[Bug tree-optimization/83957] New: ICE: Segmentation fault (in gimple_phi_arg)

[asolokha at gmx dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=83957

            Bug ID: 83957
           Summary: ICE: Segmentation fault (in gimple_phi_arg)
           Product: gcc
           Version: unknown
            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-alpha20180114 snapshot (r256677), 7.2, and 6.3 all ICE when compiling
the following snippet w/ -O1 -ftree-parallelize-loops=2 -fno-tree-dce --param
parloops-schedule=runtime (=dynamic, =guided):

void
k2 (int *ch, int fw)
{
  for (*ch = 0; *ch < 16; ++*ch)
    {
    }

  fw += *ch & 1;
  if (fw < 0)
    while (fw < 1)
      {
        ch = &fw;
        ++fw;
      }
}

% gcc-8.0.0-alpha20180114 -O1 -ftree-parallelize-loops=2 -fno-tree-dce --param
parloops-schedule=runtime -c clnvri9r.c
during GIMPLE pass: ompexpssa
clnvri9r.c: In function 'k2':
clnvri9r.c:10:11: internal compiler error: Segmentation fault
     while (fw < 1)
           ^
0xc9910f crash_signal
       
/var/tmp/portage/sys-devel/gcc-8.0.0_alpha20180114/work/gcc-8-20180114/gcc/toplev.c:325
0xb7719e gimple_phi_arg
       
/var/tmp/portage/sys-devel/gcc-8.0.0_alpha20180114/work/gcc-8-20180114/gcc/gimple.h:4368
0xb7719e gimple_phi_arg_def
       
/var/tmp/portage/sys-devel/gcc-8.0.0_alpha20180114/work/gcc-8-20180114/gcc/gimple.h:4413
0xb7719e expand_omp_for_generic
       
/var/tmp/portage/sys-devel/gcc-8.0.0_alpha20180114/work/gcc-8-20180114/gcc/omp-expand.c:3172
0xb79c3e expand_omp_for
       
/var/tmp/portage/sys-devel/gcc-8.0.0_alpha20180114/work/gcc-8-20180114/gcc/omp-expand.c:5700
0xb7a0da expand_omp
       
/var/tmp/portage/sys-devel/gcc-8.0.0_alpha20180114/work/gcc-8-20180114/gcc/omp-expand.c:7730
0xb7a557 expand_omp
       
/var/tmp/portage/sys-devel/gcc-8.0.0_alpha20180114/work/gcc-8-20180114/gcc/omp-expand.c:7716
0xb7bd1d execute_expand_omp
       
/var/tmp/portage/sys-devel/gcc-8.0.0_alpha20180114/work/gcc-8-20180114/gcc/omp-expand.c:7954

Earlier gcc versions don't have parloops-schedule parameter.