[Bug lto/85422] New: [openacc] ICE at cfgloop.c:468: segfault in flow_loops_find

["vries at gcc dot gnu.org" <gcc-bugzilla at gcc dot gnu dot org>]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=85422

            Bug ID: 85422
           Summary: [openacc] ICE at cfgloop.c:468: segfault in
                    flow_loops_find
           Product: gcc
           Version: 8.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: lto
          Assignee: unassigned at gcc dot gnu.org
          Reporter: vries at gcc dot gnu.org
                CC: marxin at gcc dot gnu.org
  Target Milestone: ---

When compiling this program:
...
int
main (void)
{
#pragma acc parallel
#pragma acc loop
  for (int i = 1; i < 10; i++)
      for (;;)
        ;

  return 0;
}
...

we run into this ICE:
...
to1: internal compiler error: Segmentation fault
0xac51ff crash_signal
        gcc/toplev.c:325
0x62cc08 flow_loops_find(loops*)
        gcc/cfgloop.c:468
0x961b3b input_cfg
        gcc/lto-streamer-in.c:841
0x961b3b input_function
        gcc/lto-streamer-in.c:1069
0x961b3b lto_read_body_or_constructor
        gcc/lto-streamer-in.c:1287
0x961b3b lto_input_variable_constructor(lto_file_decl_data*, varpool_node*,
char const*)
        gcc/lto-streamer-in.c:1345
0x651d4e cgraph_node::get_untransformed_body()
        gcc/cgraph.c:3667
0x6604d2 cgraph_node::expand()
        gcc/cgraphunit.c:2109
0x661df2 output_in_order
        gcc/cgraphunit.c:2381
0x661df2 symbol_table::compile()
        gcc/cgraphunit.c:2623
0x5adccc lto_main()
        gcc/lto/lto.c:3382
...