Ensure double alignment when deserializing.

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/compiler.h"
 #include "src/hashmap.h"
 #include "src/heap-profiler.h"
@@ skipping 283 matching lines @@
 
   static int nop() { return kNop; }
 
   // No reservation for large object space necessary.
   static const int kNumberOfPreallocatedSpaces = LO_SPACE;
   static const int kNumberOfSpaces = LAST_SPACE + 1;
 
  protected:
   // Where the pointed-to object can be found:
   enum Where {
-    kNewObject = 0,  // Object is next in snapshot.
-    // 1-7                             One per space.
+    kNewObject = 0,  //              Object is next in snapshot.
+    // 1-7                           One per space.
     kRootArray = 0x9,             // Object is found in root array.
     kPartialSnapshotCache = 0xa,  // Object is in the cache.
     kExternalReference = 0xb,     // Pointer to an external reference.
     kSkip = 0xc,                  // Skip n bytes.
     kBuiltin = 0xd,               // Builtin code object.
     kAttachedReference = 0xe,     // Object is described in an attached list.
-    kNop = 0xf,                   // Does nothing, used to pad.
-    kBackref = 0x10,              // Object is described relative to end.
-    // 0x11-0x17                       One per space.
-    kBackrefWithSkip = 0x18,  // Object is described relative to end.
-    // 0x19-0x1f                       One per space.
-    // 0x20-0x3f                       Used by misc. tags below.
+    // 0xf                           Used by misc. See below.
+    kBackref = 0x10,  //             Object is described relative to end.
+    // 0x11-0x17                     One per space.
+    kBackrefWithSkip = 0x18,  //     Object is described relative to end.
+    // 0x19-0x1f                     One per space.
+    // 0x20-0x3f                     Used by misc. See below.
     kPointedToMask = 0x3f
   };
 
   // How to code the pointer to the object.
   enum HowToCode {
     kPlain = 0,                          // Straight pointer.
     // What this means depends on the architecture:
     kFromCode = 0x40,                    // A pointer inlined in code.
     kHowToCodeMask = 0x40
   };
@@ skipping 40 matching lines @@
     DCHECK(byte_code >= kConstantRepeat && byte_code <= 0x7f);
     return byte_code - 0x72;
   }
   static const int kRootArrayConstants = 0xa0;
   // 0xa0-0xbf            Things from the first 32 elements of the root array.
   static const int kRootArrayNumberOfConstantEncodings = 0x20;
   static int RootArrayConstantFromByteCode(int byte_code) {
     return byte_code & 0x1f;
   }
 
+  static const int kNop = 0xf;                 // Do nothing, used for padding.
+  static const int kDoubleAlignPrefix = 0x4f;  // Double align next object.
+
   static const int kAnyOldSpace = -1;
 
   // A bitmask for getting the space out of an instruction.
   static const int kSpaceMask = 7;
   STATIC_ASSERT(kNumberOfSpaces <= kSpaceMask + 1);
 };
 
 
 // A Deserializer reads a snapshot and reconstructs the Object graph it defines.
 class Deserializer: public SerializerDeserializer {
@@ skipping 42 matching lines @@
   // a list at deserialization time.
   void RelinkAllocationSite(AllocationSite* site);
 
   // Fills in some heap data in an area from start to end (non-inclusive).  The
   // space id is used for the write barrier.  The object_address is the address
   // of the object we are writing into, or NULL if we are not writing into an
   // object, i.e. if we are writing a series of tagged values that are not on
   // the heap.
   void ReadData(Object** start, Object** end, int space,
                 Address object_address);
-  void ReadObject(int space_number, Object** write_back);
+  void ReadObject(int space_number, Object** write_back, bool double_align);
   Address Allocate(int space_index, int size);
 
   // Special handling for serialized code like hooking up internalized strings.
   HeapObject* ProcessNewObjectFromSerializedCode(HeapObject* obj);
   Object* ProcessBackRefInSerializedCode(Object* obj);
 
   // This returns the address of an object that has been described in the
   // snapshot by chunk index and offset.
   HeapObject* GetBackReferencedObject(int space) {
     if (space == LO_SPACE) {
@@ skipping 410 matching lines @@
   // Following the header, we store, in sequential order
   // - code stub keys
   // - serialization payload
 
   ScriptData* script_data_;
   bool owns_script_data_;
 };
 } }  // namespace v8::internal
 
 #endif  // V8_SERIALIZE_H_