summaryrefslogtreecommitdiff
path: root/deps/v8/src/snapshot/startup-serializer.h
blob: 223e1c7bff3b34c67d0f05ea281ce2ad8c077430 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
// Copyright 2016 the V8 project authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#ifndef V8_SNAPSHOT_STARTUP_SERIALIZER_H_
#define V8_SNAPSHOT_STARTUP_SERIALIZER_H_

#include <bitset>
#include "include/v8.h"
#include "src/snapshot/serializer.h"

namespace v8 {
namespace internal {

class StartupSerializer : public Serializer {
 public:
  StartupSerializer(
      Isolate* isolate,
      v8::SnapshotCreator::FunctionCodeHandling function_code_handling);
  ~StartupSerializer() override;

  // Serialize the current state of the heap.  The order is:
  // 1) Immortal immovable roots
  // 2) Remaining strong references.
  // 3) Partial snapshot cache.
  // 4) Weak references (e.g. the string table).
  void SerializeStrongReferences();
  void SerializeWeakReferencesAndDeferred();

  int PartialSnapshotCacheIndex(HeapObject* o);

 private:
  class PartialCacheIndexMap {
   public:
    PartialCacheIndexMap() : map_(), next_index_(0) {}

    // Lookup object in the map. Return its index if found, or create
    // a new entry with new_index as value, and return kInvalidIndex.
    bool LookupOrInsert(HeapObject* obj, int* index_out) {
      Maybe<uint32_t> maybe_index = map_.Get(obj);
      if (maybe_index.IsJust()) {
        *index_out = maybe_index.FromJust();
        return true;
      }
      *index_out = next_index_;
      map_.Set(obj, next_index_++);
      return false;
    }

   private:
    DisallowHeapAllocation no_allocation_;
    HeapObjectToIndexHashMap map_;
    int next_index_;

    DISALLOW_COPY_AND_ASSIGN(PartialCacheIndexMap);
  };

  // The StartupSerializer has to serialize the root array, which is slightly
  // different.
  void VisitRootPointers(Root root, Object** start, Object** end) override;
  void SerializeObject(HeapObject* o, HowToCode how_to_code,
                       WhereToPoint where_to_point, int skip) override;
  void Synchronize(VisitorSynchronization::SyncTag tag) override;

  // Some roots should not be serialized, because their actual value depends on
  // absolute addresses and they are reset after deserialization, anyway.
  // In the first pass over the root list, we only serialize immortal immovable
  // roots. In the second pass, we serialize the rest.
  bool RootShouldBeSkipped(int root_index);

  bool clear_function_code_;
  bool serializing_builtins_;
  bool serializing_immortal_immovables_roots_;
  std::bitset<Heap::kStrongRootListLength> root_has_been_serialized_;
  PartialCacheIndexMap partial_cache_index_map_;
  List<AccessorInfo*> accessor_infos_;
  DISALLOW_COPY_AND_ASSIGN(StartupSerializer);
};

}  // namespace internal
}  // namespace v8

#endif  // V8_SNAPSHOT_STARTUP_SERIALIZER_H_