- Make array immutable first, then canonicalize it.

runtime/vm/snapshot.cc

 // 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.
 
 #include "vm/snapshot.h"
 
 #include "platform/assert.h"
 #include "vm/bootstrap.h"
 #include "vm/class_finalizer.h"
 #include "vm/exceptions.h"
@@ skipping 933 matching lines @@
     } else {
       cls_ ^= ReadObjectImpl();
       ASSERT(!cls_.IsNull());
       instance_size = cls_.instance_size();
     }
     intptr_t next_field_offset = cls_.next_field_offset();
     intptr_t type_argument_field_offset = cls_.type_arguments_field_offset();
     ASSERT(next_field_offset > 0);
     // Instance::NextFieldOffset() returns the offset of the first field in
     // a Dart object.
+    bool is_canonical = RawObject::IsCanonical(tags);
     intptr_t offset = Instance::NextFieldOffset();
     intptr_t result_cid = result->GetClassId();
     while (offset < next_field_offset) {
-      pobj_ = ReadObjectRef();
+      pobj_ = is_canonical ? ReadObjectImpl() : ReadObjectRef();
       result->SetFieldAtOffset(offset, pobj_);
       if ((offset != type_argument_field_offset) &&
           (kind_ == Snapshot::kMessage)) {
         // TODO(fschneider): Consider hoisting these lookups out of the loop.
         // This would involve creating a handle, since cls_ can't be reused
         // across the call to ReadObjectRef.
         cls_ = isolate()->class_table()->At(result_cid);
         array_ = cls_.OffsetToFieldMap();
         field_ ^= array_.At(offset >> kWordSizeLog2);
         ASSERT(!field_.IsNull());
         ASSERT(field_.Offset() == offset);
         obj_ = pobj_.raw();
         field_.RecordStore(obj_);
       }
       // TODO(fschneider): Verify the guarded cid and length for other kinds of
       // snapshot (kFull, kScript) with asserts.
       offset += kWordSize;
     }
     if (kind_ == Snapshot::kFull) {
       // We create an uninitialized object in the case of full snapshots, so
       // we need to initialize any remaining padding area with the Null object.
       while (offset < instance_size) {
         result->SetFieldAtOffset(offset, Object::null_object());
         offset += kWordSize;
       }
       result->SetCreatedFromSnapshot();
-    } else if (false && RawObject::IsCanonical(tags)) {
+    } else if (RawObject::IsCanonical(tags)) {
       *result = result->CheckAndCanonicalize(NULL);
       ASSERT(!result->IsNull());
     }
     return result->raw();
   }
   ASSERT((class_header & kSmiTagMask) != kSmiTag);
   intptr_t class_id = LookupInternalClass(class_header);
   switch (class_id) {
 #define SNAPSHOT_READ(clazz)                                                   \
     case clazz::kClassId: {                                                    \
@@ skipping 32 matching lines @@
 void SnapshotReader::ArrayReadFrom(const Array& result,
                                    intptr_t len,
                                    intptr_t tags) {
   // Set the object tags.
   result.set_tags(tags);
 
   // Setup the object fields.
   *TypeArgumentsHandle() ^= ReadObjectImpl();
   result.SetTypeArguments(*TypeArgumentsHandle());
 
+  bool is_canonical = RawObject::IsCanonical(tags);
+
   for (intptr_t i = 0; i < len; i++) {
-    *PassiveObjectHandle() = ReadObjectRef();
+    *PassiveObjectHandle() = is_canonical ? ReadObjectImpl() : ReadObjectRef();
     result.SetAt(i, *PassiveObjectHandle());
   }
 }
 
 
 SnapshotWriter::SnapshotWriter(Snapshot::Kind kind,
                                uint8_t** buffer,
                                ReAlloc alloc,
                                intptr_t initial_size)
     : BaseWriter(buffer, alloc, initial_size),
@@ skipping 537 matching lines @@
   WriteIndexedObject(array_kind);
   WriteTags(tags);
 
   // Write out the length field.
   Write<RawObject*>(length);
 
   // Write out the type arguments.
   WriteObjectImpl(type_arguments);
 
   // Write out the individual object ids.
+  bool is_canonical = RawObject::IsCanonical(tags);
   for (intptr_t i = 0; i < len; i++) {
-    WriteObjectRef(data[i]);
+    if (is_canonical) {
+      WriteObjectImpl(data[i]);
+    } else {
+      WriteObjectRef(data[i]);
+    }
   }
 }
 
 
 void SnapshotWriter::CheckIfSerializable(RawClass* cls) {
   if (Class::IsSignatureClass(cls)) {
     // We do not allow closure objects in an isolate message.
     SetWriteException(Exceptions::kArgument,
                       "Illegal argument in isolate message"
                       " : (object is a closure)");
@@ skipping 37 matching lines @@
 
   // Write out the tags.
   WriteTags(tags);
 
   // Write out the class information for this object.
   WriteObjectImpl(cls);
 
   // Write out all the fields for the object.
   // Instance::NextFieldOffset() returns the offset of the first field in
   // a Dart object.
+  bool is_canonical = RawObject::IsCanonical(tags);
   intptr_t offset = Instance::NextFieldOffset();
   while (offset < next_field_offset) {
-    WriteObjectRef(*reinterpret_cast<RawObject**>(
-        reinterpret_cast<uword>(raw->ptr()) + offset));
+    RawObject* raw_obj = *reinterpret_cast<RawObject**>(
+        reinterpret_cast<uword>(raw->ptr()) + offset);
+    if (is_canonical) {
+      WriteObjectImpl(raw_obj);
+    } else {
+      WriteObjectRef(raw_obj);
+    }
     offset += kWordSize;
   }
   return;
 }
 
 
 void SnapshotWriter::WriteInstanceRef(RawObject* raw, RawClass* cls) {
   // First check if object is a closure or has native fields.
   CheckIfSerializable(cls);
 
@@ skipping 92 matching lines @@
     NoGCScope no_gc;
     WriteObject(obj.raw());
     UnmarkAll();
   } else {
     ThrowException(exception_type(), exception_msg());
   }
 }
 
 
 }  // namespace dart