[Bug c/96823] New: ice from irange::irange_intersect

[dcb314 at hotmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=96823

            Bug ID: 96823
           Summary: ice from irange::irange_intersect
           Product: gcc
           Version: unknown
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c
          Assignee: unassigned at gcc dot gnu.org
          Reporter: dcb314 at hotmail dot com
  Target Milestone: ---

Sometime between yesterday (20200826) and today, the following C code

int a, b, c;
void d() {
  unsigned short e;
  while (b)
    ;
  e = (e + 5) / 0;
  switch (e)
  case 0:
  case 3:
    c = a;
}

broke in this way:

/home/dcb/gcc/results.20200826/bin/gcc
/home/dcb/gcc/results.20200827/bin/gcc
during GIMPLE pass: vrp
resample_f.c: In function ‘rs_vib_loop’:
resample_f.c:3230:20: internal compiler error: in decompose, at wide-int.h:984
0xfc1e55 irange::irange_intersect(irange const&)
        ../../trunk.git/gcc/value-range.cc:0
0xfc15ca irange::intersect(irange const*)
        ../../trunk.git/gcc/value-range.cc:1539
0xf6a036 find_case_label_range(gswitch*, irange const*)
        ../../trunk.git/gcc/tree-vrp.c:3853

Flag -O2 required.