re PR tree-optimization/23129 (VRP propagates division of antiranges incorrectly)

2005-08-02  James A. Morrison  <phython@gcc.gnu.org>

        PR tree-optimization/23129
        * tree-vrp.c (extract_range_from_binary_expr): Set value range to
        varying for divisions with anti-ranges.

From-SVN: r102653

gcc/ChangeLog

+2005-08-02  James A. Morrison  <phython@gcc.gnu.org>
+
+	PR tree-optimization/23129
+	* tree-vrp.c (extract_range_from_binary_expr): Set value range to
+	varying for divisions with anti-ranges.
+
 2005-08-02  Jan Hubicka  <jh@suse.cz>
 
 	* tree-ssa-dom.c (thread_across_edge): Remove updating here.

gcc/testsuite/ChangeLog

+2005-08-02  James A. Morrison  <phython@gcc.gnu.org>
+
+	* gcc.c-torture/execute/vrp-4.c: New test.
+
 2005-08-02  Jan Hubicka  <jh@suse.cz>
 
 	* update-threading.c: New test.

gcc/testsuite/gcc.c-torture/execute/vrp-4.c

+extern void exit (int);
+extern void abort ();
+
+void test(int x, int y)
+{
+	int c;
+
+	if (x == 1) abort();
+	if (y == 1) abort();
+
+	c = x / y;
+
+	if (c != 1) abort();
+}
+
+int main()
+{
+	test(2, 2);
+	exit (0);
+}

gcc/tree-vrp.c

@@ -1136,7 +1136,8 @@ extract_range_from_binary_expr (value_range_t *vr, tree expr)
 	 the new range.  */
 
       /* Divisions by zero result in a VARYING value.  */
-      if (code != MULT_EXPR && range_includes_zero_p (&vr1))
+      if (code != MULT_EXPR
+	  && (vr0.type == VR_ANTI_RANGE || range_includes_zero_p (&vr1)))
 	{
 	  set_value_range_to_varying (vr);
 	  return;