(layout_type...

(layout_type, case ARRAY_TYPE): Compute length using MAX of length and
zero if sizetype signed and neither bound constant.

From-SVN: r9668

diff --git a/gcc/stor-layout.c b/gcc/stor-layout.c
index 669a1de..e37c8df 100644 (file)
--- a/gcc/stor-layout.c
+++ b/gcc/stor-layout.c
@@ -1,5 +1,5 @@
 /* C-compiler utilities for types and variables storage layout
-   Copyright (C) 1987, 1988, 1992, 1993, 1994, 1995 Free Software Foundation, Inc.
+   Copyright (C) 1987, 88, 92, 93, 94, 1995 Free Software Foundation, Inc.
 
 This file is part of GNU CC.
 
@@ -740,6 +740,15 @@ layout_type (type)
                            size_binop (MINUS_EXPR, TYPE_MAX_VALUE (index),
                                        TYPE_MIN_VALUE (index)));
 
+           /* If neither bound is a constant and sizetype is signed, make
+              sure the size is never negative.  We should really do this
+              if *either* bound is non-constant, but this is the best
+              compromise between C and Ada.  */
+           if (! TREE_UNSIGNED (sizetype)
+               && TREE_CODE (TYPE_MIN_VALUE (index)) != INTEGER_CST
+               && TREE_CODE (TYPE_MAX_VALUE (index)) != INTEGER_CST)
+             length = size_binop (MAX_EXPR, length, size_zero_node);
+
            TYPE_SIZE (type) = size_binop (MULT_EXPR, length,
                                           TYPE_SIZE (element));
          }