dependency.c (gfc_check_dependency): Improve handling of pointers...

	* dependency.c (gfc_check_dependency): Improve handling of pointers;
	Two variables of different types can't have a dependency, and two
	variables with the same symbol are equal, even if pointers.

	* gfortran.dg/dependency_12.f90: New test case.

From-SVN: r112377

gcc/fortran/ChangeLog

+2006-03-25  Roger Sayle  <roger@eyesopen.com>
+
+	* dependency.c (gfc_check_dependency): Improve handling of pointers;
+	Two variables of different types can't have a dependency, and two
+	variables with the same symbol are equal, even if pointers.
+
 2006-03-24  Roger Sayle  <roger@eyesopen.com>
 
 	* gfortran.h (gfc_symbol): Add a new "forall_index" bit field.

gcc/fortran/dependency.c

@@ -494,15 +494,6 @@ gfc_check_dependency (gfc_expr * expr1, gfc_expr * expr2, bool identical)
 
   gcc_assert (expr1->expr_type == EXPR_VARIABLE);
 
-  /* TODO: -fassume-no-pointer-aliasing */
-  if (expr1->symtree->n.sym->attr.pointer)
-    return 1;
-  for (ref = expr1->ref; ref; ref = ref->next)
-    {
-      if (ref->type == REF_COMPONENT && ref->u.c.component->pointer)
-	return 1;
-    }
-
   switch (expr2->expr_type)
     {
     case EXPR_OP:
@@ -514,21 +505,44 @@ gfc_check_dependency (gfc_expr * expr1, gfc_expr * expr2, bool identical)
       return 0;
 
     case EXPR_VARIABLE:
-      if (expr2->symtree->n.sym->attr.pointer)
-	return 1;
-
-      for (ref = expr2->ref; ref; ref = ref->next)
+      /* The interesting cases are when the symbols don't match.  */
+      if (expr1->symtree->n.sym != expr2->symtree->n.sym)
 	{
-	  if (ref->type == REF_COMPONENT && ref->u.c.component->pointer)
+	  gfc_typespec *ts1 = &expr1->symtree->n.sym->ts;
+	  gfc_typespec *ts2 = &expr2->symtree->n.sym->ts;
+
+	  /* Return 1 if expr1 and expr2 are equivalenced arrays.  */
+	  if (gfc_are_equivalenced_arrays (expr1, expr2))
 	    return 1;
-	}
 
-      /* Return 1 if expr1 and expr2 are equivalenced arrays.  */
-      if (gfc_are_equivalenced_arrays (expr1, expr2))
-	return 1;
+	  /* Symbols can only alias if they have the same type.  */
+	  if (ts1->type != BT_UNKNOWN
+	      && ts2->type != BT_UNKNOWN
+	      && ts1->type != BT_DERIVED
+	      && ts2->type != BT_DERIVED)
+	    {
+	      if (ts1->type != ts2->type
+		  || ts1->kind != ts2->kind)
+		return 0;
+	    }
 
-      if (expr1->symtree->n.sym != expr2->symtree->n.sym)
-	return 0;
+	  /* If either variable is a pointer, assume the worst.  */
+	  /* TODO: -fassume-no-pointer-aliasing */
+	  if (expr1->symtree->n.sym->attr.pointer)
+	    return 1;
+	  for (ref = expr1->ref; ref; ref = ref->next)
+	    if (ref->type == REF_COMPONENT && ref->u.c.component->pointer)
+	      return 1;
+
+	  if (expr2->symtree->n.sym->attr.pointer)
+	    return 1;
+	  for (ref = expr2->ref; ref; ref = ref->next)
+	    if (ref->type == REF_COMPONENT && ref->u.c.component->pointer)
+	      return 1;
+
+	  /* Otherwise distinct symbols have no dependencies.  */
+	  return 0;
+	}
 
       if (identical)
 	return 1;

gcc/testsuite/ChangeLog

+2006-03-25  Roger Sayle  <roger@eyesopen.com>
+
+	* gfortran.dg/dependency_12.f90: New test case.
+
 2006-03-24  Roger Sayle  <roger@eyesopen.com>
 
 	* gfortran.dg/dependency_9.f90: New (resurected) test case.

gcc/testsuite/gfortran.dg/dependency_12.f90

+! { dg-do compile }
+! { dg-options "-O2 -fdump-tree-original" }
+subroutine foo(a,b)
+  integer, pointer, dimension (:,:) :: a
+  real, dimension(:,:) :: b
+
+  where (a == 0)
+    b = 0.0
+  endwhere
+end subroutine
+! { dg-final { scan-tree-dump-times "malloc" 0 "original" } }
+! { dg-final { cleanup-tree-dump "original" } }