:7;) 
Fence 28[2] has not changed

Scheduling on fences: (uid:28;seqno:7;) 
Fence 28[2] has not changed

Scheduling on fences: (uid:28;seqno:7;) 
Fence 28[2] has not changed

Scheduling on fences: (uid:28;seqno:7;) 
Fence 28[2] has not changed

Scheduling on fences: (uid:28;seqno:7;) 
Fence 28[2] has not changed

Scheduling on fences: (uid:28;seqno:7;) 
Fence 28[2] has not changed

[Bug rtl-optimization/63384] scheduler loops on endless fence list with -fselective-scheduling2 on x86

[andi-gcc at firstfloor dot org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=63384

--- Comment #4 from Andi Kleen <andi-gcc at firstfloor dot org> ---
It loops forever in this loop in sel_sched_region_2

  while (fences)
    {
      int min_seqno, max_seqno;
      ilist_t scheduled_insns = NULL;
      ilist_t *scheduled_insns_tailp = &scheduled_insns;

      find_min_max_seqno (fences, &min_seqno, &max_seqno);
      schedule_on_fences (fences, max_seqno, &scheduled_insns_tailp);
      fences = calculate_new_fences (fences, orig_max_seqno, &max_time);
      highest_seqno_in_use = update_seqnos_and_stage (min_seqno, max_seqno,
                                                      highest_seqno_in_use,
                                                      &scheduled_insns);
    }

because calculate_new_fences always comes up with a list which is the same as
before. In move_fence_to_fences it always goes into the else

 f = flist_lookup (FLIST_TAIL_HEAD (new_fences),
                    FENCE_INSN (FLIST_FENCE (old_fences)));
  if (f)
    {
      merge_fences (f, old->insn, old->state, old->dc, old->tc,
                    old->last_scheduled_insn, old->executing_insns,
                    old->ready_ticks, old->ready_ticks_size,
                    old->sched_next, old->cycle, old->issue_more,
                    old->after_stall_p);
    }
  else
    {
      _list_add (tailp);
      FLIST_TAIL_TAILP (new_fences) = &FLIST_NEXT (*tailp);


So something is going wrong in flist_lookup.

[Bug rtl-optimization/63384] scheduler loops on endless fence list with -fselective-scheduling2 on x86

[andi-gcc at firstfloor dot org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=63384

Andi Kleen <andi-gcc at firstfloor dot org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
         Resolution|---                         |FIXED
             Status|ASSIGNED                    |RESOLVED

--- Comment #9 from Andi Kleen <andi-gcc at firstfloor dot org> ---
Long fixed.