// Copyright 2012 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. #ifndef V8_OBJECTS_VISITING_INL_H_ #define V8_OBJECTS_VISITING_INL_H_ namespace v8 { namespace internal { template void StaticNewSpaceVisitor::Initialize() { table_.Register(kVisitShortcutCandidate, &FixedBodyVisitor::Visit); table_.Register(kVisitConsString, &FixedBodyVisitor::Visit); table_.Register(kVisitSlicedString, &FixedBodyVisitor::Visit); table_.Register(kVisitFixedArray, &FlexibleBodyVisitor::Visit); table_.Register(kVisitFixedDoubleArray, &VisitFixedDoubleArray); table_.Register(kVisitNativeContext, &FixedBodyVisitor::Visit); table_.Register(kVisitByteArray, &VisitByteArray); table_.Register(kVisitSharedFunctionInfo, &FixedBodyVisitor::Visit); table_.Register(kVisitSeqAsciiString, &VisitSeqAsciiString); table_.Register(kVisitSeqTwoByteString, &VisitSeqTwoByteString); table_.Register(kVisitJSFunction, &VisitJSFunction); table_.Register(kVisitFreeSpace, &VisitFreeSpace); table_.Register(kVisitJSWeakMap, &JSObjectVisitor::Visit); table_.Register(kVisitJSRegExp, &JSObjectVisitor::Visit); table_.template RegisterSpecializations(); table_.template RegisterSpecializations(); table_.template RegisterSpecializations(); } template void StaticMarkingVisitor::Initialize() { table_.Register(kVisitShortcutCandidate, &FixedBodyVisitor::Visit); table_.Register(kVisitConsString, &FixedBodyVisitor::Visit); table_.Register(kVisitSlicedString, &FixedBodyVisitor::Visit); table_.Register(kVisitFixedArray, &FlexibleBodyVisitor::Visit); table_.Register(kVisitFixedDoubleArray, &DataObjectVisitor::Visit); table_.Register(kVisitNativeContext, &VisitNativeContext); table_.Register(kVisitByteArray, &DataObjectVisitor::Visit); table_.Register(kVisitFreeSpace, &DataObjectVisitor::Visit); table_.Register(kVisitSeqAsciiString, &DataObjectVisitor::Visit); table_.Register(kVisitSeqTwoByteString, &DataObjectVisitor::Visit); table_.Register(kVisitJSWeakMap, &StaticVisitor::VisitJSWeakMap); table_.Register(kVisitOddball, &FixedBodyVisitor::Visit); table_.Register(kVisitMap, &VisitMap); table_.Register(kVisitCode, &VisitCode); table_.Register(kVisitSharedFunctionInfo, &VisitSharedFunctionInfo); table_.Register(kVisitJSFunction, &VisitJSFunction); // Registration for kVisitJSRegExp is done by StaticVisitor. table_.Register(kVisitPropertyCell, &FixedBodyVisitor::Visit); table_.template RegisterSpecializations(); table_.template RegisterSpecializations(); table_.template RegisterSpecializations(); } template void StaticMarkingVisitor::VisitCodeEntry( Heap* heap, Address entry_address) { Code* code = Code::cast(Code::GetObjectFromEntryAddress(entry_address)); heap->mark_compact_collector()->RecordCodeEntrySlot(entry_address, code); StaticVisitor::MarkObject(heap, code); } template void StaticMarkingVisitor::VisitEmbeddedPointer( Heap* heap, RelocInfo* rinfo) { ASSERT(rinfo->rmode() == RelocInfo::EMBEDDED_OBJECT); ASSERT(!rinfo->target_object()->IsConsString()); HeapObject* object = HeapObject::cast(rinfo->target_object()); heap->mark_compact_collector()->RecordRelocSlot(rinfo, object); StaticVisitor::MarkObject(heap, object); } template void StaticMarkingVisitor::VisitGlobalPropertyCell( Heap* heap, RelocInfo* rinfo) { ASSERT(rinfo->rmode() == RelocInfo::GLOBAL_PROPERTY_CELL); JSGlobalPropertyCell* cell = rinfo->target_cell(); StaticVisitor::MarkObject(heap, cell); } template void StaticMarkingVisitor::VisitDebugTarget( Heap* heap, RelocInfo* rinfo) { ASSERT((RelocInfo::IsJSReturn(rinfo->rmode()) && rinfo->IsPatchedReturnSequence()) || (RelocInfo::IsDebugBreakSlot(rinfo->rmode()) && rinfo->IsPatchedDebugBreakSlotSequence())); Code* target = Code::GetCodeFromTargetAddress(rinfo->call_address()); heap->mark_compact_collector()->RecordRelocSlot(rinfo, target); StaticVisitor::MarkObject(heap, target); } template void StaticMarkingVisitor::VisitCodeTarget( Heap* heap, RelocInfo* rinfo) { ASSERT(RelocInfo::IsCodeTarget(rinfo->rmode())); Code* target = Code::GetCodeFromTargetAddress(rinfo->target_address()); // Monomorphic ICs are preserved when possible, but need to be flushed // when they might be keeping a Context alive, or when the heap is about // to be serialized. if (FLAG_cleanup_code_caches_at_gc && target->is_inline_cache_stub() && (target->ic_state() == MEGAMORPHIC || Serializer::enabled() || heap->isolate()->context_exit_happened() || target->ic_age() != heap->global_ic_age())) { IC::Clear(rinfo->pc()); target = Code::GetCodeFromTargetAddress(rinfo->target_address()); } heap->mark_compact_collector()->RecordRelocSlot(rinfo, target); StaticVisitor::MarkObject(heap, target); } template void StaticMarkingVisitor::VisitNativeContext( Map* map, HeapObject* object) { FixedBodyVisitor::Visit(map, object); MarkCompactCollector* collector = map->GetHeap()->mark_compact_collector(); for (int idx = Context::FIRST_WEAK_SLOT; idx < Context::NATIVE_CONTEXT_SLOTS; ++idx) { Object** slot = HeapObject::RawField(object, FixedArray::OffsetOfElementAt(idx)); collector->RecordSlot(slot, slot, *slot); } } template void StaticMarkingVisitor::VisitMap( Map* map, HeapObject* object) { Heap* heap = map->GetHeap(); Map* map_object = Map::cast(object); // Clears the cache of ICs related to this map. if (FLAG_cleanup_code_caches_at_gc) { map_object->ClearCodeCache(heap); } // When map collection is enabled we have to mark through map's // transitions and back pointers in a special way to make these links // weak. Only maps for subclasses of JSReceiver can have transitions. STATIC_ASSERT(LAST_TYPE == LAST_JS_RECEIVER_TYPE); if (FLAG_collect_maps && map_object->instance_type() >= FIRST_JS_RECEIVER_TYPE) { MarkMapContents(heap, map_object); } else { StaticVisitor::VisitPointers(heap, HeapObject::RawField(object, Map::kPointerFieldsBeginOffset), HeapObject::RawField(object, Map::kPointerFieldsEndOffset)); } } template void StaticMarkingVisitor::VisitCode( Map* map, HeapObject* object) { Heap* heap = map->GetHeap(); Code* code = Code::cast(object); if (FLAG_cleanup_code_caches_at_gc) { code->ClearTypeFeedbackCells(heap); } code->CodeIterateBody(heap); } template void StaticMarkingVisitor::VisitSharedFunctionInfo( Map* map, HeapObject* object) { Heap* heap = map->GetHeap(); SharedFunctionInfo* shared = SharedFunctionInfo::cast(object); if (shared->ic_age() != heap->global_ic_age()) { shared->ResetForNewContext(heap->global_ic_age()); } MarkCompactCollector* collector = heap->mark_compact_collector(); if (collector->is_code_flushing_enabled()) { if (IsFlushable(heap, shared)) { // This function's code looks flushable. But we have to postpone // the decision until we see all functions that point to the same // SharedFunctionInfo because some of them might be optimized. // That would also make the non-optimized version of the code // non-flushable, because it is required for bailing out from // optimized code. collector->code_flusher()->AddCandidate(shared); // Treat the reference to the code object weakly. VisitSharedFunctionInfoWeakCode(heap, object); return; } } VisitSharedFunctionInfoStrongCode(heap, object); } template void StaticMarkingVisitor::VisitJSFunction( Map* map, HeapObject* object) { Heap* heap = map->GetHeap(); JSFunction* function = JSFunction::cast(object); MarkCompactCollector* collector = heap->mark_compact_collector(); if (collector->is_code_flushing_enabled()) { if (IsFlushable(heap, function)) { // This function's code looks flushable. But we have to postpone // the decision until we see all functions that point to the same // SharedFunctionInfo because some of them might be optimized. // That would also make the non-optimized version of the code // non-flushable, because it is required for bailing out from // optimized code. collector->code_flusher()->AddCandidate(function); // Visit shared function info immediately to avoid double checking // of its flushability later. This is just an optimization because // the shared function info would eventually be visited. SharedFunctionInfo* shared = function->unchecked_shared(); if (StaticVisitor::MarkObjectWithoutPush(heap, shared)) { StaticVisitor::MarkObject(heap, shared->map()); VisitSharedFunctionInfoWeakCode(heap, shared); } // Treat the reference to the code object weakly. VisitJSFunctionWeakCode(heap, object); return; } else { // Visit all unoptimized code objects to prevent flushing them. StaticVisitor::MarkObject(heap, function->shared()->code()); if (function->code()->kind() == Code::OPTIMIZED_FUNCTION) { MarkInlinedFunctionsCode(heap, function->code()); } } } VisitJSFunctionStrongCode(heap, object); } template void StaticMarkingVisitor::VisitJSRegExp( Map* map, HeapObject* object) { int last_property_offset = JSRegExp::kSize + kPointerSize * map->inobject_properties(); StaticVisitor::VisitPointers(map->GetHeap(), HeapObject::RawField(object, JSRegExp::kPropertiesOffset), HeapObject::RawField(object, last_property_offset)); } template void StaticMarkingVisitor::MarkMapContents( Heap* heap, Map* map) { // Make sure that the back pointer stored either in the map itself or // inside its transitions array is marked. Skip recording the back // pointer slot since map space is not compacted. StaticVisitor::MarkObject(heap, HeapObject::cast(map->GetBackPointer())); // Treat pointers in the transitions array as weak and also mark that // array to prevent visiting it later. Skip recording the transition // array slot, since it will be implicitly recorded when the pointer // fields of this map are visited. TransitionArray* transitions = map->unchecked_transition_array(); if (transitions->IsTransitionArray()) { MarkTransitionArray(heap, transitions); } else { // Already marked by marking map->GetBackPointer() above. ASSERT(transitions->IsMap() || transitions->IsUndefined()); } // Mark the pointer fields of the Map. Since the transitions array has // been marked already, it is fine that one of these fields contains a // pointer to it. StaticVisitor::VisitPointers(heap, HeapObject::RawField(map, Map::kPointerFieldsBeginOffset), HeapObject::RawField(map, Map::kPointerFieldsEndOffset)); } template void StaticMarkingVisitor::MarkTransitionArray( Heap* heap, TransitionArray* transitions) { if (!StaticVisitor::MarkObjectWithoutPush(heap, transitions)) return; // Skip recording the descriptors_pointer slot since the cell space // is not compacted and descriptors are referenced through a cell. Object** descriptors_slot = transitions->GetDescriptorsSlot(); HeapObject* descriptors = HeapObject::cast(*descriptors_slot); StaticVisitor::MarkObject(heap, descriptors); heap->mark_compact_collector()->RecordSlot( descriptors_slot, descriptors_slot, descriptors); // Simple transitions do not have keys nor prototype transitions. if (transitions->IsSimpleTransition()) return; if (transitions->HasPrototypeTransitions()) { // Mark prototype transitions array but do not push it onto marking // stack, this will make references from it weak. We will clean dead // prototype transitions in ClearNonLiveTransitions. Object** slot = transitions->GetPrototypeTransitionsSlot(); HeapObject* obj = HeapObject::cast(*slot); heap->mark_compact_collector()->RecordSlot(slot, slot, obj); StaticVisitor::MarkObjectWithoutPush(heap, obj); } for (int i = 0; i < transitions->number_of_transitions(); ++i) { StaticVisitor::VisitPointer(heap, transitions->GetKeySlot(i)); } } template void StaticMarkingVisitor::MarkInlinedFunctionsCode( Heap* heap, Code* code) { // For optimized functions we should retain both non-optimized version // of its code and non-optimized version of all inlined functions. // This is required to support bailing out from inlined code. DeoptimizationInputData* data = DeoptimizationInputData::cast(code->deoptimization_data()); FixedArray* literals = data->LiteralArray(); for (int i = 0, count = data->InlinedFunctionCount()->value(); i < count; i++) { JSFunction* inlined = JSFunction::cast(literals->get(i)); StaticVisitor::MarkObject(heap, inlined->shared()->code()); } } inline static bool IsValidNonBuiltinContext(Object* context) { return context->IsContext() && !Context::cast(context)->global_object()->IsJSBuiltinsObject(); } inline static bool HasSourceCode(Heap* heap, SharedFunctionInfo* info) { Object* undefined = heap->undefined_value(); return (info->script() != undefined) && (reinterpret_cast(info->script())->source() != undefined); } template bool StaticMarkingVisitor::IsFlushable( Heap* heap, JSFunction* function) { SharedFunctionInfo* shared_info = function->unchecked_shared(); // Code is either on stack, in compilation cache or referenced // by optimized version of function. MarkBit code_mark = Marking::MarkBitFrom(function->code()); if (code_mark.Get()) { if (!Marking::MarkBitFrom(shared_info).Get()) { shared_info->set_code_age(0); } return false; } // The function must have a valid context and not be a builtin. if (!IsValidNonBuiltinContext(function->unchecked_context())) { return false; } // We do not flush code for optimized functions. if (function->code() != shared_info->code()) { return false; } return IsFlushable(heap, shared_info); } template bool StaticMarkingVisitor::IsFlushable( Heap* heap, SharedFunctionInfo* shared_info) { // Code is either on stack, in compilation cache or referenced // by optimized version of function. MarkBit code_mark = Marking::MarkBitFrom(shared_info->code()); if (code_mark.Get()) { return false; } // The function must be compiled and have the source code available, // to be able to recompile it in case we need the function again. if (!(shared_info->is_compiled() && HasSourceCode(heap, shared_info))) { return false; } // We never flush code for API functions. Object* function_data = shared_info->function_data(); if (function_data->IsFunctionTemplateInfo()) { return false; } // Only flush code for functions. if (shared_info->code()->kind() != Code::FUNCTION) { return false; } // Function must be lazy compilable. if (!shared_info->allows_lazy_compilation()) { return false; } // If this is a full script wrapped in a function we do no flush the code. if (shared_info->is_toplevel()) { return false; } // TODO(mstarzinger): The following will soon be replaced by a new way of // aging code, that is based on an aging stub in the function prologue. // How many collections newly compiled code object will survive before being // flushed. static const int kCodeAgeThreshold = 5; // Age this shared function info. if (shared_info->code_age() < kCodeAgeThreshold) { shared_info->set_code_age(shared_info->code_age() + 1); return false; } return true; } template void StaticMarkingVisitor::VisitSharedFunctionInfoStrongCode( Heap* heap, HeapObject* object) { StaticVisitor::BeforeVisitingSharedFunctionInfo(object); Object** start_slot = HeapObject::RawField(object, SharedFunctionInfo::BodyDescriptor::kStartOffset); Object** end_slot = HeapObject::RawField(object, SharedFunctionInfo::BodyDescriptor::kEndOffset); StaticVisitor::VisitPointers(heap, start_slot, end_slot); } template void StaticMarkingVisitor::VisitSharedFunctionInfoWeakCode( Heap* heap, HeapObject* object) { StaticVisitor::BeforeVisitingSharedFunctionInfo(object); Object** name_slot = HeapObject::RawField(object, SharedFunctionInfo::kNameOffset); StaticVisitor::VisitPointer(heap, name_slot); // Skip visiting kCodeOffset as it is treated weakly here. STATIC_ASSERT(SharedFunctionInfo::kNameOffset + kPointerSize == SharedFunctionInfo::kCodeOffset); STATIC_ASSERT(SharedFunctionInfo::kCodeOffset + kPointerSize == SharedFunctionInfo::kOptimizedCodeMapOffset); Object** start_slot = HeapObject::RawField(object, SharedFunctionInfo::kOptimizedCodeMapOffset); Object** end_slot = HeapObject::RawField(object, SharedFunctionInfo::BodyDescriptor::kEndOffset); StaticVisitor::VisitPointers(heap, start_slot, end_slot); } template void StaticMarkingVisitor::VisitJSFunctionStrongCode( Heap* heap, HeapObject* object) { Object** start_slot = HeapObject::RawField(object, JSFunction::kPropertiesOffset); Object** end_slot = HeapObject::RawField(object, JSFunction::kCodeEntryOffset); StaticVisitor::VisitPointers(heap, start_slot, end_slot); VisitCodeEntry(heap, object->address() + JSFunction::kCodeEntryOffset); STATIC_ASSERT(JSFunction::kCodeEntryOffset + kPointerSize == JSFunction::kPrototypeOrInitialMapOffset); start_slot = HeapObject::RawField(object, JSFunction::kPrototypeOrInitialMapOffset); end_slot = HeapObject::RawField(object, JSFunction::kNonWeakFieldsEndOffset); StaticVisitor::VisitPointers(heap, start_slot, end_slot); } template void StaticMarkingVisitor::VisitJSFunctionWeakCode( Heap* heap, HeapObject* object) { Object** start_slot = HeapObject::RawField(object, JSFunction::kPropertiesOffset); Object** end_slot = HeapObject::RawField(object, JSFunction::kCodeEntryOffset); StaticVisitor::VisitPointers(heap, start_slot, end_slot); // Skip visiting kCodeEntryOffset as it is treated weakly here. STATIC_ASSERT(JSFunction::kCodeEntryOffset + kPointerSize == JSFunction::kPrototypeOrInitialMapOffset); start_slot = HeapObject::RawField(object, JSFunction::kPrototypeOrInitialMapOffset); end_slot = HeapObject::RawField(object, JSFunction::kNonWeakFieldsEndOffset); StaticVisitor::VisitPointers(heap, start_slot, end_slot); } void Code::CodeIterateBody(ObjectVisitor* v) { int mode_mask = RelocInfo::kCodeTargetMask | RelocInfo::ModeMask(RelocInfo::EMBEDDED_OBJECT) | RelocInfo::ModeMask(RelocInfo::GLOBAL_PROPERTY_CELL) | RelocInfo::ModeMask(RelocInfo::EXTERNAL_REFERENCE) | RelocInfo::ModeMask(RelocInfo::JS_RETURN) | RelocInfo::ModeMask(RelocInfo::DEBUG_BREAK_SLOT) | RelocInfo::ModeMask(RelocInfo::RUNTIME_ENTRY); // There are two places where we iterate code bodies: here and the // templated CodeIterateBody (below). They should be kept in sync. IteratePointer(v, kRelocationInfoOffset); IteratePointer(v, kHandlerTableOffset); IteratePointer(v, kDeoptimizationDataOffset); IteratePointer(v, kTypeFeedbackInfoOffset); RelocIterator it(this, mode_mask); for (; !it.done(); it.next()) { it.rinfo()->Visit(v); } } template void Code::CodeIterateBody(Heap* heap) { int mode_mask = RelocInfo::kCodeTargetMask | RelocInfo::ModeMask(RelocInfo::EMBEDDED_OBJECT) | RelocInfo::ModeMask(RelocInfo::GLOBAL_PROPERTY_CELL) | RelocInfo::ModeMask(RelocInfo::EXTERNAL_REFERENCE) | RelocInfo::ModeMask(RelocInfo::JS_RETURN) | RelocInfo::ModeMask(RelocInfo::DEBUG_BREAK_SLOT) | RelocInfo::ModeMask(RelocInfo::RUNTIME_ENTRY); // There are two places where we iterate code bodies: here and the // non-templated CodeIterateBody (above). They should be kept in sync. StaticVisitor::VisitPointer( heap, reinterpret_cast(this->address() + kRelocationInfoOffset)); StaticVisitor::VisitPointer( heap, reinterpret_cast(this->address() + kHandlerTableOffset)); StaticVisitor::VisitPointer( heap, reinterpret_cast(this->address() + kDeoptimizationDataOffset)); StaticVisitor::VisitPointer( heap, reinterpret_cast(this->address() + kTypeFeedbackInfoOffset)); RelocIterator it(this, mode_mask); for (; !it.done(); it.next()) { it.rinfo()->template Visit(heap); } } } } // namespace v8::internal #endif // V8_OBJECTS_VISITING_INL_H_