fold-const.c (make_range): Only narrow to signed range if the signed range is…

fold-const.c (make_range): Only narrow to signed range if the signed range is smaller than the unsigned range.

        * fold-const.c (make_range): Only narrow to signed range if
        the signed range is smaller than the unsigned range.

	* gcc.c-torture/execute/20020911-1.c: New.

From-SVN: r57050

gcc/ChangeLog

+2002-09-11  Hartmut Penner  <hpenner@de.ibm.com>
+
+	* fold-const.c (make_range): Only narrow to signed range if
+	the signed range is smaller than the unsigned range.
+
 2002-09-12  Alan Modra  <amodra@bigpond.net.au>
 
 	* emit-rtl.c (set_mem_size): New function.

gcc/fold-const.c

@@ -3089,9 +3089,10 @@ make_range (exp, pin_p, plow, phigh)
 		= TYPE_MAX_VALUE (equiv_type) ? TYPE_MAX_VALUE (equiv_type)
 		  : TYPE_MAX_VALUE (type);
 
-	      high_positive = fold (build (RSHIFT_EXPR, type,
-					   convert (type, high_positive),
-					   convert (type, integer_one_node)));
+	      if (TYPE_PRECISION (type) == TYPE_PRECISION (TREE_TYPE (exp)))
+	        high_positive = fold (build (RSHIFT_EXPR, type,
+					     convert (type, high_positive),
+					     convert (type, integer_one_node)));
 
 	      /* If the low bound is specified, "and" the range with the
 		 range for which the original unsigned value will be

gcc/testsuite/gcc.c-torture/execute/20020911-1.c

+extern void abort (void);
+unsigned short c = 0x8000;
+int main()
+{
+  if ((c-0x8000) < 0 || (c-0x8000) > 0x7fff)
+    abort();
+  return 0;
+}