Cache initial (empty) ic_data arrays so that they are not repeatedly allocated. Factor out descript…

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 1994 matching lines @@
 
   // It is only meaningful to interptret range feedback stored in the ICData
   // when all checks are Mint or Smi.
   bool HasRangeFeedback() const;
   RangeFeedback DecodeRangeFeedbackAt(intptr_t idx) const;
 
   void PrintToJSONArray(const JSONArray& jsarray,
                         intptr_t token_pos,
                         bool is_static_call) const;
 
+  // Initialize the preallocated empty ICData entry arrays.
+  static void InitOnce();
+
+  enum {
+    kCachedICDataArrayCount = 4
+  };
+
  private:
   static RawICData* New();
 
   RawArray* ic_data() const {
     return raw_ptr()->ic_data_;
   }
 
   void set_owner(const Function& value) const;
   void set_target_name(const String& value) const;
   void set_arguments_descriptor(const Array& value) const;
@@ skipping 19 matching lines @@
   class IssuedJSWarningBit : public BitField<bool, kIssuedJSWarningBit, 1> {};
   class RangeFeedbackBits : public BitField<uint32_t,
       ICData::kRangeFeedbackPos, ICData::kRangeFeedbackSize> {};  // NOLINT
 
 #if defined(DEBUG)
   // Used in asserts to verify that a check is not added twice.
   bool HasCheck(const GrowableArray<intptr_t>& cids) const;
 #endif  // DEBUG
 
   intptr_t TestEntryLength() const;
+  static RawArray* NewNonCachedEmptyICDataArray(intptr_t num_args_tested);
+  static RawArray* NewEmptyICDataArray(intptr_t num_args_tested);
+  static RawICData* NewDescriptor(Zone* zone,
+                                  const Function& owner,
+                                  const String& target_name,
+                                  const Array& arguments_descriptor,
+                                  intptr_t deopt_id,
+                                  intptr_t num_args_tested);
+
   static void WriteSentinel(const Array& data, intptr_t test_entry_length);
 
+  // A cache of VM heap allocated preinitialized empty ic data entry arrays.
+  static RawArray* cached_icdata_arrays_[kCachedICDataArrayCount];
+
   FINAL_HEAP_OBJECT_IMPLEMENTATION(ICData, Object);
   friend class Class;
+  friend class SnapshotReader;
+  friend class SnapshotWriter;
 };
 
 
 class Function : public Object {
  public:
   RawString* name() const { return raw_ptr()->name_; }
   RawString* PrettyName() const;
   RawString* UserVisibleName() const;
   RawString* QualifiedPrettyName() const;
   RawString* QualifiedUserVisibleName() const;
@@ skipping 6108 matching lines @@
 
 
 RawObject* MegamorphicCache::GetTargetFunction(const Array& array,
                                                intptr_t index) {
   return array.At((index * kEntryLength) + kTargetFunctionIndex);
 }
 
 }  // namespace dart
 
 #endif  // VM_OBJECT_H_