- Allow for experimentation with different header sizes.

runtime/vm/object.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/object.h"
 
 #include "include/dart_api.h"
 #include "platform/assert.h"
 #include "vm/assembler.h"
 #include "vm/bigint_operations.h"
@@ skipping 575 matching lines @@
 void Object::MakeUnusedSpaceTraversable(const Object& obj,
                                         intptr_t original_size,
                                         intptr_t used_size) {
   ASSERT(Isolate::Current()->no_gc_scope_depth() > 0);
   ASSERT(!obj.IsNull());
   ASSERT(original_size >= used_size);
   if (original_size > used_size) {
     intptr_t leftover_size = original_size - used_size;
 
     uword addr = RawObject::ToAddr(obj.raw()) + used_size;
-    ASSERT(TypedData::InstanceSize(0) == Object::InstanceSize());
-    // Update the leftover space as an TypedDataInt8Array object.
-    RawTypedData* raw =
-        reinterpret_cast<RawTypedData*>(RawObject::FromAddr(addr));
-    uword tags = 0;
-    tags = RawObject::SizeTag::update(leftover_size, tags);
-    tags = RawObject::ClassIdTag::update(kTypedDataInt8ArrayCid, tags);
-    raw->ptr()->tags_ = tags;
-    intptr_t leftover_len = (leftover_size - TypedData::InstanceSize(0));
-    ASSERT(TypedData::InstanceSize(leftover_len) == leftover_size);
-    raw->ptr()->length_ = Smi::New(leftover_len);
+    if (leftover_size >= TypedData::InstanceSize(0)) {
+      // Update the leftover space as an TypedDataInt8Array object.
+      RawTypedData* raw =
+          reinterpret_cast<RawTypedData*>(RawObject::FromAddr(addr));
+      uword tags = 0;
+      tags = RawObject::SizeTag::update(leftover_size, tags);
+      tags = RawObject::ClassIdTag::update(kTypedDataInt8ArrayCid, tags);
+      raw->ptr()->tags_ = tags;
+      intptr_t leftover_len = (leftover_size - TypedData::InstanceSize(0));
+      ASSERT(TypedData::InstanceSize(leftover_len) == leftover_size);
+      raw->ptr()->length_ = Smi::New(leftover_len);
+    } else {
+      // Update the leftover space as a basic object.
+      ASSERT(leftover_size == Object::InstanceSize());
+      RawObject* raw = reinterpret_cast<RawObject*>(RawObject::FromAddr(addr));
+      uword tags = 0;
+      tags = RawObject::SizeTag::update(leftover_size, tags);
+      tags = RawObject::ClassIdTag::update(kInstanceCid, tags);
+      raw->ptr()->tags_ = tags;
+    }
   }
 }
 
 
 void Object::VerifyBuiltinVtables() {
 #if defined(DEBUG)
   Isolate* isolate = Isolate::Current();
   ASSERT(isolate != NULL);
   Class& cls = Class::Handle(isolate, Class::null());
   for (intptr_t cid = (kIllegalCid + 1); cid < kNumPredefinedCids; cid++) {
@@ skipping 12472 matching lines @@
   }
   return result.raw();
 }
 
 
 const char* WeakProperty::ToCString() const {
   return "_WeakProperty";
 }
 
 }  // namespace dart