re PR tree-optimization/49984 (VRP does not handle BIT_XOR_EXPR)

2011-08-05  Richard Guenther  <rguenther@suse.de>

	PR tree-optimization/49984
	* tree-vrp.c (extract_range_from_binary_expr_1): Handle BIT_XOR_EXPR.

	* gcc.dg/tree-ssa/vrp59.c: New testcase.

From-SVN: r177425

gcc/ChangeLog

 2011-08-05  Richard Guenther  <rguenther@suse.de>
 
+	PR tree-optimization/49984
+	* tree-vrp.c (extract_range_from_binary_expr_1): Handle BIT_XOR_EXPR.
+
+2011-08-05  Richard Guenther  <rguenther@suse.de>
+
 	* tree-vrp.c (zero_nonzero_bits_from_vr): Make sure to always
 	return true for constant integer ranges.
 	(extract_range_from_binary_expr_1): Simplify BIT_AND_EXPR and

gcc/testsuite/ChangeLog

 2011-08-05  Richard Guenther  <rguenther@suse.de>
 
+	PR tree-optimization/49984
+	* gcc.dg/tree-ssa/vrp59.c: New testcase.
+
+2011-08-05  Richard Guenther  <rguenther@suse.de>
+
 	* gcc.dg/tree-ssa/vrp51.c: Disable CCP.
 	* gcc.dg/tree-ssa/vrp52.c: Likewise.
 	* gcc.dg/tree-ssa/vrp53.c: Likewise.

gcc/testsuite/gcc.dg/tree-ssa/vrp59.c

+/* { dg-do compile } */
+/* { dg-options "-O2 -fno-tree-ccp -fdump-tree-vrp1" } */
+
+int f(int x)
+{
+  if (x >= 0 && x <= 3)
+    {
+      x = x ^ 3;
+      x = x & 3;
+    }
+  return x;
+}
+
+int g(int x)
+{
+  if (x >= 0 && x <= 3)
+    {
+      x = x ^ 2;
+      x = x & 3;
+    }
+  return x;
+}
+
+int h(int x)
+{
+  if (x >= 0 && x <= 3)
+    {
+      x = x ^ 1;
+      x = x & 3;
+    }
+  return x;
+}
+
+/* { dg-final { scan-tree-dump-not " & 3;" "vrp1" } } */
+/* { dg-final { cleanup-tree-dump "vrp1" } } */

gcc/tree-vrp.c

@@ -2214,7 +2214,8 @@ extract_range_from_binary_expr_1 (value_range_t *vr,
       && code != MIN_EXPR
       && code != MAX_EXPR
       && code != BIT_AND_EXPR
-      && code != BIT_IOR_EXPR)
+      && code != BIT_IOR_EXPR
+      && code != BIT_XOR_EXPR)
     {
       set_value_range_to_varying (vr);
       return;
@@ -2635,7 +2636,7 @@ extract_range_from_binary_expr_1 (value_range_t *vr,
       min = vrp_int_const_binop (code, vr0.min, vr1.max);
       max = vrp_int_const_binop (code, vr0.max, vr1.min);
     }
-  else if (code == BIT_AND_EXPR || code == BIT_IOR_EXPR)
+  else if (code == BIT_AND_EXPR || code == BIT_IOR_EXPR || code == BIT_XOR_EXPR)
     {
       bool int_cst_range0, int_cst_range1;
       double_int may_be_nonzero0, may_be_nonzero1;
@@ -2694,6 +2695,35 @@ extract_range_from_binary_expr_1 (value_range_t *vr,
 	  if (int_cst_range1)
 	    min = vrp_int_const_binop (MAX_EXPR, min, vr1.min);
 	}
+      else if (code == BIT_XOR_EXPR)
+	{
+	  double_int result_zero_bits, result_one_bits;
+	  result_zero_bits
+	    = double_int_ior (double_int_and (must_be_nonzero0,
+					      must_be_nonzero1),
+			      double_int_not
+			        (double_int_ior (may_be_nonzero0,
+						 may_be_nonzero1)));
+	  result_one_bits
+	    = double_int_ior (double_int_and
+			        (must_be_nonzero0,
+				 double_int_not (may_be_nonzero1)),
+			      double_int_and
+			        (must_be_nonzero1,
+				 double_int_not (may_be_nonzero0)));
+	  max = double_int_to_tree (expr_type,
+				    double_int_not (result_zero_bits));
+	  min = double_int_to_tree (expr_type, result_one_bits);
+	  /* Return a [min, max] range if we know the
+	     result range is either positive or negative.  */
+	  if (tree_int_cst_sgn (max) >= 0)
+	    /* The range is bound by a lower value of 0.  */;
+	  else if (tree_int_cst_sgn (min) < 0)
+	    /* The range is bound by an upper value of -1.  */;
+	  else
+	    /* We don't know whether the sign bit is set or not.  */
+	    max = min = NULL_TREE;
+	}
       else
 	{
 	  set_value_range_to_varying (vr);