[Bug fortran/80965] New: ICE with class argument and -O2 optimization

["david.sagan at gmail dot com" <gcc-bugzilla at gcc dot gnu dot org>]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=80965

            Bug ID: 80965
           Summary: ICE with class argument and -O2 optimization
           Product: gcc
           Version: 7.0.1
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: fortran
          Assignee: unassigned at gcc dot gnu.org
          Reporter: david.sagan at gmail dot com
  Target Milestone: ---

Consider the code:

module mode3_mod
contains
subroutine xyz(loc)
implicit none
class(*) :: loc
real X(6)
integer ix_use
select type (loc)
type is (integer)
  x = 0
type is (real)
  ix_use = 0
end select
end subroutine xyz
end module mode3_mod


Compiling with -O2 optimization gives an error:

Davids-Mac-mini:~/Bmad/test> gfortran -c -O2 mode3_mod.f90
mode3_mod.f90:24:0:
 end subroutine xyz
internal compiler error: in compare_values_warnv, at tree-vrp.c:1223
mode3_mod.f90:24:0: internal compiler error: Abort trap: 6
gfortran: internal compiler error: Abort trap: 6 (program f951)


I am running on a Mac (10.12.5) with gcc version:
  gcc (MacPorts gcc7 7-20170420_0) 7.0.1 20170420 (prerelease)