[Patch, fortran] PR29396 PR29606 PR30625 and PR30871 - subreference array pointers.

[Tobias Burnus]

Paul Thomas wrote:
> It is my opinion that this patch is ready for 4.3 simply because it
> provides an extra functionality that is ringfenced by specific tests. 
> Such pointer assignements, at present, either lead to ICEs or wrong
> code.  Hence, even if it is not in its final form, it will not break
> anything, whilst filling in the missing f95 feature.
I looked at the patch plus at the following, which I extracted from your
follow up:
  http://gcc.gnu.org/ml/fortran/2007-09/msg00175.html

As the diff looks quite different, I'm not 100% sure that I got it right.

@@ -4124,10 +4120,12 @@ gfc_trans_assignment (gfc_expr * expr1,
     }

   /* Special case copying one array to another.  */
-  if (copyable_array_p (expr1)
-      && copyable_array_p (expr2)
-      && gfc_compare_types (&expr1->ts, &expr2->ts)
-      && !gfc_check_dependency (expr1, expr2, 0))
+   if (expr1->expr_type == EXPR_VARIABLE
+       && copyable_array_p (expr1)
+       && gfc_full_array_ref_p (expr1->ref)
+       && !expr1->ref->next
+       && expr2->expr_type == EXPR_ARRAY
+       && gfc_compare_types (&expr1->ts, &expr2->ts))
     {
       tmp = gfc_trans_array_copy (expr1, expr2);
       if (tmp)


Looking at all the failures I got, I'm almost positive that I have not got it right. :-(


Now to the patch:

@@ -206,7 +206,9 @@ gfc_get_expr_charlen (gfc_expr *e)
        default:
          /* We should never got substring references here.  These will be
             broken down by the scalarizer.  */
-         gcc_unreachable ();
+         if (is_subref_array (e))
+           length = e->symtree->n.sym->ts.cl->backend_decl;
+         break;


Shouldn't one update the comment?


@@ -321,7 +323,28 @@ gfc_build_array_ref (tree base, tree off
+  if (decl && (TREE_CODE (decl) == FIELD_DECL
+                    || TREE_CODE (decl) == VAR_DECL
+                    || TREE_CODE (decl) == PARM_DECL)

The indenting looks wrong.


Otherwise, the patch seems to be ok. (It would great if someone else would also review the patch!)


Note: I still get a ICE with the test case from PR29606:

internal compiler error: in gfc_get_element_type, at fortran/trans-types.c:935

(This might be because I wrongly applied the follow-up patch; or it might be not.)


For the example of PR30871 I get an ICE (segmentation fault):

==23839== Invalid read of size 8
==23839==    at 0x4985B6: gfc_get_expr_charlen (trans-expr.c:210)
==23839==    by 0x487115: gfc_conv_expr_descriptor (trans-array.c:4614)
==23839==    by 0x49CF3D: gfc_trans_pointer_assignment (trans-expr.c:3465)


And if I try to regression test, There are legions of failures.

gfortran.dg/alloc_comp_constructor_1.f90:102: internal compiler error: Segmentation fault
==31732== Invalid read of size 8
==31732==    at 0x49C380: gfc_trans_assignment (trans-expr.c:3824)
==31732==    by 0x47FE80: gfc_trans_code (trans.c:993)
==31732==    by 0x494E42: gfc_generate_function_code (trans-decl.c:3277)

gfortran.dg/allocatable_dummy_1.f90:28: internal compiler error: Segmentation fault
==31752== Invalid read of size 8
==31752==    at 0x49C380: gfc_trans_assignment (trans-expr.c:3824)
==31752==    by 0x47FE80: gfc_trans_code (trans.c:993)
==31752==    by 0x494E42: gfc_generate_function_code (trans-decl.c:3277)

etc.


Tobias