Change fold_range to return a boolean result.

2019-11-14  Andrew MacLeod  <amacleod@redhat.com>

	* range-op.h (range_operator::fold_range): Return a bool.
	* range-op.cc (range_operator::wi_fold): Assert supported type.
	(range_operator::fold_range): Assert supported type and return true.
	(operator_equal::fold_range): Return true.
	(operator_not_equal::fold_range): Same.
	(operator_lt::fold_range): Same.
	(operator_le::fold_range): Same.
	(operator_gt::fold_range): Same.
	(operator_ge::fold_range): Same.
	(operator_plus::op1_range): Adjust call to fold_range.
	(operator_plus::op2_range): Same.
	(operator_minus::op1_range): Same.
	(operator_minus::op2_range): Same.
	(operator_exact_divide::op1_range): Same.
	(operator_lshift::fold_range): Return true and adjust fold_range call.
	(operator_rshift::fold_range): Same.
	(operator_cast::fold_range): Return true.
	(operator_logical_and::fold_range): Same.
	(operator_logical_or::fold_range): Same.
	(operator_logical_not::fold_range): Same.
	(operator_bitwise_not::fold_range): Adjust call to fold_range.
	(operator_bitwise_not::op1_range): Same.
	(operator_cst::fold_range): Return true.
	(operator_identity::fold_range): Return true.
	(operator_negate::fold_range): Return true and adjust fold_range call.
	(operator_addr_expr::fold_range): Return true.
	(operator_addr_expr::op1_range): Adjust call to fold_range.
	(range_cast): Same.
	* tree-vrp.c (range_fold_binary_symbolics_p): Adjust call to fold_range.
	(range_fold_unary_symbolics_p): Same.

From-SVN: r278266

4 files changed, 130 insertions, 90 deletions

diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index 9f76c92..240bda5 100644
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,5 +1,38 @@
 2019-11-14  Andrew MacLeod  <amacleod@redhat.com>
 
+	* range-op.h (range_operator::fold_range): Return a bool.
+	* range-op.cc (range_operator::wi_fold): Assert supported type.
+	(range_operator::fold_range): Assert supported type and return true.
+	(operator_equal::fold_range): Return true.
+	(operator_not_equal::fold_range): Same.
+	(operator_lt::fold_range): Same.
+	(operator_le::fold_range): Same.
+	(operator_gt::fold_range): Same.
+	(operator_ge::fold_range): Same.
+	(operator_plus::op1_range): Adjust call to fold_range.
+	(operator_plus::op2_range): Same.
+	(operator_minus::op1_range): Same.
+	(operator_minus::op2_range): Same.
+	(operator_exact_divide::op1_range): Same.
+	(operator_lshift::fold_range): Return true and adjust fold_range call.
+	(operator_rshift::fold_range): Same.
+	(operator_cast::fold_range): Return true.
+	(operator_logical_and::fold_range): Same.
+	(operator_logical_or::fold_range): Same.
+	(operator_logical_not::fold_range): Same.
+	(operator_bitwise_not::fold_range): Adjust call to fold_range.
+	(operator_bitwise_not::op1_range): Same.
+	(operator_cst::fold_range): Return true.
+	(operator_identity::fold_range): Return true.
+	(operator_negate::fold_range): Return true and adjust fold_range call.
+	(operator_addr_expr::fold_range): Return true.
+	(operator_addr_expr::op1_range): Adjust call to fold_range.
+	(range_cast): Same.
+	* tree-vrp.c (range_fold_binary_symbolics_p): Adjust call to fold_range.
+	(range_fold_unary_symbolics_p): Same.
+
+2019-11-14  Andrew MacLeod  <amacleod@redhat.com>
+
 	PR tree-optimization/92506
 	* range-op.cc (range_operator::fold_range): Start with range undefined.
 	(operator_abs::wi_fold): Fix wrong line copy... With wrapv, abs with
diff --git a/gcc/range-op.cc b/gcc/range-op.cc
index 39c3591..59d5d00 100644
--- a/gcc/range-op.cc
+++ b/gcc/range-op.cc
@@ -131,19 +131,21 @@ range_operator::wi_fold (value_range &r, tree type,
 			 const wide_int &rh_lb ATTRIBUTE_UNUSED,
 			 const wide_int &rh_ub ATTRIBUTE_UNUSED) const
 {
+  gcc_checking_assert (value_range::supports_type_p (type));
   r = value_range (type);
 }
 
 // The default for fold is to break all ranges into sub-ranges and
 // invoke the wi_fold method on each sub-range pair.
 
-void
+bool
 range_operator::fold_range (value_range &r, tree type,
 			    const value_range &lh,
 			    const value_range &rh) const
 {
+  gcc_checking_assert (value_range::supports_type_p (type));
   if (empty_range_check (r, lh, rh))
-    return;
+    return true;
 
   value_range tmp;
   r.set_undefined ();
@@ -157,8 +159,9 @@ range_operator::fold_range (value_range &r, tree type,
 	wi_fold (tmp, type, lh_lb, lh_ub, rh_lb, rh_ub);
 	r.union_ (tmp);
 	if (r.varying_p ())
-	  return;
+	  return true;
       }
+  return true;
 }
 
 // The default for op1_range is to return false.
@@ -364,7 +367,7 @@ get_bool_state (value_range &r, const value_range &lhs, tree val_type)
 class operator_equal : public range_operator
 {
 public:
-  virtual void fold_range (value_range &r, tree type,
+  virtual bool fold_range (value_range &r, tree type,
 			   const value_range &op1,
 			   const value_range &op2) const;
   virtual bool op1_range (value_range &r, tree type,
@@ -375,13 +378,13 @@ public:
 			  const value_range &val) const;
 } op_equal;
 
-void
+bool
 operator_equal::fold_range (value_range &r, tree type,
 			    const value_range &op1,
 			    const value_range &op2) const
 {
   if (empty_range_check (r, op1, op2))
-    return;
+    return true;
 
   // We can be sure the values are always equal or not if both ranges
   // consist of a single value, and then compare them.
@@ -404,6 +407,7 @@ operator_equal::fold_range (value_range &r, tree type,
       else
 	r = range_true_and_false (type);
     }
+  return true;
 }
 
 bool
@@ -448,7 +452,7 @@ operator_equal::op2_range (value_range &r, tree type,
 class operator_not_equal : public range_operator
 {
 public:
-  virtual void fold_range (value_range &r, tree type,
+  virtual bool fold_range (value_range &r, tree type,
 			   const value_range &op1,
 			   const value_range &op2) const;
   virtual bool op1_range (value_range &r, tree type,
@@ -459,13 +463,13 @@ public:
 			  const value_range &op1) const;
 } op_not_equal;
 
-void
+bool
 operator_not_equal::fold_range (value_range &r, tree type,
 				const value_range &op1,
 				const value_range &op2) const
 {
   if (empty_range_check (r, op1, op2))
-    return;
+    return true;
 
   // We can be sure the values are always equal or not if both ranges
   // consist of a single value, and then compare them.
@@ -488,6 +492,7 @@ operator_not_equal::fold_range (value_range &r, tree type,
       else
 	r = range_true_and_false (type);
     }
+  return true;
 }
 
 bool
@@ -578,7 +583,7 @@ build_ge (value_range &r, tree type, const wide_int &val)
 class operator_lt :  public range_operator
 {
 public:
-  virtual void fold_range (value_range &r, tree type,
+  virtual bool fold_range (value_range &r, tree type,
 			   const value_range &op1,
 			   const value_range &op2) const;
   virtual bool op1_range (value_range &r, tree type,
@@ -589,13 +594,13 @@ public:
 			  const value_range &op1) const;
 } op_lt;
 
-void
+bool
 operator_lt::fold_range (value_range &r, tree type,
 			 const value_range &op1,
 			 const value_range &op2) const
 {
   if (empty_range_check (r, op1, op2))
-    return;
+    return true;
 
   signop sign = TYPE_SIGN (op1.type ());
   gcc_checking_assert (sign == TYPE_SIGN (op2.type ()));
@@ -606,6 +611,7 @@ operator_lt::fold_range (value_range &r, tree type,
     r = range_false (type);
   else
     r = range_true_and_false (type);
+  return true;
 }
 
 bool
@@ -654,7 +660,7 @@ operator_lt::op2_range (value_range &r, tree type,
 class operator_le :  public range_operator
 {
 public:
-  virtual void fold_range (value_range &r, tree type,
+  virtual bool fold_range (value_range &r, tree type,
 			   const value_range &op1,
 			   const value_range &op2) const;
   virtual bool op1_range (value_range &r, tree type,
@@ -665,13 +671,13 @@ public:
 			  const value_range &op1) const;
 } op_le;
 
-void
+bool
 operator_le::fold_range (value_range &r, tree type,
 			 const value_range &op1,
 			 const value_range &op2) const
 {
   if (empty_range_check (r, op1, op2))
-    return;
+    return true;
 
   signop sign = TYPE_SIGN (op1.type ());
   gcc_checking_assert (sign == TYPE_SIGN (op2.type ()));
@@ -682,6 +688,7 @@ operator_le::fold_range (value_range &r, tree type,
     r = range_false (type);
   else
     r = range_true_and_false (type);
+  return true;
 }
 
 bool
@@ -730,7 +737,7 @@ operator_le::op2_range (value_range &r, tree type,
 class operator_gt :  public range_operator
 {
 public:
-  virtual void fold_range (value_range &r, tree type,
+  virtual bool fold_range (value_range &r, tree type,
 			   const value_range &op1,
 			   const value_range &op2) const;
   virtual bool op1_range (value_range &r, tree type,
@@ -741,12 +748,12 @@ public:
 			  const value_range &op1) const;
 } op_gt;
 
-void
+bool
 operator_gt::fold_range (value_range &r, tree type,
 			 const value_range &op1, const value_range &op2) const
 {
   if (empty_range_check (r, op1, op2))
-    return;
+    return true;
 
   signop sign = TYPE_SIGN (op1.type ());
   gcc_checking_assert (sign == TYPE_SIGN (op2.type ()));
@@ -757,6 +764,7 @@ operator_gt::fold_range (value_range &r, tree type,
     r = range_false (type);
   else
     r = range_true_and_false (type);
+  return true;
 }
 
 bool
@@ -804,7 +812,7 @@ operator_gt::op2_range (value_range &r, tree type,
 class operator_ge :  public range_operator
 {
 public:
-  virtual void fold_range (value_range &r, tree type,
+  virtual bool fold_range (value_range &r, tree type,
 			   const value_range &op1,
 			   const value_range &op2) const;
   virtual bool op1_range (value_range &r, tree type,
@@ -815,13 +823,13 @@ public:
 			  const value_range &op1) const;
 } op_ge;
 
-void
+bool
 operator_ge::fold_range (value_range &r, tree type,
 			 const value_range &op1,
 			 const value_range &op2) const
 {
   if (empty_range_check (r, op1, op2))
-    return;
+    return true;
 
   signop sign = TYPE_SIGN (op1.type ());
   gcc_checking_assert (sign == TYPE_SIGN (op2.type ()));
@@ -832,6 +840,7 @@ operator_ge::fold_range (value_range &r, tree type,
     r = range_false (type);
   else
     r = range_true_and_false (type);
+  return true;
 }
 
 bool
@@ -910,8 +919,7 @@ operator_plus::op1_range (value_range &r, tree type,
 			  const value_range &lhs,
 			  const value_range &op2) const
 {
-  range_op_handler (MINUS_EXPR, type)->fold_range (r, type, lhs, op2);
-  return true;
+  return range_op_handler (MINUS_EXPR, type)->fold_range (r, type, lhs, op2);
 }
 
 bool
@@ -919,8 +927,7 @@ operator_plus::op2_range (value_range &r, tree type,
 			  const value_range &lhs,
 			  const value_range &op1) const
 {
-  range_op_handler (MINUS_EXPR, type)->fold_range (r, type, lhs, op1);
-  return true;
+  return range_op_handler (MINUS_EXPR, type)->fold_range (r, type, lhs, op1);
 }
 
 
@@ -957,8 +964,7 @@ operator_minus::op1_range (value_range &r, tree type,
 			   const value_range &lhs,
 			   const value_range &op2) const
 {
-  range_op_handler (PLUS_EXPR, type)->fold_range (r, type, lhs, op2);
-  return true;
+  return range_op_handler (PLUS_EXPR, type)->fold_range (r, type, lhs, op2);
 }
 
 bool
@@ -966,8 +972,7 @@ operator_minus::op2_range (value_range &r, tree type,
 			   const value_range &lhs,
 			   const value_range &op1) const
 {
-  fold_range (r, type, op1, lhs);
-  return true;
+  return fold_range (r, type, op1, lhs);
 }
 
 
@@ -1351,10 +1356,7 @@ operator_exact_divide::op1_range (value_range &r, tree type,
   // If op2 is a multiple of 2, we would be able to set some non-zero bits.
   if (op2.singleton_p (&offset)
       && !integer_zerop (offset))
-    {
-      range_op_handler (MULT_EXPR, type)->fold_range (r, type, lhs, op2);
-      return true;
-    }
+    return range_op_handler (MULT_EXPR, type)->fold_range (r, type, lhs, op2);
   return false;
 }
 
@@ -1362,7 +1364,7 @@ operator_exact_divide::op1_range (value_range &r, tree type,
 class operator_lshift : public cross_product_operator
 {
 public:
-  virtual void fold_range (value_range &r, tree type,
+  virtual bool fold_range (value_range &r, tree type,
 			   const value_range &op1,
 			   const value_range &op2) const;
 
@@ -1375,13 +1377,13 @@ public:
 				const wide_int &) const;
 } op_lshift;
 
-void
+bool
 operator_lshift::fold_range (value_range &r, tree type,
 			     const value_range &op1,
 			     const value_range &op2) const
 {
   if (undefined_shift_range_check (r, type, op2))
-    return;
+    return true;
 
   // Transform left shifts by constants into multiplies.
   if (op2.singleton_p ())
@@ -1395,14 +1397,15 @@ operator_lshift::fold_range (value_range &r, tree type,
       bool saved_flag_wrapv_pointer = flag_wrapv_pointer;
       flag_wrapv = 1;
       flag_wrapv_pointer = 1;
-      range_op_handler (MULT_EXPR, type)->fold_range (r, type, op1, mult);
+      bool b = range_op_handler (MULT_EXPR, type)->fold_range (r, type, op1,
+							       mult);
       flag_wrapv = saved_flag_wrapv;
       flag_wrapv_pointer = saved_flag_wrapv_pointer;
-      return;
+      return b;
     }
-
-  // Otherwise, invoke the generic fold routine.
-  range_operator::fold_range (r, type, op1, op2);
+  else
+    // Otherwise, invoke the generic fold routine.
+    return range_operator::fold_range (r, type, op1, op2);
 }
 
 void
@@ -1486,7 +1489,7 @@ operator_lshift::wi_op_overflows (wide_int &res, tree type,
 class operator_rshift : public cross_product_operator
 {
 public:
-  virtual void fold_range (value_range &r, tree type,
+  virtual bool fold_range (value_range &r, tree type,
 			   const value_range &op1,
 			   const value_range &op2) const;
   virtual void wi_fold (value_range &r, tree type,
@@ -1519,16 +1522,16 @@ operator_rshift::wi_op_overflows (wide_int &res,
   return false;
 }
 
-void
+bool
 operator_rshift::fold_range (value_range &r, tree type,
 			     const value_range &op1,
 			     const value_range &op2) const
 {
+  // Invoke the generic fold routine if not undefined..
   if (undefined_shift_range_check (r, type, op2))
-    return;
+    return true;
 
-  // Otherwise, invoke the generic fold routine.
-  range_operator::fold_range (r, type, op1, op2);
+  return range_operator::fold_range (r, type, op1, op2);
 }
 
 void
@@ -1543,7 +1546,7 @@ operator_rshift::wi_fold (value_range &r, tree type,
 class operator_cast: public range_operator
 {
 public:
-  virtual void fold_range (value_range &r, tree type,
+  virtual bool fold_range (value_range &r, tree type,
 			   const value_range &op1,
 			   const value_range &op2) const;
   virtual bool op1_range (value_range &r, tree type,
@@ -1552,13 +1555,13 @@ public:
 
 } op_convert;
 
-void
+bool
 operator_cast::fold_range (value_range &r, tree type ATTRIBUTE_UNUSED,
 			   const value_range &lh,
 			   const value_range &rh) const
 {
   if (empty_range_check (r, lh, rh))
-    return;
+    return true;
   
   tree inner = lh.type ();
   tree outer = rh.type ();
@@ -1598,8 +1601,9 @@ operator_cast::fold_range (value_range &r, tree type ATTRIBUTE_UNUSED,
 	    }
 	}
       r = value_range (type);
-      return;
+      break;
     }
+  return true;
 }
 
 bool
@@ -1682,7 +1686,7 @@ operator_cast::op1_range (value_range &r, tree type,
 class operator_logical_and : public range_operator
 {
 public:
-  virtual void fold_range (value_range &r, tree type,
+  virtual bool fold_range (value_range &r, tree type,
 			   const value_range &lh,
 			   const value_range &rh) const;
   virtual bool op1_range (value_range &r, tree type,
@@ -1694,13 +1698,13 @@ public:
 } op_logical_and;
 
 
-void
+bool
 operator_logical_and::fold_range (value_range &r, tree type,
 				  const value_range &lh,
 				  const value_range &rh) const
 {
   if (empty_range_check (r, lh, rh))
-    return;
+    return true;
 
   // 0 && anything is 0.
   if ((wi::eq_p (lh.lower_bound (), 0) && wi::eq_p (lh.upper_bound (), 0))
@@ -1713,6 +1717,7 @@ operator_logical_and::fold_range (value_range &r, tree type,
     r = range_true_and_false (type);
   else
     r = range_true (type);
+  return true;
 }
 
 bool
@@ -1964,7 +1969,7 @@ operator_bitwise_and::op2_range (value_range &r, tree type,
 class operator_logical_or : public range_operator
 {
 public:
-  virtual void fold_range (value_range &r, tree type,
+  virtual bool fold_range (value_range &r, tree type,
 			   const value_range &lh,
 			   const value_range &rh) const;
   virtual bool op1_range (value_range &r, tree type,
@@ -1975,16 +1980,17 @@ public:
 			  const value_range &op1) const;
 } op_logical_or;
 
-void
+bool
 operator_logical_or::fold_range (value_range &r, tree type ATTRIBUTE_UNUSED,
 				 const value_range &lh,
 				 const value_range &rh) const
 {
   if (empty_range_check (r, lh, rh))
-    return;
+    return true;
 
   r = lh;
   r.union_ (rh);
+  return true;
 }
 
 bool
@@ -2198,7 +2204,7 @@ operator_trunc_mod::wi_fold (value_range &r, tree type,
 class operator_logical_not : public range_operator
 {
 public:
-  virtual void fold_range (value_range &r, tree type,
+  virtual bool fold_range (value_range &r, tree type,
 			   const value_range &lh,
 			   const value_range &rh) const;
   virtual bool op1_range (value_range &r, tree type,
@@ -2220,13 +2226,13 @@ public:
 // 	 b_2 = x_1 < 20		[0,0] = x_1 < 20,   false, so x_1 == [20, 255]
 //   which is the result we are looking for.. so.. pass it through.
 
-void
+bool
 operator_logical_not::fold_range (value_range &r, tree type,
 				  const value_range &lh,
 				  const value_range &rh ATTRIBUTE_UNUSED) const
 {
   if (empty_range_check (r, lh, rh))
-    return;
+    return true;
 
   if (lh.varying_p () || lh.undefined_p ())
     r = lh;
@@ -2236,7 +2242,7 @@ operator_logical_not::fold_range (value_range &r, tree type,
       r.invert ();
     }
   gcc_checking_assert (lh.type() == type);
-  return;
+  return true;
 }
 
 bool
@@ -2255,7 +2261,7 @@ operator_logical_not::op1_range (value_range &r,
 class operator_bitwise_not : public range_operator
 {
 public:
-  virtual void fold_range (value_range &r, tree type,
+  virtual bool fold_range (value_range &r, tree type,
 			   const value_range &lh,
 			   const value_range &rh) const;
   virtual bool op1_range (value_range &r, tree type,
@@ -2263,19 +2269,19 @@ public:
 			  const value_range &op2) const;
 } op_bitwise_not;
 
-void
+bool
 operator_bitwise_not::fold_range (value_range &r, tree type,
 				  const value_range &lh,
 				  const value_range &rh) const
 {
   if (empty_range_check (r, lh, rh))
-    return;
+    return true;
 
   // ~X is simply -1 - X.
   value_range minusone (type, wi::minus_one (TYPE_PRECISION (type)),
 			wi::minus_one (TYPE_PRECISION (type)));
-  range_op_handler (MINUS_EXPR, type)->fold_range (r, type, minusone, lh);
-  return;
+  return range_op_handler (MINUS_EXPR, type)->fold_range (r, type, minusone,
+							  lh);
 }
 
 bool
@@ -2284,32 +2290,32 @@ operator_bitwise_not::op1_range (value_range &r, tree type,
 				 const value_range &op2) const
 {
   // ~X is -1 - X and since bitwise NOT is involutary...do it again.
-  fold_range (r, type, lhs, op2);
-  return true;
+  return fold_range (r, type, lhs, op2);
 }
 
 
 class operator_cst : public range_operator
 {
 public:
-  virtual void fold_range (value_range &r, tree type,
+  virtual bool fold_range (value_range &r, tree type,
 			   const value_range &op1,
 			   const value_range &op2) const;
 } op_integer_cst;
 
-void
+bool
 operator_cst::fold_range (value_range &r, tree type ATTRIBUTE_UNUSED,
 			  const value_range &lh,
 			  const value_range &rh ATTRIBUTE_UNUSED) const
 {
   r = lh;
+  return true;
 }
 
 
 class operator_identity : public range_operator
 {
 public:
-  virtual void fold_range (value_range &r, tree type,
+  virtual bool fold_range (value_range &r, tree type,
 			   const value_range &op1,
 			   const value_range &op2) const;
   virtual bool op1_range (value_range &r, tree type,
@@ -2317,12 +2323,13 @@ public:
 			  const value_range &op2) const;
 } op_identity;
 
-void
+bool
 operator_identity::fold_range (value_range &r, tree type ATTRIBUTE_UNUSED,
 			       const value_range &lh,
 			       const value_range &rh ATTRIBUTE_UNUSED) const
 {
   r = lh;
+  return true;
 }
 
 bool
@@ -2485,7 +2492,7 @@ operator_absu::wi_fold (value_range &r, tree type,
 class operator_negate : public range_operator
 {
  public:
-  virtual void fold_range (value_range &r, tree type,
+  virtual bool fold_range (value_range &r, tree type,
 			   const value_range &op1,
 			   const value_range &op2) const;
   virtual bool op1_range (value_range &r, tree type,
@@ -2493,16 +2500,17 @@ class operator_negate : public range_operator
 			  const value_range &op2) const;
 } op_negate;
 
-void
+bool
 operator_negate::fold_range (value_range &r, tree type,
 			     const value_range &lh,
 			     const value_range &rh) const
 {
   if (empty_range_check (r, lh, rh))
-    return;
+    return true;
   // -X is simply 0 - X.
-  range_op_handler (MINUS_EXPR, type)->fold_range (r, type,
-						   range_zero (type), lh);
+  return range_op_handler (MINUS_EXPR, type)->fold_range (r, type,
+							  range_zero (type),
+							  lh);
 }
 
 bool
@@ -2511,15 +2519,14 @@ operator_negate::op1_range (value_range &r, tree type,
 			    const value_range &op2) const
 {
   // NEGATE is involutory.
-  fold_range (r, type, lhs, op2);
-  return true;
+  return fold_range (r, type, lhs, op2);
 }
 
 
 class operator_addr_expr : public range_operator
 {
 public:
-  virtual void fold_range (value_range &r, tree type,
+  virtual bool fold_range (value_range &r, tree type,
 			   const value_range &op1,
 			   const value_range &op2) const;
   virtual bool op1_range (value_range &r, tree type,
@@ -2527,13 +2534,13 @@ public:
 			  const value_range &op2) const;
 } op_addr;
 
-void
+bool
 operator_addr_expr::fold_range (value_range &r, tree type,
 				const value_range &lh,
 				const value_range &rh) const
 {
   if (empty_range_check (r, lh, rh))
-    return;
+    return true;
 
   // Return a non-null pointer of the LHS type (passed in op2).
   if (lh.zero_p ())
@@ -2542,6 +2549,7 @@ operator_addr_expr::fold_range (value_range &r, tree type,
     r = range_nonzero (type);
   else
     r = value_range (type);
+  return true;
 }
 
 bool
@@ -2549,8 +2557,7 @@ operator_addr_expr::op1_range (value_range &r, tree type,
 			       const value_range &lhs,
 			       const value_range &op2) const
 {
-  operator_addr_expr::fold_range (r, type, lhs, op2);
-  return true;
+  return operator_addr_expr::fold_range (r, type, lhs, op2);
 }
 
 
@@ -2808,7 +2815,9 @@ range_cast (value_range &r, tree type)
 {
   value_range tmp = r;
   range_operator *op = range_op_handler (CONVERT_EXPR, type);
-  op->fold_range (r, type, tmp, value_range (type));
+  // Call op_convert, if it fails, the result is varying.
+  if (!op->fold_range (r, type, tmp, value_range (type)))
+    r = value_range (type);
 }
 
 #if CHECKING_P
diff --git a/gcc/range-op.h b/gcc/range-op.h
index 4b0b572..458b42f 100644
--- a/gcc/range-op.h
+++ b/gcc/range-op.h
@@ -50,7 +50,7 @@ class range_operator
 {
 public:
   // Perform an operation between 2 ranges and return it.
-  virtual void fold_range (value_range &r, tree type,
+  virtual bool fold_range (value_range &r, tree type,
 			   const value_range &lh,
 			   const value_range &rh) const;
 
@@ -73,7 +73,7 @@ public:
 			  const value_range &op1) const;
 
 protected:
-  // Perform an operation between 2 sub-ranges and return it.
+  // Perform an integral operation between 2 sub-ranges and return it.
   virtual void wi_fold (value_range &r, tree type,
 		        const wide_int &lh_lb,
 		        const wide_int &lh_ub,
diff --git a/gcc/tree-vrp.c b/gcc/tree-vrp.c
index ff66bed..bbcf237 100644
--- a/gcc/tree-vrp.c
+++ b/gcc/tree-vrp.c
@@ -1185,8 +1185,7 @@ range_fold_binary_symbolics_p (value_range *vr,
       value_range vr0_cst (*vr0), vr1_cst (*vr1);
       vr0_cst.normalize_symbolics ();
       vr1_cst.normalize_symbolics ();
-      op->fold_range (*vr, expr_type, vr0_cst, vr1_cst);
-      return true;
+      return op->fold_range (*vr, expr_type, vr0_cst, vr1_cst);
     }
   return false;
 }
@@ -1221,8 +1220,7 @@ range_fold_unary_symbolics_p (value_range *vr,
       const range_operator *op = get_range_op_handler (vr, code, expr_type);
       value_range vr0_cst (*vr0);
       vr0_cst.normalize_symbolics ();
-      op->fold_range (*vr, expr_type, vr0_cst, value_range (expr_type));
-      return true;
+      return op->fold_range (*vr, expr_type, vr0_cst, value_range (expr_type));
     }
   return false;
 }