Further improve type optimization reusing the type argument vector of the

runtime/vm/object.h

 // 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.
 
 #ifndef VM_OBJECT_H_
 #define VM_OBJECT_H_
 
 #include "include/dart_api.h"
 #include "platform/assert.h"
 #include "platform/utils.h"
@@ skipping 1006 matching lines @@
 
   bool Equals(const AbstractTypeArguments& other) const;
 
   // UNREACHABLEs as AbstractTypeArguments is an abstract class.
   virtual intptr_t Length() const;
   virtual RawAbstractType* TypeAt(intptr_t index) const;
   virtual void SetTypeAt(intptr_t index, const AbstractType& value) const;
   virtual bool IsResolved() const;
   virtual bool IsInstantiated() const;
   virtual bool IsUninstantiatedIdentity() const;
+  virtual bool CanShareInstantiatorTypeArguments(
+      const Class& instantiator_class) const;
   virtual bool IsBounded() const;
 
   virtual intptr_t Hash() const;
 
  private:
   // Check if this type argument vector consists solely of DynamicType,
   // considering only a prefix of length 'len'.
   // If raw_instantiated is true, consider each type parameter to be first
   // instantiated from a vector of dynamic types.
   bool IsDynamicTypes(bool raw_instantiated, intptr_t len) const;
@@ skipping 23 matching lines @@
  public:
   virtual intptr_t Length() const;
   virtual RawAbstractType* TypeAt(intptr_t index) const;
   static intptr_t type_at_offset(intptr_t index) {
     return OFFSET_OF(RawTypeArguments, types_) + index * kWordSize;
   }
   virtual void SetTypeAt(intptr_t index, const AbstractType& value) const;
   virtual bool IsResolved() const;
   virtual bool IsInstantiated() const;
   virtual bool IsUninstantiatedIdentity() const;
+  virtual bool CanShareInstantiatorTypeArguments(
+      const Class& instantiator_class) const;
   virtual bool IsBounded() const;
   // Canonicalize only if instantiated, otherwise returns 'this'.
   virtual RawAbstractTypeArguments* Canonicalize() const;
 
   virtual RawAbstractTypeArguments* InstantiateFrom(
       const AbstractTypeArguments& instantiator_type_arguments,
       Error* malformed_error) const;
 
   static const intptr_t kBytesPerElement = kWordSize;
   static const intptr_t kMaxElements = kSmiMax / kBytesPerElement;
@@ skipping 36 matching lines @@
 // The second type argument vector is the instantiator, because each type
 // parameter with index i in the first vector can be substituted (or
 // "instantiated") with the type at index i in the second type argument vector.
 class InstantiatedTypeArguments : public AbstractTypeArguments {
  public:
   virtual intptr_t Length() const;
   virtual RawAbstractType* TypeAt(intptr_t index) const;
   virtual void SetTypeAt(intptr_t index, const AbstractType& value) const;
   virtual bool IsResolved() const { return true; }
   virtual bool IsInstantiated() const { return true; }
-  virtual bool IsUninstantiatedIdentity() const  { return false; }
+  virtual bool IsUninstantiatedIdentity() const {
+    UNREACHABLE();
+    return false;
+  }
+  virtual bool CanShareInstantiatorTypeArguments(
+      const Class& instantiator_class) const {
+    UNREACHABLE();
+    return false;
+  }
   virtual bool IsBounded() const { return false; }  // Bounds were checked.
 
   RawAbstractTypeArguments* uninstantiated_type_arguments() const {
     return raw_ptr()->uninstantiated_type_arguments_;
   }
   static intptr_t uninstantiated_type_arguments_offset() {
     return OFFSET_OF(RawInstantiatedTypeArguments,
                      uninstantiated_type_arguments_);
   }
 
@@ skipping 4572 matching lines @@
 
 
 RawObject* MegamorphicCache::GetTargetFunction(const Array& array,
                                                intptr_t index) {
   return array.At((index * kEntryLength) + kTargetFunctionIndex);
 }
 
 }  // namespace dart
 
 #endif  // VM_OBJECT_H_