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Diffstat (limited to 'v8/src/heap.cc')
| -rw-r--r-- | v8/src/heap.cc | 3363 |
1 files changed, 3363 insertions, 0 deletions
diff --git a/v8/src/heap.cc b/v8/src/heap.cc new file mode 100644 index 0000000..26be5a4 --- /dev/null +++ b/v8/src/heap.cc @@ -0,0 +1,3363 @@ +// Copyright 2009 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 "v8.h" + +#include "accessors.h" +#include "api.h" +#include "bootstrapper.h" +#include "codegen-inl.h" +#include "compilation-cache.h" +#include "debug.h" +#include "global-handles.h" +#include "mark-compact.h" +#include "natives.h" +#include "scanner.h" +#include "scopeinfo.h" +#include "v8threads.h" + +namespace v8 { namespace internal { + +#define ROOT_ALLOCATION(type, name) type* Heap::name##_; + ROOT_LIST(ROOT_ALLOCATION) +#undef ROOT_ALLOCATION + + +#define STRUCT_ALLOCATION(NAME, Name, name) Map* Heap::name##_map_; + STRUCT_LIST(STRUCT_ALLOCATION) +#undef STRUCT_ALLOCATION + + +#define SYMBOL_ALLOCATION(name, string) String* Heap::name##_; + SYMBOL_LIST(SYMBOL_ALLOCATION) +#undef SYMBOL_ALLOCATION + +String* Heap::hidden_symbol_; + +NewSpace Heap::new_space_; +OldSpace* Heap::old_pointer_space_ = NULL; +OldSpace* Heap::old_data_space_ = NULL; +OldSpace* Heap::code_space_ = NULL; +MapSpace* Heap::map_space_ = NULL; +LargeObjectSpace* Heap::lo_space_ = NULL; + +static const int kMinimumPromotionLimit = 2*MB; +static const int kMinimumAllocationLimit = 8*MB; + +int Heap::old_gen_promotion_limit_ = kMinimumPromotionLimit; +int Heap::old_gen_allocation_limit_ = kMinimumAllocationLimit; + +int Heap::old_gen_exhausted_ = false; + +int Heap::amount_of_external_allocated_memory_ = 0; +int Heap::amount_of_external_allocated_memory_at_last_global_gc_ = 0; + +// semispace_size_ should be a power of 2 and old_generation_size_ should be +// a multiple of Page::kPageSize. +int Heap::semispace_size_ = 2*MB; +int Heap::old_generation_size_ = 512*MB; +int Heap::initial_semispace_size_ = 256*KB; + +GCCallback Heap::global_gc_prologue_callback_ = NULL; +GCCallback Heap::global_gc_epilogue_callback_ = NULL; + +// Variables set based on semispace_size_ and old_generation_size_ in +// ConfigureHeap. +int Heap::young_generation_size_ = 0; // Will be 2 * semispace_size_. + +// Double the new space after this many scavenge collections. +int Heap::new_space_growth_limit_ = 8; +int Heap::scavenge_count_ = 0; +Heap::HeapState Heap::gc_state_ = NOT_IN_GC; + +int Heap::mc_count_ = 0; +int Heap::gc_count_ = 0; + +int Heap::always_allocate_scope_depth_ = 0; +bool Heap::context_disposed_pending_ = false; + +#ifdef DEBUG +bool Heap::allocation_allowed_ = true; + +int Heap::allocation_timeout_ = 0; +bool Heap::disallow_allocation_failure_ = false; +#endif // DEBUG + + +int Heap::Capacity() { + if (!HasBeenSetup()) return 0; + + return new_space_.Capacity() + + old_pointer_space_->Capacity() + + old_data_space_->Capacity() + + code_space_->Capacity() + + map_space_->Capacity(); +} + + +int Heap::Available() { + if (!HasBeenSetup()) return 0; + + return new_space_.Available() + + old_pointer_space_->Available() + + old_data_space_->Available() + + code_space_->Available() + + map_space_->Available(); +} + + +bool Heap::HasBeenSetup() { + return old_pointer_space_ != NULL && + old_data_space_ != NULL && + code_space_ != NULL && + map_space_ != NULL && + lo_space_ != NULL; +} + + +GarbageCollector Heap::SelectGarbageCollector(AllocationSpace space) { + // Is global GC requested? + if (space != NEW_SPACE || FLAG_gc_global) { + Counters::gc_compactor_caused_by_request.Increment(); + return MARK_COMPACTOR; + } + + // Is enough data promoted to justify a global GC? + if (OldGenerationPromotionLimitReached()) { + Counters::gc_compactor_caused_by_promoted_data.Increment(); + return MARK_COMPACTOR; + } + + // Have allocation in OLD and LO failed? + if (old_gen_exhausted_) { + Counters::gc_compactor_caused_by_oldspace_exhaustion.Increment(); + return MARK_COMPACTOR; + } + + // Is there enough space left in OLD to guarantee that a scavenge can + // succeed? + // + // Note that MemoryAllocator->MaxAvailable() undercounts the memory available + // for object promotion. It counts only the bytes that the memory + // allocator has not yet allocated from the OS and assigned to any space, + // and does not count available bytes already in the old space or code + // space. Undercounting is safe---we may get an unrequested full GC when + // a scavenge would have succeeded. + if (MemoryAllocator::MaxAvailable() <= new_space_.Size()) { + Counters::gc_compactor_caused_by_oldspace_exhaustion.Increment(); + return MARK_COMPACTOR; + } + + // Default + return SCAVENGER; +} + + +// TODO(1238405): Combine the infrastructure for --heap-stats and +// --log-gc to avoid the complicated preprocessor and flag testing. +#if defined(DEBUG) || defined(ENABLE_LOGGING_AND_PROFILING) +void Heap::ReportStatisticsBeforeGC() { + // Heap::ReportHeapStatistics will also log NewSpace statistics when + // compiled with ENABLE_LOGGING_AND_PROFILING and --log-gc is set. The + // following logic is used to avoid double logging. +#if defined(DEBUG) && defined(ENABLE_LOGGING_AND_PROFILING) + if (FLAG_heap_stats || FLAG_log_gc) new_space_.CollectStatistics(); + if (FLAG_heap_stats) { + ReportHeapStatistics("Before GC"); + } else if (FLAG_log_gc) { + new_space_.ReportStatistics(); + } + if (FLAG_heap_stats || FLAG_log_gc) new_space_.ClearHistograms(); +#elif defined(DEBUG) + if (FLAG_heap_stats) { + new_space_.CollectStatistics(); + ReportHeapStatistics("Before GC"); + new_space_.ClearHistograms(); + } +#elif defined(ENABLE_LOGGING_AND_PROFILING) + if (FLAG_log_gc) { + new_space_.CollectStatistics(); + new_space_.ReportStatistics(); + new_space_.ClearHistograms(); + } +#endif +} + + +// TODO(1238405): Combine the infrastructure for --heap-stats and +// --log-gc to avoid the complicated preprocessor and flag testing. +void Heap::ReportStatisticsAfterGC() { + // Similar to the before GC, we use some complicated logic to ensure that + // NewSpace statistics are logged exactly once when --log-gc is turned on. +#if defined(DEBUG) && defined(ENABLE_LOGGING_AND_PROFILING) + if (FLAG_heap_stats) { + ReportHeapStatistics("After GC"); + } else if (FLAG_log_gc) { + new_space_.ReportStatistics(); + } +#elif defined(DEBUG) + if (FLAG_heap_stats) ReportHeapStatistics("After GC"); +#elif defined(ENABLE_LOGGING_AND_PROFILING) + if (FLAG_log_gc) new_space_.ReportStatistics(); +#endif +} +#endif // defined(DEBUG) || defined(ENABLE_LOGGING_AND_PROFILING) + + +void Heap::GarbageCollectionPrologue() { + gc_count_++; +#ifdef DEBUG + ASSERT(allocation_allowed_ && gc_state_ == NOT_IN_GC); + allow_allocation(false); + + if (FLAG_verify_heap) { + Verify(); + } + + if (FLAG_gc_verbose) Print(); + + if (FLAG_print_rset) { + // Not all spaces have remembered set bits that we care about. + old_pointer_space_->PrintRSet(); + map_space_->PrintRSet(); + lo_space_->PrintRSet(); + } +#endif + +#if defined(DEBUG) || defined(ENABLE_LOGGING_AND_PROFILING) + ReportStatisticsBeforeGC(); +#endif +} + +int Heap::SizeOfObjects() { + int total = 0; + AllSpaces spaces; + while (Space* space = spaces.next()) total += space->Size(); + return total; +} + +void Heap::GarbageCollectionEpilogue() { +#ifdef DEBUG + allow_allocation(true); + ZapFromSpace(); + + if (FLAG_verify_heap) { + Verify(); + } + + if (FLAG_print_global_handles) GlobalHandles::Print(); + if (FLAG_print_handles) PrintHandles(); + if (FLAG_gc_verbose) Print(); + if (FLAG_code_stats) ReportCodeStatistics("After GC"); +#endif + + Counters::alive_after_last_gc.Set(SizeOfObjects()); + + SymbolTable* symbol_table = SymbolTable::cast(Heap::symbol_table_); + Counters::symbol_table_capacity.Set(symbol_table->Capacity()); + Counters::number_of_symbols.Set(symbol_table->NumberOfElements()); +#if defined(DEBUG) || defined(ENABLE_LOGGING_AND_PROFILING) + ReportStatisticsAfterGC(); +#endif +} + + +void Heap::CollectAllGarbage() { + // Since we are ignoring the return value, the exact choice of space does + // not matter, so long as we do not specify NEW_SPACE, which would not + // cause a full GC. + CollectGarbage(0, OLD_POINTER_SPACE); +} + + +void Heap::CollectAllGarbageIfContextDisposed() { + // If the garbage collector interface is exposed through the global + // gc() function, we avoid being clever about forcing GCs when + // contexts are disposed and leave it to the embedder to make + // informed decisions about when to force a collection. + if (!FLAG_expose_gc && context_disposed_pending_) { + HistogramTimerScope scope(&Counters::gc_context); + CollectAllGarbage(); + } + context_disposed_pending_ = false; +} + + +void Heap::NotifyContextDisposed() { + context_disposed_pending_ = true; +} + + +bool Heap::CollectGarbage(int requested_size, AllocationSpace space) { + // The VM is in the GC state until exiting this function. + VMState state(GC); + +#ifdef DEBUG + // Reset the allocation timeout to the GC interval, but make sure to + // allow at least a few allocations after a collection. The reason + // for this is that we have a lot of allocation sequences and we + // assume that a garbage collection will allow the subsequent + // allocation attempts to go through. + allocation_timeout_ = Max(6, FLAG_gc_interval); +#endif + + { GCTracer tracer; + GarbageCollectionPrologue(); + // The GC count was incremented in the prologue. Tell the tracer about + // it. + tracer.set_gc_count(gc_count_); + + GarbageCollector collector = SelectGarbageCollector(space); + // Tell the tracer which collector we've selected. + tracer.set_collector(collector); + + HistogramTimer* rate = (collector == SCAVENGER) + ? &Counters::gc_scavenger + : &Counters::gc_compactor; + rate->Start(); + PerformGarbageCollection(space, collector, &tracer); + rate->Stop(); + + GarbageCollectionEpilogue(); + } + + +#ifdef ENABLE_LOGGING_AND_PROFILING + if (FLAG_log_gc) HeapProfiler::WriteSample(); +#endif + + switch (space) { + case NEW_SPACE: + return new_space_.Available() >= requested_size; + case OLD_POINTER_SPACE: + return old_pointer_space_->Available() >= requested_size; + case OLD_DATA_SPACE: + return old_data_space_->Available() >= requested_size; + case CODE_SPACE: + return code_space_->Available() >= requested_size; + case MAP_SPACE: + return map_space_->Available() >= requested_size; + case LO_SPACE: + return lo_space_->Available() >= requested_size; + } + return false; +} + + +void Heap::PerformScavenge() { + GCTracer tracer; + PerformGarbageCollection(NEW_SPACE, SCAVENGER, &tracer); +} + + +void Heap::PerformGarbageCollection(AllocationSpace space, + GarbageCollector collector, + GCTracer* tracer) { + if (collector == MARK_COMPACTOR && global_gc_prologue_callback_) { + ASSERT(!allocation_allowed_); + global_gc_prologue_callback_(); + } + + if (collector == MARK_COMPACTOR) { + MarkCompact(tracer); + + int old_gen_size = PromotedSpaceSize(); + old_gen_promotion_limit_ = + old_gen_size + Max(kMinimumPromotionLimit, old_gen_size / 3); + old_gen_allocation_limit_ = + old_gen_size + Max(kMinimumAllocationLimit, old_gen_size / 3); + old_gen_exhausted_ = false; + + // If we have used the mark-compact collector to collect the new + // space, and it has not compacted the new space, we force a + // separate scavenge collection. This is a hack. It covers the + // case where (1) a new space collection was requested, (2) the + // collector selection policy selected the mark-compact collector, + // and (3) the mark-compact collector policy selected not to + // compact the new space. In that case, there is no more (usable) + // free space in the new space after the collection compared to + // before. + if (space == NEW_SPACE && !MarkCompactCollector::HasCompacted()) { + Scavenge(); + } + } else { + Scavenge(); + } + Counters::objs_since_last_young.Set(0); + + PostGarbageCollectionProcessing(); + + if (collector == MARK_COMPACTOR) { + // Register the amount of external allocated memory. + amount_of_external_allocated_memory_at_last_global_gc_ = + amount_of_external_allocated_memory_; + } + + if (collector == MARK_COMPACTOR && global_gc_epilogue_callback_) { + ASSERT(!allocation_allowed_); + global_gc_epilogue_callback_(); + } +} + + +void Heap::PostGarbageCollectionProcessing() { + // Process weak handles post gc. + GlobalHandles::PostGarbageCollectionProcessing(); + // Update flat string readers. + FlatStringReader::PostGarbageCollectionProcessing(); +} + + +void Heap::MarkCompact(GCTracer* tracer) { + gc_state_ = MARK_COMPACT; + mc_count_++; + tracer->set_full_gc_count(mc_count_); + LOG(ResourceEvent("markcompact", "begin")); + + MarkCompactCollector::Prepare(tracer); + + bool is_compacting = MarkCompactCollector::IsCompacting(); + + MarkCompactPrologue(is_compacting); + + MarkCompactCollector::CollectGarbage(); + + MarkCompactEpilogue(is_compacting); + + LOG(ResourceEvent("markcompact", "end")); + + gc_state_ = NOT_IN_GC; + + Shrink(); + + Counters::objs_since_last_full.Set(0); + context_disposed_pending_ = false; +} + + +void Heap::MarkCompactPrologue(bool is_compacting) { + // At any old GC clear the keyed lookup cache to enable collection of unused + // maps. + ClearKeyedLookupCache(); + + CompilationCache::MarkCompactPrologue(); + + Top::MarkCompactPrologue(is_compacting); + ThreadManager::MarkCompactPrologue(is_compacting); +} + + +void Heap::MarkCompactEpilogue(bool is_compacting) { + Top::MarkCompactEpilogue(is_compacting); + ThreadManager::MarkCompactEpilogue(is_compacting); +} + + +Object* Heap::FindCodeObject(Address a) { + Object* obj = code_space_->FindObject(a); + if (obj->IsFailure()) { + obj = lo_space_->FindObject(a); + } + ASSERT(!obj->IsFailure()); + return obj; +} + + +// Helper class for copying HeapObjects +class ScavengeVisitor: public ObjectVisitor { + public: + + void VisitPointer(Object** p) { ScavengePointer(p); } + + void VisitPointers(Object** start, Object** end) { + // Copy all HeapObject pointers in [start, end) + for (Object** p = start; p < end; p++) ScavengePointer(p); + } + + private: + void ScavengePointer(Object** p) { + Object* object = *p; + if (!Heap::InNewSpace(object)) return; + Heap::ScavengeObject(reinterpret_cast<HeapObject**>(p), + reinterpret_cast<HeapObject*>(object)); + } +}; + + +// Shared state read by the scavenge collector and set by ScavengeObject. +static Address promoted_top = NULL; + + +#ifdef DEBUG +// Visitor class to verify pointers in code or data space do not point into +// new space. +class VerifyNonPointerSpacePointersVisitor: public ObjectVisitor { + public: + void VisitPointers(Object** start, Object**end) { + for (Object** current = start; current < end; current++) { + if ((*current)->IsHeapObject()) { + ASSERT(!Heap::InNewSpace(HeapObject::cast(*current))); + } + } + } +}; +#endif + +void Heap::Scavenge() { +#ifdef DEBUG + if (FLAG_enable_slow_asserts) { + VerifyNonPointerSpacePointersVisitor v; + HeapObjectIterator it(code_space_); + while (it.has_next()) { + HeapObject* object = it.next(); + if (object->IsCode()) { + Code::cast(object)->ConvertICTargetsFromAddressToObject(); + } + object->Iterate(&v); + if (object->IsCode()) { + Code::cast(object)->ConvertICTargetsFromObjectToAddress(); + } + } + } +#endif + + gc_state_ = SCAVENGE; + + // Implements Cheney's copying algorithm + LOG(ResourceEvent("scavenge", "begin")); + + scavenge_count_++; + if (new_space_.Capacity() < new_space_.MaximumCapacity() && + scavenge_count_ > new_space_growth_limit_) { + // Double the size of the new space, and double the limit. The next + // doubling attempt will occur after the current new_space_growth_limit_ + // more collections. + // TODO(1240712): NewSpace::Double has a return value which is + // ignored here. + new_space_.Double(); + new_space_growth_limit_ *= 2; + } + + // Flip the semispaces. After flipping, to space is empty, from space has + // live objects. + new_space_.Flip(); + new_space_.ResetAllocationInfo(); + + // We need to sweep newly copied objects which can be in either the to space + // or the old space. For to space objects, we use a mark. Newly copied + // objects lie between the mark and the allocation top. For objects + // promoted to old space, we write their addresses downward from the top of + // the new space. Sweeping newly promoted objects requires an allocation + // pointer and a mark. Note that the allocation pointer 'top' actually + // moves downward from the high address in the to space. + // + // There is guaranteed to be enough room at the top of the to space for the + // addresses of promoted objects: every object promoted frees up its size in + // bytes from the top of the new space, and objects are at least one pointer + // in size. Using the new space to record promoted addresses makes the + // scavenge collector agnostic to the allocation strategy (eg, linear or + // free-list) used in old space. + Address new_mark = new_space_.ToSpaceLow(); + Address promoted_mark = new_space_.ToSpaceHigh(); + promoted_top = new_space_.ToSpaceHigh(); + + ScavengeVisitor scavenge_visitor; + // Copy roots. + IterateRoots(&scavenge_visitor); + + // Copy objects reachable from the old generation. By definition, there + // are no intergenerational pointers in code or data spaces. + IterateRSet(old_pointer_space_, &ScavengePointer); + IterateRSet(map_space_, &ScavengePointer); + lo_space_->IterateRSet(&ScavengePointer); + + bool has_processed_weak_pointers = false; + + while (true) { + ASSERT(new_mark <= new_space_.top()); + ASSERT(promoted_mark >= promoted_top); + + // Copy objects reachable from newly copied objects. + while (new_mark < new_space_.top() || promoted_mark > promoted_top) { + // Sweep newly copied objects in the to space. The allocation pointer + // can change during sweeping. + Address previous_top = new_space_.top(); + SemiSpaceIterator new_it(new_space(), new_mark); + while (new_it.has_next()) { + new_it.next()->Iterate(&scavenge_visitor); + } + new_mark = previous_top; + + // Sweep newly copied objects in the old space. The promotion 'top' + // pointer could change during sweeping. + previous_top = promoted_top; + for (Address current = promoted_mark - kPointerSize; + current >= previous_top; + current -= kPointerSize) { + HeapObject* object = HeapObject::cast(Memory::Object_at(current)); + object->Iterate(&scavenge_visitor); + UpdateRSet(object); + } + promoted_mark = previous_top; + } + + if (has_processed_weak_pointers) break; // We are done. + // Copy objects reachable from weak pointers. + GlobalHandles::IterateWeakRoots(&scavenge_visitor); + has_processed_weak_pointers = true; + } + + // Set age mark. + new_space_.set_age_mark(new_mark); + + LOG(ResourceEvent("scavenge", "end")); + + gc_state_ = NOT_IN_GC; +} + + +void Heap::ClearRSetRange(Address start, int size_in_bytes) { + uint32_t start_bit; + Address start_word_address = + Page::ComputeRSetBitPosition(start, 0, &start_bit); + uint32_t end_bit; + Address end_word_address = + Page::ComputeRSetBitPosition(start + size_in_bytes - kIntSize, + 0, + &end_bit); + + // We want to clear the bits in the starting word starting with the + // first bit, and in the ending word up to and including the last + // bit. Build a pair of bitmasks to do that. + uint32_t start_bitmask = start_bit - 1; + uint32_t end_bitmask = ~((end_bit << 1) - 1); + + // If the start address and end address are the same, we mask that + // word once, otherwise mask the starting and ending word + // separately and all the ones in between. + if (start_word_address == end_word_address) { + Memory::uint32_at(start_word_address) &= (start_bitmask | end_bitmask); + } else { + Memory::uint32_at(start_word_address) &= start_bitmask; + Memory::uint32_at(end_word_address) &= end_bitmask; + start_word_address += kIntSize; + memset(start_word_address, 0, end_word_address - start_word_address); + } +} + + +class UpdateRSetVisitor: public ObjectVisitor { + public: + + void VisitPointer(Object** p) { + UpdateRSet(p); + } + + void VisitPointers(Object** start, Object** end) { + // Update a store into slots [start, end), used (a) to update remembered + // set when promoting a young object to old space or (b) to rebuild + // remembered sets after a mark-compact collection. + for (Object** p = start; p < end; p++) UpdateRSet(p); + } + private: + + void UpdateRSet(Object** p) { + // The remembered set should not be set. It should be clear for objects + // newly copied to old space, and it is cleared before rebuilding in the + // mark-compact collector. + ASSERT(!Page::IsRSetSet(reinterpret_cast<Address>(p), 0)); + if (Heap::InNewSpace(*p)) { + Page::SetRSet(reinterpret_cast<Address>(p), 0); + } + } +}; + + +int Heap::UpdateRSet(HeapObject* obj) { + ASSERT(!InNewSpace(obj)); + // Special handling of fixed arrays to iterate the body based on the start + // address and offset. Just iterating the pointers as in UpdateRSetVisitor + // will not work because Page::SetRSet needs to have the start of the + // object. + if (obj->IsFixedArray()) { + FixedArray* array = FixedArray::cast(obj); + int length = array->length(); + for (int i = 0; i < length; i++) { + int offset = FixedArray::kHeaderSize + i * kPointerSize; + ASSERT(!Page::IsRSetSet(obj->address(), offset)); + if (Heap::InNewSpace(array->get(i))) { + Page::SetRSet(obj->address(), offset); + } + } + } else if (!obj->IsCode()) { + // Skip code object, we know it does not contain inter-generational + // pointers. + UpdateRSetVisitor v; + obj->Iterate(&v); + } + return obj->Size(); +} + + +void Heap::RebuildRSets() { + // By definition, we do not care about remembered set bits in code or data + // spaces. + map_space_->ClearRSet(); + RebuildRSets(map_space_); + + old_pointer_space_->ClearRSet(); + RebuildRSets(old_pointer_space_); + + Heap::lo_space_->ClearRSet(); + RebuildRSets(lo_space_); +} + + +void Heap::RebuildRSets(PagedSpace* space) { + HeapObjectIterator it(space); + while (it.has_next()) Heap::UpdateRSet(it.next()); +} + + +void Heap::RebuildRSets(LargeObjectSpace* space) { + LargeObjectIterator it(space); + while (it.has_next()) Heap::UpdateRSet(it.next()); +} + + +#if defined(DEBUG) || defined(ENABLE_LOGGING_AND_PROFILING) +void Heap::RecordCopiedObject(HeapObject* obj) { + bool should_record = false; +#ifdef DEBUG + should_record = FLAG_heap_stats; +#endif +#ifdef ENABLE_LOGGING_AND_PROFILING + should_record = should_record || FLAG_log_gc; +#endif + if (should_record) { + if (new_space_.Contains(obj)) { + new_space_.RecordAllocation(obj); + } else { + new_space_.RecordPromotion(obj); + } + } +} +#endif // defined(DEBUG) || defined(ENABLE_LOGGING_AND_PROFILING) + + + +HeapObject* Heap::MigrateObject(HeapObject* source, + HeapObject* target, + int size) { + // Copy the content of source to target. + CopyBlock(reinterpret_cast<Object**>(target->address()), + reinterpret_cast<Object**>(source->address()), + size); + + // Set the forwarding address. + source->set_map_word(MapWord::FromForwardingAddress(target)); + + // Update NewSpace stats if necessary. +#if defined(DEBUG) || defined(ENABLE_LOGGING_AND_PROFILING) + RecordCopiedObject(target); +#endif + + return target; +} + + +// Inlined function. +void Heap::ScavengeObject(HeapObject** p, HeapObject* object) { + ASSERT(InFromSpace(object)); + + // We use the first word (where the map pointer usually is) of a heap + // object to record the forwarding pointer. A forwarding pointer can + // point to an old space, the code space, or the to space of the new + // generation. + MapWord first_word = object->map_word(); + + // If the first word is a forwarding address, the object has already been + // copied. + if (first_word.IsForwardingAddress()) { + *p = first_word.ToForwardingAddress(); + return; + } + + // Call the slow part of scavenge object. + return ScavengeObjectSlow(p, object); +} + + +static inline bool IsShortcutCandidate(HeapObject* object, Map* map) { + // A ConsString object with Heap::empty_string() as the right side + // is a candidate for being shortcut by the scavenger. + ASSERT(object->map() == map); + if (map->instance_type() >= FIRST_NONSTRING_TYPE) return false; + return (StringShape(map).representation_tag() == kConsStringTag) && + (ConsString::cast(object)->unchecked_second() == Heap::empty_string()); +} + + +void Heap::ScavengeObjectSlow(HeapObject** p, HeapObject* object) { + ASSERT(InFromSpace(object)); + MapWord first_word = object->map_word(); + ASSERT(!first_word.IsForwardingAddress()); + + // Optimization: Bypass flattened ConsString objects. + if (IsShortcutCandidate(object, first_word.ToMap())) { + object = HeapObject::cast(ConsString::cast(object)->unchecked_first()); + *p = object; + // After patching *p we have to repeat the checks that object is in the + // active semispace of the young generation and not already copied. + if (!InNewSpace(object)) return; + first_word = object->map_word(); + if (first_word.IsForwardingAddress()) { + *p = first_word.ToForwardingAddress(); + return; + } + } + + int object_size = object->SizeFromMap(first_word.ToMap()); + // If the object should be promoted, we try to copy it to old space. + if (ShouldBePromoted(object->address(), object_size)) { + OldSpace* target_space = Heap::TargetSpace(object); + ASSERT(target_space == Heap::old_pointer_space_ || + target_space == Heap::old_data_space_); + Object* result = target_space->AllocateRaw(object_size); + if (!result->IsFailure()) { + *p = MigrateObject(object, HeapObject::cast(result), object_size); + if (target_space == Heap::old_pointer_space_) { + // Record the object's address at the top of the to space, to allow + // it to be swept by the scavenger. + promoted_top -= kPointerSize; + Memory::Object_at(promoted_top) = *p; + } else { +#ifdef DEBUG + // Objects promoted to the data space should not have pointers to + // new space. + VerifyNonPointerSpacePointersVisitor v; + (*p)->Iterate(&v); +#endif + } + return; + } + } + + // The object should remain in new space or the old space allocation failed. + Object* result = new_space_.AllocateRaw(object_size); + // Failed allocation at this point is utterly unexpected. + ASSERT(!result->IsFailure()); + *p = MigrateObject(object, HeapObject::cast(result), object_size); +} + + +void Heap::ScavengePointer(HeapObject** p) { + ScavengeObject(p, *p); +} + + +Object* Heap::AllocatePartialMap(InstanceType instance_type, + int instance_size) { + Object* result = AllocateRawMap(Map::kSize); + if (result->IsFailure()) return result; + + // Map::cast cannot be used due to uninitialized map field. + reinterpret_cast<Map*>(result)->set_map(meta_map()); + reinterpret_cast<Map*>(result)->set_instance_type(instance_type); + reinterpret_cast<Map*>(result)->set_instance_size(instance_size); + reinterpret_cast<Map*>(result)->set_inobject_properties(0); + reinterpret_cast<Map*>(result)->set_unused_property_fields(0); + return result; +} + + +Object* Heap::AllocateMap(InstanceType instance_type, int instance_size) { + Object* result = AllocateRawMap(Map::kSize); + if (result->IsFailure()) return result; + + Map* map = reinterpret_cast<Map*>(result); + map->set_map(meta_map()); + map->set_instance_type(instance_type); + map->set_prototype(null_value()); + map->set_constructor(null_value()); + map->set_instance_size(instance_size); + map->set_inobject_properties(0); + map->set_instance_descriptors(empty_descriptor_array()); + map->set_code_cache(empty_fixed_array()); + map->set_unused_property_fields(0); + map->set_bit_field(0); + return map; +} + + +bool Heap::CreateInitialMaps() { + Object* obj = AllocatePartialMap(MAP_TYPE, Map::kSize); + if (obj->IsFailure()) return false; + + // Map::cast cannot be used due to uninitialized map field. + meta_map_ = reinterpret_cast<Map*>(obj); + meta_map()->set_map(meta_map()); + + obj = AllocatePartialMap(FIXED_ARRAY_TYPE, Array::kHeaderSize); + if (obj->IsFailure()) return false; + fixed_array_map_ = Map::cast(obj); + + obj = AllocatePartialMap(ODDBALL_TYPE, Oddball::kSize); + if (obj->IsFailure()) return false; + oddball_map_ = Map::cast(obj); + + // Allocate the empty array + obj = AllocateEmptyFixedArray(); + if (obj->IsFailure()) return false; + empty_fixed_array_ = FixedArray::cast(obj); + + obj = Allocate(oddball_map(), OLD_DATA_SPACE); + if (obj->IsFailure()) return false; + null_value_ = obj; + + // Allocate the empty descriptor array. AllocateMap can now be used. + obj = AllocateEmptyFixedArray(); + if (obj->IsFailure()) return false; + // There is a check against empty_descriptor_array() in cast(). + empty_descriptor_array_ = reinterpret_cast<DescriptorArray*>(obj); + + // Fix the instance_descriptors for the existing maps. + meta_map()->set_instance_descriptors(empty_descriptor_array()); + meta_map()->set_code_cache(empty_fixed_array()); + + fixed_array_map()->set_instance_descriptors(empty_descriptor_array()); + fixed_array_map()->set_code_cache(empty_fixed_array()); + + oddball_map()->set_instance_descriptors(empty_descriptor_array()); + oddball_map()->set_code_cache(empty_fixed_array()); + + // Fix prototype object for existing maps. + meta_map()->set_prototype(null_value()); + meta_map()->set_constructor(null_value()); + + fixed_array_map()->set_prototype(null_value()); + fixed_array_map()->set_constructor(null_value()); + oddball_map()->set_prototype(null_value()); + oddball_map()->set_constructor(null_value()); + + obj = AllocateMap(HEAP_NUMBER_TYPE, HeapNumber::kSize); + if (obj->IsFailure()) return false; + heap_number_map_ = Map::cast(obj); + + obj = AllocateMap(PROXY_TYPE, Proxy::kSize); + if (obj->IsFailure()) return false; + proxy_map_ = Map::cast(obj); + +#define ALLOCATE_STRING_MAP(type, size, name) \ + obj = AllocateMap(type, size); \ + if (obj->IsFailure()) return false; \ + name##_map_ = Map::cast(obj); + STRING_TYPE_LIST(ALLOCATE_STRING_MAP); +#undef ALLOCATE_STRING_MAP + + obj = AllocateMap(SHORT_STRING_TYPE, SeqTwoByteString::kHeaderSize); + if (obj->IsFailure()) return false; + undetectable_short_string_map_ = Map::cast(obj); + undetectable_short_string_map_->set_is_undetectable(); + + obj = AllocateMap(MEDIUM_STRING_TYPE, SeqTwoByteString::kHeaderSize); + if (obj->IsFailure()) return false; + undetectable_medium_string_map_ = Map::cast(obj); + undetectable_medium_string_map_->set_is_undetectable(); + + obj = AllocateMap(LONG_STRING_TYPE, SeqTwoByteString::kHeaderSize); + if (obj->IsFailure()) return false; + undetectable_long_string_map_ = Map::cast(obj); + undetectable_long_string_map_->set_is_undetectable(); + + obj = AllocateMap(SHORT_ASCII_STRING_TYPE, SeqAsciiString::kHeaderSize); + if (obj->IsFailure()) return false; + undetectable_short_ascii_string_map_ = Map::cast(obj); + undetectable_short_ascii_string_map_->set_is_undetectable(); + + obj = AllocateMap(MEDIUM_ASCII_STRING_TYPE, SeqAsciiString::kHeaderSize); + if (obj->IsFailure()) return false; + undetectable_medium_ascii_string_map_ = Map::cast(obj); + undetectable_medium_ascii_string_map_->set_is_undetectable(); + + obj = AllocateMap(LONG_ASCII_STRING_TYPE, SeqAsciiString::kHeaderSize); + if (obj->IsFailure()) return false; + undetectable_long_ascii_string_map_ = Map::cast(obj); + undetectable_long_ascii_string_map_->set_is_undetectable(); + + obj = AllocateMap(BYTE_ARRAY_TYPE, Array::kHeaderSize); + if (obj->IsFailure()) return false; + byte_array_map_ = Map::cast(obj); + + obj = AllocateMap(CODE_TYPE, Code::kHeaderSize); + if (obj->IsFailure()) return false; + code_map_ = Map::cast(obj); + + obj = AllocateMap(FILLER_TYPE, kPointerSize); + if (obj->IsFailure()) return false; + one_word_filler_map_ = Map::cast(obj); + + obj = AllocateMap(FILLER_TYPE, 2 * kPointerSize); + if (obj->IsFailure()) return false; + two_word_filler_map_ = Map::cast(obj); + +#define ALLOCATE_STRUCT_MAP(NAME, Name, name) \ + obj = AllocateMap(NAME##_TYPE, Name::kSize); \ + if (obj->IsFailure()) return false; \ + name##_map_ = Map::cast(obj); + STRUCT_LIST(ALLOCATE_STRUCT_MAP) +#undef ALLOCATE_STRUCT_MAP + + obj = AllocateMap(FIXED_ARRAY_TYPE, HeapObject::kHeaderSize); + if (obj->IsFailure()) return false; + hash_table_map_ = Map::cast(obj); + + obj = AllocateMap(FIXED_ARRAY_TYPE, HeapObject::kHeaderSize); + if (obj->IsFailure()) return false; + context_map_ = Map::cast(obj); + + obj = AllocateMap(FIXED_ARRAY_TYPE, HeapObject::kHeaderSize); + if (obj->IsFailure()) return false; + catch_context_map_ = Map::cast(obj); + + obj = AllocateMap(FIXED_ARRAY_TYPE, HeapObject::kHeaderSize); + if (obj->IsFailure()) return false; + global_context_map_ = Map::cast(obj); + + obj = AllocateMap(JS_FUNCTION_TYPE, JSFunction::kSize); + if (obj->IsFailure()) return false; + boilerplate_function_map_ = Map::cast(obj); + + obj = AllocateMap(SHARED_FUNCTION_INFO_TYPE, SharedFunctionInfo::kSize); + if (obj->IsFailure()) return false; + shared_function_info_map_ = Map::cast(obj); + + ASSERT(!Heap::InNewSpace(Heap::empty_fixed_array())); + return true; +} + + +Object* Heap::AllocateHeapNumber(double value, PretenureFlag pretenure) { + // Statically ensure that it is safe to allocate heap numbers in paged + // spaces. + STATIC_ASSERT(HeapNumber::kSize <= Page::kMaxHeapObjectSize); + AllocationSpace space = (pretenure == TENURED) ? OLD_DATA_SPACE : NEW_SPACE; + Object* result = AllocateRaw(HeapNumber::kSize, space, OLD_DATA_SPACE); + if (result->IsFailure()) return result; + + HeapObject::cast(result)->set_map(heap_number_map()); + HeapNumber::cast(result)->set_value(value); + return result; +} + + +Object* Heap::AllocateHeapNumber(double value) { + // Use general version, if we're forced to always allocate. + if (always_allocate()) return AllocateHeapNumber(value, NOT_TENURED); + // This version of AllocateHeapNumber is optimized for + // allocation in new space. + STATIC_ASSERT(HeapNumber::kSize <= Page::kMaxHeapObjectSize); + ASSERT(allocation_allowed_ && gc_state_ == NOT_IN_GC); + Object* result = new_space_.AllocateRaw(HeapNumber::kSize); + if (result->IsFailure()) return result; + HeapObject::cast(result)->set_map(heap_number_map()); + HeapNumber::cast(result)->set_value(value); + return result; +} + + +Object* Heap::CreateOddball(Map* map, + const char* to_string, + Object* to_number) { + Object* result = Allocate(map, OLD_DATA_SPACE); + if (result->IsFailure()) return result; + return Oddball::cast(result)->Initialize(to_string, to_number); +} + + +bool Heap::CreateApiObjects() { + Object* obj; + + obj = AllocateMap(JS_OBJECT_TYPE, JSObject::kHeaderSize); + if (obj->IsFailure()) return false; + neander_map_ = Map::cast(obj); + + obj = Heap::AllocateJSObjectFromMap(neander_map_); + if (obj->IsFailure()) return false; + Object* elements = AllocateFixedArray(2); + if (elements->IsFailure()) return false; + FixedArray::cast(elements)->set(0, Smi::FromInt(0)); + JSObject::cast(obj)->set_elements(FixedArray::cast(elements)); + message_listeners_ = JSObject::cast(obj); + + return true; +} + +void Heap::CreateFixedStubs() { + // Here we create roots for fixed stubs. They are needed at GC + // for cooking and uncooking (check out frames.cc). + // The eliminates the need for doing dictionary lookup in the + // stub cache for these stubs. + HandleScope scope; + { + CEntryStub stub; + c_entry_code_ = *stub.GetCode(); + } + { + CEntryDebugBreakStub stub; + c_entry_debug_break_code_ = *stub.GetCode(); + } + { + JSEntryStub stub; + js_entry_code_ = *stub.GetCode(); + } + { + JSConstructEntryStub stub; + js_construct_entry_code_ = *stub.GetCode(); + } +} + + +bool Heap::CreateInitialObjects() { + Object* obj; + + // The -0 value must be set before NumberFromDouble works. + obj = AllocateHeapNumber(-0.0, TENURED); + if (obj->IsFailure()) return false; + minus_zero_value_ = obj; + ASSERT(signbit(minus_zero_value_->Number()) != 0); + + obj = AllocateHeapNumber(OS::nan_value(), TENURED); + if (obj->IsFailure()) return false; + nan_value_ = obj; + + obj = Allocate(oddball_map(), OLD_DATA_SPACE); + if (obj->IsFailure()) return false; + undefined_value_ = obj; + ASSERT(!InNewSpace(undefined_value())); + + // Allocate initial symbol table. + obj = SymbolTable::Allocate(kInitialSymbolTableSize); + if (obj->IsFailure()) return false; + symbol_table_ = obj; + + // Assign the print strings for oddballs after creating symboltable. + Object* symbol = LookupAsciiSymbol("undefined"); + if (symbol->IsFailure()) return false; + Oddball::cast(undefined_value_)->set_to_string(String::cast(symbol)); + Oddball::cast(undefined_value_)->set_to_number(nan_value_); + + // Assign the print strings for oddballs after creating symboltable. + symbol = LookupAsciiSymbol("null"); + if (symbol->IsFailure()) return false; + Oddball::cast(null_value_)->set_to_string(String::cast(symbol)); + Oddball::cast(null_value_)->set_to_number(Smi::FromInt(0)); + + // Allocate the null_value + obj = Oddball::cast(null_value())->Initialize("null", Smi::FromInt(0)); + if (obj->IsFailure()) return false; + + obj = CreateOddball(oddball_map(), "true", Smi::FromInt(1)); + if (obj->IsFailure()) return false; + true_value_ = obj; + + obj = CreateOddball(oddball_map(), "false", Smi::FromInt(0)); + if (obj->IsFailure()) return false; + false_value_ = obj; + + obj = CreateOddball(oddball_map(), "hole", Smi::FromInt(-1)); + if (obj->IsFailure()) return false; + the_hole_value_ = obj; + + // Allocate the empty string. + obj = AllocateRawAsciiString(0, TENURED); + if (obj->IsFailure()) return false; + empty_string_ = String::cast(obj); + +#define SYMBOL_INITIALIZE(name, string) \ + obj = LookupAsciiSymbol(string); \ + if (obj->IsFailure()) return false; \ + (name##_) = String::cast(obj); + SYMBOL_LIST(SYMBOL_INITIALIZE) +#undef SYMBOL_INITIALIZE + + // Allocate the hidden symbol which is used to identify the hidden properties + // in JSObjects. The hash code has a special value so that it will not match + // the empty string when searching for the property. It cannot be part of the + // SYMBOL_LIST because it needs to be allocated manually with the special + // hash code in place. The hash code for the hidden_symbol is zero to ensure + // that it will always be at the first entry in property descriptors. + obj = AllocateSymbol(CStrVector(""), 0, String::kHashComputedMask); + if (obj->IsFailure()) return false; + hidden_symbol_ = String::cast(obj); + + // Allocate the proxy for __proto__. + obj = AllocateProxy((Address) &Accessors::ObjectPrototype); + if (obj->IsFailure()) return false; + prototype_accessors_ = Proxy::cast(obj); + + // Allocate the code_stubs dictionary. + obj = Dictionary::Allocate(4); + if (obj->IsFailure()) return false; + code_stubs_ = Dictionary::cast(obj); + + // Allocate the non_monomorphic_cache used in stub-cache.cc + obj = Dictionary::Allocate(4); + if (obj->IsFailure()) return false; + non_monomorphic_cache_ = Dictionary::cast(obj); + + CreateFixedStubs(); + + // Allocate the number->string conversion cache + obj = AllocateFixedArray(kNumberStringCacheSize * 2); + if (obj->IsFailure()) return false; + number_string_cache_ = FixedArray::cast(obj); + + // Allocate cache for single character strings. + obj = AllocateFixedArray(String::kMaxAsciiCharCode+1); + if (obj->IsFailure()) return false; + single_character_string_cache_ = FixedArray::cast(obj); + + // Allocate cache for external strings pointing to native source code. + obj = AllocateFixedArray(Natives::GetBuiltinsCount()); + if (obj->IsFailure()) return false; + natives_source_cache_ = FixedArray::cast(obj); + + // Handling of script id generation is in Factory::NewScript. + last_script_id_ = undefined_value(); + + // Initialize keyed lookup cache. + ClearKeyedLookupCache(); + + // Initialize compilation cache. + CompilationCache::Clear(); + + return true; +} + + +static inline int double_get_hash(double d) { + DoubleRepresentation rep(d); + return ((static_cast<int>(rep.bits) ^ static_cast<int>(rep.bits >> 32)) & + (Heap::kNumberStringCacheSize - 1)); +} + + +static inline int smi_get_hash(Smi* smi) { + return (smi->value() & (Heap::kNumberStringCacheSize - 1)); +} + + + +Object* Heap::GetNumberStringCache(Object* number) { + int hash; + if (number->IsSmi()) { + hash = smi_get_hash(Smi::cast(number)); + } else { + hash = double_get_hash(number->Number()); + } + Object* key = number_string_cache_->get(hash * 2); + if (key == number) { + return String::cast(number_string_cache_->get(hash * 2 + 1)); + } else if (key->IsHeapNumber() && + number->IsHeapNumber() && + key->Number() == number->Number()) { + return String::cast(number_string_cache_->get(hash * 2 + 1)); + } + return undefined_value(); +} + + +void Heap::SetNumberStringCache(Object* number, String* string) { + int hash; + if (number->IsSmi()) { + hash = smi_get_hash(Smi::cast(number)); + number_string_cache_->set(hash * 2, number, SKIP_WRITE_BARRIER); + } else { + hash = double_get_hash(number->Number()); + number_string_cache_->set(hash * 2, number); + } + number_string_cache_->set(hash * 2 + 1, string); +} + + +Object* Heap::SmiOrNumberFromDouble(double value, + bool new_object, + PretenureFlag pretenure) { + // We need to distinguish the minus zero value and this cannot be + // done after conversion to int. Doing this by comparing bit + // patterns is faster than using fpclassify() et al. + static const DoubleRepresentation plus_zero(0.0); + static const DoubleRepresentation minus_zero(-0.0); + static const DoubleRepresentation nan(OS::nan_value()); + ASSERT(minus_zero_value_ != NULL); + ASSERT(sizeof(plus_zero.value) == sizeof(plus_zero.bits)); + + DoubleRepresentation rep(value); + if (rep.bits == plus_zero.bits) return Smi::FromInt(0); // not uncommon + if (rep.bits == minus_zero.bits) { + return new_object ? AllocateHeapNumber(-0.0, pretenure) + : minus_zero_value_; + } + if (rep.bits == nan.bits) { + return new_object + ? AllocateHeapNumber(OS::nan_value(), pretenure) + : nan_value_; + } + + // Try to represent the value as a tagged small integer. + int int_value = FastD2I(value); + if (value == FastI2D(int_value) && Smi::IsValid(int_value)) { + return Smi::FromInt(int_value); + } + + // Materialize the value in the heap. + return AllocateHeapNumber(value, pretenure); +} + + +Object* Heap::NewNumberFromDouble(double value, PretenureFlag pretenure) { + return SmiOrNumberFromDouble(value, + true /* number object must be new */, + pretenure); +} + + +Object* Heap::NumberFromDouble(double value, PretenureFlag pretenure) { + return SmiOrNumberFromDouble(value, + false /* use preallocated NaN, -0.0 */, + pretenure); +} + + +Object* Heap::AllocateProxy(Address proxy, PretenureFlag pretenure) { + // Statically ensure that it is safe to allocate proxies in paged spaces. + STATIC_ASSERT(Proxy::kSize <= Page::kMaxHeapObjectSize); + AllocationSpace space = + (pretenure == TENURED) ? OLD_DATA_SPACE : NEW_SPACE; + Object* result = Allocate(proxy_map(), space); + if (result->IsFailure()) return result; + + Proxy::cast(result)->set_proxy(proxy); + return result; +} + + +Object* Heap::AllocateSharedFunctionInfo(Object* name) { + Object* result = Allocate(shared_function_info_map(), NEW_SPACE); + if (result->IsFailure()) return result; + + SharedFunctionInfo* share = SharedFunctionInfo::cast(result); + share->set_name(name); + Code* illegal = Builtins::builtin(Builtins::Illegal); + share->set_code(illegal); + share->set_expected_nof_properties(0); + share->set_length(0); + share->set_formal_parameter_count(0); + share->set_instance_class_name(Object_symbol()); + share->set_function_data(undefined_value()); + share->set_lazy_load_data(undefined_value()); + share->set_script(undefined_value()); + share->set_start_position_and_type(0); + share->set_debug_info(undefined_value()); + return result; +} + + +Object* Heap::AllocateConsString(String* first, + String* second) { + int first_length = first->length(); + int second_length = second->length(); + int length = first_length + second_length; + bool is_ascii = StringShape(first).IsAsciiRepresentation() + && StringShape(second).IsAsciiRepresentation(); + + // If the resulting string is small make a flat string. + if (length < String::kMinNonFlatLength) { + ASSERT(first->IsFlat()); + ASSERT(second->IsFlat()); + if (is_ascii) { + Object* result = AllocateRawAsciiString(length); + if (result->IsFailure()) return result; + // Copy the characters into the new object. + char* dest = SeqAsciiString::cast(result)->GetChars(); + String::WriteToFlat(first, dest, 0, first_length); + String::WriteToFlat(second, dest + first_length, 0, second_length); + return result; + } else { + Object* result = AllocateRawTwoByteString(length); + if (result->IsFailure()) return result; + // Copy the characters into the new object. + uc16* dest = SeqTwoByteString::cast(result)->GetChars(); + String::WriteToFlat(first, dest, 0, first_length); + String::WriteToFlat(second, dest + first_length, 0, second_length); + return result; + } + } + + Map* map; + if (length <= String::kMaxShortStringSize) { + map = is_ascii ? short_cons_ascii_string_map() + : short_cons_string_map(); + } else if (length <= String::kMaxMediumStringSize) { + map = is_ascii ? medium_cons_ascii_string_map() + : medium_cons_string_map(); + } else { + map = is_ascii ? long_cons_ascii_string_map() + : long_cons_string_map(); + } + + Object* result = Allocate(map, NEW_SPACE); + if (result->IsFailure()) return result; + ASSERT(InNewSpace(result)); + ConsString* cons_string = ConsString::cast(result); + cons_string->set_first(first, SKIP_WRITE_BARRIER); + cons_string->set_second(second, SKIP_WRITE_BARRIER); + cons_string->set_length(length); + return result; +} + + +Object* Heap::AllocateSlicedString(String* buffer, + int start, + int end) { + int length = end - start; + + // If the resulting string is small make a sub string. + if (end - start <= String::kMinNonFlatLength) { + return Heap::AllocateSubString(buffer, start, end); + } + + Map* map; + if (length <= String::kMaxShortStringSize) { + map = StringShape(buffer).IsAsciiRepresentation() ? + short_sliced_ascii_string_map() : + short_sliced_string_map(); + } else if (length <= String::kMaxMediumStringSize) { + map = StringShape(buffer).IsAsciiRepresentation() ? + medium_sliced_ascii_string_map() : + medium_sliced_string_map(); + } else { + map = StringShape(buffer).IsAsciiRepresentation() ? + long_sliced_ascii_string_map() : + long_sliced_string_map(); + } + + Object* result = Allocate(map, NEW_SPACE); + if (result->IsFailure()) return result; + + SlicedString* sliced_string = SlicedString::cast(result); + sliced_string->set_buffer(buffer); + sliced_string->set_start(start); + sliced_string->set_length(length); + + return result; +} + + +Object* Heap::AllocateSubString(String* buffer, + int start, + int end) { + int length = end - start; + + if (length == 1) { + return Heap::LookupSingleCharacterStringFromCode( + buffer->Get(start)); + } + + // Make an attempt to flatten the buffer to reduce access time. + if (!buffer->IsFlat()) { + buffer->TryFlatten(); + } + + Object* result = StringShape(buffer).IsAsciiRepresentation() + ? AllocateRawAsciiString(length) + : AllocateRawTwoByteString(length); + if (result->IsFailure()) return result; + + // Copy the characters into the new object. + String* string_result = String::cast(result); + StringHasher hasher(length); + int i = 0; + for (; i < length && hasher.is_array_index(); i++) { + uc32 c = buffer->Get(start + i); + hasher.AddCharacter(c); + string_result->Set(i, c); + } + for (; i < length; i++) { + uc32 c = buffer->Get(start + i); + hasher.AddCharacterNoIndex(c); + string_result->Set(i, c); + } + string_result->set_length_field(hasher.GetHashField()); + return result; +} + + +Object* Heap::AllocateExternalStringFromAscii( + ExternalAsciiString::Resource* resource) { + Map* map; + int length = resource->length(); + if (length <= String::kMaxShortStringSize) { + map = short_external_ascii_string_map(); + } else if (length <= String::kMaxMediumStringSize) { + map = medium_external_ascii_string_map(); + } else { + map = long_external_ascii_string_map(); + } + + Object* result = Allocate(map, NEW_SPACE); + if (result->IsFailure()) return result; + + ExternalAsciiString* external_string = ExternalAsciiString::cast(result); + external_string->set_length(length); + external_string->set_resource(resource); + + return result; +} + + +Object* Heap::AllocateExternalStringFromTwoByte( + ExternalTwoByteString::Resource* resource) { + int length = resource->length(); + + Map* map = ExternalTwoByteString::StringMap(length); + Object* result = Allocate(map, NEW_SPACE); + if (result->IsFailure()) return result; + + ExternalTwoByteString* external_string = ExternalTwoByteString::cast(result); + external_string->set_length(length); + external_string->set_resource(resource); + + return result; +} + + +Object* Heap::LookupSingleCharacterStringFromCode(uint16_t code) { + if (code <= String::kMaxAsciiCharCode) { + Object* value = Heap::single_character_string_cache()->get(code); + if (value != Heap::undefined_value()) return value; + + char buffer[1]; + buffer[0] = static_cast<char>(code); + Object* result = LookupSymbol(Vector<const char>(buffer, 1)); + + if (result->IsFailure()) return result; + Heap::single_character_string_cache()->set(code, result); + return result; + } + + Object* result = Heap::AllocateRawTwoByteString(1); + if (result->IsFailure()) return result; + String* answer = String::cast(result); + answer->Set(0, code); + return answer; +} + + +Object* Heap::AllocateByteArray(int length, PretenureFlag pretenure) { + if (pretenure == NOT_TENURED) { + return AllocateByteArray(length); + } + int size = ByteArray::SizeFor(length); + AllocationSpace space = + size > MaxHeapObjectSize() ? LO_SPACE : OLD_DATA_SPACE; + + Object* result = AllocateRaw(size, space, OLD_DATA_SPACE); + + if (result->IsFailure()) return result; + + reinterpret_cast<Array*>(result)->set_map(byte_array_map()); + reinterpret_cast<Array*>(result)->set_length(length); + return result; +} + + +Object* Heap::AllocateByteArray(int length) { + int size = ByteArray::SizeFor(length); + AllocationSpace space = + size > MaxHeapObjectSize() ? LO_SPACE : NEW_SPACE; + + Object* result = AllocateRaw(size, space, OLD_DATA_SPACE); + + if (result->IsFailure()) return result; + + reinterpret_cast<Array*>(result)->set_map(byte_array_map()); + reinterpret_cast<Array*>(result)->set_length(length); + return result; +} + + +void Heap::CreateFillerObjectAt(Address addr, int size) { + if (size == 0) return; + HeapObject* filler = HeapObject::FromAddress(addr); + if (size == kPointerSize) { + filler->set_map(Heap::one_word_filler_map()); + } else { + filler->set_map(Heap::byte_array_map()); + ByteArray::cast(filler)->set_length(ByteArray::LengthFor(size)); + } +} + + +Object* Heap::CreateCode(const CodeDesc& desc, + ScopeInfo<>* sinfo, + Code::Flags flags, + Handle<Object> self_reference) { + // Compute size + int body_size = RoundUp(desc.instr_size + desc.reloc_size, kObjectAlignment); + int sinfo_size = 0; + if (sinfo != NULL) sinfo_size = sinfo->Serialize(NULL); + int obj_size = Code::SizeFor(body_size, sinfo_size); + ASSERT(IsAligned(obj_size, Code::kCodeAlignment)); + Object* result; + if (obj_size > MaxHeapObjectSize()) { + result = lo_space_->AllocateRawCode(obj_size); + } else { + result = code_space_->AllocateRaw(obj_size); + } + + if (result->IsFailure()) return result; + + // Initialize the object + HeapObject::cast(result)->set_map(code_map()); + Code* code = Code::cast(result); + code->set_instruction_size(desc.instr_size); + code->set_relocation_size(desc.reloc_size); + code->set_sinfo_size(sinfo_size); + code->set_flags(flags); + code->set_ic_flag(Code::IC_TARGET_IS_ADDRESS); + // Allow self references to created code object by patching the handle to + // point to the newly allocated Code object. + if (!self_reference.is_null()) { + *(self_reference.location()) = code; + } + // Migrate generated code. + // The generated code can contain Object** values (typically from handles) + // that are dereferenced during the copy to point directly to the actual heap + // objects. These pointers can include references to the code object itself, + // through the self_reference parameter. + code->CopyFrom(desc); + if (sinfo != NULL) sinfo->Serialize(code); // write scope info + LOG(CodeAllocateEvent(code, desc.origin)); + +#ifdef DEBUG + code->Verify(); +#endif + return code; +} + + +Object* Heap::CopyCode(Code* code) { + // Allocate an object the same size as the code object. + int obj_size = code->Size(); + Object* result; + if (obj_size > MaxHeapObjectSize()) { + result = lo_space_->AllocateRawCode(obj_size); + } else { + result = code_space_->AllocateRaw(obj_size); + } + + if (result->IsFailure()) return result; + + // Copy code object. + Address old_addr = code->address(); + Address new_addr = reinterpret_cast<HeapObject*>(result)->address(); + CopyBlock(reinterpret_cast<Object**>(new_addr), + reinterpret_cast<Object**>(old_addr), + obj_size); + // Relocate the copy. + Code* new_code = Code::cast(result); + new_code->Relocate(new_addr - old_addr); + return new_code; +} + + +Object* Heap::Allocate(Map* map, AllocationSpace space) { + ASSERT(gc_state_ == NOT_IN_GC); + ASSERT(map->instance_type() != MAP_TYPE); + Object* result = AllocateRaw(map->instance_size(), + space, + TargetSpaceId(map->instance_type())); + if (result->IsFailure()) return result; + HeapObject::cast(result)->set_map(map); + return result; +} + + +Object* Heap::InitializeFunction(JSFunction* function, + SharedFunctionInfo* shared, + Object* prototype) { + ASSERT(!prototype->IsMap()); + function->initialize_properties(); + function->initialize_elements(); + function->set_shared(shared); + function->set_prototype_or_initial_map(prototype); + function->set_context(undefined_value()); + function->set_literals(empty_fixed_array(), SKIP_WRITE_BARRIER); + return function; +} + + +Object* Heap::AllocateFunctionPrototype(JSFunction* function) { + // Allocate the prototype. Make sure to use the object function + // from the function's context, since the function can be from a + // different context. + JSFunction* object_function = + function->context()->global_context()->object_function(); + Object* prototype = AllocateJSObject(object_function); + if (prototype->IsFailure()) return prototype; + // When creating the prototype for the function we must set its + // constructor to the function. + Object* result = + JSObject::cast(prototype)->SetProperty(constructor_symbol(), + function, + DONT_ENUM); + if (result->IsFailure()) return result; + return prototype; +} + + +Object* Heap::AllocateFunction(Map* function_map, + SharedFunctionInfo* shared, + Object* prototype) { + Object* result = Allocate(function_map, OLD_POINTER_SPACE); + if (result->IsFailure()) return result; + return InitializeFunction(JSFunction::cast(result), shared, prototype); +} + + +Object* Heap::AllocateArgumentsObject(Object* callee, int length) { + // To get fast allocation and map sharing for arguments objects we + // allocate them based on an arguments boilerplate. + + // This calls Copy directly rather than using Heap::AllocateRaw so we + // duplicate the check here. + ASSERT(allocation_allowed_ && gc_state_ == NOT_IN_GC); + + JSObject* boilerplate = + Top::context()->global_context()->arguments_boilerplate(); + + // Make the clone. + Map* map = boilerplate->map(); + int object_size = map->instance_size(); + Object* result = AllocateRaw(object_size, NEW_SPACE, OLD_POINTER_SPACE); + if (result->IsFailure()) return result; + + // Copy the content. The arguments boilerplate doesn't have any + // fields that point to new space so it's safe to skip the write + // barrier here. + CopyBlock(reinterpret_cast<Object**>(HeapObject::cast(result)->address()), + reinterpret_cast<Object**>(boilerplate->address()), + object_size); + + // Set the two properties. + JSObject::cast(result)->InObjectPropertyAtPut(arguments_callee_index, + callee); + JSObject::cast(result)->InObjectPropertyAtPut(arguments_length_index, + Smi::FromInt(length), + SKIP_WRITE_BARRIER); + + // Check the state of the object + ASSERT(JSObject::cast(result)->HasFastProperties()); + ASSERT(JSObject::cast(result)->HasFastElements()); + + return result; +} + + +Object* Heap::AllocateInitialMap(JSFunction* fun) { + ASSERT(!fun->has_initial_map()); + + // First create a new map with the expected number of properties being + // allocated in-object. + int expected_nof_properties = fun->shared()->expected_nof_properties(); + int instance_size = JSObject::kHeaderSize + + expected_nof_properties * kPointerSize; + if (instance_size > JSObject::kMaxInstanceSize) { + instance_size = JSObject::kMaxInstanceSize; + expected_nof_properties = (instance_size - JSObject::kHeaderSize) / + kPointerSize; + } + Object* map_obj = Heap::AllocateMap(JS_OBJECT_TYPE, instance_size); + if (map_obj->IsFailure()) return map_obj; + + // Fetch or allocate prototype. + Object* prototype; + if (fun->has_instance_prototype()) { + prototype = fun->instance_prototype(); + } else { + prototype = AllocateFunctionPrototype(fun); + if (prototype->IsFailure()) return prototype; + } + Map* map = Map::cast(map_obj); + map->set_inobject_properties(expected_nof_properties); + map->set_unused_property_fields(expected_nof_properties); + map->set_prototype(prototype); + return map; +} + + +void Heap::InitializeJSObjectFromMap(JSObject* obj, + FixedArray* properties, + Map* map) { + obj->set_properties(properties); + obj->initialize_elements(); + // TODO(1240798): Initialize the object's body using valid initial values + // according to the object's initial map. For example, if the map's + // instance type is JS_ARRAY_TYPE, the length field should be initialized + // to a number (eg, Smi::FromInt(0)) and the elements initialized to a + // fixed array (eg, Heap::empty_fixed_array()). Currently, the object + // verification code has to cope with (temporarily) invalid objects. See + // for example, JSArray::JSArrayVerify). + obj->InitializeBody(map->instance_size()); +} + + +Object* Heap::AllocateJSObjectFromMap(Map* map, PretenureFlag pretenure) { + // JSFunctions should be allocated using AllocateFunction to be + // properly initialized. + ASSERT(map->instance_type() != JS_FUNCTION_TYPE); + + // Allocate the backing storage for the properties. + int prop_size = map->unused_property_fields() - map->inobject_properties(); + Object* properties = AllocateFixedArray(prop_size); + if (properties->IsFailure()) return properties; + + // Allocate the JSObject. + AllocationSpace space = + (pretenure == TENURED) ? OLD_POINTER_SPACE : NEW_SPACE; + if (map->instance_size() > MaxHeapObjectSize()) space = LO_SPACE; + Object* obj = Allocate(map, space); + if (obj->IsFailure()) return obj; + + // Initialize the JSObject. + InitializeJSObjectFromMap(JSObject::cast(obj), + FixedArray::cast(properties), + map); + return obj; +} + + +Object* Heap::AllocateJSObject(JSFunction* constructor, + PretenureFlag pretenure) { + // Allocate the initial map if absent. + if (!constructor->has_initial_map()) { + Object* initial_map = AllocateInitialMap(constructor); + if (initial_map->IsFailure()) return initial_map; + constructor->set_initial_map(Map::cast(initial_map)); + Map::cast(initial_map)->set_constructor(constructor); + } + // Allocate the object based on the constructors initial map. + return AllocateJSObjectFromMap(constructor->initial_map(), pretenure); +} + + +Object* Heap::CopyJSObject(JSObject* source) { + // Never used to copy functions. If functions need to be copied we + // have to be careful to clear the literals array. + ASSERT(!source->IsJSFunction()); + + // Make the clone. + Map* map = source->map(); + int object_size = map->instance_size(); + Object* clone; + + // If we're forced to always allocate, we use the general allocation + // functions which may leave us with an object in old space. + if (always_allocate()) { + clone = AllocateRaw(object_size, NEW_SPACE, OLD_POINTER_SPACE); + if (clone->IsFailure()) return clone; + Address clone_address = HeapObject::cast(clone)->address(); + CopyBlock(reinterpret_cast<Object**>(clone_address), + reinterpret_cast<Object**>(source->address()), + object_size); + // Update write barrier for all fields that lie beyond the header. + for (int offset = JSObject::kHeaderSize; + offset < object_size; + offset += kPointerSize) { + RecordWrite(clone_address, offset); + } + } else { + clone = new_space_.AllocateRaw(object_size); + if (clone->IsFailure()) return clone; + ASSERT(Heap::InNewSpace(clone)); + // Since we know the clone is allocated in new space, we can copy + // the contents without worrying about updating the write barrier. + CopyBlock(reinterpret_cast<Object**>(HeapObject::cast(clone)->address()), + reinterpret_cast<Object**>(source->address()), + object_size); + } + + FixedArray* elements = FixedArray::cast(source->elements()); + FixedArray* properties = FixedArray::cast(source->properties()); + // Update elements if necessary. + if (elements->length()> 0) { + Object* elem = CopyFixedArray(elements); + if (elem->IsFailure()) return elem; + JSObject::cast(clone)->set_elements(FixedArray::cast(elem)); + } + // Update properties if necessary. + if (properties->length() > 0) { + Object* prop = CopyFixedArray(properties); + if (prop->IsFailure()) return prop; + JSObject::cast(clone)->set_properties(FixedArray::cast(prop)); + } + // Return the new clone. + return clone; +} + + +Object* Heap::ReinitializeJSGlobalProxy(JSFunction* constructor, + JSGlobalProxy* object) { + // Allocate initial map if absent. + if (!constructor->has_initial_map()) { + Object* initial_map = AllocateInitialMap(constructor); + if (initial_map->IsFailure()) return initial_map; + constructor->set_initial_map(Map::cast(initial_map)); + Map::cast(initial_map)->set_constructor(constructor); + } + + Map* map = constructor->initial_map(); + + // Check that the already allocated object has the same size as + // objects allocated using the constructor. + ASSERT(map->instance_size() == object->map()->instance_size()); + + // Allocate the backing storage for the properties. + int prop_size = map->unused_property_fields() - map->inobject_properties(); + Object* properties = AllocateFixedArray(prop_size); + if (properties->IsFailure()) return properties; + + // Reset the map for the object. + object->set_map(constructor->initial_map()); + + // Reinitialize the object from the constructor map. + InitializeJSObjectFromMap(object, FixedArray::cast(properties), map); + return object; +} + + +Object* Heap::AllocateStringFromAscii(Vector<const char> string, + PretenureFlag pretenure) { + Object* result = AllocateRawAsciiString(string.length(), pretenure); + if (result->IsFailure()) return result; + + // Copy the characters into the new object. + SeqAsciiString* string_result = SeqAsciiString::cast(result); + for (int i = 0; i < string.length(); i++) { + string_result->SeqAsciiStringSet(i, string[i]); + } + return result; +} + + +Object* Heap::AllocateStringFromUtf8(Vector<const char> string, + PretenureFlag pretenure) { + // Count the number of characters in the UTF-8 string and check if + // it is an ASCII string. + Access<Scanner::Utf8Decoder> decoder(Scanner::utf8_decoder()); + decoder->Reset(string.start(), string.length()); + int chars = 0; + bool is_ascii = true; + while (decoder->has_more()) { + uc32 r = decoder->GetNext(); + if (r > String::kMaxAsciiCharCode) is_ascii = false; + chars++; + } + + // If the string is ascii, we do not need to convert the characters + // since UTF8 is backwards compatible with ascii. + if (is_ascii) return AllocateStringFromAscii(string, pretenure); + + Object* result = AllocateRawTwoByteString(chars, pretenure); + if (result->IsFailure()) return result; + + // Convert and copy the characters into the new object. + String* string_result = String::cast(result); + decoder->Reset(string.start(), string.length()); + for (int i = 0; i < chars; i++) { + uc32 r = decoder->GetNext(); + string_result->Set(i, r); + } + return result; +} + + +Object* Heap::AllocateStringFromTwoByte(Vector<const uc16> string, + PretenureFlag pretenure) { + // Check if the string is an ASCII string. + int i = 0; + while (i < string.length() && string[i] <= String::kMaxAsciiCharCode) i++; + + Object* result; + if (i == string.length()) { // It's an ASCII string. + result = AllocateRawAsciiString(string.length(), pretenure); + } else { // It's not an ASCII string. + result = AllocateRawTwoByteString(string.length(), pretenure); + } + if (result->IsFailure()) return result; + + // Copy the characters into the new object, which may be either ASCII or + // UTF-16. + String* string_result = String::cast(result); + for (int i = 0; i < string.length(); i++) { + string_result->Set(i, string[i]); + } + return result; +} + + +Map* Heap::SymbolMapForString(String* string) { + // If the string is in new space it cannot be used as a symbol. + if (InNewSpace(string)) return NULL; + + // Find the corresponding symbol map for strings. + Map* map = string->map(); + + if (map == short_ascii_string_map()) return short_ascii_symbol_map(); + if (map == medium_ascii_string_map()) return medium_ascii_symbol_map(); + if (map == long_ascii_string_map()) return long_ascii_symbol_map(); + + if (map == short_string_map()) return short_symbol_map(); + if (map == medium_string_map()) return medium_symbol_map(); + if (map == long_string_map()) return long_symbol_map(); + + if (map == short_cons_string_map()) return short_cons_symbol_map(); + if (map == medium_cons_string_map()) return medium_cons_symbol_map(); + if (map == long_cons_string_map()) return long_cons_symbol_map(); + + if (map == short_cons_ascii_string_map()) { + return short_cons_ascii_symbol_map(); + } + if (map == medium_cons_ascii_string_map()) { + return medium_cons_ascii_symbol_map(); + } + if (map == long_cons_ascii_string_map()) { + return long_cons_ascii_symbol_map(); + } + + if (map == short_sliced_string_map()) return short_sliced_symbol_map(); + if (map == medium_sliced_string_map()) return medium_sliced_symbol_map(); + if (map == long_sliced_string_map()) return long_sliced_symbol_map(); + + if (map == short_sliced_ascii_string_map()) { + return short_sliced_ascii_symbol_map(); + } + if (map == medium_sliced_ascii_string_map()) { + return medium_sliced_ascii_symbol_map(); + } + if (map == long_sliced_ascii_string_map()) { + return long_sliced_ascii_symbol_map(); + } + + if (map == short_external_string_map()) { + return short_external_symbol_map(); + } + if (map == medium_external_string_map()) { + return medium_external_symbol_map(); + } + if (map == long_external_string_map()) { + return long_external_symbol_map(); + } + + if (map == short_external_ascii_string_map()) { + return short_external_ascii_symbol_map(); + } + if (map == medium_external_ascii_string_map()) { + return medium_external_ascii_symbol_map(); + } + if (map == long_external_ascii_string_map()) { + return long_external_ascii_symbol_map(); + } + + // No match found. + return NULL; +} + + +Object* Heap::AllocateInternalSymbol(unibrow::CharacterStream* buffer, + int chars, + uint32_t length_field) { + // Ensure the chars matches the number of characters in the buffer. + ASSERT(static_cast<unsigned>(chars) == buffer->Length()); + // Determine whether the string is ascii. + bool is_ascii = true; + while (buffer->has_more() && is_ascii) { + if (buffer->GetNext() > unibrow::Utf8::kMaxOneByteChar) is_ascii = false; + } + buffer->Rewind(); + + // Compute map and object size. + int size; + Map* map; + + if (is_ascii) { + if (chars <= String::kMaxShortStringSize) { + map = short_ascii_symbol_map(); + } else if (chars <= String::kMaxMediumStringSize) { + map = medium_ascii_symbol_map(); + } else { + map = long_ascii_symbol_map(); + } + size = SeqAsciiString::SizeFor(chars); + } else { + if (chars <= String::kMaxShortStringSize) { + map = short_symbol_map(); + } else if (chars <= String::kMaxMediumStringSize) { + map = medium_symbol_map(); + } else { + map = long_symbol_map(); + } + size = SeqTwoByteString::SizeFor(chars); + } + + // Allocate string. + AllocationSpace space = + (size > MaxHeapObjectSize()) ? LO_SPACE : OLD_DATA_SPACE; + Object* result = AllocateRaw(size, space, OLD_DATA_SPACE); + if (result->IsFailure()) return result; + + reinterpret_cast<HeapObject*>(result)->set_map(map); + // The hash value contains the length of the string. + String* answer = String::cast(result); + answer->set_length_field(length_field); + + ASSERT_EQ(size, answer->Size()); + + // Fill in the characters. + for (int i = 0; i < chars; i++) { + answer->Set(i, buffer->GetNext()); + } + return answer; +} + + +Object* Heap::AllocateRawAsciiString(int length, PretenureFlag pretenure) { + AllocationSpace space = (pretenure == TENURED) ? OLD_DATA_SPACE : NEW_SPACE; + int size = SeqAsciiString::SizeFor(length); + if (size > MaxHeapObjectSize()) { + space = LO_SPACE; + } + + // Use AllocateRaw rather than Allocate because the object's size cannot be + // determined from the map. + Object* result = AllocateRaw(size, space, OLD_DATA_SPACE); + if (result->IsFailure()) return result; + + // Determine the map based on the string's length. + Map* map; + if (length <= String::kMaxShortStringSize) { + map = short_ascii_string_map(); + } else if (length <= String::kMaxMediumStringSize) { + map = medium_ascii_string_map(); + } else { + map = long_ascii_string_map(); + } + + // Partially initialize the object. + HeapObject::cast(result)->set_map(map); + String::cast(result)->set_length(length); + ASSERT_EQ(size, HeapObject::cast(result)->Size()); + return result; +} + + +Object* Heap::AllocateRawTwoByteString(int length, PretenureFlag pretenure) { + AllocationSpace space = (pretenure == TENURED) ? OLD_DATA_SPACE : NEW_SPACE; + int size = SeqTwoByteString::SizeFor(length); + if (size > MaxHeapObjectSize()) { + space = LO_SPACE; + } + + // Use AllocateRaw rather than Allocate because the object's size cannot be + // determined from the map. + Object* result = AllocateRaw(size, space, OLD_DATA_SPACE); + if (result->IsFailure()) return result; + + // Determine the map based on the string's length. + Map* map; + if (length <= String::kMaxShortStringSize) { + map = short_string_map(); + } else if (length <= String::kMaxMediumStringSize) { + map = medium_string_map(); + } else { + map = long_string_map(); + } + + // Partially initialize the object. + HeapObject::cast(result)->set_map(map); + String::cast(result)->set_length(length); + ASSERT_EQ(size, HeapObject::cast(result)->Size()); + return result; +} + + +Object* Heap::AllocateEmptyFixedArray() { + int size = FixedArray::SizeFor(0); + Object* result = AllocateRaw(size, OLD_DATA_SPACE, OLD_DATA_SPACE); + if (result->IsFailure()) return result; + // Initialize the object. + reinterpret_cast<Array*>(result)->set_map(fixed_array_map()); + reinterpret_cast<Array*>(result)->set_length(0); + return result; +} + + +Object* Heap::AllocateRawFixedArray(int length) { + // Use the general function if we're forced to always allocate. + if (always_allocate()) return AllocateFixedArray(length, NOT_TENURED); + // Allocate the raw data for a fixed array. + int size = FixedArray::SizeFor(length); + return (size > MaxHeapObjectSize()) + ? lo_space_->AllocateRawFixedArray(size) + : new_space_.AllocateRaw(size); +} + + +Object* Heap::CopyFixedArray(FixedArray* src) { + int len = src->length(); + Object* obj = AllocateRawFixedArray(len); + if (obj->IsFailure()) return obj; + if (Heap::InNewSpace(obj)) { + HeapObject* dst = HeapObject::cast(obj); + CopyBlock(reinterpret_cast<Object**>(dst->address()), + reinterpret_cast<Object**>(src->address()), + FixedArray::SizeFor(len)); + return obj; + } + HeapObject::cast(obj)->set_map(src->map()); + FixedArray* result = FixedArray::cast(obj); + result->set_length(len); + // Copy the content + WriteBarrierMode mode = result->GetWriteBarrierMode(); + for (int i = 0; i < len; i++) result->set(i, src->get(i), mode); + return result; +} + + +Object* Heap::AllocateFixedArray(int length) { + if (length == 0) return empty_fixed_array(); + Object* result = AllocateRawFixedArray(length); + if (!result->IsFailure()) { + // Initialize header. + reinterpret_cast<Array*>(result)->set_map(fixed_array_map()); + FixedArray* array = FixedArray::cast(result); + array->set_length(length); + Object* value = undefined_value(); + // Initialize body. + for (int index = 0; index < length; index++) { + array->set(index, value, SKIP_WRITE_BARRIER); + } + } + return result; +} + + +Object* Heap::AllocateFixedArray(int length, PretenureFlag pretenure) { + ASSERT(empty_fixed_array()->IsFixedArray()); + if (length == 0) return empty_fixed_array(); + + int size = FixedArray::SizeFor(length); + Object* result; + if (size > MaxHeapObjectSize()) { + result = lo_space_->AllocateRawFixedArray(size); + } else { + AllocationSpace space = + (pretenure == TENURED) ? OLD_POINTER_SPACE : NEW_SPACE; + result = AllocateRaw(size, space, OLD_POINTER_SPACE); + } + if (result->IsFailure()) return result; + + // Initialize the object. + reinterpret_cast<Array*>(result)->set_map(fixed_array_map()); + FixedArray* array = FixedArray::cast(result); + array->set_length(length); + Object* value = undefined_value(); + for (int index = 0; index < length; index++) { + array->set(index, value, SKIP_WRITE_BARRIER); + } + return array; +} + + +Object* Heap::AllocateFixedArrayWithHoles(int length) { + if (length == 0) return empty_fixed_array(); + Object* result = AllocateRawFixedArray(length); + if (!result->IsFailure()) { + // Initialize header. + reinterpret_cast<Array*>(result)->set_map(fixed_array_map()); + FixedArray* array = FixedArray::cast(result); + array->set_length(length); + // Initialize body. + Object* value = the_hole_value(); + for (int index = 0; index < length; index++) { + array->set(index, value, SKIP_WRITE_BARRIER); + } + } + return result; +} + + +Object* Heap::AllocateHashTable(int length) { + Object* result = Heap::AllocateFixedArray(length); + if (result->IsFailure()) return result; + reinterpret_cast<Array*>(result)->set_map(hash_table_map()); + ASSERT(result->IsDictionary()); + return result; +} + + +Object* Heap::AllocateGlobalContext() { + Object* result = Heap::AllocateFixedArray(Context::GLOBAL_CONTEXT_SLOTS); + if (result->IsFailure()) return result; + Context* context = reinterpret_cast<Context*>(result); + context->set_map(global_context_map()); + ASSERT(context->IsGlobalContext()); + ASSERT(result->IsContext()); + return result; +} + + +Object* Heap::AllocateFunctionContext(int length, JSFunction* function) { + ASSERT(length >= Context::MIN_CONTEXT_SLOTS); + Object* result = Heap::AllocateFixedArray(length); + if (result->IsFailure()) return result; + Context* context = reinterpret_cast<Context*>(result); + context->set_map(context_map()); + context->set_closure(function); + context->set_fcontext(context); + context->set_previous(NULL); + context->set_extension(NULL); + context->set_global(function->context()->global()); + ASSERT(!context->IsGlobalContext()); + ASSERT(context->is_function_context()); + ASSERT(result->IsContext()); + return result; +} + + +Object* Heap::AllocateWithContext(Context* previous, + JSObject* extension, + bool is_catch_context) { + Object* result = Heap::AllocateFixedArray(Context::MIN_CONTEXT_SLOTS); + if (result->IsFailure()) return result; + Context* context = reinterpret_cast<Context*>(result); + context->set_map(is_catch_context ? catch_context_map() : context_map()); + context->set_closure(previous->closure()); + context->set_fcontext(previous->fcontext()); + context->set_previous(previous); + context->set_extension(extension); + context->set_global(previous->global()); + ASSERT(!context->IsGlobalContext()); + ASSERT(!context->is_function_context()); + ASSERT(result->IsContext()); + return result; +} + + +Object* Heap::AllocateStruct(InstanceType type) { + Map* map; + switch (type) { +#define MAKE_CASE(NAME, Name, name) case NAME##_TYPE: map = name##_map(); break; +STRUCT_LIST(MAKE_CASE) +#undef MAKE_CASE + default: + UNREACHABLE(); + return Failure::InternalError(); + } + int size = map->instance_size(); + AllocationSpace space = + (size > MaxHeapObjectSize()) ? LO_SPACE : OLD_POINTER_SPACE; + Object* result = Heap::Allocate(map, space); + if (result->IsFailure()) return result; + Struct::cast(result)->InitializeBody(size); + return result; +} + + +#ifdef DEBUG + +void Heap::Print() { + if (!HasBeenSetup()) return; + Top::PrintStack(); + AllSpaces spaces; + while (Space* space = spaces.next()) space->Print(); +} + + +void Heap::ReportCodeStatistics(const char* title) { + PrintF(">>>>>> Code Stats (%s) >>>>>>\n", title); + PagedSpace::ResetCodeStatistics(); + // We do not look for code in new space, map space, or old space. If code + // somehow ends up in those spaces, we would miss it here. + code_space_->CollectCodeStatistics(); + lo_space_->CollectCodeStatistics(); + PagedSpace::ReportCodeStatistics(); +} + + +// This function expects that NewSpace's allocated objects histogram is +// populated (via a call to CollectStatistics or else as a side effect of a +// just-completed scavenge collection). +void Heap::ReportHeapStatistics(const char* title) { + USE(title); + PrintF(">>>>>> =============== %s (%d) =============== >>>>>>\n", + title, gc_count_); + PrintF("mark-compact GC : %d\n", mc_count_); + PrintF("old_gen_promotion_limit_ %d\n", old_gen_promotion_limit_); + PrintF("old_gen_allocation_limit_ %d\n", old_gen_allocation_limit_); + + PrintF("\n"); + PrintF("Number of handles : %d\n", HandleScope::NumberOfHandles()); + GlobalHandles::PrintStats(); + PrintF("\n"); + + PrintF("Heap statistics : "); + MemoryAllocator::ReportStatistics(); + PrintF("To space : "); + new_space_.ReportStatistics(); + PrintF("Old pointer space : "); + old_pointer_space_->ReportStatistics(); + PrintF("Old data space : "); + old_data_space_->ReportStatistics(); + PrintF("Code space : "); + code_space_->ReportStatistics(); + PrintF("Map space : "); + map_space_->ReportStatistics(); + PrintF("Large object space : "); + lo_space_->ReportStatistics(); + PrintF(">>>>>> ========================================= >>>>>>\n"); +} + +#endif // DEBUG + +bool Heap::Contains(HeapObject* value) { + return Contains(value->address()); +} + + +bool Heap::Contains(Address addr) { + if (OS::IsOutsideAllocatedSpace(addr)) return false; + return HasBeenSetup() && + (new_space_.ToSpaceContains(addr) || + old_pointer_space_->Contains(addr) || + old_data_space_->Contains(addr) || + code_space_->Contains(addr) || + map_space_->Contains(addr) || + lo_space_->SlowContains(addr)); +} + + +bool Heap::InSpace(HeapObject* value, AllocationSpace space) { + return InSpace(value->address(), space); +} + + +bool Heap::InSpace(Address addr, AllocationSpace space) { + if (OS::IsOutsideAllocatedSpace(addr)) return false; + if (!HasBeenSetup()) return false; + + switch (space) { + case NEW_SPACE: + return new_space_.ToSpaceContains(addr); + case OLD_POINTER_SPACE: + return old_pointer_space_->Contains(addr); + case OLD_DATA_SPACE: + return old_data_space_->Contains(addr); + case CODE_SPACE: + return code_space_->Contains(addr); + case MAP_SPACE: + return map_space_->Contains(addr); + case LO_SPACE: + return lo_space_->SlowContains(addr); + } + + return false; +} + + +#ifdef DEBUG +void Heap::Verify() { + ASSERT(HasBeenSetup()); + + VerifyPointersVisitor visitor; + Heap::IterateRoots(&visitor); + + AllSpaces spaces; + while (Space* space = spaces.next()) { + space->Verify(); + } +} +#endif // DEBUG + + +Object* Heap::LookupSymbol(Vector<const char> string) { + Object* symbol = NULL; + Object* new_table = + SymbolTable::cast(symbol_table_)->LookupSymbol(string, &symbol); + if (new_table->IsFailure()) return new_table; + symbol_table_ = new_table; + ASSERT(symbol != NULL); + return symbol; +} + + +Object* Heap::LookupSymbol(String* string) { + if (string->IsSymbol()) return string; + Object* symbol = NULL; + Object* new_table = + SymbolTable::cast(symbol_table_)->LookupString(string, &symbol); + if (new_table->IsFailure()) return new_table; + symbol_table_ = new_table; + ASSERT(symbol != NULL); + return symbol; +} + + +bool Heap::LookupSymbolIfExists(String* string, String** symbol) { + if (string->IsSymbol()) { + *symbol = string; + return true; + } + SymbolTable* table = SymbolTable::cast(symbol_table_); + return table->LookupSymbolIfExists(string, symbol); +} + + +#ifdef DEBUG +void Heap::ZapFromSpace() { + ASSERT(HAS_HEAP_OBJECT_TAG(kFromSpaceZapValue)); + for (Address a = new_space_.FromSpaceLow(); + a < new_space_.FromSpaceHigh(); + a += kPointerSize) { + Memory::Address_at(a) = kFromSpaceZapValue; + } +} +#endif // DEBUG + + +void Heap::IterateRSetRange(Address object_start, + Address object_end, + Address rset_start, + ObjectSlotCallback copy_object_func) { + Address object_address = object_start; + Address rset_address = rset_start; + + // Loop over all the pointers in [object_start, object_end). + while (object_address < object_end) { + uint32_t rset_word = Memory::uint32_at(rset_address); + if (rset_word != 0) { + uint32_t result_rset = rset_word; + for (uint32_t bitmask = 1; bitmask != 0; bitmask = bitmask << 1) { + // Do not dereference pointers at or past object_end. + if ((rset_word & bitmask) != 0 && object_address < object_end) { + Object** object_p = reinterpret_cast<Object**>(object_address); + if (Heap::InNewSpace(*object_p)) { + copy_object_func(reinterpret_cast<HeapObject**>(object_p)); + } + // If this pointer does not need to be remembered anymore, clear + // the remembered set bit. + if (!Heap::InNewSpace(*object_p)) result_rset &= ~bitmask; + } + object_address += kPointerSize; + } + // Update the remembered set if it has changed. + if (result_rset != rset_word) { + Memory::uint32_at(rset_address) = result_rset; + } + } else { + // No bits in the word were set. This is the common case. + object_address += kPointerSize * kBitsPerInt; + } + rset_address += kIntSize; + } +} + + +void Heap::IterateRSet(PagedSpace* space, ObjectSlotCallback copy_object_func) { + ASSERT(Page::is_rset_in_use()); + ASSERT(space == old_pointer_space_ || space == map_space_); + + PageIterator it(space, PageIterator::PAGES_IN_USE); + while (it.has_next()) { + Page* page = it.next(); + IterateRSetRange(page->ObjectAreaStart(), page->AllocationTop(), + page->RSetStart(), copy_object_func); + } +} + + +#ifdef DEBUG +#define SYNCHRONIZE_TAG(tag) v->Synchronize(tag) +#else +#define SYNCHRONIZE_TAG(tag) +#endif + +void Heap::IterateRoots(ObjectVisitor* v) { + IterateStrongRoots(v); + v->VisitPointer(reinterpret_cast<Object**>(&symbol_table_)); + SYNCHRONIZE_TAG("symbol_table"); +} + + +void Heap::IterateStrongRoots(ObjectVisitor* v) { +#define ROOT_ITERATE(type, name) \ + v->VisitPointer(bit_cast<Object**, type**>(&name##_)); + STRONG_ROOT_LIST(ROOT_ITERATE); +#undef ROOT_ITERATE + SYNCHRONIZE_TAG("strong_root_list"); + +#define STRUCT_MAP_ITERATE(NAME, Name, name) \ + v->VisitPointer(bit_cast<Object**, Map**>(&name##_map_)); + STRUCT_LIST(STRUCT_MAP_ITERATE); +#undef STRUCT_MAP_ITERATE + SYNCHRONIZE_TAG("struct_map"); + +#define SYMBOL_ITERATE(name, string) \ + v->VisitPointer(bit_cast<Object**, String**>(&name##_)); + SYMBOL_LIST(SYMBOL_ITERATE) +#undef SYMBOL_ITERATE + v->VisitPointer(bit_cast<Object**, String**>(&hidden_symbol_)); + SYNCHRONIZE_TAG("symbol"); + + Bootstrapper::Iterate(v); + SYNCHRONIZE_TAG("bootstrapper"); + Top::Iterate(v); + SYNCHRONIZE_TAG("top"); + Debug::Iterate(v); + SYNCHRONIZE_TAG("debug"); + CompilationCache::Iterate(v); + SYNCHRONIZE_TAG("compilationcache"); + + // Iterate over local handles in handle scopes. + HandleScopeImplementer::Iterate(v); + SYNCHRONIZE_TAG("handlescope"); + + // Iterate over the builtin code objects and code stubs in the heap. Note + // that it is not strictly necessary to iterate over code objects on + // scavenge collections. We still do it here because this same function + // is used by the mark-sweep collector and the deserializer. + Builtins::IterateBuiltins(v); + SYNCHRONIZE_TAG("builtins"); + + // Iterate over global handles. + GlobalHandles::IterateRoots(v); + SYNCHRONIZE_TAG("globalhandles"); + + // Iterate over pointers being held by inactive threads. + ThreadManager::Iterate(v); + SYNCHRONIZE_TAG("threadmanager"); +} +#undef SYNCHRONIZE_TAG + + +// Flag is set when the heap has been configured. The heap can be repeatedly +// configured through the API until it is setup. +static bool heap_configured = false; + +// TODO(1236194): Since the heap size is configurable on the command line +// and through the API, we should gracefully handle the case that the heap +// size is not big enough to fit all the initial objects. +bool Heap::ConfigureHeap(int semispace_size, int old_gen_size) { + if (HasBeenSetup()) return false; + + if (semispace_size > 0) semispace_size_ = semispace_size; + if (old_gen_size > 0) old_generation_size_ = old_gen_size; + + // The new space size must be a power of two to support single-bit testing + // for containment. + semispace_size_ = RoundUpToPowerOf2(semispace_size_); + initial_semispace_size_ = Min(initial_semispace_size_, semispace_size_); + young_generation_size_ = 2 * semispace_size_; + + // The old generation is paged. + old_generation_size_ = RoundUp(old_generation_size_, Page::kPageSize); + + heap_configured = true; + return true; +} + + +bool Heap::ConfigureHeapDefault() { + return ConfigureHeap(FLAG_new_space_size, FLAG_old_space_size); +} + + +int Heap::PromotedSpaceSize() { + return old_pointer_space_->Size() + + old_data_space_->Size() + + code_space_->Size() + + map_space_->Size() + + lo_space_->Size(); +} + + +int Heap::PromotedExternalMemorySize() { + if (amount_of_external_allocated_memory_ + <= amount_of_external_allocated_memory_at_last_global_gc_) return 0; + return amount_of_external_allocated_memory_ + - amount_of_external_allocated_memory_at_last_global_gc_; +} + + +bool Heap::Setup(bool create_heap_objects) { + // Initialize heap spaces and initial maps and objects. Whenever something + // goes wrong, just return false. The caller should check the results and + // call Heap::TearDown() to release allocated memory. + // + // If the heap is not yet configured (eg, through the API), configure it. + // Configuration is based on the flags new-space-size (really the semispace + // size) and old-space-size if set or the initial values of semispace_size_ + // and old_generation_size_ otherwise. + if (!heap_configured) { + if (!ConfigureHeapDefault()) return false; + } + + // Setup memory allocator and allocate an initial chunk of memory. The + // initial chunk is double the size of the new space to ensure that we can + // find a pair of semispaces that are contiguous and aligned to their size. + if (!MemoryAllocator::Setup(MaxCapacity())) return false; + void* chunk + = MemoryAllocator::ReserveInitialChunk(2 * young_generation_size_); + if (chunk == NULL) return false; + + // Put the initial chunk of the old space at the start of the initial + // chunk, then the two new space semispaces, then the initial chunk of + // code space. Align the pair of semispaces to their size, which must be + // a power of 2. + ASSERT(IsPowerOf2(young_generation_size_)); + Address code_space_start = reinterpret_cast<Address>(chunk); + Address new_space_start = RoundUp(code_space_start, young_generation_size_); + Address old_space_start = new_space_start + young_generation_size_; + int code_space_size = new_space_start - code_space_start; + int old_space_size = young_generation_size_ - code_space_size; + + // Initialize new space. + if (!new_space_.Setup(new_space_start, young_generation_size_)) return false; + + // Initialize old space, set the maximum capacity to the old generation + // size. It will not contain code. + old_pointer_space_ = + new OldSpace(old_generation_size_, OLD_POINTER_SPACE, NOT_EXECUTABLE); + if (old_pointer_space_ == NULL) return false; + if (!old_pointer_space_->Setup(old_space_start, old_space_size >> 1)) { + return false; + } + old_data_space_ = + new OldSpace(old_generation_size_, OLD_DATA_SPACE, NOT_EXECUTABLE); + if (old_data_space_ == NULL) return false; + if (!old_data_space_->Setup(old_space_start + (old_space_size >> 1), + old_space_size >> 1)) { + return false; + } + + // Initialize the code space, set its maximum capacity to the old + // generation size. It needs executable memory. + code_space_ = + new OldSpace(old_generation_size_, CODE_SPACE, EXECUTABLE); + if (code_space_ == NULL) return false; + if (!code_space_->Setup(code_space_start, code_space_size)) return false; + + // Initialize map space. + map_space_ = new MapSpace(kMaxMapSpaceSize, MAP_SPACE); + if (map_space_ == NULL) return false; + // Setting up a paged space without giving it a virtual memory range big + // enough to hold at least a page will cause it to allocate. + if (!map_space_->Setup(NULL, 0)) return false; + + // The large object code space may contain code or data. We set the memory + // to be non-executable here for safety, but this means we need to enable it + // explicitly when allocating large code objects. + lo_space_ = new LargeObjectSpace(LO_SPACE); + if (lo_space_ == NULL) return false; + if (!lo_space_->Setup()) return false; + + if (create_heap_objects) { + // Create initial maps. + if (!CreateInitialMaps()) return false; + if (!CreateApiObjects()) return false; + + // Create initial objects + if (!CreateInitialObjects()) return false; + } + + LOG(IntEvent("heap-capacity", Capacity())); + LOG(IntEvent("heap-available", Available())); + + return true; +} + + +void Heap::TearDown() { + GlobalHandles::TearDown(); + + new_space_.TearDown(); + + if (old_pointer_space_ != NULL) { + old_pointer_space_->TearDown(); + delete old_pointer_space_; + old_pointer_space_ = NULL; + } + + if (old_data_space_ != NULL) { + old_data_space_->TearDown(); + delete old_data_space_; + old_data_space_ = NULL; + } + + if (code_space_ != NULL) { + code_space_->TearDown(); + delete code_space_; + code_space_ = NULL; + } + + if (map_space_ != NULL) { + map_space_->TearDown(); + delete map_space_; + map_space_ = NULL; + } + + if (lo_space_ != NULL) { + lo_space_->TearDown(); + delete lo_space_; + lo_space_ = NULL; + } + + MemoryAllocator::TearDown(); +} + + +void Heap::Shrink() { + // Try to shrink map, old, and code spaces. + map_space_->Shrink(); + old_pointer_space_->Shrink(); + old_data_space_->Shrink(); + code_space_->Shrink(); +} + + +#ifdef ENABLE_HEAP_PROTECTION + +void Heap::Protect() { + if (HasBeenSetup()) { + new_space_.Protect(); + map_space_->Protect(); + old_pointer_space_->Protect(); + old_data_space_->Protect(); + code_space_->Protect(); + lo_space_->Protect(); + } +} + + +void Heap::Unprotect() { + if (HasBeenSetup()) { + new_space_.Unprotect(); + map_space_->Unprotect(); + old_pointer_space_->Unprotect(); + old_data_space_->Unprotect(); + code_space_->Unprotect(); + lo_space_->Unprotect(); + } +} + +#endif + + +#ifdef DEBUG + +class PrintHandleVisitor: public ObjectVisitor { + public: + void VisitPointers(Object** start, Object** end) { + for (Object** p = start; p < end; p++) + PrintF(" handle %p to %p\n", p, *p); + } +}; + +void Heap::PrintHandles() { + PrintF("Handles:\n"); + PrintHandleVisitor v; + HandleScopeImplementer::Iterate(&v); +} + +#endif + + +Space* AllSpaces::next() { + switch (counter_++) { + case NEW_SPACE: + return Heap::new_space(); + case OLD_POINTER_SPACE: + return Heap::old_pointer_space(); + case OLD_DATA_SPACE: + return Heap::old_data_space(); + case CODE_SPACE: + return Heap::code_space(); + case MAP_SPACE: + return Heap::map_space(); + case LO_SPACE: + return Heap::lo_space(); + default: + return NULL; + } +} + + +PagedSpace* PagedSpaces::next() { + switch (counter_++) { + case OLD_POINTER_SPACE: + return Heap::old_pointer_space(); + case OLD_DATA_SPACE: + return Heap::old_data_space(); + case CODE_SPACE: + return Heap::code_space(); + case MAP_SPACE: + return Heap::map_space(); + default: + return NULL; + } +} + + + +OldSpace* OldSpaces::next() { + switch (counter_++) { + case OLD_POINTER_SPACE: + return Heap::old_pointer_space(); + case OLD_DATA_SPACE: + return Heap::old_data_space(); + case CODE_SPACE: + return Heap::code_space(); + default: + return NULL; + } +} + + +SpaceIterator::SpaceIterator() : current_space_(FIRST_SPACE), iterator_(NULL) { +} + + +SpaceIterator::~SpaceIterator() { + // Delete active iterator if any. + delete iterator_; +} + + +bool SpaceIterator::has_next() { + // Iterate until no more spaces. + return current_space_ != LAST_SPACE; +} + + +ObjectIterator* SpaceIterator::next() { + if (iterator_ != NULL) { + delete iterator_; + iterator_ = NULL; + // Move to the next space + current_space_++; + if (current_space_ > LAST_SPACE) { + return NULL; + } + } + + // Return iterator for the new current space. + return CreateIterator(); +} + + +// Create an iterator for the space to iterate. +ObjectIterator* SpaceIterator::CreateIterator() { + ASSERT(iterator_ == NULL); + + switch (current_space_) { + case NEW_SPACE: + iterator_ = new SemiSpaceIterator(Heap::new_space()); + break; + case OLD_POINTER_SPACE: + iterator_ = new HeapObjectIterator(Heap::old_pointer_space()); + break; + case OLD_DATA_SPACE: + iterator_ = new HeapObjectIterator(Heap::old_data_space()); + break; + case CODE_SPACE: + iterator_ = new HeapObjectIterator(Heap::code_space()); + break; + case MAP_SPACE: + iterator_ = new HeapObjectIterator(Heap::map_space()); + break; + case LO_SPACE: + iterator_ = new LargeObjectIterator(Heap::lo_space()); + break; + } + + // Return the newly allocated iterator; + ASSERT(iterator_ != NULL); + return iterator_; +} + + +HeapIterator::HeapIterator() { + Init(); +} + + +HeapIterator::~HeapIterator() { + Shutdown(); +} + + +void HeapIterator::Init() { + // Start the iteration. + space_iterator_ = new SpaceIterator(); + object_iterator_ = space_iterator_->next(); +} + + +void HeapIterator::Shutdown() { + // Make sure the last iterator is deallocated. + delete space_iterator_; + space_iterator_ = NULL; + object_iterator_ = NULL; +} + + +bool HeapIterator::has_next() { + // No iterator means we are done. + if (object_iterator_ == NULL) return false; + + if (object_iterator_->has_next_object()) { + // If the current iterator has more objects we are fine. + return true; + } else { + // Go though the spaces looking for one that has objects. + while (space_iterator_->has_next()) { + object_iterator_ = space_iterator_->next(); + if (object_iterator_->has_next_object()) { + return true; + } + } + } + // Done with the last space. + object_iterator_ = NULL; + return false; +} + + +HeapObject* HeapIterator::next() { + if (has_next()) { + return object_iterator_->next_object(); + } else { + return NULL; + } +} + + +void HeapIterator::reset() { + // Restart the iterator. + Shutdown(); + Init(); +} + + +// +// HeapProfiler class implementation. +// +#ifdef ENABLE_LOGGING_AND_PROFILING +void HeapProfiler::CollectStats(HeapObject* obj, HistogramInfo* info) { + InstanceType type = obj->map()->instance_type(); + ASSERT(0 <= type && type <= LAST_TYPE); + info[type].increment_number(1); + info[type].increment_bytes(obj->Size()); +} +#endif + + +#ifdef ENABLE_LOGGING_AND_PROFILING +void HeapProfiler::WriteSample() { + LOG(HeapSampleBeginEvent("Heap", "allocated")); + + HistogramInfo info[LAST_TYPE+1]; +#define DEF_TYPE_NAME(name) info[name].set_name(#name); + INSTANCE_TYPE_LIST(DEF_TYPE_NAME) +#undef DEF_TYPE_NAME + + HeapIterator iterator; + while (iterator.has_next()) { + CollectStats(iterator.next(), info); + } + + // Lump all the string types together. + int string_number = 0; + int string_bytes = 0; +#define INCREMENT_SIZE(type, size, name) \ + string_number += info[type].number(); \ + string_bytes += info[type].bytes(); + STRING_TYPE_LIST(INCREMENT_SIZE) +#undef INCREMENT_SIZE + if (string_bytes > 0) { + LOG(HeapSampleItemEvent("STRING_TYPE", string_number, string_bytes)); + } + + for (int i = FIRST_NONSTRING_TYPE; i <= LAST_TYPE; ++i) { + if (info[i].bytes() > 0) { + LOG(HeapSampleItemEvent(info[i].name(), info[i].number(), + info[i].bytes())); + } + } + + LOG(HeapSampleEndEvent("Heap", "allocated")); +} + + +#endif + + + +#ifdef DEBUG + +static bool search_for_any_global; +static Object* search_target; +static bool found_target; +static List<Object*> object_stack(20); + + +// Tags 0, 1, and 3 are used. Use 2 for marking visited HeapObject. +static const int kMarkTag = 2; + +static void MarkObjectRecursively(Object** p); +class MarkObjectVisitor : public ObjectVisitor { + public: + void VisitPointers(Object** start, Object** end) { + // Copy all HeapObject pointers in [start, end) + for (Object** p = start; p < end; p++) { + if ((*p)->IsHeapObject()) + MarkObjectRecursively(p); + } + } +}; + +static MarkObjectVisitor mark_visitor; + +static void MarkObjectRecursively(Object** p) { + if (!(*p)->IsHeapObject()) return; + + HeapObject* obj = HeapObject::cast(*p); + + Object* map = obj->map(); + + if (!map->IsHeapObject()) return; // visited before + + if (found_target) return; // stop if target found + object_stack.Add(obj); + if ((search_for_any_global && obj->IsJSGlobalObject()) || + (!search_for_any_global && (obj == search_target))) { + found_target = true; + return; + } + + if (obj->IsCode()) { + Code::cast(obj)->ConvertICTargetsFromAddressToObject(); + } + + // not visited yet + Map* map_p = reinterpret_cast<Map*>(HeapObject::cast(map)); + + Address map_addr = map_p->address(); + + obj->set_map(reinterpret_cast<Map*>(map_addr + kMarkTag)); + + MarkObjectRecursively(&map); + + obj->IterateBody(map_p->instance_type(), obj->SizeFromMap(map_p), + &mark_visitor); + + if (!found_target) // don't pop if found the target + object_stack.RemoveLast(); +} + + +static void UnmarkObjectRecursively(Object** p); +class UnmarkObjectVisitor : public ObjectVisitor { + public: + void VisitPointers(Object** start, Object** end) { + // Copy all HeapObject pointers in [start, end) + for (Object** p = start; p < end; p++) { + if ((*p)->IsHeapObject()) + UnmarkObjectRecursively(p); + } + } +}; + +static UnmarkObjectVisitor unmark_visitor; + +static void UnmarkObjectRecursively(Object** p) { + if (!(*p)->IsHeapObject()) return; + + HeapObject* obj = HeapObject::cast(*p); + + Object* map = obj->map(); + + if (map->IsHeapObject()) return; // unmarked already + + Address map_addr = reinterpret_cast<Address>(map); + + map_addr -= kMarkTag; + + ASSERT_TAG_ALIGNED(map_addr); + + HeapObject* map_p = HeapObject::FromAddress(map_addr); + + obj->set_map(reinterpret_cast<Map*>(map_p)); + + UnmarkObjectRecursively(reinterpret_cast<Object**>(&map_p)); + + obj->IterateBody(Map::cast(map_p)->instance_type(), + obj->SizeFromMap(Map::cast(map_p)), + &unmark_visitor); + + if (obj->IsCode()) { + Code::cast(obj)->ConvertICTargetsFromObjectToAddress(); + } +} + + +static void MarkRootObjectRecursively(Object** root) { + if (search_for_any_global) { + ASSERT(search_target == NULL); + } else { + ASSERT(search_target->IsHeapObject()); + } + found_target = false; + object_stack.Clear(); + + MarkObjectRecursively(root); + UnmarkObjectRecursively(root); + + if (found_target) { + PrintF("=====================================\n"); + PrintF("==== Path to object ====\n"); + PrintF("=====================================\n\n"); + + ASSERT(!object_stack.is_empty()); + for (int i = 0; i < object_stack.length(); i++) { + if (i > 0) PrintF("\n |\n |\n V\n\n"); + Object* obj = object_stack[i]; + obj->Print(); + } + PrintF("=====================================\n"); + } +} + + +// Helper class for visiting HeapObjects recursively. +class MarkRootVisitor: public ObjectVisitor { + public: + void VisitPointers(Object** start, Object** end) { + // Visit all HeapObject pointers in [start, end) + for (Object** p = start; p < end; p++) { + if ((*p)->IsHeapObject()) + MarkRootObjectRecursively(p); + } + } +}; + + +// Triggers a depth-first traversal of reachable objects from roots +// and finds a path to a specific heap object and prints it. +void Heap::TracePathToObject() { + search_target = NULL; + search_for_any_global = false; + + MarkRootVisitor root_visitor; + IterateRoots(&root_visitor); +} + + +// Triggers a depth-first traversal of reachable objects from roots +// and finds a path to any global object and prints it. Useful for +// determining the source for leaks of global objects. +void Heap::TracePathToGlobal() { + search_target = NULL; + search_for_any_global = true; + + MarkRootVisitor root_visitor; + IterateRoots(&root_visitor); +} +#endif + + +GCTracer::GCTracer() + : start_time_(0.0), + start_size_(0.0), + gc_count_(0), + full_gc_count_(0), + is_compacting_(false), + marked_count_(0) { + // These two fields reflect the state of the previous full collection. + // Set them before they are changed by the collector. + previous_has_compacted_ = MarkCompactCollector::HasCompacted(); + previous_marked_count_ = MarkCompactCollector::previous_marked_count(); + if (!FLAG_trace_gc) return; + start_time_ = OS::TimeCurrentMillis(); + start_size_ = SizeOfHeapObjects(); +} + + +GCTracer::~GCTracer() { + if (!FLAG_trace_gc) return; + // Printf ONE line iff flag is set. + PrintF("%s %.1f -> %.1f MB, %d ms.\n", + CollectorString(), + start_size_, SizeOfHeapObjects(), + static_cast<int>(OS::TimeCurrentMillis() - start_time_)); +} + + +const char* GCTracer::CollectorString() { + switch (collector_) { + case SCAVENGER: + return "Scavenge"; + case MARK_COMPACTOR: + return MarkCompactCollector::HasCompacted() ? "Mark-compact" + : "Mark-sweep"; + } + return "Unknown GC"; +} + + +#ifdef DEBUG +bool Heap::GarbageCollectionGreedyCheck() { + ASSERT(FLAG_gc_greedy); + if (Bootstrapper::IsActive()) return true; + if (disallow_allocation_failure()) return true; + return CollectGarbage(0, NEW_SPACE); +} +#endif + +} } // namespace v8::internal |