Optimize is-check to instanceof when it eliminates an interceptor

pkg/compiler/lib/src/ssa/nodes.dart

 // Copyright (c) 2012, 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.
 
 part of ssa;
 
 abstract class HVisitor<R> {
   R visitAdd(HAdd node);
   R visitBitAnd(HBitAnd node);
   R visitBitNot(HBitNot node);
@@ skipping 2403 matching lines @@
 class HIs extends HInstruction {
   /// A check against a raw type: 'o is int', 'o is A'.
   static const int RAW_CHECK = 0;
   /// A check against a type with type arguments: 'o is List<int>', 'o is C<T>'.
   static const int COMPOUND_CHECK = 1;
   /// A check against a single type variable: 'o is T'.
   static const int VARIABLE_CHECK = 2;
 
   final DartType typeExpression;
   final int kind;
+  final bool useInstanceOf;
 
   HIs.direct(DartType typeExpression,
              HInstruction expression,
              TypeMask type)
       : this.internal(typeExpression, [expression], RAW_CHECK, type);
 
+  // Pre-verified that the check can be done using 'instanceof'.
+  HIs.instanceOf(DartType typeExpression,
+                 HInstruction expression,
+                 TypeMask type)
+      : this.internal(typeExpression, [expression], RAW_CHECK, type,
+          useInstanceOf: true);
+
   HIs.raw(DartType typeExpression,
           HInstruction expression,
           HInterceptor interceptor,
           TypeMask type)
       : this.internal(
             typeExpression, [expression, interceptor], RAW_CHECK, type);
 
   HIs.compound(DartType typeExpression,
                HInstruction expression,
                HInstruction call,
                TypeMask type)
       : this.internal(typeExpression, [expression, call], COMPOUND_CHECK, type);
 
   HIs.variable(DartType typeExpression,
                HInstruction expression,
                HInstruction call,
                TypeMask type)
       : this.internal(typeExpression, [expression, call], VARIABLE_CHECK, type);
 
-  HIs.internal(this.typeExpression, List<HInstruction> inputs, this.kind, type)
+  HIs.internal(this.typeExpression, List<HInstruction> inputs, this.kind,
+      TypeMask type, {bool this.useInstanceOf: false})
       : super(inputs, type) {
     assert(kind >= RAW_CHECK && kind <= VARIABLE_CHECK);
     setUseGvn();
   }
 
   HInstruction get expression => inputs[0];
 
   HInstruction get interceptor {
     assert(kind == RAW_CHECK);
     return inputs.length > 1 ? inputs[1] : null;
@@ skipping 631 matching lines @@
 class HDynamicType extends HRuntimeType {
   HDynamicType(DynamicType dartType, TypeMask instructionType)
       : super(const <HInstruction>[], dartType, instructionType);
 
   accept(HVisitor visitor) => visitor.visitDynamicType(this);
 
   int typeCode() => HInstruction.DYNAMIC_TYPE_TYPECODE;
 
   bool typeEquals(HInstruction other) => other is HDynamicType;
 }