[Bug fortran/103474] New: ICE in simplify_cobound, at fortran/simplify.c:4415

[Bug fortran/103474] New: ICE in simplify_cobound, at fortran/simplify.c:4415

[gscfq@t-online.de]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=103474

            Bug ID: 103474
           Summary: ICE in simplify_cobound, at fortran/simplify.c:4415
           Product: gcc
           Version: 12.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: fortran
          Assignee: unassigned at gcc dot gnu.org
          Reporter: gscfq@t-online.de
  Target Milestone: ---

With a missing attribute allocatable or pointer :
(affects version down to at least r5)
(gcc configured with --enable-checking=yes)


$ cat z1.f90
program p
   type t
      integer :: a
   end type
   class(t) :: x[:]
   print *, ucobound(x)
end


$ cat z2.f90   # ok
program p
   type t
      integer :: a
   end type
   class(t), allocatable :: x[:]
   print *, ucobound(x)
end


$ gfortran-12-20211128 -c z1.f90 -fcoarray=lib
z1.f90:5:19:

    5 |    class(t) :: x[:]
      |                   1
Error: Coarray variable 'x' at (1) shall not have codimensions with deferred
shape
f951: internal compiler error: in simplify_cobound, at fortran/simplify.c:4415
0x866f12 simplify_cobound
        ../../gcc/fortran/simplify.c:4415
0x7ee36a do_simplify
        ../../gcc/fortran/intrinsic.c:4655
0x7f94aa gfc_intrinsic_func_interface(gfc_expr*, int)
        ../../gcc/fortran/intrinsic.c:5034
0x84d41c resolve_unknown_f
        ../../gcc/fortran/resolve.c:2972
0x84d41c resolve_function
        ../../gcc/fortran/resolve.c:3329
0x84d41c gfc_resolve_expr(gfc_expr*)
        ../../gcc/fortran/resolve.c:7166
0x853944 gfc_resolve_expr(gfc_expr*)
        ../../gcc/fortran/resolve.c:7133
0x853944 gfc_resolve_code(gfc_code*, gfc_namespace*)
        ../../gcc/fortran/resolve.c:11928
0x85228f gfc_resolve_blocks(gfc_code*, gfc_namespace*)
        ../../gcc/fortran/resolve.c:10944
0x852658 gfc_resolve_code(gfc_code*, gfc_namespace*)
        ../../gcc/fortran/resolve.c:11918
0x854f97 resolve_codes
        ../../gcc/fortran/resolve.c:17536
0x85505e gfc_resolve(gfc_namespace*)
        ../../gcc/fortran/resolve.c:17571
0x83d314 resolve_all_program_units
        ../../gcc/fortran/parse.c:6573
0x83d314 gfc_parse_file()
        ../../gcc/fortran/parse.c:6829
0x88b37f gfc_be_parse_file
        ../../gcc/fortran/f95-lang.c:216

[Bug fortran/103474] ICE in simplify_cobound, at fortran/simplify.c:4415

[kargl at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=103474

kargl at gcc dot gnu.org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
           Priority|P3                          |P4
             Status|UNCONFIRMED                 |NEW
     Ever confirmed|0                           |1
   Last reconfirmed|                            |2021-11-29
                 CC|                            |kargl at gcc dot gnu.org

--- Comment #1 from kargl at gcc dot gnu.org ---
An gcc_unreachable() conditional can obviously be reached with invalid code.
Return NULL instead of an ICE.

diff --git a/gcc/fortran/simplify.c b/gcc/fortran/simplify.c
index c9e13b59da9..2c4240c8f0d 100644
--- a/gcc/fortran/simplify.c
+++ b/gcc/fortran/simplify.c
@@ -4411,12 +4411,9 @@ simplify_cobound (gfc_expr *array, gfc_expr *dim,
gfc_expr *kind, int upper)
        }
     }

-  if (!as)
-    gcc_unreachable ();
-
  done:

-  if (as->cotype == AS_DEFERRED || as->cotype == AS_ASSUMED_SHAPE)
+  if (!as || as->cotype == AS_DEFERRED || as->cotype == AS_ASSUMED_SHAPE)
     return NULL;

   if (dim == NULL)

[Bug fortran/103474] ICE in simplify_cobound, at fortran/simplify.c:4415

[gscfq@t-online.de]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=103474

--- Comment #2 from G. Steinmetz <gscfq@t-online.de> ---
Additionally :


$ cat z3.f90
program p
   type t
      integer :: a
   end type
   class(t) :: x[:]
   if ( any(lcobound(x) < 1) ) stop
end


$ cat zz1.f90
program p
   type t
      integer :: a
   end type
   class(t), allocatable :: x[:]
   print *, lcobound(x%a)
end


$ cat zz2.f90
program p
   type t
      integer :: a(2)
   end type
   class(t), allocatable :: x[:]
   print *, lcobound(x%a)
end


$ gfortran-12-20220123 -c zz1.f90 -fcoarray=single   # release version
f951: internal compiler error: in simplify_cobound, at fortran/simplify.cc:4383
0x77ac55 simplify_cobound
        ../../gcc/fortran/simplify.cc:4383
0x70210a do_simplify
        ../../gcc/fortran/intrinsic.cc:4676
0x70cfea gfc_intrinsic_func_interface(gfc_expr*, int)
        ../../gcc/fortran/intrinsic.cc:5055
0x761368 resolve_unknown_f
        ../../gcc/fortran/resolve.cc:2972
0x761368 resolve_function
        ../../gcc/fortran/resolve.cc:3329
0x761368 gfc_resolve_expr(gfc_expr*)
        ../../gcc/fortran/resolve.cc:7169
0x767754 gfc_resolve_expr(gfc_expr*)
        ../../gcc/fortran/resolve.cc:7136
0x767754 gfc_resolve_code(gfc_code*, gfc_namespace*)
        ../../gcc/fortran/resolve.cc:11928
0x76610f gfc_resolve_blocks(gfc_code*, gfc_namespace*)
        ../../gcc/fortran/resolve.cc:10944
0x766468 gfc_resolve_code(gfc_code*, gfc_namespace*)
        ../../gcc/fortran/resolve.cc:11918
0x768da7 resolve_codes
        ../../gcc/fortran/resolve.cc:17537
0x768e6e gfc_resolve(gfc_namespace*)
        ../../gcc/fortran/resolve.cc:17572
0x751194 resolve_all_program_units
        ../../gcc/fortran/parse.cc:6586
0x751194 gfc_parse_file()
        ../../gcc/fortran/parse.cc:6842
0x79e86f gfc_be_parse_file
        ../../gcc/fortran/f95-lang.cc:216

[Bug fortran/103474] ICE in simplify_cobound, at fortran/simplify.c:4415

[anlauf at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=103474

anlauf at gcc dot gnu.org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |anlauf at gcc dot gnu.org

--- Comment #3 from anlauf at gcc dot gnu.org ---
The patch in comment#1 fixes comment#0, but not comment#2, which hits another
assert.  That one needs additionally something like

@@ -4353,7 +4356,8 @@ simplify_cobound (gfc_expr *array, gfc_expr *dim,
gfc_expr *kind, int upper)
            case AR_ELEMENT:
              if (ref->u.ar.as->corank > 0)
                {
-                 gcc_assert (as == ref->u.ar.as);
+//               gcc_assert (as == ref->u.ar.as);
+                 as = ref->u.ar.as;
                  goto done;
                }
              as = NULL;

However, that would lead to silent acceptance of invalid code which needs
checking elsewhere.

[Bug fortran/103474] ICE in simplify_cobound, at fortran/simplify.c:4415

[anlauf at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=103474

--- Comment #4 from anlauf at gcc dot gnu.org ---
Another part which is needed to avoid an ice-on-valid code:
(Note F2018:5.4.7(5): A subobject of a coarray is a coarray if ...)

diff --git a/gcc/fortran/expr.cc b/gcc/fortran/expr.cc
index 69d0b57c688..ef8f042a7e4 100644
--- a/gcc/fortran/expr.cc
+++ b/gcc/fortran/expr.cc
@@ -5845,6 +5845,8 @@ gfc_get_corank (gfc_expr *e)
       if (ref->type == REF_ARRAY)
        corank = ref->u.ar.as->corank;
       gcc_assert (ref->type != REF_SUBSTRING);
+      if (corank)
+       break;
     }

   return corank;

[Bug fortran/103474] ICE in simplify_cobound, at fortran/simplify.c:4415

[anlauf at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=103474

--- Comment #5 from anlauf at gcc dot gnu.org ---
I am now stuck with the following code, which I believe is valid.
(It is accepted by Crayftn and rejected by Intel, but I thought it is
covered by F2018:5.4.7(5)):

program p
  type t
     integer :: a(1,2)
  end type
  class(t), allocatable :: x[:]
  print *, ucobound (x%a)
end

The problem I have is that gfc_conv_expr_descriptor invokes walk_coarray,
but the result depends on the rank of the array a in type t.
The comment before walk_coarray states:

/* Convert the last ref of a scalar coarray from an AR_ELEMENT to an
   AR_FULL, suitable for the scalarizer.  */

However, we should find a way to only extract the "co-descriptor".
We might also need that when implement COSHAPE.