expr.c (safe_from_p): Change code to ERROR_MARK only when not accessing nodes.

	* expr.c (safe_from_p): Change code to ERROR_MARK only when not
	accessing nodes.
	* toplev.c (display_help): Add braces to shut up warnings.
	* fold-const.c (non_lvalue): Don't deal with null pointer
	constants here.
	(fold, case COMPOUND_EXPR): Wrap a constant 0 in a NOP_EXPR.

From-SVN: r21698

gcc/ChangeLog

+Thu Aug 13 16:09:53 1998  Martin von Loewis  <loewis@informatik.hu-berlin.de>
+
+	* expr.c (safe_from_p): Change code to ERROR_MARK only when not
+	accessing nodes.
+
 Thu Aug 13 15:24:48 1998  Jason Merrill  <jason@yorick.cygnus.com>
 
+	* toplev.c (display_help): Add braces to shut up warnings.
+
+	* fold-const.c (non_lvalue): Don't deal with null pointer 
+	constants here.
+	(fold, case COMPOUND_EXPR): Wrap a constant 0 in a NOP_EXPR.
+
 	* c-typeck.c (initializer_constant_valid_p): Allow conversion of 0
 	of any size to a pointer.
 

gcc/expr.c

@@ -4983,13 +4983,19 @@ safe_from_p (x, exp, top_p)
 	  if (save_expr_count >= save_expr_size)
 	    return 0;
 	  save_expr_rewritten[save_expr_count++] = exp;
-	  TREE_SET_CODE (exp, ERROR_MARK);
 
 	  nops = tree_code_length[(int) SAVE_EXPR];
 	  for (i = 0; i < nops; i++)
-	    if (TREE_OPERAND (exp, i) != 0
-		&& ! safe_from_p (x, TREE_OPERAND (exp, i), 0))
+	    {
+	      tree operand = TREE_OPERAND (exp, i);
+	      if (operand == NULL_TREE)
+		continue;
+	      TREE_SET_CODE (exp, ERROR_MARK);
+	      if (!safe_from_p (x, operand, 0))
 		return 0;
+	      TREE_SET_CODE (exp, SAVE_EXPR);
+	    }
+	  TREE_SET_CODE (exp, ERROR_MARK);
 	  return 1;
 
 	case BIND_EXPR:

gcc/fold-const.c

@@ -1679,8 +1679,7 @@ fold_convert (t, arg1)
   return t;
 }
 
-/* Return an expr equal to X but certainly not valid as an lvalue.
-   Also make sure it is not valid as an null pointer constant.  */
+/* Return an expr equal to X but certainly not valid as an lvalue.  */
 
 tree
 non_lvalue (x)
@@ -1694,18 +1693,7 @@ non_lvalue (x)
       || TREE_CODE (x) == REAL_CST
       || TREE_CODE (x) == STRING_CST
       || TREE_CODE (x) == ADDR_EXPR)
-    {
-      if (TREE_CODE (x) == INTEGER_CST && integer_zerop (x))
-	{
-	  /* Use NOP_EXPR instead of NON_LVALUE_EXPR
-	     so convert_for_assignment won't strip it.
-	     This is so this 0 won't be treated as a null pointer constant.  */
-	  result = build1 (NOP_EXPR, TREE_TYPE (x), x);
-	  TREE_CONSTANT (result) = TREE_CONSTANT (x);
-	  return result;
-	}
     return x;
-    }
 
   result = build1 (NON_LVALUE_EXPR, TREE_TYPE (x), x);
   TREE_CONSTANT (result) = TREE_CONSTANT (x);
@@ -6060,7 +6048,7 @@ fold (expr)
 	return t;
       /* Don't let (0, 0) be null pointer constant.  */
       if (integer_zerop (arg1))
-	return non_lvalue (arg1);
+	return build1 (NOP_EXPR, TREE_TYPE (arg1), arg1);
       return arg1;
 
     case COMPLEX_EXPR:

gcc/toplev.c

@@ -4094,11 +4094,13 @@ display_help ()
 	}
 #endif
       if (undoc)
+	{
 	  if (doc)
 	    printf ("\nThere are undocumented target specific options as well.\n");
 	  else
 	    printf ("  They exist, but they are not documented.\n");
 	}
+    }
 }
 
 /* Compare the user specified 'option' with the language