[Bug rtl-optimization/84872] New: [8 Regression] ICE in create_preheader, at cfgloopmanip.c:1536

[asolokha at gmx dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=84872

            Bug ID: 84872
           Summary: [8 Regression] ICE in create_preheader, at
                    cfgloopmanip.c:1536
           Product: gcc
           Version: 8.0
            Status: UNCONFIRMED
          Keywords: 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-alpha20180311 snapshot (r258438) ICEs when compiling the following
snippet w/ -O1 -floop-parallelize-all -freorder-blocks-and-partition
-fschedule-insns2 -fselective-scheduling2 -fsel-sched-pipelining -fno-tree-dce:

void
s6 (int nx)
{
  int z8[2];
  int uw, vs = 0;

  for (uw = 0; uw < 2; ++uw)
    z8[uw] = 0;
  for (uw = 0; uw < 2; ++uw)
    z8[uw] = 0;

  while (vs < 1)
    while (nx < 1)
      ++nx;
}

% gcc-8.0.0-alpha20180311 -O1 -floop-parallelize-all
-freorder-blocks-and-partition -fschedule-insns2 -fselective-scheduling2
-fsel-sched-pipelining -fno-tree-dce -c cix8q525.c
during RTL pass: sched2
cix8q525.c: In function 's6':
cix8q525.c:15:1: internal compiler error: in create_preheader, at
cfgloopmanip.c:1536
 }
 ^
0x5cfe79 create_preheader(loop*, int)
       
/var/tmp/portage/sys-devel/gcc-8.0.0_alpha20180311/work/gcc-8-20180311/gcc/cfgloopmanip.c:1535
0x89aa57 create_preheaders(int)
       
/var/tmp/portage/sys-devel/gcc-8.0.0_alpha20180311/work/gcc-8-20180311/gcc/cfgloopmanip.c:1552
0xb156b9 apply_loop_flags
       
/var/tmp/portage/sys-devel/gcc-8.0.0_alpha20180311/work/gcc-8-20180311/gcc/loop-init.c:64
0xb160ec loop_optimizer_init(unsigned int)
       
/var/tmp/portage/sys-devel/gcc-8.0.0_alpha20180311/work/gcc-8-20180311/gcc/loop-init.c:123
0xc5714d sel_init_pipelining()
       
/var/tmp/portage/sys-devel/gcc-8.0.0_alpha20180311/work/gcc-8-20180311/gcc/sel-sched-ir.c:6093
0xc57582 sel_find_rgns()
       
/var/tmp/portage/sys-devel/gcc-8.0.0_alpha20180311/work/gcc-8-20180311/gcc/sel-sched-ir.c:6240
0xc4ca74 find_rgns
       
/var/tmp/portage/sys-devel/gcc-8.0.0_alpha20180311/work/gcc-8-20180311/gcc/sched-rgn.c:1077
0xc4ca74 sched_rgn_init(bool)
       
/var/tmp/portage/sys-devel/gcc-8.0.0_alpha20180311/work/gcc-8-20180311/gcc/sched-rgn.c:3250
0xc6e181 sel_global_init
       
/var/tmp/portage/sys-devel/gcc-8.0.0_alpha20180311/work/gcc-8-20180311/gcc/sel-sched.c:7661
0xc6e181 run_selective_scheduling()
       
/var/tmp/portage/sys-devel/gcc-8.0.0_alpha20180311/work/gcc-8-20180311/gcc/sel-sched.c:7715
0xc4de55 rest_of_handle_sched2
       
/var/tmp/portage/sys-devel/gcc-8.0.0_alpha20180311/work/gcc-8-20180311/gcc/sched-rgn.c:3729
0xc4de55 execute
       
/var/tmp/portage/sys-devel/gcc-8.0.0_alpha20180311/work/gcc-8-20180311/gcc/sched-rgn.c:3873