[Bug fortran/88611] [9 Regression] ICE in eliminate_stmt, at tree-ssa-sccvn.c:5011

[rguenth at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=88611

Richard Biener <rguenth at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|ASSIGNED                    |NEW
                 CC|                            |burnus at gcc dot gnu.org
          Component|tree-optimization           |fortran
           Assignee|rguenth at gcc dot gnu.org         |unassigned at gcc dot gnu.org

--- Comment #2 from Richard Biener <rguenth at gcc dot gnu.org> ---
OK, so this is

 <var_decl 0x7ffff7fefab0 p
    type <pointer_type 0x7ffff6896000
        type <void_type 0x7ffff688ff18 void VOID
            align:8 warn_if_not_align:0 symtab:0 alias-set -1 canonical-type
0x7ffff688ff18
            pointer_to_this <pointer_type 0x7ffff6896000>>
        public unsigned DI
        size <integer_cst 0x7ffff687ab70 constant 64>
        unit-size <integer_cst 0x7ffff687ab88 constant 8>
        align:64 warn_if_not_align:0 symtab:0 alias-set 4 canonical-type
0x7ffff6896000
        pointer_to_this <pointer_type 0x7ffff689b738>>
    readonly used static unsigned DI t.f90:8:0 size <integer_cst 0x7ffff687ab70
64> unit-size <integer_cst 0x7ffff687ab88 8>
    align:64 warn_if_not_align:0 context <function_decl 0x7ffff6a44c00
pr82869_8> initial <integer_cst 0x7ffff689a210 0> chain <var_decl
0x7ffff7fefb40 s>>

where the DECL_INITIAL is

 <integer_cst 0x7ffff689a210 type <integer_type 0x7ffff688f738 integer(kind=8)>
constant 0>

so a frontend type mismatch we do not "expect" ...

  type(c_ptr) :: p = c_null_ptr

My change uncovers this.  The inital value is set here:

tree
gfc_get_symbol_decl (gfc_symbol * sym)
{
...
      /* Add static initializer. For procedures, it is only needed if
         SAVE is specified otherwise they need to be reinitialized
         every time the procedure is entered. The TREE_STATIC is
         in this case due to -fmax-stack-var-size=.  */

      DECL_INITIAL (decl) = gfc_conv_initializer (sym->value, &sym->ts,
                                    TREE_TYPE (decl), sym->attr.dimension
                                    || (sym->attr.codimension
                                        && sym->attr.allocatable),
                                    sym->attr.pointer || sym->attr.allocatable
                                    || sym->ts.type == BT_CLASS,
                                    sym->attr.proc_pointer);

and there

  /* Check if we have ISOCBINDING_NULL_PTR or ISOCBINDING_NULL_FUNPTR
     (these are the only two iso_c_binding derived types that can be
     used as initialization expressions).  If so, we need to modify
     the 'expr' to be that for a (void *).  */
  if (expr != NULL && expr->ts.type == BT_DERIVED
      && expr->ts.is_iso_c && expr->ts.u.derived)
    {
      gfc_symbol *derived = expr->ts.u.derived;

      /* The derived symbol has already been converted to a (void *).  Use
         its kind.  */
      if (derived->ts.kind == 0)
        derived->ts.kind = gfc_default_integer_kind;
      expr = gfc_get_int_expr (derived->ts.kind, NULL, 0);
      expr->ts.f90_type = derived->ts.f90_type;

      gfc_init_se (&se, NULL);
      gfc_conv_constant (&se, expr);
      gcc_assert (TREE_CODE (se.expr) != CONSTRUCTOR);
      return se.expr;

but it looks like gfc_conv_constant doesn't do the pointer conversion
required.  It also looks overly complicated to me where at the same
time it doesn't try to distinguish between (void *) and void (*)()
or whatever type ISOCBINDING_NULL_FUNPTR is supposed to map to...

Well.  The following "fixes" this for me.  Fortran folks?

diff --git a/gcc/fortran/trans-expr.c b/gcc/fortran/trans-expr.c
index 27eb2d2ee38..798952c2336 100644
--- a/gcc/fortran/trans-expr.c
+++ b/gcc/fortran/trans-expr.c
@@ -7085,21 +7085,7 @@ gfc_conv_initializer (gfc_expr * expr, gfc_typespec *
ts, tree type,
      the 'expr' to be that for a (void *).  */
   if (expr != NULL && expr->ts.type == BT_DERIVED
       && expr->ts.is_iso_c && expr->ts.u.derived)
-    {
-      gfc_symbol *derived = expr->ts.u.derived;
-
-      /* The derived symbol has already been converted to a (void *).  Use
-        its kind.  */
-      if (derived->ts.kind == 0)
-       derived->ts.kind = gfc_default_integer_kind;
-      expr = gfc_get_int_expr (derived->ts.kind, NULL, 0);
-      expr->ts.f90_type = derived->ts.f90_type;
-
-      gfc_init_se (&se, NULL);
-      gfc_conv_constant (&se, expr);
-      gcc_assert (TREE_CODE (se.expr) != CONSTRUCTOR);
-      return se.expr;
-    }
+    return build_int_cst (ptr_type_node, 0);

   if (array && !procptr)
     {