Last snapshot bits to get working precompiled hello_world on x64.

runtime/vm/snapshot.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_SNAPSHOT_H_
 #define VM_SNAPSHOT_H_
 
 #include "platform/assert.h"
 #include "vm/allocation.h"
 #include "vm/bitfield.h"
@@ skipping 14 matching lines @@
 class Code;
 class ExternalTypedData;
 class GrowableObjectArray;
 class Heap;
 class Instructions;
 class LanguageError;
 class Library;
 class Object;
 class PassiveObject;
 class ObjectStore;
+class MegamorphicCache;
 class PageSpace;
 class RawApiError;
 class RawArray;
 class RawBigint;
 class RawBoundedType;
 class RawCapability;
 class RawClass;
 class RawClosureData;
 class RawContext;
 class RawContextScope;
@@ skipping 287 matching lines @@
   PassiveObject* PassiveObjectHandle() { return &pobj_; }
   Array* ArrayHandle() { return &array_; }
   String* StringHandle() { return &str_; }
   AbstractType* TypeHandle() { return &type_; }
   TypeArguments* TypeArgumentsHandle() { return &type_arguments_; }
   Array* TokensHandle() { return &tokens_; }
   TokenStream* StreamHandle() { return &stream_; }
   ExternalTypedData* DataHandle() { return &data_; }
   TypedData* TypedDataHandle() { return &typed_data_; }
   Code* CodeHandle() { return &code_; }
+  Function* FunctionHandle() { return &function_; }
+  MegamorphicCache* MegamorphicCacheHandle() { return &megamorphic_cache_; }
   Snapshot::Kind kind() const { return kind_; }
   bool snapshot_code() const { return snapshot_code_; }
 
   // Reads an object.
   RawObject* ReadObject();
 
   // Add object to backward references.
   void AddBackRef(intptr_t id,
                   Object* obj,
                   DeserializeState state,
@@ skipping 162 matching lines @@
   Field& field_;  // Temporary Field handle.
   String& str_;  // Temporary String handle.
   Library& library_;  // Temporary library handle.
   AbstractType& type_;  // Temporary type handle.
   TypeArguments& type_arguments_;  // Temporary type argument handle.
   Array& tokens_;  // Temporary tokens handle.
   TokenStream& stream_;  // Temporary token stream handle.
   ExternalTypedData& data_;  // Temporary stream data handle.
   TypedData& typed_data_;  // Temporary typed data handle.
   Code& code_;  // Temporary code handle.
+  Function& function_;  // Temporary function handle.
+  MegamorphicCache& megamorphic_cache_;  // Temporary megamorphic cache handle.
   UnhandledException& error_;  // Error handle.
   intptr_t max_vm_isolate_object_id_;
   ZoneGrowableArray<BackRefNode>* backward_references_;
   InstructionsReader* instructions_reader_;
 
   friend class ApiError;
   friend class Array;
   friend class Bigint;
   friend class BoundedType;
   friend class Class;
@@ skipping 239 matching lines @@
   DISALLOW_COPY_AND_ASSIGN(ForwardList);
 };
 
 
 class InstructionsWriter : public ZoneAllocated {
  public:
   InstructionsWriter(uint8_t** buffer,
                      ReAlloc alloc,
                      intptr_t initial_size)
     : stream_(buffer, alloc, initial_size),
-      next_offset_(0),
+      next_offset_(HeaderSize()),
       instructions_() {
     ASSERT(buffer != NULL);
     ASSERT(alloc != NULL);
   }
 
   // Size of the snapshot.
   intptr_t BytesWritten() const { return stream_.bytes_written(); }
 
   int32_t GetOffsetFor(RawInstructions* instructions);
 
   void SetInstructionsCode(RawInstructions* insns, RawCode* code) {
     for (intptr_t i = 0; i < instructions_.length(); i++) {
       if (instructions_[i].raw_insns_ == insns) {
         instructions_[i].raw_code_ = code;
         return;
       }
     }
     UNREACHABLE();
   }
 
   void WriteAssembly();
 
+  intptr_t HeaderSize() {
+    ASSERT(OS::kMaxPreferredCodeAlignment > sizeof(uint64_t));
+    return OS::kMaxPreferredCodeAlignment;
+  }
+
  private:
   struct InstructionsData {
     explicit InstructionsData(RawInstructions* insns)
         : raw_insns_(insns), raw_code_(NULL) { }
 
     union {
       RawInstructions* raw_insns_;
       const Instructions* insns_;
     };
     union {
       RawCode* raw_code_;
       const Code* code_;
     };
   };
 
+  void WriteWordLiteral(uword value) {
+    // Padding is helpful for comparing the .S with --disassemble.
+#if defined(ARCH_IS_64_BIT)
+    stream_.Print(".word 0x%0.16" Px "\n", value);
+#else
+    stream_.Print(".word 0x%0.8" Px "\n", value);
+#endif
+  }
 
   WriteStream stream_;
   intptr_t next_offset_;
   GrowableArray<InstructionsData> instructions_;
 
   DISALLOW_COPY_AND_ASSIGN(InstructionsWriter);
 };
 
 
 class SnapshotWriter : public BaseWriter {
@@ skipping 257 matching lines @@
  private:
   SnapshotWriter* writer_;
   bool as_references_;
 
   DISALLOW_COPY_AND_ASSIGN(SnapshotWriterVisitor);
 };
 
 }  // namespace dart
 
 #endif  // VM_SNAPSHOT_H_