Tweak memory management in the serializer.

src/serialize.h

 // Copyright 2012 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_SERIALIZE_H_
 #define V8_SERIALIZE_H_
 
 #include "src/hashmap.h"
 #include "src/heap-profiler.h"
 #include "src/isolate.h"
@@ skipping 554 matching lines @@
   MaybeHandle<Object> DeserializePartial(
       Isolate* isolate, Handle<JSGlobalProxy> global_proxy,
       Handle<FixedArray>* outdated_contexts_out);
 
   // Deserialize a shared function info. Fail gracefully.
   MaybeHandle<SharedFunctionInfo> DeserializeCode(Isolate* isolate);
 
   void FlushICacheForNewCodeObjects();
 
   // Pass a vector of externally-provided objects referenced by the snapshot.
-  // The ownership to its backing store is handed over as well.
+  // The ownership to its backing store is not handed over.
   void SetAttachedObjects(Vector<Handle<Object> > attached_objects) {
     attached_objects_ = attached_objects;
   }
 
  private:
   virtual void VisitPointers(Object** start, Object** end);
 
   virtual void VisitRuntimeEntry(RelocInfo* rinfo) {
     UNREACHABLE();
   }
@@ skipping 110 matching lines @@
 
     enum ReturnSkip { kCanReturnSkipInsteadOfSkipping, kIgnoringReturn };
     // This function outputs or skips the raw data between the last pointer and
     // up to the current position.  It optionally can just return the number of
     // bytes to skip instead of performing a skip instruction, in case the skip
     // can be merged into the next instruction.
     int OutputRawData(Address up_to, ReturnSkip return_skip = kIgnoringReturn);
     // External strings are serialized in a way to resemble sequential strings.
     void SerializeExternalString();
 
+    Address PrepareCode();
+
     Serializer* serializer_;
     HeapObject* object_;
     SnapshotByteSink* sink_;
     int reference_representation_;
     int bytes_processed_so_far_;
     bool code_object_;
     bool code_has_been_output_;
   };
 
   virtual void SerializeObject(HeapObject* o, HowToCode how_to_code,
@@ skipping 27 matching lines @@
   void Pad();
 
   // Some roots should not be serialized, because their actual value depends on
   // absolute addresses and they are reset after deserialization, anyway.
   bool ShouldBeSkipped(Object** current);
 
   // We may not need the code address map for logging for every instance
   // of the serializer.  Initialize it on demand.
   void InitializeCodeAddressMap();
 
+  inline Address GetCodeBuffer(int size) {
+    if (size > code_buffer_.length()) code_buffer_.Dispose();
+    code_buffer_ = Vector<byte>::New(size);
+    return code_buffer_.start();
+  }
+
   inline uint32_t max_chunk_size(int space) const {
     DCHECK_LE(0, space);
     DCHECK_LT(space, kNumberOfSpaces);
     return max_chunk_size_[space];
   }
 
   SnapshotByteSink* sink() const { return sink_; }
 
   Isolate* isolate_;
 
@@ skipping 14 matching lines @@
   // page. So we track the chunk size in pending_chunk_ of a space, but
   // when it exceeds a page, we complete the current chunk and start a new one.
   uint32_t pending_chunk_[kNumberOfPreallocatedSpaces];
   List<uint32_t> completed_chunks_[kNumberOfPreallocatedSpaces];
   uint32_t max_chunk_size_[kNumberOfPreallocatedSpaces];
 
   // We map serialized large objects to indexes for back-referencing.
   uint32_t large_objects_total_size_;
   uint32_t seen_large_objects_index_;
 
+  Vector<byte> code_buffer_;
+
   DISALLOW_COPY_AND_ASSIGN(Serializer);
 };
 
 
 class PartialSerializer : public Serializer {
  public:
   PartialSerializer(Isolate* isolate, Serializer* startup_snapshot_serializer,
                     SnapshotByteSink* sink)
       : Serializer(isolate, sink),
         startup_serializer_(startup_snapshot_serializer),
@@ skipping 219 matching lines @@
       kNumInternalizedStringsOffset + kInt32Size;
   static const int kNumCodeStubKeysOffset = kNumReservationsOffset + kInt32Size;
   static const int kPayloadLengthOffset = kNumCodeStubKeysOffset + kInt32Size;
   static const int kChecksum1Offset = kPayloadLengthOffset + kInt32Size;
   static const int kChecksum2Offset = kChecksum1Offset + kInt32Size;
   static const int kHeaderSize = kChecksum2Offset + kInt32Size;
 };
 } }  // namespace v8::internal
 
 #endif  // V8_SERIALIZE_H_