[Bug middle-end/67005] New: ICE: in verify_loop_structure, at cfgloop.c:1647 (loop with header n not in loop tree)

[antoine.balestrat at gmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=67005

            Bug ID: 67005
           Summary: ICE: in verify_loop_structure, at cfgloop.c:1647 (loop
                    with header n not in loop tree)
           Product: gcc
           Version: 6.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: middle-end
          Assignee: unassigned at gcc dot gnu.org
          Reporter: antoine.balestrat at gmail dot com
  Target Milestone: ---

Hello ! Please consider the following testcase which makes a freshly built GCC
6.0 ICE at -O2.

$ cat test.c
int a;
void f(void)
{
    if(!a);
    else
lbl:
        a = a;

    if(a)
        a = 8;
    goto lbl;
}

$ xgcc -w -O2 test.c
test.c: In function ‘f’:
test.c:12:1: error: loop with header 4 not in loop tree
 }
 ^
current.c:12:1: internal compiler error: in verify_loop_structure, at
cfgloop.c:1647
0x708a75 verify_loop_structure()
        ../../srcdir/gcc/cfgloop.c:1647
0xa20955 loop_optimizer_init(unsigned int)
        ../../srcdir/gcc/loop-init.c:109
0xadc9e2 execute
        ../../srcdir/gcc/predict.c:3032
Please submit a full bug report,
with preprocessed source if appropriate.
Please include the complete backtrace with any bug report.
See <http://gcc.gnu.org/bugs.html> for instructions.