[Bug tree-optimization/83126] New: [8 Regression] ICE in transform_to_exit_first_loop_alt, at tree-parloops.c:1713

[asolokha at gmx dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=83126

            Bug ID: 83126
           Summary: [8 Regression] ICE in
                    transform_to_exit_first_loop_alt, at
                    tree-parloops.c:1713
           Product: gcc
           Version: 8.0
            Status: UNCONFIRMED
          Keywords: ice-on-valid-code
          Severity: normal
          Priority: P3
         Component: tree-optimization
          Assignee: unassigned at gcc dot gnu.org
          Reporter: asolokha at gmx dot com
  Target Milestone: ---

gcc-8.0.0-alpha20171119 snapshot (r254939) ICEs when compiling the following
snippet w/ -O1 -ftree-parallelize-loops=2 -floop-parallelize-all:

void
ew (unsigned short int c9)
{
  int e1;

  for (;;)
    {
      unsigned int *by = &e1;
      int *fd;

      *fd = c9;
      fd = *fd;
      if (*fd != 0)
        for (*by = 0; *by < 2; ++*by)
          c9 *= e1;
    }
}

% gcc-8.0.0-alpha20171119 -O1 -ftree-parallelize-loops=2 -floop-parallelize-all
-w -c dbuks5p2.c
during GIMPLE pass: parloops
dbuks5p2.c: In function 'ew':
dbuks5p2.c:2:1: internal compiler error: in transform_to_exit_first_loop_alt,
at tree-parloops.c:1713
 ew (unsigned short int c9)
 ^~
0xcf558a transform_to_exit_first_loop_alt
       
/var/tmp/portage/sys-devel/gcc-8.0.0_alpha20171119/work/gcc-8-20171119/gcc/tree-parloops.c:1711
0xcf5eac try_transform_to_exit_first_loop_alt
       
/var/tmp/portage/sys-devel/gcc-8.0.0_alpha20171119/work/gcc-8-20171119/gcc/tree-parloops.c:1835
0xcf7d45 gen_parallel_loop
       
/var/tmp/portage/sys-devel/gcc-8.0.0_alpha20171119/work/gcc-8-20171119/gcc/tree-parloops.c:2379
0xcf826c parallelize_loops
       
/var/tmp/portage/sys-devel/gcc-8.0.0_alpha20171119/work/gcc-8-20171119/gcc/tree-parloops.c:3366
0xcf852f execute
       
/var/tmp/portage/sys-devel/gcc-8.0.0_alpha20171119/work/gcc-8-20171119/gcc/tree-parloops.c:3448