dart2js cps_ir: Use interceptors for is-checks (version 2)

pkg/compiler/lib/src/tree_ir/optimization/logical_rewriter.dart

 // Copyright (c) 2014, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 library tree_ir.optimization.logical_rewriter;
 
 import '../tree_ir_nodes.dart';
 import 'optimization.dart' show Pass;
 import '../../constants/values.dart' as values;
 
@@ skipping 317 matching lines @@
   }
 
   /// True if the given expression is known to evaluate to a boolean.
   /// This will not recursively traverse [Conditional] expressions, but if
   /// applied to the result of [visitExpression] conditionals will have been
   /// rewritten anyway.
   bool isBooleanValued(Expression e) {
     return isTrue(e) ||
            isFalse(e) ||
            e is Not ||
-           e is LogicalOperator ||
-           e is ApplyBuiltinOperator && operatorReturnsBool(e.operator);
+           e is LogicalOperator && isBooleanValuedLogicalOperator(e) ||
+           e is ApplyBuiltinOperator && operatorReturnsBool(e.operator) ||
+           e is TypeOperator && isBooleanValuedTypeOperator(e);
+  }
+
+  bool isBooleanValuedLogicalOperator(LogicalOperator e) {
+    return isBooleanValued(e.left) && isBooleanValued(e.right);
   }
 
   /// True if the given operator always returns `true` or `false`.
   bool operatorReturnsBool(BuiltinOperator operator) {
     switch (operator) {
       case BuiltinOperator.StrictEq:
       case BuiltinOperator.StrictNeq:
       case BuiltinOperator.LooseEq:
       case BuiltinOperator.LooseNeq:
       case BuiltinOperator.NumLt:
       case BuiltinOperator.NumLe:
       case BuiltinOperator.NumGt:
       case BuiltinOperator.NumGe:
       case BuiltinOperator.IsNumber:
       case BuiltinOperator.IsNotNumber:
       case BuiltinOperator.IsFloor:
       case BuiltinOperator.IsNumberAndFloor:
       case BuiltinOperator.Identical:
         return true;
       default:
         return false;
     }
   }
 
+  bool isBooleanValuedTypeOperator(TypeOperator e) {
+    return e.isTypeTest;
+  }
+
   BuiltinOperator negateBuiltin(BuiltinOperator operator) {
     switch (operator) {
       case BuiltinOperator.StrictEq: return BuiltinOperator.StrictNeq;
       case BuiltinOperator.StrictNeq: return BuiltinOperator.StrictEq;
       case BuiltinOperator.LooseEq: return BuiltinOperator.LooseNeq;
       case BuiltinOperator.LooseNeq: return BuiltinOperator.LooseEq;
       case BuiltinOperator.IsNumber: return BuiltinOperator.IsNotNumber;
       case BuiltinOperator.IsNotNumber: return BuiltinOperator.IsNumber;
 
       // Because of NaN, these do not have a negated form.
@@ skipping 171 matching lines @@
     } else if (e1 is Assign) {
       return e2 is VariableUse && e1.variable == e2.variable;
     }
     return false;
   }
 
   void destroyVariableUse(VariableUse node) {
     --node.variable.readCount;
   }
 }
-