2010-02-20 Paul Thomas <pault@gcc.gnu.org>

[pf3gnuchains/gcc-fork.git] / gcc / fortran / dependency.c

diff --git a/gcc/fortran/dependency.c b/gcc/fortran/dependency.c
index eb07e7c..1f3d0ed 100644 (file)
--- a/gcc/fortran/dependency.c
+++ b/gcc/fortran/dependency.c
@@ -467,7 +467,7 @@ gfc_check_argument_var_dependency (gfc_expr *var, sym_intent intent,
       /* In case of elemental subroutines, there is no dependency 
          between two same-range array references.  */
       if (gfc_ref_needs_temporary_p (expr->ref)
-         || gfc_check_dependency (var, expr, !elemental))
+         || gfc_check_dependency (var, expr, elemental == NOT_ELEMENTAL))
        {
          if (elemental == ELEM_DONT_CHECK_VARIABLE)
            {
@@ -677,6 +677,78 @@ gfc_are_equivalenced_arrays (gfc_expr *e1, gfc_expr *e2)
 }
 
 
+/* Return true if there is no possibility of aliasing because of a type
+   mismatch between all the possible pointer references and the
+   potential target.  Note that this function is asymmetric in the
+   arguments and so must be called twice with the arguments exchanged.  */
+
+static bool
+check_data_pointer_types (gfc_expr *expr1, gfc_expr *expr2)
+{
+  gfc_component *cm1;
+  gfc_symbol *sym1;
+  gfc_symbol *sym2;
+  gfc_ref *ref1;
+  bool seen_component_ref;
+
+  if (expr1->expr_type != EXPR_VARIABLE
+       || expr1->expr_type != EXPR_VARIABLE)
+    return false;
+
+  sym1 = expr1->symtree->n.sym;
+  sym2 = expr2->symtree->n.sym;
+
+  /* Keep it simple for now.  */
+  if (sym1->ts.type == BT_DERIVED && sym2->ts.type == BT_DERIVED)
+    return false;
+
+  if (sym1->attr.pointer)
+    {
+      if (gfc_compare_types (&sym1->ts, &sym2->ts))
+       return false;
+    }
+
+  /* This is a conservative check on the components of the derived type
+     if no component references have been seen.  Since we will not dig
+     into the components of derived type components, we play it safe by
+     returning false.  First we check the reference chain and then, if
+     no component references have been seen, the components.  */
+  seen_component_ref = false;
+  if (sym1->ts.type == BT_DERIVED)
+    {
+      for (ref1 = expr1->ref; ref1; ref1 = ref1->next)
+       {
+         if (ref1->type != REF_COMPONENT)
+           continue;
+
+         if (ref1->u.c.component->ts.type == BT_DERIVED)
+           return false;
+
+         if ((sym2->attr.pointer || ref1->u.c.component->attr.pointer)
+               && gfc_compare_types (&ref1->u.c.component->ts, &sym2->ts))
+           return false;
+
+         seen_component_ref = true;
+       }
+    }
+
+  if (sym1->ts.type == BT_DERIVED && !seen_component_ref)
+    {
+      for (cm1 = sym1->ts.u.derived->components; cm1; cm1 = cm1->next)
+       {
+         if (cm1->ts.type == BT_DERIVED)
+           return false;
+
+         if ((sym2->attr.pointer || cm1->attr.pointer)
+               && gfc_compare_types (&cm1->ts, &sym2->ts))
+           return false;
+       }
+    }
+
+  return true;
+}
+
+
 /* Return true if the statement body redefines the condition.  Returns
    true if expr2 depends on expr1.  expr1 should be a single term
    suitable for the lhs of an assignment.  The IDENTICAL flag indicates
@@ -726,7 +798,13 @@ gfc_check_dependency (gfc_expr *expr1, gfc_expr *expr2, bool identical)
          /* If either variable is a pointer, assume the worst.  */
          /* TODO: -fassume-no-pointer-aliasing */
          if (gfc_is_data_pointer (expr1) || gfc_is_data_pointer (expr2))
-           return 1;
+           {
+             if (check_data_pointer_types (expr1, expr2)
+                   && check_data_pointer_types (expr2, expr1))
+               return 0;
+
+             return 1;
+           }
 
          /* Otherwise distinct symbols have no dependencies.  */
          return 0;
@@ -1197,10 +1275,17 @@ gfc_full_array_ref_p (gfc_ref *ref, bool *contiguous)
   bool lbound_OK = true;
   bool ubound_OK = true;
 
+  if (contiguous)
+    *contiguous = false;
+
   if (ref->type != REF_ARRAY)
     return false;
   if (ref->u.ar.type == AR_FULL)
-    return true;
+    {
+      if (contiguous)
+       *contiguous = true;
+      return true;
+    }
   if (ref->u.ar.type != AR_SECTION)
     return false;
   if (ref->next)