Add missing int_cst_rangeN checks to tree-vrp.c

The BIT_AND_EXPR handling in extract_range_from_binary_expr_1
was using value_range_constant_singleton without first checking
whether the range was a constant.  The earlier handling was correctly
guarded:

	  /* If either input range contains only non-negative values
	     we can truncate the result range maximum to the respective
	     maximum of the input range.  */
	  if (int_cst_range0 && tree_int_cst_sgn (vr0.min) >= 0)
	    wmax = wi::min (wmax, vr0.max, TYPE_SIGN (expr_type));
	  if (int_cst_range1 && tree_int_cst_sgn (vr1.min) >= 0)
	    wmax = wi::min (wmax, vr1.max, TYPE_SIGN (expr_type));

so this patch uses the same guards again.

Existing tests showed the need for this once polynomial constants
are added.

2017-09-21  Richard Sandiford  <richard.sandiford@linaro.org>
	    Alan Hayward  <alan.hayward@arm.com>
	    David Sherwood  <david.sherwood@arm.com>

gcc/
	* tree-vrp.c (extract_range_from_binary_expr_1): Check
	int_cst_rangeN before calling value_range_constant_singleton (&vrN).

Co-Authored-By: Alan Hayward <alan.hayward@arm.com>
Co-Authored-By: David Sherwood <david.sherwood@arm.com>

From-SVN: r253054

gcc/ChangeLog

+2017-09-21  Richard Sandiford  <richard.sandiford@linaro.org>
+	    Alan Hayward  <alan.hayward@arm.com>
+	    David Sherwood  <david.sherwood@arm.com>
+
+	* tree-vrp.c (extract_range_from_binary_expr_1): Check
+	int_cst_rangeN before calling value_range_constant_singleton (&vrN).
+
 2017-09-21  Richard Biener  <rguenther@suse.de>
 
 	PR tree-optimization/71351

gcc/tree-vrp.c

@@ -2930,9 +2930,11 @@ extract_range_from_binary_expr_1 (value_range *vr,
 		= wi::set_bit_in_zero (TYPE_PRECISION (expr_type) - 1,
 				       TYPE_PRECISION (expr_type));
 	      if (!TYPE_UNSIGNED (expr_type)
-		  && ((value_range_constant_singleton (&vr0)
+		  && ((int_cst_range0
+		       && value_range_constant_singleton (&vr0)
 		       && !wi::cmps (vr0.min, sign_bit))
-		      || (value_range_constant_singleton (&vr1)
+		      || (int_cst_range1
+			  && value_range_constant_singleton (&vr1)
 			  && !wi::cmps (vr1.min, sign_bit))))
 		{
 		  min = TYPE_MIN_VALUE (expr_type);