test/cctest/test-mark-compact.cc - platform/external/v8 - Git at Google

 // Copyright 2006-2008 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
 //       with the distribution.
 //     * Neither the name of Google Inc. nor the names of its
 //       contributors may be used to endorse or promote products derived
 //       from this software without specific prior written permission.
 //
 // THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 // "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
 // LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
 // A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
 // OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
 // SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
 // LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
 // DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
 // THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 // (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 // OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

 #include <stdlib.h>

 #include "v8.h"

 #include "global-handles.h"
 #include "snapshot.h"
 #include "cctest.h"

 using namespace v8::internal;

 static v8::Persistent<v8::Context> env;

 static void InitializeVM() {
   if (env.IsEmpty()) env = v8::Context::New();
   v8::HandleScope scope;
   env->Enter();
 }


 TEST(MarkingStack) {
   int mem_size = 20 * kPointerSize;
   byte* mem = NewArray<byte>(20*kPointerSize);
   Address low = reinterpret_cast<Address>(mem);
   Address high = low + mem_size;
   MarkingStack s;
   s.Initialize(low, high);

   Address address = NULL;
   while (!s.is_full()) {
     s.Push(HeapObject::FromAddress(address));
     address += kPointerSize;
   }

   while (!s.is_empty()) {
     Address value = s.Pop()->address();
     address -= kPointerSize;
     CHECK_EQ(address, value);
   }

   CHECK_EQ(NULL, address);
   DeleteArray(mem);
 }


 TEST(Promotion) {
   // This test requires compaction. If compaction is turned off, we
   // skip the entire test.
   if (FLAG_never_compact) return;

   // Ensure that we get a compacting collection so that objects are promoted
   // from new space.
   FLAG_gc_global = true;
   FLAG_always_compact = true;
   HEAP->ConfigureHeap(2*256*KB, 4*MB, 4*MB);

   InitializeVM();

   v8::HandleScope sc;

   // Allocate a fixed array in the new space.
   int array_size =
       (HEAP->MaxObjectSizeInPagedSpace() - FixedArray::kHeaderSize) /
       (kPointerSize * 4);
   Object* obj = HEAP->AllocateFixedArray(array_size)->ToObjectChecked();

   Handle<FixedArray> array(FixedArray::cast(obj));

   // Array should be in the new space.
   CHECK(HEAP->InSpace(*array, NEW_SPACE));

   // Call the m-c collector, so array becomes an old object.
   HEAP->CollectGarbage(OLD_POINTER_SPACE);

   // Array now sits in the old space
   CHECK(HEAP->InSpace(*array, OLD_POINTER_SPACE));
 }


 TEST(NoPromotion) {
   HEAP->ConfigureHeap(2*256*KB, 4*MB, 4*MB);

   // Test the situation that some objects in new space are promoted to
   // the old space
   InitializeVM();

   v8::HandleScope sc;

   // Do a mark compact GC to shrink the heap.
   HEAP->CollectGarbage(OLD_POINTER_SPACE);

   // Allocate a big Fixed array in the new space.
   int size = (HEAP->MaxObjectSizeInPagedSpace() - FixedArray::kHeaderSize) /
       kPointerSize;
   Object* obj = HEAP->AllocateFixedArray(size)->ToObjectChecked();

   Handle<FixedArray> array(FixedArray::cast(obj));

   // Array still stays in the new space.
   CHECK(HEAP->InSpace(*array, NEW_SPACE));

   // Allocate objects in the old space until out of memory.
   FixedArray* host = *array;
   while (true) {
     Object* obj;
     { MaybeObject* maybe_obj = HEAP->AllocateFixedArray(100, TENURED);
       if (!maybe_obj->ToObject(&obj)) break;
     }

     host->set(0, obj);
     host = FixedArray::cast(obj);
   }

   // Call mark compact GC, and it should pass.
   HEAP->CollectGarbage(OLD_POINTER_SPACE);

   // array should not be promoted because the old space is full.
   CHECK(HEAP->InSpace(*array, NEW_SPACE));
 }


 TEST(MarkCompactCollector) {
   InitializeVM();

   v8::HandleScope sc;
   // call mark-compact when heap is empty
   HEAP->CollectGarbage(OLD_POINTER_SPACE);

   // keep allocating garbage in new space until it fails
   const int ARRAY_SIZE = 100;
   Object* array;
   MaybeObject* maybe_array;
   do {
     maybe_array = HEAP->AllocateFixedArray(ARRAY_SIZE);
   } while (maybe_array->ToObject(&array));
   HEAP->CollectGarbage(NEW_SPACE);

   array = HEAP->AllocateFixedArray(ARRAY_SIZE)->ToObjectChecked();

   // keep allocating maps until it fails
   Object* mapp;
   MaybeObject* maybe_mapp;
   do {
     maybe_mapp = HEAP->AllocateMap(JS_OBJECT_TYPE, JSObject::kHeaderSize);
   } while (maybe_mapp->ToObject(&mapp));
   HEAP->CollectGarbage(MAP_SPACE);
   mapp = HEAP->AllocateMap(JS_OBJECT_TYPE,
                            JSObject::kHeaderSize)->ToObjectChecked();

   // allocate a garbage
   String* func_name =
       String::cast(HEAP->LookupAsciiSymbol("theFunction")->ToObjectChecked());
   SharedFunctionInfo* function_share = SharedFunctionInfo::cast(
       HEAP->AllocateSharedFunctionInfo(func_name)->ToObjectChecked());
   JSFunction* function = JSFunction::cast(
       HEAP->AllocateFunction(*Isolate::Current()->function_map(),
                              function_share,
                              HEAP->undefined_value())->ToObjectChecked());
   Map* initial_map =
       Map::cast(HEAP->AllocateMap(JS_OBJECT_TYPE,
                                   JSObject::kHeaderSize)->ToObjectChecked());
   function->set_initial_map(initial_map);
   Isolate::Current()->context()->global()->SetProperty(
       func_name, function, NONE, kNonStrictMode)->ToObjectChecked();

   JSObject* obj = JSObject::cast(
       HEAP->AllocateJSObject(function)->ToObjectChecked());
   HEAP->CollectGarbage(OLD_POINTER_SPACE);

   func_name =
       String::cast(HEAP->LookupAsciiSymbol("theFunction")->ToObjectChecked());
   CHECK(Isolate::Current()->context()->global()->HasLocalProperty(func_name));
   Object* func_value = Isolate::Current()->context()->global()->
       GetProperty(func_name)->ToObjectChecked();
   CHECK(func_value->IsJSFunction());
   function = JSFunction::cast(func_value);

   obj = JSObject::cast(HEAP->AllocateJSObject(function)->ToObjectChecked());
   String* obj_name =
       String::cast(HEAP->LookupAsciiSymbol("theObject")->ToObjectChecked());
   Isolate::Current()->context()->global()->SetProperty(
       obj_name, obj, NONE, kNonStrictMode)->ToObjectChecked();
   String* prop_name =
       String::cast(HEAP->LookupAsciiSymbol("theSlot")->ToObjectChecked());
   obj->SetProperty(prop_name,
                    Smi::FromInt(23),
                    NONE,
                    kNonStrictMode)->ToObjectChecked();

   HEAP->CollectGarbage(OLD_POINTER_SPACE);

   obj_name =
       String::cast(HEAP->LookupAsciiSymbol("theObject")->ToObjectChecked());
   CHECK(Isolate::Current()->context()->global()->HasLocalProperty(obj_name));
   CHECK(Isolate::Current()->context()->global()->
         GetProperty(obj_name)->ToObjectChecked()->IsJSObject());
   obj = JSObject::cast(Isolate::Current()->context()->global()->
                        GetProperty(obj_name)->ToObjectChecked());
   prop_name =
       String::cast(HEAP->LookupAsciiSymbol("theSlot")->ToObjectChecked());
   CHECK(obj->GetProperty(prop_name) == Smi::FromInt(23));
 }


 static Handle<Map> CreateMap() {
   return FACTORY->NewMap(JS_OBJECT_TYPE, JSObject::kHeaderSize);
 }


 TEST(MapCompact) {
   FLAG_max_map_space_pages = 16;
   InitializeVM();

   {
     v8::HandleScope sc;
     // keep allocating maps while pointers are still encodable and thus
     // mark compact is permitted.
     Handle<JSObject> root = FACTORY->NewJSObjectFromMap(CreateMap());
     do {
       Handle<Map> map = CreateMap();
       map->set_prototype(*root);
       root = FACTORY->NewJSObjectFromMap(map);
     } while (HEAP->map_space()->MapPointersEncodable());
   }
   // Now, as we don't have any handles to just allocated maps, we should
   // be able to trigger map compaction.
   // To give an additional chance to fail, try to force compaction which
   // should be impossible right now.
   HEAP->CollectAllGarbage(true);
   // And now map pointers should be encodable again.
   CHECK(HEAP->map_space()->MapPointersEncodable());
 }


 static int gc_starts = 0;
 static int gc_ends = 0;

 static void GCPrologueCallbackFunc() {
   CHECK(gc_starts == gc_ends);
   gc_starts++;
 }


 static void GCEpilogueCallbackFunc() {
   CHECK(gc_starts == gc_ends + 1);
   gc_ends++;
 }


 TEST(GCCallback) {
   InitializeVM();

   HEAP->SetGlobalGCPrologueCallback(&GCPrologueCallbackFunc);
   HEAP->SetGlobalGCEpilogueCallback(&GCEpilogueCallbackFunc);

   // Scavenge does not call GC callback functions.
   HEAP->PerformScavenge();

   CHECK_EQ(0, gc_starts);
   CHECK_EQ(gc_ends, gc_starts);

   HEAP->CollectGarbage(OLD_POINTER_SPACE);
   CHECK_EQ(1, gc_starts);
   CHECK_EQ(gc_ends, gc_starts);
 }


 static int NumberOfWeakCalls = 0;
 static void WeakPointerCallback(v8::Persistent<v8::Value> handle, void* id) {
   ASSERT(id == reinterpret_cast<void*>(1234));
   NumberOfWeakCalls++;
   handle.Dispose();
 }

 TEST(ObjectGroups) {
   InitializeVM();
   GlobalHandles* global_handles = Isolate::Current()->global_handles();

   NumberOfWeakCalls = 0;
   v8::HandleScope handle_scope;

   Handle<Object> g1s1 =
       global_handles->Create(HEAP->AllocateFixedArray(1)->ToObjectChecked());
   Handle<Object> g1s2 =
       global_handles->Create(HEAP->AllocateFixedArray(1)->ToObjectChecked());
   Handle<Object> g1c1 =
       global_handles->Create(HEAP->AllocateFixedArray(1)->ToObjectChecked());
   global_handles->MakeWeak(g1s1.location(),
                            reinterpret_cast<void*>(1234),
                            &WeakPointerCallback);
   global_handles->MakeWeak(g1s2.location(),
                            reinterpret_cast<void*>(1234),
                            &WeakPointerCallback);
   global_handles->MakeWeak(g1c1.location(),
                            reinterpret_cast<void*>(1234),
                            &WeakPointerCallback);

   Handle<Object> g2s1 =
       global_handles->Create(HEAP->AllocateFixedArray(1)->ToObjectChecked());
   Handle<Object> g2s2 =
     global_handles->Create(HEAP->AllocateFixedArray(1)->ToObjectChecked());
   Handle<Object> g2c1 =
     global_handles->Create(HEAP->AllocateFixedArray(1)->ToObjectChecked());
   global_handles->MakeWeak(g2s1.location(),
                            reinterpret_cast<void*>(1234),
                            &WeakPointerCallback);
   global_handles->MakeWeak(g2s2.location(),
                            reinterpret_cast<void*>(1234),
                            &WeakPointerCallback);
   global_handles->MakeWeak(g2c1.location(),
                            reinterpret_cast<void*>(1234),
                            &WeakPointerCallback);

   Handle<Object> root = global_handles->Create(*g1s1);  // make a root.

   // Connect group 1 and 2, make a cycle.
   Handle<FixedArray>::cast(g1s2)->set(0, *g2s2);
   Handle<FixedArray>::cast(g2s1)->set(0, *g1s1);

   {
     Object** g1_objects[] = { g1s1.location(), g1s2.location() };
     Object** g1_children[] = { g1c1.location() };
     Object** g2_objects[] = { g2s1.location(), g2s2.location() };
     Object** g2_children[] = { g2c1.location() };
     global_handles->AddObjectGroup(g1_objects, 2, NULL);
     global_handles->AddImplicitReferences(
         Handle<HeapObject>::cast(g1s1).location(), g1_children, 1);
     global_handles->AddObjectGroup(g2_objects, 2, NULL);
     global_handles->AddImplicitReferences(
         Handle<HeapObject>::cast(g2s2).location(), g2_children, 1);
   }
   // Do a full GC
   HEAP->CollectGarbage(OLD_POINTER_SPACE);

   // All object should be alive.
   CHECK_EQ(0, NumberOfWeakCalls);

   // Weaken the root.
   global_handles->MakeWeak(root.location(),
                            reinterpret_cast<void*>(1234),
                            &WeakPointerCallback);
   // But make children strong roots---all the objects (except for children)
   // should be collectable now.
   global_handles->ClearWeakness(g1c1.location());
   global_handles->ClearWeakness(g2c1.location());

   // Groups are deleted, rebuild groups.
   {
     Object** g1_objects[] = { g1s1.location(), g1s2.location() };
     Object** g1_children[] = { g1c1.location() };
     Object** g2_objects[] = { g2s1.location(), g2s2.location() };
     Object** g2_children[] = { g2c1.location() };
     global_handles->AddObjectGroup(g1_objects, 2, NULL);
     global_handles->AddImplicitReferences(
         Handle<HeapObject>::cast(g1s1).location(), g1_children, 1);
     global_handles->AddObjectGroup(g2_objects, 2, NULL);
     global_handles->AddImplicitReferences(
         Handle<HeapObject>::cast(g2s2).location(), g2_children, 1);
   }

   HEAP->CollectGarbage(OLD_POINTER_SPACE);

   // All objects should be gone. 5 global handles in total.
   CHECK_EQ(5, NumberOfWeakCalls);

   // And now make children weak again and collect them.
   global_handles->MakeWeak(g1c1.location(),
                            reinterpret_cast<void*>(1234),
                            &WeakPointerCallback);
   global_handles->MakeWeak(g2c1.location(),
                            reinterpret_cast<void*>(1234),
                            &WeakPointerCallback);

   HEAP->CollectGarbage(OLD_POINTER_SPACE);
   CHECK_EQ(7, NumberOfWeakCalls);
 }


 class TestRetainedObjectInfo : public v8::RetainedObjectInfo {
  public:
   TestRetainedObjectInfo() : has_been_disposed_(false) {}

   bool has_been_disposed() { return has_been_disposed_; }

   virtual void Dispose() {
     ASSERT(!has_been_disposed_);
     has_been_disposed_ = true;
   }

   virtual bool IsEquivalent(v8::RetainedObjectInfo* other) {
     return other == this;
   }

   virtual intptr_t GetHash() { return 0; }

   virtual const char* GetLabel() { return "whatever"; }

  private:
   bool has_been_disposed_;
 };


 TEST(EmptyObjectGroups) {
   InitializeVM();
   GlobalHandles* global_handles = Isolate::Current()->global_handles();

   v8::HandleScope handle_scope;

   Handle<Object> object =
       global_handles->Create(HEAP->AllocateFixedArray(1)->ToObjectChecked());

   TestRetainedObjectInfo info;
   global_handles->AddObjectGroup(NULL, 0, &info);
   ASSERT(info.has_been_disposed());

   global_handles->AddImplicitReferences(
         Handle<HeapObject>::cast(object).location(), NULL, 0);
 }
	// Copyright 2006-2008 the V8 project authors. All rights reserved.
	// Redistribution and use in source and binary forms, with or without
	// modification, are permitted provided that the following conditions are
	// met:
	//
	// * Redistributions of source code must retain the above copyright
	// notice, this list of conditions and the following disclaimer.
	// * Redistributions in binary form must reproduce the above
	// copyright notice, this list of conditions and the following
	// disclaimer in the documentation and/or other materials provided
	// with the distribution.
	// * Neither the name of Google Inc. nor the names of its
	// contributors may be used to endorse or promote products derived
	// from this software without specific prior written permission.
	//
	// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
	// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
	// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
	// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
	// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
	// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
	// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
	// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
	// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
	// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
	// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

	#include <stdlib.h>

	#include "v8.h"

	#include "global-handles.h"
	#include "snapshot.h"
	#include "cctest.h"

	using namespace v8::internal;

	static v8::Persistent<v8::Context> env;

	static void InitializeVM() {
	if (env.IsEmpty()) env = v8::Context::New();
	v8::HandleScope scope;
	env->Enter();
	}


	TEST(MarkingStack) {
	int mem_size = 20 * kPointerSize;
	byte* mem = NewArray<byte>(20*kPointerSize);
	Address low = reinterpret_cast<Address>(mem);
	Address high = low + mem_size;
	MarkingStack s;
	s.Initialize(low, high);

	Address address = NULL;
	while (!s.is_full()) {
	s.Push(HeapObject::FromAddress(address));
	address += kPointerSize;
	}

	while (!s.is_empty()) {
	Address value = s.Pop()->address();
	address -= kPointerSize;
	CHECK_EQ(address, value);
	}

	CHECK_EQ(NULL, address);
	DeleteArray(mem);
	}


	TEST(Promotion) {
	// This test requires compaction. If compaction is turned off, we
	// skip the entire test.
	if (FLAG_never_compact) return;

	// Ensure that we get a compacting collection so that objects are promoted
	// from new space.
	FLAG_gc_global = true;
	FLAG_always_compact = true;
	HEAP->ConfigureHeap(2256KB, 4MB, 4MB);

	InitializeVM();

	v8::HandleScope sc;

	// Allocate a fixed array in the new space.
	int array_size =
	(HEAP->MaxObjectSizeInPagedSpace() - FixedArray::kHeaderSize) /
	(kPointerSize * 4);
	Object* obj = HEAP->AllocateFixedArray(array_size)->ToObjectChecked();

	Handle<FixedArray> array(FixedArray::cast(obj));

	// Array should be in the new space.
	CHECK(HEAP->InSpace(*array, NEW_SPACE));

	// Call the m-c collector, so array becomes an old object.
	HEAP->CollectGarbage(OLD_POINTER_SPACE);

	// Array now sits in the old space
	CHECK(HEAP->InSpace(*array, OLD_POINTER_SPACE));
	}


	TEST(NoPromotion) {
	HEAP->ConfigureHeap(2256KB, 4MB, 4MB);

	// Test the situation that some objects in new space are promoted to
	// the old space
	InitializeVM();

	v8::HandleScope sc;

	// Do a mark compact GC to shrink the heap.
	HEAP->CollectGarbage(OLD_POINTER_SPACE);

	// Allocate a big Fixed array in the new space.
	int size = (HEAP->MaxObjectSizeInPagedSpace() - FixedArray::kHeaderSize) /
	kPointerSize;
	Object* obj = HEAP->AllocateFixedArray(size)->ToObjectChecked();

	Handle<FixedArray> array(FixedArray::cast(obj));

	// Array still stays in the new space.
	CHECK(HEAP->InSpace(*array, NEW_SPACE));

	// Allocate objects in the old space until out of memory.
	FixedArray* host = *array;
	while (true) {
	Object* obj;
	{ MaybeObject* maybe_obj = HEAP->AllocateFixedArray(100, TENURED);
	if (!maybe_obj->ToObject(&obj)) break;
	}

	host->set(0, obj);
	host = FixedArray::cast(obj);
	}

	// Call mark compact GC, and it should pass.
	HEAP->CollectGarbage(OLD_POINTER_SPACE);

	// array should not be promoted because the old space is full.
	CHECK(HEAP->InSpace(*array, NEW_SPACE));
	}


	TEST(MarkCompactCollector) {
	InitializeVM();

	v8::HandleScope sc;
	// call mark-compact when heap is empty
	HEAP->CollectGarbage(OLD_POINTER_SPACE);

	// keep allocating garbage in new space until it fails
	const int ARRAY_SIZE = 100;
	Object* array;
	MaybeObject* maybe_array;
	do {
	maybe_array = HEAP->AllocateFixedArray(ARRAY_SIZE);
	} while (maybe_array->ToObject(&array));
	HEAP->CollectGarbage(NEW_SPACE);

	array = HEAP->AllocateFixedArray(ARRAY_SIZE)->ToObjectChecked();

	// keep allocating maps until it fails
	Object* mapp;
	MaybeObject* maybe_mapp;
	do {
	maybe_mapp = HEAP->AllocateMap(JS_OBJECT_TYPE, JSObject::kHeaderSize);
	} while (maybe_mapp->ToObject(&mapp));
	HEAP->CollectGarbage(MAP_SPACE);
	mapp = HEAP->AllocateMap(JS_OBJECT_TYPE,
	JSObject::kHeaderSize)->ToObjectChecked();

	// allocate a garbage
	String* func_name =
	String::cast(HEAP->LookupAsciiSymbol("theFunction")->ToObjectChecked());
	SharedFunctionInfo* function_share = SharedFunctionInfo::cast(
	HEAP->AllocateSharedFunctionInfo(func_name)->ToObjectChecked());
	JSFunction* function = JSFunction::cast(
	HEAP->AllocateFunction(*Isolate::Current()->function_map(),
	function_share,
	HEAP->undefined_value())->ToObjectChecked());
	Map* initial_map =
	Map::cast(HEAP->AllocateMap(JS_OBJECT_TYPE,
	JSObject::kHeaderSize)->ToObjectChecked());
	function->set_initial_map(initial_map);
	Isolate::Current()->context()->global()->SetProperty(
	func_name, function, NONE, kNonStrictMode)->ToObjectChecked();

	JSObject* obj = JSObject::cast(
	HEAP->AllocateJSObject(function)->ToObjectChecked());
	HEAP->CollectGarbage(OLD_POINTER_SPACE);

	func_name =
	String::cast(HEAP->LookupAsciiSymbol("theFunction")->ToObjectChecked());
	CHECK(Isolate::Current()->context()->global()->HasLocalProperty(func_name));
	Object* func_value = Isolate::Current()->context()->global()->
	GetProperty(func_name)->ToObjectChecked();
	CHECK(func_value->IsJSFunction());
	function = JSFunction::cast(func_value);

	obj = JSObject::cast(HEAP->AllocateJSObject(function)->ToObjectChecked());
	String* obj_name =
	String::cast(HEAP->LookupAsciiSymbol("theObject")->ToObjectChecked());
	Isolate::Current()->context()->global()->SetProperty(
	obj_name, obj, NONE, kNonStrictMode)->ToObjectChecked();
	String* prop_name =
	String::cast(HEAP->LookupAsciiSymbol("theSlot")->ToObjectChecked());
	obj->SetProperty(prop_name,
	Smi::FromInt(23),
	NONE,
	kNonStrictMode)->ToObjectChecked();

	HEAP->CollectGarbage(OLD_POINTER_SPACE);

	obj_name =
	String::cast(HEAP->LookupAsciiSymbol("theObject")->ToObjectChecked());
	CHECK(Isolate::Current()->context()->global()->HasLocalProperty(obj_name));
	CHECK(Isolate::Current()->context()->global()->
	GetProperty(obj_name)->ToObjectChecked()->IsJSObject());
	obj = JSObject::cast(Isolate::Current()->context()->global()->
	GetProperty(obj_name)->ToObjectChecked());
	prop_name =
	String::cast(HEAP->LookupAsciiSymbol("theSlot")->ToObjectChecked());
	CHECK(obj->GetProperty(prop_name) == Smi::FromInt(23));
	}


	static Handle<Map> CreateMap() {
	return FACTORY->NewMap(JS_OBJECT_TYPE, JSObject::kHeaderSize);
	}


	TEST(MapCompact) {
	FLAG_max_map_space_pages = 16;
	InitializeVM();

	{
	v8::HandleScope sc;
	// keep allocating maps while pointers are still encodable and thus
	// mark compact is permitted.
	Handle<JSObject> root = FACTORY->NewJSObjectFromMap(CreateMap());
	do {
	Handle<Map> map = CreateMap();
	map->set_prototype(*root);
	root = FACTORY->NewJSObjectFromMap(map);
	} while (HEAP->map_space()->MapPointersEncodable());
	}
	// Now, as we don't have any handles to just allocated maps, we should
	// be able to trigger map compaction.
	// To give an additional chance to fail, try to force compaction which
	// should be impossible right now.
	HEAP->CollectAllGarbage(true);
	// And now map pointers should be encodable again.
	CHECK(HEAP->map_space()->MapPointersEncodable());
	}


	static int gc_starts = 0;
	static int gc_ends = 0;

	static void GCPrologueCallbackFunc() {
	CHECK(gc_starts == gc_ends);
	gc_starts++;
	}


	static void GCEpilogueCallbackFunc() {
	CHECK(gc_starts == gc_ends + 1);
	gc_ends++;
	}


	TEST(GCCallback) {
	InitializeVM();

	HEAP->SetGlobalGCPrologueCallback(&GCPrologueCallbackFunc);
	HEAP->SetGlobalGCEpilogueCallback(&GCEpilogueCallbackFunc);

	// Scavenge does not call GC callback functions.
	HEAP->PerformScavenge();

	CHECK_EQ(0, gc_starts);
	CHECK_EQ(gc_ends, gc_starts);

	HEAP->CollectGarbage(OLD_POINTER_SPACE);
	CHECK_EQ(1, gc_starts);
	CHECK_EQ(gc_ends, gc_starts);
	}


	static int NumberOfWeakCalls = 0;
	static void WeakPointerCallback(v8::Persistent<v8::Value> handle, void* id) {
	ASSERT(id == reinterpret_cast<void*>(1234));
	NumberOfWeakCalls++;
	handle.Dispose();
	}

	TEST(ObjectGroups) {
	InitializeVM();
	GlobalHandles* global_handles = Isolate::Current()->global_handles();

	NumberOfWeakCalls = 0;
	v8::HandleScope handle_scope;

	Handle<Object> g1s1 =
	global_handles->Create(HEAP->AllocateFixedArray(1)->ToObjectChecked());
	Handle<Object> g1s2 =
	global_handles->Create(HEAP->AllocateFixedArray(1)->ToObjectChecked());
	Handle<Object> g1c1 =
	global_handles->Create(HEAP->AllocateFixedArray(1)->ToObjectChecked());
	global_handles->MakeWeak(g1s1.location(),
	reinterpret_cast<void*>(1234),
	&WeakPointerCallback);
	global_handles->MakeWeak(g1s2.location(),
	reinterpret_cast<void*>(1234),
	&WeakPointerCallback);
	global_handles->MakeWeak(g1c1.location(),
	reinterpret_cast<void*>(1234),
	&WeakPointerCallback);

	Handle<Object> g2s1 =
	global_handles->Create(HEAP->AllocateFixedArray(1)->ToObjectChecked());
	Handle<Object> g2s2 =
	global_handles->Create(HEAP->AllocateFixedArray(1)->ToObjectChecked());
	Handle<Object> g2c1 =
	global_handles->Create(HEAP->AllocateFixedArray(1)->ToObjectChecked());
	global_handles->MakeWeak(g2s1.location(),
	reinterpret_cast<void*>(1234),
	&WeakPointerCallback);
	global_handles->MakeWeak(g2s2.location(),
	reinterpret_cast<void*>(1234),
	&WeakPointerCallback);
	global_handles->MakeWeak(g2c1.location(),
	reinterpret_cast<void*>(1234),
	&WeakPointerCallback);

	Handle<Object> root = global_handles->Create(*g1s1); // make a root.

	// Connect group 1 and 2, make a cycle.
	Handle<FixedArray>::cast(g1s2)->set(0, *g2s2);
	Handle<FixedArray>::cast(g2s1)->set(0, *g1s1);

	{
	Object** g1_objects[] = { g1s1.location(), g1s2.location() };
	Object** g1_children[] = { g1c1.location() };
	Object** g2_objects[] = { g2s1.location(), g2s2.location() };
	Object** g2_children[] = { g2c1.location() };
	global_handles->AddObjectGroup(g1_objects, 2, NULL);
	global_handles->AddImplicitReferences(
	Handle<HeapObject>::cast(g1s1).location(), g1_children, 1);
	global_handles->AddObjectGroup(g2_objects, 2, NULL);
	global_handles->AddImplicitReferences(
	Handle<HeapObject>::cast(g2s2).location(), g2_children, 1);
	}
	// Do a full GC
	HEAP->CollectGarbage(OLD_POINTER_SPACE);

	// All object should be alive.
	CHECK_EQ(0, NumberOfWeakCalls);

	// Weaken the root.
	global_handles->MakeWeak(root.location(),
	reinterpret_cast<void*>(1234),
	&WeakPointerCallback);
	// But make children strong roots---all the objects (except for children)
	// should be collectable now.
	global_handles->ClearWeakness(g1c1.location());
	global_handles->ClearWeakness(g2c1.location());

	// Groups are deleted, rebuild groups.
	{
	Object** g1_objects[] = { g1s1.location(), g1s2.location() };
	Object** g1_children[] = { g1c1.location() };
	Object** g2_objects[] = { g2s1.location(), g2s2.location() };
	Object** g2_children[] = { g2c1.location() };
	global_handles->AddObjectGroup(g1_objects, 2, NULL);
	global_handles->AddImplicitReferences(
	Handle<HeapObject>::cast(g1s1).location(), g1_children, 1);
	global_handles->AddObjectGroup(g2_objects, 2, NULL);
	global_handles->AddImplicitReferences(
	Handle<HeapObject>::cast(g2s2).location(), g2_children, 1);
	}

	HEAP->CollectGarbage(OLD_POINTER_SPACE);

	// All objects should be gone. 5 global handles in total.
	CHECK_EQ(5, NumberOfWeakCalls);

	// And now make children weak again and collect them.
	global_handles->MakeWeak(g1c1.location(),
	reinterpret_cast<void*>(1234),
	&WeakPointerCallback);
	global_handles->MakeWeak(g2c1.location(),
	reinterpret_cast<void*>(1234),
	&WeakPointerCallback);

	HEAP->CollectGarbage(OLD_POINTER_SPACE);
	CHECK_EQ(7, NumberOfWeakCalls);
	}


	class TestRetainedObjectInfo : public v8::RetainedObjectInfo {
	public:
	TestRetainedObjectInfo() : has_been_disposed_(false) {}

	bool has_been_disposed() { return has_been_disposed_; }

	virtual void Dispose() {
	ASSERT(!has_been_disposed_);
	has_been_disposed_ = true;
	}

	virtual bool IsEquivalent(v8::RetainedObjectInfo* other) {
	return other == this;
	}

	virtual intptr_t GetHash() { return 0; }

	virtual const char* GetLabel() { return "whatever"; }

	private:
	bool has_been_disposed_;
	};


	TEST(EmptyObjectGroups) {
	InitializeVM();
	GlobalHandles* global_handles = Isolate::Current()->global_handles();

	v8::HandleScope handle_scope;

	Handle<Object> object =
	global_handles->Create(HEAP->AllocateFixedArray(1)->ToObjectChecked());

	TestRetainedObjectInfo info;
	global_handles->AddObjectGroup(NULL, 0, &info);
	ASSERT(info.has_been_disposed());

	global_handles->AddImplicitReferences(
	Handle<HeapObject>::cast(object).location(), NULL, 0);
	}