[Bug rtl-optimization/85455] New: [8 Regression] ICE in verify_loop_structure, at cfgloop.c:1708 (error: basic block 3 should be marked irreducible)

[asolokha at gmx dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=85455

            Bug ID: 85455
           Summary: [8 Regression] ICE in verify_loop_structure, at
                    cfgloop.c:1708 (error: basic block 3 should be marked
                    irreducible)
           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-alpha20180415 snapshot (r259389) ICEs when compiling the following
snippet w/ -O1 -fthread-jumps -fno-tree-dominator-opts -fno-tree-reassoc
-fno-tree-sink -fno-tree-slsr:

void
ty (void);

void
um (void);

void
au (int qj)
{
  if (qj < 1)
    {
 vq:
      ty ();
    }

  um ();

  goto vq;
}

% gcc-8.0.0-alpha20180415 -O1 -fthread-jumps -fno-tree-dominator-opts
-fno-tree-reassoc -fno-tree-sink -fno-tree-slsr -c ad6zjqua.c 
ad6zjqua.c: In function 'au':
ad6zjqua.c:19:1: error: basic block 3 should be marked irreducible
 }
 ^
ad6zjqua.c:19:1: error: basic block 4 should be marked irreducible
during RTL pass: jump
ad6zjqua.c:19:1: internal compiler error: in verify_loop_structure, at
cfgloop.c:1708
0x88fd64 verify_loop_structure()
       
/var/tmp/portage/sys-devel/gcc-8.0.0_alpha20180415/work/gcc-8-20180415/gcc/cfgloop.c:1708
0xbc7767 execute_function_todo
       
/var/tmp/portage/sys-devel/gcc-8.0.0_alpha20180415/work/gcc-8-20180415/gcc/passes.c:2010
0xbc857e execute_todo
       
/var/tmp/portage/sys-devel/gcc-8.0.0_alpha20180415/work/gcc-8-20180415/gcc/passes.c:2048