[Bug rtl-optimization/69032] New: [5/6 Regression] ICE: in cfg_preds_1, at sel-sched-ir.c:4809 with -fsched-pressure -fsel-sched-pipelining -fselective-scheduling

[zsojka at seznam dot cz]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=69032

            Bug ID: 69032
           Summary: [5/6 Regression] ICE: in cfg_preds_1, at
                    sel-sched-ir.c:4809 with -fsched-pressure
                    -fsel-sched-pipelining -fselective-scheduling
           Product: gcc
           Version: 6.0
            Status: UNCONFIRMED
          Keywords: ice-on-valid-code
          Severity: normal
          Priority: P3
         Component: rtl-optimization
          Assignee: unassigned at gcc dot gnu.org
          Reporter: zsojka at seznam dot cz
  Target Milestone: ---
              Host: x86_64-pc-linux-gnu
            Target: powerpc-unknown-linux-gnu

Created attachment 37117
  --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=37117&action=edit
reduced testcase

Compiler output:
$ powerpc-unknown-linux-gnu-gcc -O2 -fsched-pressure -fsel-sched-pipelining
-fselective-scheduling testcase.c 
testcase.c: In function 'foo':
testcase.c:8:1: internal compiler error: in cfg_preds_1, at sel-sched-ir.c:4753
 }
 ^

0xadf08f cfg_preds_1
        /repo/gcc-trunk/gcc/sel-sched-ir.c:4753
0xadf15c cfg_preds
        /repo/gcc-trunk/gcc/sel-sched-ir.c:4793
0xadf15c get_seqno_by_preds(rtx_insn*)
        /repo/gcc-trunk/gcc/sel-sched-ir.c:4094
0xafb2f6 find_seqno_for_bookkeeping
        /repo/gcc-trunk/gcc/sel-sched.c:4723
0xafb2f6 generate_bookkeeping_insn
        /repo/gcc-trunk/gcc/sel-sched.c:4779
0xafb2f6 move_op_at_first_insn
        /repo/gcc-trunk/gcc/sel-sched.c:6052
0xaf1268 code_motion_path_driver
        /repo/gcc-trunk/gcc/sel-sched.c:6643
0xaf1793 code_motion_process_successors
        /repo/gcc-trunk/gcc/sel-sched.c:6331
0xaf1793 code_motion_path_driver
        /repo/gcc-trunk/gcc/sel-sched.c:6597
0xaf1793 code_motion_process_successors
        /repo/gcc-trunk/gcc/sel-sched.c:6331
0xaf1793 code_motion_path_driver
        /repo/gcc-trunk/gcc/sel-sched.c:6597
0xaf65c3 move_op
        /repo/gcc-trunk/gcc/sel-sched.c:6688
0xaf65c3 move_exprs_to_boundary
        /repo/gcc-trunk/gcc/sel-sched.c:5212
0xaf65c3 schedule_expr_on_boundary
        /repo/gcc-trunk/gcc/sel-sched.c:5424
0xaf7e2e fill_insns
        /repo/gcc-trunk/gcc/sel-sched.c:5566
0xaf9a0d schedule_on_fences
        /repo/gcc-trunk/gcc/sel-sched.c:7342
0xaf9a0d sel_sched_region_2
        /repo/gcc-trunk/gcc/sel-sched.c:7480
0xafc43b sel_sched_region_1
        /repo/gcc-trunk/gcc/sel-sched.c:7522
0xafc43b sel_sched_region(int)
        /repo/gcc-trunk/gcc/sel-sched.c:7623
0xafd9a9 run_selective_scheduling()
        /repo/gcc-trunk/gcc/sel-sched.c:7699
Please submit a full bug report,
with preprocessed source if appropriate.
Please include the complete backtrace with any bug report.
See <http://gcc.gnu.org/bugs.html> for instructions.

Other targets do not seem to have this issue.

Tested revisions:
r231903 - FAIL
5-branch r231870 - FAIL
4_9-branch r231865 - OK
4_8-branch r224828 - OK