Canonicalize generic types in an isolate specific hash table

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 1699 matching lines @@
   static const intptr_t kMaxElements = kSmiMax / kBytesPerElement;
 
   static intptr_t InstanceSize() {
     ASSERT(sizeof(RawTypeArguments) ==
            OFFSET_OF_RETURNED_VALUE(RawTypeArguments, types));
     return 0;
   }
 
   static intptr_t InstanceSize(intptr_t len) {
     // Ensure that the types() is not adding to the object size, which includes
-    // 2 fields: instantiations_ and length_.
-    ASSERT(sizeof(RawTypeArguments) == (sizeof(RawObject) + (2 * kWordSize)));
+    // 3 fields: instantiations_, length_ and hash_.
+    ASSERT(sizeof(RawTypeArguments) == (sizeof(RawObject) + (3 * kWordSize)));
     ASSERT(0 <= len && len <= kMaxElements);
     return RoundedAllocationSize(
         sizeof(RawTypeArguments) + (len * kBytesPerElement));
   }
 
   intptr_t Hash() const;
 
   static RawTypeArguments* New(intptr_t len, Heap::Space space = Heap::kOld);
 
  private:
+  intptr_t ComputeHash() const;
+  void SetHash(intptr_t value) const;
+
   // Check if the subvector of length 'len' starting at 'from_index' of this
   // type argument vector consists solely of DynamicType.
   // 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 from_index,
                       intptr_t len) const;
 
   // Check the subtype or 'more specific' relationship, considering only a
   // subvector of length 'len' starting at 'from_index'.
@@ skipping 3936 matching lines @@
 
   // The finalized type of the given non-parameterized class.
   static RawType* NewNonParameterizedType(const Class& type_class);
 
   static RawType* New(const Object& clazz,
                       const TypeArguments& arguments,
                       TokenPosition token_pos,
                       Heap::Space space = Heap::kOld);
 
  private:
+  intptr_t ComputeHash() const;
+  void SetHash(intptr_t value) const;
+
   void set_token_pos(TokenPosition token_pos) const;
   void set_type_state(int8_t state) const;
 
   static RawType* New(Heap::Space space = Heap::kOld);
 
   FINAL_HEAP_OBJECT_IMPLEMENTATION(Type, AbstractType);
   friend class Class;
   friend class TypeArguments;
 };
 
@@ skipping 131 matching lines @@
     return RoundedAllocationSize(sizeof(RawTypeParameter));
   }
 
   static RawTypeParameter* New(const Class& parameterized_class,
                                intptr_t index,
                                const String& name,
                                const AbstractType& bound,
                                TokenPosition token_pos);
 
  private:
+  intptr_t ComputeHash() const;
+  void SetHash(intptr_t value) const;
+
   void set_parameterized_class(const Class& value) const;
   void set_name(const String& value) const;
   void set_token_pos(TokenPosition token_pos) const;
   void set_type_state(int8_t state) const;
 
   static RawTypeParameter* New();
 
   FINAL_HEAP_OBJECT_IMPLEMENTATION(TypeParameter, AbstractType);
   friend class Class;
 };
@@ skipping 65 matching lines @@
 
   static intptr_t InstanceSize() {
     return RoundedAllocationSize(sizeof(RawBoundedType));
   }
 
   static RawBoundedType* New(const AbstractType& type,
                              const AbstractType& bound,
                              const TypeParameter& type_parameter);
 
  private:
+  intptr_t ComputeHash() const;
+  void SetHash(intptr_t value) const;
+
   void set_type(const AbstractType& value) const;
   void set_bound(const AbstractType& value) const;
   void set_type_parameter(const TypeParameter& value) const;
 
   static RawBoundedType* New();
 
   FINAL_HEAP_OBJECT_IMPLEMENTATION(BoundedType, AbstractType);
   friend class Class;
 };
 
@@ skipping 2587 matching lines @@
 RawObject* MegamorphicCache::GetClassId(const Array& array, intptr_t index) {
   return array.At((index * kEntryLength) + kClassIdIndex);
 }
 
 
 RawObject* MegamorphicCache::GetTargetFunction(const Array& array,
                                                intptr_t index) {
   return array.At((index * kEntryLength) + kTargetFunctionIndex);
 }
 
+
+inline intptr_t Type::Hash() const {
+  intptr_t result = Smi::Value(raw_ptr()->hash_);
+  if (result != 0) {

[regis, 2016/05/10 18:14:26]

What if the hash is 0?

[siva, 2016/05/13 23:16:13]

I have fixed this similar to the StringHasher to return 1 if the has ever
becomes 0.

+    return result;
+  }
+  return ComputeHash();
+}
+
+
+inline void Type::SetHash(intptr_t value) const {
+  // This is only safe because we create a new Smi, which does not cause
+  // heap allocation.
+  StoreSmi(&raw_ptr()->hash_, Smi::New(value));
+}
+
+
+inline intptr_t TypeParameter::Hash() const {
+  ASSERT(IsFinalized());
+  intptr_t result = Smi::Value(raw_ptr()->hash_);
+  if (result != 0) {
+    return result;
+  }
+  return ComputeHash();
+}
+
+
+inline void TypeParameter::SetHash(intptr_t value) const {
+  // This is only safe because we create a new Smi, which does not cause
+  // heap allocation.
+  StoreSmi(&raw_ptr()->hash_, Smi::New(value));

[regis, 2016/05/10 18:14:26]

What if the value does not fit in a Smi?

[siva, 2016/05/13 23:16:13]

I have fixed this similar to the StringHasher by having a max hash bits which is
30 as it should be Smi consistently on all platforms where a snapshot can be
read

+}
+
+
+inline intptr_t BoundedType::Hash() const {
+  intptr_t result = Smi::Value(raw_ptr()->hash_);
+  if (result != 0) {
+    return result;
+  }
+  return ComputeHash();
+}
+
+
+inline void BoundedType::SetHash(intptr_t value) const {
+  // This is only safe because we create a new Smi, which does not cause
+  // heap allocation.
+  StoreSmi(&raw_ptr()->hash_, Smi::New(value));
+}
+
+
+inline intptr_t TypeArguments::Hash() const {
+  if (IsNull()) return 0;
+  intptr_t result = Smi::Value(raw_ptr()->hash_);
+  if (result != 0) {
+    return result;
+  }
+  return ComputeHash();
+}
+
+
+inline void TypeArguments::SetHash(intptr_t value) const {
+  // This is only safe because we create a new Smi, which does not cause
+  // heap allocation.
+  StoreSmi(&raw_ptr()->hash_, Smi::New(value));
+}
+
 }  // namespace dart
 
 #endif  // VM_OBJECT_H_