tree-vrp.c (extract_range_from_binary_expr): Handle overflow from unsigned additions.

2009-04-24  Richard Guenther  <rguenther@suse.de>

	* tree-vrp.c (extract_range_from_binary_expr): Handle overflow
	from unsigned additions.

	* gcc.dg/tree-ssa/vrp48.c: New testcase.

From-SVN: r146742

gcc/ChangeLog

+2009-04-24  Richard Guenther  <rguenther@suse.de>
+
+	* tree-vrp.c (extract_range_from_binary_expr): Handle overflow
+	from unsigned additions.
+
 2009-04-24  Joseph Myers  <joseph@codesourcery.com>
 
 	* c-typeck.c (set_init_index): Allow array designators that are

gcc/testsuite/ChangeLog

+2009-04-24  Richard Guenther  <rguenther@suse.de>
+
+	* gcc.dg/tree-ssa/vrp48.c: New testcase.
+
 2009-04-24  Joseph Myers  <joseph@codesourcery.com>
 
 	* gcc.dg/array-const-1.c, gcc.dg/array-const-2.c,

gcc/testsuite/gcc.dg/tree-ssa/vrp48.c

+extern void link_failure (void);
+
+static int __attribute__ ((noinline)) foo (int x)
+{
+  if (x >= 1)
+    if (x <= 10)
+      {
+	if (x < 1 || x > 10)
+	  link_failure ();
+	x = x + 1;
+      }
+  return x;
+}
+
+int main (void)
+{
+  int i = foo (0);
+  return 0;
+}
+

gcc/tree-vrp.c

@@ -2248,6 +2248,22 @@ extract_range_from_binary_expr (value_range_t *vr,
 	 the same end of each range.  */
       min = vrp_int_const_binop (code, vr0.min, vr1.min);
       max = vrp_int_const_binop (code, vr0.max, vr1.max);
+
+      /* If both additions overflowed the range kind is still correct.
+	 This happens regularly with subtracting something in unsigned
+	 arithmetic.
+         ???  See PR30318 for all the cases we do not handle.  */
+      if (code == PLUS_EXPR
+	  && (TREE_OVERFLOW (min) && !is_overflow_infinity (min))
+	  && (TREE_OVERFLOW (max) && !is_overflow_infinity (max)))
+	{
+	  min = build_int_cst_wide (TREE_TYPE (min),
+				    TREE_INT_CST_LOW (min),
+				    TREE_INT_CST_HIGH (min));
+	  max = build_int_cst_wide (TREE_TYPE (max),
+				    TREE_INT_CST_LOW (max),
+				    TREE_INT_CST_HIGH (max));
+	}
     }
   else if (code == MULT_EXPR
 	   || code == TRUNC_DIV_EXPR