[Bug rtl-optimization/83886] New: [8 Regression] ICE in cfg_layout_redirect_edge_and_branch, at cfgrtl.c:4433

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

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=83886

            Bug ID: 83886
           Summary: [8 Regression] ICE in
                    cfg_layout_redirect_edge_and_branch, at cfgrtl.c:4433
           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-alpha20180114 snapshot (r256677) ICEs when compiling the following
snippet w/ -O2 -floop-parallelize-all -fmodulo-sched -fno-tree-forwprop
-fno-tree-loop-im:

int ga, as;

void
xj (int sm, int vs)
{
  if (0)
    for (;;)
      while (sm < 1)
        for (as = 0; as < 1; ++as)
          {
 o3:
            ;
          }

  while (vs < 1)
    {
      for (ga = 0; ga < 9; ++ga)
        {
        }

      ++vs;
    }

  goto o3;
}

% gcc-8.0.0-alpha20180114 -O2 -floop-parallelize-all -fmodulo-sched
-fno-tree-forwprop -fno-tree-loop-im -c pa4nrhpq.c
during RTL pass: sms
pa4nrhpq.c: In function 'xj':
pa4nrhpq.c:25:1: internal compiler error: in
cfg_layout_redirect_edge_and_branch, at cfgrtl.c:4433
 }
 ^
0x5ce23b cfg_layout_redirect_edge_and_branch
       
/var/tmp/portage/sys-devel/gcc-8.0.0_alpha20180114/work/gcc-8-20180114/gcc/cfgrtl.c:4433
0x8990f8 cfg_layout_redirect_edge_and_branch_force
       
/var/tmp/portage/sys-devel/gcc-8.0.0_alpha20180114/work/gcc-8-20180114/gcc/cfgrtl.c:4443
0x8825b3 redirect_edge_and_branch_force(edge_def*, basic_block_def*)
       
/var/tmp/portage/sys-devel/gcc-8.0.0_alpha20180114/work/gcc-8-20180114/gcc/cfghooks.c:486
0x882fbd make_forwarder_block(basic_block_def*, bool (*)(edge_def*), void
(*)(basic_block_def*))
       
/var/tmp/portage/sys-devel/gcc-8.0.0_alpha20180114/work/gcc-8-20180114/gcc/cfghooks.c:893
0x88b74b merge_latch_edges
       
/var/tmp/portage/sys-devel/gcc-8.0.0_alpha20180114/work/gcc-8-20180114/gcc/cfgloop.c:780
0x88b74b disambiguate_multiple_latches
       
/var/tmp/portage/sys-devel/gcc-8.0.0_alpha20180114/work/gcc-8-20180114/gcc/cfgloop.c:831
0x88b74b disambiguate_loops_with_multiple_latches()
       
/var/tmp/portage/sys-devel/gcc-8.0.0_alpha20180114/work/gcc-8-20180114/gcc/cfgloop.c:844
0xb0aec4 apply_loop_flags
       
/var/tmp/portage/sys-devel/gcc-8.0.0_alpha20180114/work/gcc-8-20180114/gcc/loop-init.c:54
0xb0b8ec loop_optimizer_init(unsigned int)
       
/var/tmp/portage/sys-devel/gcc-8.0.0_alpha20180114/work/gcc-8-20180114/gcc/loop-init.c:123
0x14ce819 sms_schedule
       
/var/tmp/portage/sys-devel/gcc-8.0.0_alpha20180114/work/gcc-8-20180114/gcc/modulo-sched.c:1354
0x14d111f execute
       
/var/tmp/portage/sys-devel/gcc-8.0.0_alpha20180114/work/gcc-8-20180114/gcc/modulo-sched.c:3345