[Bug rtl-optimization/83513] New: [8 Regression] ICE: qsort checking failed (error: qsort comparator non-negative on sorted output: 3) in fill_vec_av_set in selective scheduler

["asolokha at gmx dot com" <gcc-bugzilla at gcc dot gnu dot org>]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=83513

            Bug ID: 83513
           Summary: [8 Regression] ICE: qsort checking failed (error:
                    qsort comparator non-negative on sorted output: 3) in
                    fill_vec_av_set in selective scheduler
           Product: gcc
           Version: 8.0
            Status: UNCONFIRMED
          Keywords: ice-checking, ice-on-valid-code
          Severity: normal
          Priority: P3
         Component: rtl-optimization
          Assignee: unassigned at gcc dot gnu.org
          Reporter: asolokha at gmx dot com
  Target Milestone: ---

gcc-8.0.0-alpha20171217 snapshot (r255766) ICEs when compiling the following
snippet w/ -O1 (-O2, -Os) -fschedule-insns -fselective-scheduling
-fno-guess-branch-probability:

void
oh (long int qc, short int de)
{
  {
    long int uf = 0;
    int *xu, *gx = &uf;

 p6:
    *gx = (qc == 0) ? -1 : (qc - uf);
    if (de == *gx)
      {
        ++*xu;
        de = *xu;
      }
    else
      de = qc;
  }

  goto p6;
}

% gcc-8.0.0-alpha20171217 -O1 -fschedule-insns -fselective-scheduling
-fno-guess-branch-probability -c -w vugfco5g.c                                  
vugfco5g.c: In function 'oh':
vugfco5g.c:20:1: error: qsort comparator non-negative on sorted output: 3
 }
 ^
during RTL pass: sched1
vugfco5g.c:20:1: internal compiler error: qsort checking failed
0x829340 qsort_chk_error
       
/var/tmp/portage/sys-devel/gcc-8.0.0_alpha20171217/work/gcc-8-20171217/gcc/vec.c:222
0x8293c7 qsort_chk(void*, unsigned long, unsigned long, int (*)(void const*,
void const*))
       
/var/tmp/portage/sys-devel/gcc-8.0.0_alpha20171217/work/gcc-8-20171217/gcc/vec.c:274
0xd069c4 vec<_expr*, va_heap, vl_embed>::qsort(int (*)(void const*, void
const*))
       
/var/tmp/portage/sys-devel/gcc-8.0.0_alpha20171217/work/gcc-8-20171217/gcc/vec.h:1050
0xd069c4 vec<_expr*, va_heap, vl_ptr>::qsort(int (*)(void const*, void const*))
       
/var/tmp/portage/sys-devel/gcc-8.0.0_alpha20171217/work/gcc-8-20171217/gcc/vec.h:1812
0xd069c4 fill_vec_av_set
       
/var/tmp/portage/sys-devel/gcc-8.0.0_alpha20171217/work/gcc-8-20171217/gcc/sel-sched.c:3725
0xd089ea fill_ready_list
       
/var/tmp/portage/sys-devel/gcc-8.0.0_alpha20171217/work/gcc-8-20171217/gcc/sel-sched.c:4022
0xd089ea find_best_expr
       
/var/tmp/portage/sys-devel/gcc-8.0.0_alpha20171217/work/gcc-8-20171217/gcc/sel-sched.c:4382
0xd089ea fill_insns
       
/var/tmp/portage/sys-devel/gcc-8.0.0_alpha20171217/work/gcc-8-20171217/gcc/sel-sched.c:5539
0xd0ae50 schedule_on_fences
       
/var/tmp/portage/sys-devel/gcc-8.0.0_alpha20171217/work/gcc-8-20171217/gcc/sel-sched.c:7356
0xd0ae50 sel_sched_region_2
       
/var/tmp/portage/sys-devel/gcc-8.0.0_alpha20171217/work/gcc-8-20171217/gcc/sel-sched.c:7494
0xd0c588 sel_sched_region_1
       
/var/tmp/portage/sys-devel/gcc-8.0.0_alpha20171217/work/gcc-8-20171217/gcc/sel-sched.c:7536
0xd0c588 sel_sched_region(int)
       
/var/tmp/portage/sys-devel/gcc-8.0.0_alpha20171217/work/gcc-8-20171217/gcc/sel-sched.c:7637
0xd0d5e1 run_selective_scheduling()
       
/var/tmp/portage/sys-devel/gcc-8.0.0_alpha20171217/work/gcc-8-20171217/gcc/sel-sched.c:7713
0xcedadd rest_of_handle_sched
       
/var/tmp/portage/sys-devel/gcc-8.0.0_alpha20171217/work/gcc-8-20171217/gcc/sched-rgn.c:3715
0xcedadd execute
       
/var/tmp/portage/sys-devel/gcc-8.0.0_alpha20171217/work/gcc-8-20171217/gcc/sched-rgn.c:3825