[Bug fortran/83679] New: [6 regression] r256113 causes regression on pr77942.f90

[clyon at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=83679

            Bug ID: 83679
           Summary: [6 regression] r256113 causes regression on
                    pr77942.f90
           Product: gcc
           Version: 8.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: fortran
          Assignee: unassigned at gcc dot gnu.org
          Reporter: clyon at gcc dot gnu.org
  Target Milestone: ---

Since r256113 (backport of fix for PR83650), I have noticed a regression:
FAIL: gfortran.dg/pr77942.f90   -O  (internal compiler error)

It happens on aarch64 and arm targets.

gfortran.log contains:
f951: internal compiler error: Floating point exception
0xb56845 crash_signal
        /gcc/toplev.c:333
0x5f2807 gfc_simplify_cshift(gfc_expr*, gfc_expr*, gfc_expr*)
        /gcc/fortran/simplify.c:1842
0x57cff1 do_simplify
        /gcc/fortran/intrinsic.c:4158
0x57e2ad gfc_intrinsic_func_interface(gfc_expr*, int)
        /gcc/fortran/intrinsic.c:4528
0x5d3d66 resolve_unknown_f
        /gcc/fortran/resolve.c:2718
0x5d3d66 resolve_function
        /gcc/fortran/resolve.c:3013
0x5d3d66 gfc_resolve_expr(gfc_expr*)
        /gcc/fortran/resolve.c:6384
0x5d9ed1 gfc_resolve_code(gfc_code*, gfc_namespace*)
        /gcc/fortran/resolve.c:10514
0x5d84cc gfc_resolve_blocks(gfc_code*, gfc_namespace*)
        /gcc/fortran/resolve.c:9564
0x5d91aa gfc_resolve_code(gfc_code*, gfc_namespace*)
        /gcc/fortran/resolve.c:10504
0x5dac62 resolve_codes
        /gcc/fortran/resolve.c:15775
0x5dad65 gfc_resolve(gfc_namespace*)
        /gcc/fortran/resolve.c:15810
0x5c56db resolve_all_program_units
        /gcc/fortran/parse.c:5868
0x5c56db gfc_parse_file()
        /gcc/fortran/parse.c:6120
0x609972 gfc_be_parse_file
        /gcc/fortran/f95-lang.c:201