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// Copyright 2011 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 "liveobjectlist-inl.h"
#include "macro-assembler.h"
#include "mark-compact.h"
#include "platform.h"
namespace v8 {
namespace internal {
// ----------------------------------------------------------------------------
// HeapObjectIterator
HeapObjectIterator::HeapObjectIterator(PagedSpace* space) {
// You can't actually iterate over the anchor page. It is not a real page,
// just an anchor for the double linked page list. Initialize as if we have
// reached the end of the anchor page, then the first iteration will move on
// to the first page.
Initialize(space,
NULL,
NULL,
kAllPagesInSpace,
NULL);
}
HeapObjectIterator::HeapObjectIterator(PagedSpace* space,
HeapObjectCallback size_func) {
// You can't actually iterate over the anchor page. It is not a real page,
// just an anchor for the double linked page list. Initialize the current
// address and end as NULL, then the first iteration will move on
// to the first page.
Initialize(space,
NULL,
NULL,
kAllPagesInSpace,
size_func);
}
HeapObjectIterator::HeapObjectIterator(Page* page,
HeapObjectCallback size_func) {
Space* owner = page->owner();
ASSERT(owner == HEAP->old_pointer_space() ||
owner == HEAP->old_data_space() ||
owner == HEAP->map_space() ||
owner == HEAP->cell_space() ||
owner == HEAP->code_space());
Initialize(reinterpret_cast<PagedSpace*>(owner),
page->area_start(),
page->area_end(),
kOnePageOnly,
size_func);
ASSERT(page->WasSweptPrecisely());
}
void HeapObjectIterator::Initialize(PagedSpace* space,
Address cur, Address end,
HeapObjectIterator::PageMode mode,
HeapObjectCallback size_f) {
// Check that we actually can iterate this space.
ASSERT(!space->was_swept_conservatively());
space_ = space;
cur_addr_ = cur;
cur_end_ = end;
page_mode_ = mode;
size_func_ = size_f;
}
// We have hit the end of the page and should advance to the next block of
// objects. This happens at the end of the page.
bool HeapObjectIterator::AdvanceToNextPage() {
ASSERT(cur_addr_ == cur_end_);
if (page_mode_ == kOnePageOnly) return false;
Page* cur_page;
if (cur_addr_ == NULL) {
cur_page = space_->anchor();
} else {
cur_page = Page::FromAddress(cur_addr_ - 1);
ASSERT(cur_addr_ == cur_page->area_end());
}
cur_page = cur_page->next_page();
if (cur_page == space_->anchor()) return false;
cur_addr_ = cur_page->area_start();
cur_end_ = cur_page->area_end();
ASSERT(cur_page->WasSweptPrecisely());
return true;
}
// -----------------------------------------------------------------------------
// CodeRange
CodeRange::CodeRange(Isolate* isolate)
: isolate_(isolate),
code_range_(NULL),
free_list_(0),
allocation_list_(0),
current_allocation_block_index_(0) {
}
bool CodeRange::SetUp(const size_t requested) {
ASSERT(code_range_ == NULL);
code_range_ = new VirtualMemory(requested);
CHECK(code_range_ != NULL);
if (!code_range_->IsReserved()) {
delete code_range_;
code_range_ = NULL;
return false;
}
// We are sure that we have mapped a block of requested addresses.
ASSERT(code_range_->size() == requested);
LOG(isolate_, NewEvent("CodeRange", code_range_->address(), requested));
Address base = reinterpret_cast<Address>(code_range_->address());
Address aligned_base =
RoundUp(reinterpret_cast<Address>(code_range_->address()),
MemoryChunk::kAlignment);
size_t size = code_range_->size() - (aligned_base - base);
allocation_list_.Add(FreeBlock(aligned_base, size));
current_allocation_block_index_ = 0;
return true;
}
int CodeRange::CompareFreeBlockAddress(const FreeBlock* left,
const FreeBlock* right) {
// The entire point of CodeRange is that the difference between two
// addresses in the range can be represented as a signed 32-bit int,
// so the cast is semantically correct.
return static_cast<int>(left->start - right->start);
}
void CodeRange::GetNextAllocationBlock(size_t requested) {
for (current_allocation_block_index_++;
current_allocation_block_index_ < allocation_list_.length();
current_allocation_block_index_++) {
if (requested <= allocation_list_[current_allocation_block_index_].size) {
return; // Found a large enough allocation block.
}
}
// Sort and merge the free blocks on the free list and the allocation list.
free_list_.AddAll(allocation_list_);
allocation_list_.Clear();
free_list_.Sort(&CompareFreeBlockAddress);
for (int i = 0; i < free_list_.length();) {
FreeBlock merged = free_list_[i];
i++;
// Add adjacent free blocks to the current merged block.
while (i < free_list_.length() &&
free_list_[i].start == merged.start + merged.size) {
merged.size += free_list_[i].size;
i++;
}
if (merged.size > 0) {
allocation_list_.Add(merged);
}
}
free_list_.Clear();
for (current_allocation_block_index_ = 0;
current_allocation_block_index_ < allocation_list_.length();
current_allocation_block_index_++) {
if (requested <= allocation_list_[current_allocation_block_index_].size) {
return; // Found a large enough allocation block.
}
}
// Code range is full or too fragmented.
V8::FatalProcessOutOfMemory("CodeRange::GetNextAllocationBlock");
}
Address CodeRange::AllocateRawMemory(const size_t requested,
size_t* allocated) {
ASSERT(current_allocation_block_index_ < allocation_list_.length());
if (requested > allocation_list_[current_allocation_block_index_].size) {
// Find an allocation block large enough. This function call may
// call V8::FatalProcessOutOfMemory if it cannot find a large enough block.
GetNextAllocationBlock(requested);
}
// Commit the requested memory at the start of the current allocation block.
size_t aligned_requested = RoundUp(requested, MemoryChunk::kAlignment);
FreeBlock current = allocation_list_[current_allocation_block_index_];
if (aligned_requested >= (current.size - Page::kPageSize)) {
// Don't leave a small free block, useless for a large object or chunk.
*allocated = current.size;
} else {
*allocated = aligned_requested;
}
ASSERT(*allocated <= current.size);
ASSERT(IsAddressAligned(current.start, MemoryChunk::kAlignment));
if (!MemoryAllocator::CommitCodePage(code_range_,
current.start,
*allocated)) {
*allocated = 0;
return NULL;
}
allocation_list_[current_allocation_block_index_].start += *allocated;
allocation_list_[current_allocation_block_index_].size -= *allocated;
if (*allocated == current.size) {
GetNextAllocationBlock(0); // This block is used up, get the next one.
}
return current.start;
}
void CodeRange::FreeRawMemory(Address address, size_t length) {
ASSERT(IsAddressAligned(address, MemoryChunk::kAlignment));
free_list_.Add(FreeBlock(address, length));
code_range_->Uncommit(address, length);
}
void CodeRange::TearDown() {
delete code_range_; // Frees all memory in the virtual memory range.
code_range_ = NULL;
free_list_.Free();
allocation_list_.Free();
}
// -----------------------------------------------------------------------------
// MemoryAllocator
//
MemoryAllocator::MemoryAllocator(Isolate* isolate)
: isolate_(isolate),
capacity_(0),
capacity_executable_(0),
size_(0),
size_executable_(0) {
}
bool MemoryAllocator::SetUp(intptr_t capacity, intptr_t capacity_executable) {
capacity_ = RoundUp(capacity, Page::kPageSize);
capacity_executable_ = RoundUp(capacity_executable, Page::kPageSize);
ASSERT_GE(capacity_, capacity_executable_);
size_ = 0;
size_executable_ = 0;
return true;
}
void MemoryAllocator::TearDown() {
// Check that spaces were torn down before MemoryAllocator.
ASSERT(size_ == 0);
// TODO(gc) this will be true again when we fix FreeMemory.
// ASSERT(size_executable_ == 0);
capacity_ = 0;
capacity_executable_ = 0;
}
void MemoryAllocator::FreeMemory(VirtualMemory* reservation,
Executability executable) {
// TODO(gc) make code_range part of memory allocator?
ASSERT(reservation->IsReserved());
size_t size = reservation->size();
ASSERT(size_ >= size);
size_ -= size;
isolate_->counters()->memory_allocated()->Decrement(static_cast<int>(size));
if (executable == EXECUTABLE) {
ASSERT(size_executable_ >= size);
size_executable_ -= size;
}
// Code which is part of the code-range does not have its own VirtualMemory.
ASSERT(!isolate_->code_range()->contains(
static_cast<Address>(reservation->address())));
ASSERT(executable == NOT_EXECUTABLE || !isolate_->code_range()->exists());
reservation->Release();
}
void MemoryAllocator::FreeMemory(Address base,
size_t size,
Executability executable) {
// TODO(gc) make code_range part of memory allocator?
ASSERT(size_ >= size);
size_ -= size;
isolate_->counters()->memory_allocated()->Decrement(static_cast<int>(size));
if (executable == EXECUTABLE) {
ASSERT(size_executable_ >= size);
size_executable_ -= size;
}
if (isolate_->code_range()->contains(static_cast<Address>(base))) {
ASSERT(executable == EXECUTABLE);
isolate_->code_range()->FreeRawMemory(base, size);
} else {
ASSERT(executable == NOT_EXECUTABLE || !isolate_->code_range()->exists());
bool result = VirtualMemory::ReleaseRegion(base, size);
USE(result);
ASSERT(result);
}
}
Address MemoryAllocator::ReserveAlignedMemory(size_t size,
size_t alignment,
VirtualMemory* controller) {
VirtualMemory reservation(size, alignment);
if (!reservation.IsReserved()) return NULL;
size_ += reservation.size();
Address base = RoundUp(static_cast<Address>(reservation.address()),
alignment);
controller->TakeControl(&reservation);
return base;
}
Address MemoryAllocator::AllocateAlignedMemory(size_t size,
size_t alignment,
Executability executable,
VirtualMemory* controller) {
VirtualMemory reservation;
Address base = ReserveAlignedMemory(size, alignment, &reservation);
if (base == NULL) return NULL;
if (executable == EXECUTABLE) {
CommitCodePage(&reservation, base, size);
} else {
if (!reservation.Commit(base,
size,
executable == EXECUTABLE)) {
return NULL;
}
}
controller->TakeControl(&reservation);
return base;
}
void Page::InitializeAsAnchor(PagedSpace* owner) {
set_owner(owner);
set_prev_page(this);
set_next_page(this);
}
NewSpacePage* NewSpacePage::Initialize(Heap* heap,
Address start,
SemiSpace* semi_space) {
Address area_start = start + NewSpacePage::kObjectStartOffset;
Address area_end = start + Page::kPageSize;
MemoryChunk* chunk = MemoryChunk::Initialize(heap,
start,
Page::kPageSize,
area_start,
area_end,
NOT_EXECUTABLE,
semi_space);
chunk->set_next_chunk(NULL);
chunk->set_prev_chunk(NULL);
chunk->initialize_scan_on_scavenge(true);
bool in_to_space = (semi_space->id() != kFromSpace);
chunk->SetFlag(in_to_space ? MemoryChunk::IN_TO_SPACE
: MemoryChunk::IN_FROM_SPACE);
ASSERT(!chunk->IsFlagSet(in_to_space ? MemoryChunk::IN_FROM_SPACE
: MemoryChunk::IN_TO_SPACE));
NewSpacePage* page = static_cast<NewSpacePage*>(chunk);
heap->incremental_marking()->SetNewSpacePageFlags(page);
return page;
}
void NewSpacePage::InitializeAsAnchor(SemiSpace* semi_space) {
set_owner(semi_space);
set_next_chunk(this);
set_prev_chunk(this);
// Flags marks this invalid page as not being in new-space.
// All real new-space pages will be in new-space.
SetFlags(0, ~0);
}
MemoryChunk* MemoryChunk::Initialize(Heap* heap,
Address base,
size_t size,
Address area_start,
Address area_end,
Executability executable,
Space* owner) {
MemoryChunk* chunk = FromAddress(base);
ASSERT(base == chunk->address());
chunk->heap_ = heap;
chunk->size_ = size;
chunk->area_start_ = area_start;
chunk->area_end_ = area_end;
chunk->flags_ = 0;
chunk->set_owner(owner);
chunk->InitializeReservedMemory();
chunk->slots_buffer_ = NULL;
chunk->skip_list_ = NULL;
chunk->ResetLiveBytes();
Bitmap::Clear(chunk);
chunk->initialize_scan_on_scavenge(false);
chunk->SetFlag(WAS_SWEPT_PRECISELY);
ASSERT(OFFSET_OF(MemoryChunk, flags_) == kFlagsOffset);
ASSERT(OFFSET_OF(MemoryChunk, live_byte_count_) == kLiveBytesOffset);
if (executable == EXECUTABLE) {
chunk->SetFlag(IS_EXECUTABLE);
}
if (owner == heap->old_data_space()) {
chunk->SetFlag(CONTAINS_ONLY_DATA);
}
return chunk;
}
void MemoryChunk::InsertAfter(MemoryChunk* other) {
next_chunk_ = other->next_chunk_;
prev_chunk_ = other;
other->next_chunk_->prev_chunk_ = this;
other->next_chunk_ = this;
}
void MemoryChunk::Unlink() {
if (!InNewSpace() && IsFlagSet(SCAN_ON_SCAVENGE)) {
heap_->decrement_scan_on_scavenge_pages();
ClearFlag(SCAN_ON_SCAVENGE);
}
next_chunk_->prev_chunk_ = prev_chunk_;
prev_chunk_->next_chunk_ = next_chunk_;
prev_chunk_ = NULL;
next_chunk_ = NULL;
}
MemoryChunk* MemoryAllocator::AllocateChunk(intptr_t body_size,
Executability executable,
Space* owner) {
size_t chunk_size;
Heap* heap = isolate_->heap();
Address base = NULL;
VirtualMemory reservation;
Address area_start = NULL;
Address area_end = NULL;
if (executable == EXECUTABLE) {
chunk_size = RoundUp(CodePageAreaStartOffset() + body_size,
OS::CommitPageSize()) + CodePageGuardSize();
// Check executable memory limit.
if (size_executable_ + chunk_size > capacity_executable_) {
LOG(isolate_,
StringEvent("MemoryAllocator::AllocateRawMemory",
"V8 Executable Allocation capacity exceeded"));
return NULL;
}
// Allocate executable memory either from code range or from the
// OS.
if (isolate_->code_range()->exists()) {
base = isolate_->code_range()->AllocateRawMemory(chunk_size, &chunk_size);
ASSERT(IsAligned(reinterpret_cast<intptr_t>(base),
MemoryChunk::kAlignment));
if (base == NULL) return NULL;
size_ += chunk_size;
// Update executable memory size.
size_executable_ += chunk_size;
} else {
base = AllocateAlignedMemory(chunk_size,
MemoryChunk::kAlignment,
executable,
&reservation);
if (base == NULL) return NULL;
// Update executable memory size.
size_executable_ += reservation.size();
}
#ifdef DEBUG
ZapBlock(base, CodePageGuardStartOffset());
ZapBlock(base + CodePageAreaStartOffset(), body_size);
#endif
area_start = base + CodePageAreaStartOffset();
area_end = area_start + body_size;
} else {
chunk_size = MemoryChunk::kObjectStartOffset + body_size;
base = AllocateAlignedMemory(chunk_size,
MemoryChunk::kAlignment,
executable,
&reservation);
if (base == NULL) return NULL;
#ifdef DEBUG
ZapBlock(base, chunk_size);
#endif
area_start = base + Page::kObjectStartOffset;
area_end = base + chunk_size;
}
isolate_->counters()->memory_allocated()->
Increment(static_cast<int>(chunk_size));
LOG(isolate_, NewEvent("MemoryChunk", base, chunk_size));
if (owner != NULL) {
ObjectSpace space = static_cast<ObjectSpace>(1 << owner->identity());
PerformAllocationCallback(space, kAllocationActionAllocate, chunk_size);
}
MemoryChunk* result = MemoryChunk::Initialize(heap,
base,
chunk_size,
area_start,
area_end,
executable,
owner);
result->set_reserved_memory(&reservation);
return result;
}
Page* MemoryAllocator::AllocatePage(intptr_t size,
PagedSpace* owner,
Executability executable) {
MemoryChunk* chunk = AllocateChunk(size, executable, owner);
if (chunk == NULL) return NULL;
return Page::Initialize(isolate_->heap(), chunk, executable, owner);
}
LargePage* MemoryAllocator::AllocateLargePage(intptr_t object_size,
Space* owner,
Executability executable) {
MemoryChunk* chunk = AllocateChunk(object_size, executable, owner);
if (chunk == NULL) return NULL;
return LargePage::Initialize(isolate_->heap(), chunk);
}
void MemoryAllocator::Free(MemoryChunk* chunk) {
LOG(isolate_, DeleteEvent("MemoryChunk", chunk));
if (chunk->owner() != NULL) {
ObjectSpace space =
static_cast<ObjectSpace>(1 << chunk->owner()->identity());
PerformAllocationCallback(space, kAllocationActionFree, chunk->size());
}
isolate_->heap()->RememberUnmappedPage(
reinterpret_cast<Address>(chunk), chunk->IsEvacuationCandidate());
delete chunk->slots_buffer();
delete chunk->skip_list();
VirtualMemory* reservation = chunk->reserved_memory();
if (reservation->IsReserved()) {
FreeMemory(reservation, chunk->executable());
} else {
FreeMemory(chunk->address(),
chunk->size(),
chunk->executable());
}
}
bool MemoryAllocator::CommitBlock(Address start,
size_t size,
Executability executable) {
if (!VirtualMemory::CommitRegion(start, size, executable)) return false;
#ifdef DEBUG
ZapBlock(start, size);
#endif
isolate_->counters()->memory_allocated()->Increment(static_cast<int>(size));
return true;
}
bool MemoryAllocator::UncommitBlock(Address start, size_t size) {
if (!VirtualMemory::UncommitRegion(start, size)) return false;
isolate_->counters()->memory_allocated()->Decrement(static_cast<int>(size));
return true;
}
void MemoryAllocator::ZapBlock(Address start, size_t size) {
for (size_t s = 0; s + kPointerSize <= size; s += kPointerSize) {
Memory::Address_at(start + s) = kZapValue;
}
}
void MemoryAllocator::PerformAllocationCallback(ObjectSpace space,
AllocationAction action,
size_t size) {
for (int i = 0; i < memory_allocation_callbacks_.length(); ++i) {
MemoryAllocationCallbackRegistration registration =
memory_allocation_callbacks_[i];
if ((registration.space & space) == space &&
(registration.action & action) == action)
registration.callback(space, action, static_cast<int>(size));
}
}
bool MemoryAllocator::MemoryAllocationCallbackRegistered(
MemoryAllocationCallback callback) {
for (int i = 0; i < memory_allocation_callbacks_.length(); ++i) {
if (memory_allocation_callbacks_[i].callback == callback) return true;
}
return false;
}
void MemoryAllocator::AddMemoryAllocationCallback(
MemoryAllocationCallback callback,
ObjectSpace space,
AllocationAction action) {
ASSERT(callback != NULL);
MemoryAllocationCallbackRegistration registration(callback, space, action);
ASSERT(!MemoryAllocator::MemoryAllocationCallbackRegistered(callback));
return memory_allocation_callbacks_.Add(registration);
}
void MemoryAllocator::RemoveMemoryAllocationCallback(
MemoryAllocationCallback callback) {
ASSERT(callback != NULL);
for (int i = 0; i < memory_allocation_callbacks_.length(); ++i) {
if (memory_allocation_callbacks_[i].callback == callback) {
memory_allocation_callbacks_.Remove(i);
return;
}
}
UNREACHABLE();
}
#ifdef DEBUG
void MemoryAllocator::ReportStatistics() {
float pct = static_cast<float>(capacity_ - size_) / capacity_;
PrintF(" capacity: %" V8_PTR_PREFIX "d"
", used: %" V8_PTR_PREFIX "d"
", available: %%%d\n\n",
capacity_, size_, static_cast<int>(pct*100));
}
#endif
int MemoryAllocator::CodePageGuardStartOffset() {
// We are guarding code pages: the first OS page after the header
// will be protected as non-writable.
return RoundUp(Page::kObjectStartOffset, OS::CommitPageSize());
}
int MemoryAllocator::CodePageGuardSize() {
return static_cast<int>(OS::CommitPageSize());
}
int MemoryAllocator::CodePageAreaStartOffset() {
// We are guarding code pages: the first OS page after the header
// will be protected as non-writable.
return CodePageGuardStartOffset() + CodePageGuardSize();
}
int MemoryAllocator::CodePageAreaEndOffset() {
// We are guarding code pages: the last OS page will be protected as
// non-writable.
return Page::kPageSize - static_cast<int>(OS::CommitPageSize());
}
bool MemoryAllocator::CommitCodePage(VirtualMemory* vm,
Address start,
size_t size) {
// Commit page header (not executable).
if (!vm->Commit(start,
CodePageGuardStartOffset(),
false)) {
return false;
}
// Create guard page after the header.
if (!vm->Guard(start + CodePageGuardStartOffset())) {
return false;
}
// Commit page body (executable).
size_t area_size = size - CodePageAreaStartOffset() - CodePageGuardSize();
if (!vm->Commit(start + CodePageAreaStartOffset(),
area_size,
true)) {
return false;
}
// Create guard page after the allocatable area.
if (!vm->Guard(start + CodePageAreaStartOffset() + area_size)) {
return false;
}
return true;
}
// -----------------------------------------------------------------------------
// MemoryChunk implementation
void MemoryChunk::IncrementLiveBytesFromMutator(Address address, int by) {
MemoryChunk* chunk = MemoryChunk::FromAddress(address);
if (!chunk->InNewSpace() && !static_cast<Page*>(chunk)->WasSwept()) {
static_cast<PagedSpace*>(chunk->owner())->IncrementUnsweptFreeBytes(-by);
}
chunk->IncrementLiveBytes(by);
}
// -----------------------------------------------------------------------------
// PagedSpace implementation
PagedSpace::PagedSpace(Heap* heap,
intptr_t max_capacity,
AllocationSpace id,
Executability executable)
: Space(heap, id, executable),
free_list_(this),
was_swept_conservatively_(false),
first_unswept_page_(Page::FromAddress(NULL)),
unswept_free_bytes_(0) {
if (id == CODE_SPACE) {
area_size_ = heap->isolate()->memory_allocator()->
CodePageAreaSize();
} else {
area_size_ = Page::kPageSize - Page::kObjectStartOffset;
}
max_capacity_ = (RoundDown(max_capacity, Page::kPageSize) / Page::kPageSize)
* AreaSize();
accounting_stats_.Clear();
allocation_info_.top = NULL;
allocation_info_.limit = NULL;
anchor_.InitializeAsAnchor(this);
}
bool PagedSpace::SetUp() {
return true;
}
bool PagedSpace::HasBeenSetUp() {
return true;
}
void PagedSpace::TearDown() {
PageIterator iterator(this);
while (iterator.has_next()) {
heap()->isolate()->memory_allocator()->Free(iterator.next());
}
anchor_.set_next_page(&anchor_);
anchor_.set_prev_page(&anchor_);
accounting_stats_.Clear();
}
MaybeObject* PagedSpace::FindObject(Address addr) {
// Note: this function can only be called on precisely swept spaces.
ASSERT(!heap()->mark_compact_collector()->in_use());
if (!Contains(addr)) return Failure::Exception();
Page* p = Page::FromAddress(addr);
HeapObjectIterator it(p, NULL);
for (HeapObject* obj = it.Next(); obj != NULL; obj = it.Next()) {
Address cur = obj->address();
Address next = cur + obj->Size();
if ((cur <= addr) && (addr < next)) return obj;
}
UNREACHABLE();
return Failure::Exception();
}
bool PagedSpace::CanExpand() {
ASSERT(max_capacity_ % AreaSize() == 0);
if (Capacity() == max_capacity_) return false;
ASSERT(Capacity() < max_capacity_);
// Are we going to exceed capacity for this space?
if ((Capacity() + Page::kPageSize) > max_capacity_) return false;
return true;
}
bool PagedSpace::Expand() {
if (!CanExpand()) return false;
intptr_t size = AreaSize();
if (anchor_.next_page() == &anchor_) {
size = SizeOfFirstPage();
}
Page* p = heap()->isolate()->memory_allocator()->AllocatePage(
size, this, executable());
if (p == NULL) return false;
ASSERT(Capacity() <= max_capacity_);
p->InsertAfter(anchor_.prev_page());
return true;
}
intptr_t PagedSpace::SizeOfFirstPage() {
int size = 0;
switch (identity()) {
case OLD_POINTER_SPACE:
size = 64 * kPointerSize * KB;
break;
case OLD_DATA_SPACE:
size = 192 * KB;
break;
case MAP_SPACE:
size = 128 * KB;
break;
case CELL_SPACE:
size = 96 * KB;
break;
case CODE_SPACE:
if (kPointerSize == 8) {
// On x64 we allocate code pages in a special way (from the reserved
// 2Byte area). That part of the code is not yet upgraded to handle
// small pages.
size = AreaSize();
} else {
size = 384 * KB;
}
break;
default:
UNREACHABLE();
}
return Min(size, AreaSize());
}
int PagedSpace::CountTotalPages() {
PageIterator it(this);
int count = 0;
while (it.has_next()) {
it.next();
count++;
}
return count;
}
void PagedSpace::ReleasePage(Page* page) {
ASSERT(page->LiveBytes() == 0);
ASSERT(AreaSize() == page->area_size());
// Adjust list of unswept pages if the page is the head of the list.
if (first_unswept_page_ == page) {
first_unswept_page_ = page->next_page();
if (first_unswept_page_ == anchor()) {
first_unswept_page_ = Page::FromAddress(NULL);
}
}
if (page->WasSwept()) {
intptr_t size = free_list_.EvictFreeListItems(page);
accounting_stats_.AllocateBytes(size);
ASSERT_EQ(AreaSize(), static_cast<int>(size));
} else {
DecreaseUnsweptFreeBytes(page);
}
if (Page::FromAllocationTop(allocation_info_.top) == page) {
allocation_info_.top = allocation_info_.limit = NULL;
}
page->Unlink();
if (page->IsFlagSet(MemoryChunk::CONTAINS_ONLY_DATA)) {
heap()->isolate()->memory_allocator()->Free(page);
} else {
heap()->QueueMemoryChunkForFree(page);
}
ASSERT(Capacity() > 0);
accounting_stats_.ShrinkSpace(AreaSize());
}
void PagedSpace::ReleaseAllUnusedPages() {
PageIterator it(this);
while (it.has_next()) {
Page* page = it.next();
if (!page->WasSwept()) {
if (page->LiveBytes() == 0) ReleasePage(page);
} else {
HeapObject* obj = HeapObject::FromAddress(page->area_start());
if (obj->IsFreeSpace() &&
FreeSpace::cast(obj)->size() == AreaSize()) {
// Sometimes we allocate memory from free list but don't
// immediately initialize it (e.g. see PagedSpace::ReserveSpace
// called from Heap::ReserveSpace that can cause GC before
// reserved space is actually initialized).
// Thus we can't simply assume that obj represents a valid
// node still owned by a free list
// Instead we should verify that the page is fully covered
// by free list items.
FreeList::SizeStats sizes;
free_list_.CountFreeListItems(page, &sizes);
if (sizes.Total() == AreaSize()) {
ReleasePage(page);
}
}
}
}
heap()->FreeQueuedChunks();
}
#ifdef DEBUG
void PagedSpace::Print() { }
#endif
#ifdef DEBUG
void PagedSpace::Verify(ObjectVisitor* visitor) {
// We can only iterate over the pages if they were swept precisely.
if (was_swept_conservatively_) return;
bool allocation_pointer_found_in_space =
(allocation_info_.top == allocation_info_.limit);
PageIterator page_iterator(this);
while (page_iterator.has_next()) {
Page* page = page_iterator.next();
ASSERT(page->owner() == this);
if (page == Page::FromAllocationTop(allocation_info_.top)) {
allocation_pointer_found_in_space = true;
}
ASSERT(page->WasSweptPrecisely());
HeapObjectIterator it(page, NULL);
Address end_of_previous_object = page->area_start();
Address top = page->area_end();
int black_size = 0;
for (HeapObject* object = it.Next(); object != NULL; object = it.Next()) {
ASSERT(end_of_previous_object <= object->address());
// The first word should be a map, and we expect all map pointers to
// be in map space.
Map* map = object->map();
ASSERT(map->IsMap());
ASSERT(heap()->map_space()->Contains(map));
// Perform space-specific object verification.
VerifyObject(object);
// The object itself should look OK.
object->Verify();
// All the interior pointers should be contained in the heap.
int size = object->Size();
object->IterateBody(map->instance_type(), size, visitor);
if (Marking::IsBlack(Marking::MarkBitFrom(object))) {
black_size += size;
}
ASSERT(object->address() + size <= top);
end_of_previous_object = object->address() + size;
}
ASSERT_LE(black_size, page->LiveBytes());
}
ASSERT(allocation_pointer_found_in_space);
}
#endif
// -----------------------------------------------------------------------------
// NewSpace implementation
bool NewSpace::SetUp(int reserved_semispace_capacity,
int maximum_semispace_capacity) {
// Set up new space based on the preallocated memory block defined by
// start and size. The provided space is divided into two semi-spaces.
// To support fast containment testing in the new space, the size of
// this chunk must be a power of two and it must be aligned to its size.
int initial_semispace_capacity = heap()->InitialSemiSpaceSize();
size_t size = 2 * reserved_semispace_capacity;
Address base =
heap()->isolate()->memory_allocator()->ReserveAlignedMemory(
size, size, &reservation_);
if (base == NULL) return false;
chunk_base_ = base;
chunk_size_ = static_cast<uintptr_t>(size);
LOG(heap()->isolate(), NewEvent("InitialChunk", chunk_base_, chunk_size_));
ASSERT(initial_semispace_capacity <= maximum_semispace_capacity);
ASSERT(IsPowerOf2(maximum_semispace_capacity));
// Allocate and set up the histogram arrays if necessary.
allocated_histogram_ = NewArray<HistogramInfo>(LAST_TYPE + 1);
promoted_histogram_ = NewArray<HistogramInfo>(LAST_TYPE + 1);
#define SET_NAME(name) allocated_histogram_[name].set_name(#name); \
promoted_histogram_[name].set_name(#name);
INSTANCE_TYPE_LIST(SET_NAME)
#undef SET_NAME
ASSERT(reserved_semispace_capacity == heap()->ReservedSemiSpaceSize());
ASSERT(static_cast<intptr_t>(chunk_size_) >=
2 * heap()->ReservedSemiSpaceSize());
ASSERT(IsAddressAligned(chunk_base_, 2 * reserved_semispace_capacity, 0));
to_space_.SetUp(chunk_base_,
initial_semispace_capacity,
maximum_semispace_capacity);
from_space_.SetUp(chunk_base_ + reserved_semispace_capacity,
initial_semispace_capacity,
maximum_semispace_capacity);
if (!to_space_.Commit()) {
return false;
}
ASSERT(!from_space_.is_committed()); // No need to use memory yet.
start_ = chunk_base_;
address_mask_ = ~(2 * reserved_semispace_capacity - 1);
object_mask_ = address_mask_ | kHeapObjectTagMask;
object_expected_ = reinterpret_cast<uintptr_t>(start_) | kHeapObjectTag;
ResetAllocationInfo();
return true;
}
void NewSpace::TearDown() {
if (allocated_histogram_) {
DeleteArray(allocated_histogram_);
allocated_histogram_ = NULL;
}
if (promoted_histogram_) {
DeleteArray(promoted_histogram_);
promoted_histogram_ = NULL;
}
start_ = NULL;
allocation_info_.top = NULL;
allocation_info_.limit = NULL;
to_space_.TearDown();
from_space_.TearDown();
LOG(heap()->isolate(), DeleteEvent("InitialChunk", chunk_base_));
ASSERT(reservation_.IsReserved());
heap()->isolate()->memory_allocator()->FreeMemory(&reservation_,
NOT_EXECUTABLE);
chunk_base_ = NULL;
chunk_size_ = 0;
}
void NewSpace::Flip() {
SemiSpace::Swap(&from_space_, &to_space_);
}
void NewSpace::Grow() {
// Double the semispace size but only up to maximum capacity.
ASSERT(Capacity() < MaximumCapacity());
int new_capacity = Min(MaximumCapacity(), 2 * static_cast<int>(Capacity()));
if (to_space_.GrowTo(new_capacity)) {
// Only grow from space if we managed to grow to-space.
if (!from_space_.GrowTo(new_capacity)) {
// If we managed to grow to-space but couldn't grow from-space,
// attempt to shrink to-space.
if (!to_space_.ShrinkTo(from_space_.Capacity())) {
// We are in an inconsistent state because we could not
// commit/uncommit memory from new space.
V8::FatalProcessOutOfMemory("Failed to grow new space.");
}
}
}
ASSERT_SEMISPACE_ALLOCATION_INFO(allocation_info_, to_space_);
}
void NewSpace::Shrink() {
int new_capacity = Max(InitialCapacity(), 2 * SizeAsInt());
int rounded_new_capacity = RoundUp(new_capacity, Page::kPageSize);
if (rounded_new_capacity < Capacity() &&
to_space_.ShrinkTo(rounded_new_capacity)) {
// Only shrink from-space if we managed to shrink to-space.
from_space_.Reset();
if (!from_space_.ShrinkTo(rounded_new_capacity)) {
// If we managed to shrink to-space but couldn't shrink from
// space, attempt to grow to-space again.
if (!to_space_.GrowTo(from_space_.Capacity())) {
// We are in an inconsistent state because we could not
// commit/uncommit memory from new space.
V8::FatalProcessOutOfMemory("Failed to shrink new space.");
}
}
}
allocation_info_.limit = to_space_.page_high();
ASSERT_SEMISPACE_ALLOCATION_INFO(allocation_info_, to_space_);
}
void NewSpace::UpdateAllocationInfo() {
allocation_info_.top = to_space_.page_low();
allocation_info_.limit = to_space_.page_high();
// Lower limit during incremental marking.
if (heap()->incremental_marking()->IsMarking() &&
inline_allocation_limit_step() != 0) {
Address new_limit =
allocation_info_.top + inline_allocation_limit_step();
allocation_info_.limit = Min(new_limit, allocation_info_.limit);
}
ASSERT_SEMISPACE_ALLOCATION_INFO(allocation_info_, to_space_);
}
void NewSpace::ResetAllocationInfo() {
to_space_.Reset();
UpdateAllocationInfo();
pages_used_ = 0;
// Clear all mark-bits in the to-space.
NewSpacePageIterator it(&to_space_);
while (it.has_next()) {
Bitmap::Clear(it.next());
}
}
bool NewSpace::AddFreshPage() {
Address top = allocation_info_.top;
if (NewSpacePage::IsAtStart(top)) {
// The current page is already empty. Don't try to make another.
// We should only get here if someone asks to allocate more
// than what can be stored in a single page.
// TODO(gc): Change the limit on new-space allocation to prevent this
// from happening (all such allocations should go directly to LOSpace).
return false;
}
if (!to_space_.AdvancePage()) {
// Failed to get a new page in to-space.
return false;
}
// Clear remainder of current page.
Address limit = NewSpacePage::FromLimit(top)->area_end();
if (heap()->gc_state() == Heap::SCAVENGE) {
heap()->promotion_queue()->SetNewLimit(limit);
heap()->promotion_queue()->ActivateGuardIfOnTheSamePage();
}
int remaining_in_page = static_cast<int>(limit - top);
heap()->CreateFillerObjectAt(top, remaining_in_page);
pages_used_++;
UpdateAllocationInfo();
return true;
}
MaybeObject* NewSpace::SlowAllocateRaw(int size_in_bytes) {
Address old_top = allocation_info_.top;
Address new_top = old_top + size_in_bytes;
Address high = to_space_.page_high();
if (allocation_info_.limit < high) {
// Incremental marking has lowered the limit to get a
// chance to do a step.
allocation_info_.limit = Min(
allocation_info_.limit + inline_allocation_limit_step_,
high);
int bytes_allocated = static_cast<int>(new_top - top_on_previous_step_);
heap()->incremental_marking()->Step(
bytes_allocated, IncrementalMarking::GC_VIA_STACK_GUARD);
top_on_previous_step_ = new_top;
return AllocateRaw(size_in_bytes);
} else if (AddFreshPage()) {
// Switched to new page. Try allocating again.
int bytes_allocated = static_cast<int>(old_top - top_on_previous_step_);
heap()->incremental_marking()->Step(
bytes_allocated, IncrementalMarking::GC_VIA_STACK_GUARD);
top_on_previous_step_ = to_space_.page_low();
return AllocateRaw(size_in_bytes);
} else {
return Failure::RetryAfterGC();
}
}
#ifdef DEBUG
// We do not use the SemiSpaceIterator because verification doesn't assume
// that it works (it depends on the invariants we are checking).
void NewSpace::Verify() {
// The allocation pointer should be in the space or at the very end.
ASSERT_SEMISPACE_ALLOCATION_INFO(allocation_info_, to_space_);
// There should be objects packed in from the low address up to the
// allocation pointer.
Address current = to_space_.first_page()->area_start();
CHECK_EQ(current, to_space_.space_start());
while (current != top()) {
if (!NewSpacePage::IsAtEnd(current)) {
// The allocation pointer should not be in the middle of an object.
CHECK(!NewSpacePage::FromLimit(current)->ContainsLimit(top()) ||
current < top());
HeapObject* object = HeapObject::FromAddress(current);
// The first word should be a map, and we expect all map pointers to
// be in map space.
Map* map = object->map();
CHECK(map->IsMap());
CHECK(heap()->map_space()->Contains(map));
// The object should not be code or a map.
CHECK(!object->IsMap());
CHECK(!object->IsCode());
// The object itself should look OK.
object->Verify();
// All the interior pointers should be contained in the heap.
VerifyPointersVisitor visitor;
int size = object->Size();
object->IterateBody(map->instance_type(), size, &visitor);
current += size;
} else {
// At end of page, switch to next page.
NewSpacePage* page = NewSpacePage::FromLimit(current)->next_page();
// Next page should be valid.
CHECK(!page->is_anchor());
current = page->area_start();
}
}
// Check semi-spaces.
ASSERT_EQ(from_space_.id(), kFromSpace);
ASSERT_EQ(to_space_.id(), kToSpace);
from_space_.Verify();
to_space_.Verify();
}
#endif
// -----------------------------------------------------------------------------
// SemiSpace implementation
void SemiSpace::SetUp(Address start,
int initial_capacity,
int maximum_capacity) {
// Creates a space in the young generation. The constructor does not
// allocate memory from the OS. A SemiSpace is given a contiguous chunk of
// memory of size 'capacity' when set up, and does not grow or shrink
// otherwise. In the mark-compact collector, the memory region of the from
// space is used as the marking stack. It requires contiguous memory
// addresses.
ASSERT(maximum_capacity >= Page::kPageSize);
initial_capacity_ = RoundDown(initial_capacity, Page::kPageSize);
capacity_ = initial_capacity;
maximum_capacity_ = RoundDown(maximum_capacity, Page::kPageSize);
committed_ = false;
start_ = start;
address_mask_ = ~(maximum_capacity - 1);
object_mask_ = address_mask_ | kHeapObjectTagMask;
object_expected_ = reinterpret_cast<uintptr_t>(start) | kHeapObjectTag;
age_mark_ = start_;
}
void SemiSpace::TearDown() {
start_ = NULL;
capacity_ = 0;
}
bool SemiSpace::Commit() {
ASSERT(!is_committed());
int pages = capacity_ / Page::kPageSize;
Address end = start_ + maximum_capacity_;
Address start = end - pages * Page::kPageSize;
if (!heap()->isolate()->memory_allocator()->CommitBlock(start,
capacity_,
executable())) {
return false;
}
NewSpacePage* page = anchor();
for (int i = 1; i <= pages; i++) {
NewSpacePage* new_page =
NewSpacePage::Initialize(heap(), end - i * Page::kPageSize, this);
new_page->InsertAfter(page);
page = new_page;
}
committed_ = true;
Reset();
return true;
}
bool SemiSpace::Uncommit() {
ASSERT(is_committed());
Address start = start_ + maximum_capacity_ - capacity_;
if (!heap()->isolate()->memory_allocator()->UncommitBlock(start, capacity_)) {
return false;
}
anchor()->set_next_page(anchor());
anchor()->set_prev_page(anchor());
committed_ = false;
return true;
}
bool SemiSpace::GrowTo(int new_capacity) {
if (!is_committed()) {
if (!Commit()) return false;
}
ASSERT((new_capacity & Page::kPageAlignmentMask) == 0);
ASSERT(new_capacity <= maximum_capacity_);
ASSERT(new_capacity > capacity_);
int pages_before = capacity_ / Page::kPageSize;
int pages_after = new_capacity / Page::kPageSize;
Address end = start_ + maximum_capacity_;
Address start = end - new_capacity;
size_t delta = new_capacity - capacity_;
ASSERT(IsAligned(delta, OS::AllocateAlignment()));
if (!heap()->isolate()->memory_allocator()->CommitBlock(
start, delta, executable())) {
return false;
}
capacity_ = new_capacity;
NewSpacePage* last_page = anchor()->prev_page();
ASSERT(last_page != anchor());
for (int i = pages_before + 1; i <= pages_after; i++) {
Address page_address = end - i * Page::kPageSize;
NewSpacePage* new_page = NewSpacePage::Initialize(heap(),
page_address,
this);
new_page->InsertAfter(last_page);
Bitmap::Clear(new_page);
// Duplicate the flags that was set on the old page.
new_page->SetFlags(last_page->GetFlags(),
NewSpacePage::kCopyOnFlipFlagsMask);
last_page = new_page;
}
return true;
}
bool SemiSpace::ShrinkTo(int new_capacity) {
ASSERT((new_capacity & Page::kPageAlignmentMask) == 0);
ASSERT(new_capacity >= initial_capacity_);
ASSERT(new_capacity < capacity_);
if (is_committed()) {
// Semispaces grow backwards from the end of their allocated capacity,
// so we find the before and after start addresses relative to the
// end of the space.
Address space_end = start_ + maximum_capacity_;
Address old_start = space_end - capacity_;
size_t delta = capacity_ - new_capacity;
ASSERT(IsAligned(delta, OS::AllocateAlignment()));
MemoryAllocator* allocator = heap()->isolate()->memory_allocator();
if (!allocator->UncommitBlock(old_start, delta)) {
return false;
}
int pages_after = new_capacity / Page::kPageSize;
NewSpacePage* new_last_page =
NewSpacePage::FromAddress(space_end - pages_after * Page::kPageSize);
new_last_page->set_next_page(anchor());
anchor()->set_prev_page(new_last_page);
ASSERT((current_page_ <= first_page()) && (current_page_ >= new_last_page));
}
capacity_ = new_capacity;
return true;
}
void SemiSpace::FlipPages(intptr_t flags, intptr_t mask) {
anchor_.set_owner(this);
// Fixup back-pointers to anchor. Address of anchor changes
// when we swap.
anchor_.prev_page()->set_next_page(&anchor_);
anchor_.next_page()->set_prev_page(&anchor_);
bool becomes_to_space = (id_ == kFromSpace);
id_ = becomes_to_space ? kToSpace : kFromSpace;
NewSpacePage* page = anchor_.next_page();
while (page != &anchor_) {
page->set_owner(this);
page->SetFlags(flags, mask);
if (becomes_to_space) {
page->ClearFlag(MemoryChunk::IN_FROM_SPACE);
page->SetFlag(MemoryChunk::IN_TO_SPACE);
page->ClearFlag(MemoryChunk::NEW_SPACE_BELOW_AGE_MARK);
page->ResetLiveBytes();
} else {
page->SetFlag(MemoryChunk::IN_FROM_SPACE);
page->ClearFlag(MemoryChunk::IN_TO_SPACE);
}
ASSERT(page->IsFlagSet(MemoryChunk::SCAN_ON_SCAVENGE));
ASSERT(page->IsFlagSet(MemoryChunk::IN_TO_SPACE) ||
page->IsFlagSet(MemoryChunk::IN_FROM_SPACE));
page = page->next_page();
}
}
void SemiSpace::Reset() {
ASSERT(anchor_.next_page() != &anchor_);
current_page_ = anchor_.next_page();
}
void SemiSpace::Swap(SemiSpace* from, SemiSpace* to) {
// We won't be swapping semispaces without data in them.
ASSERT(from->anchor_.next_page() != &from->anchor_);
ASSERT(to->anchor_.next_page() != &to->anchor_);
// Swap bits.
SemiSpace tmp = *from;
*from = *to;
*to = tmp;
// Fixup back-pointers to the page list anchor now that its address
// has changed.
// Swap to/from-space bits on pages.
// Copy GC flags from old active space (from-space) to new (to-space).
intptr_t flags = from->current_page()->GetFlags();
to->FlipPages(flags, NewSpacePage::kCopyOnFlipFlagsMask);
from->FlipPages(0, 0);
}
void SemiSpace::set_age_mark(Address mark) {
ASSERT(NewSpacePage::FromLimit(mark)->semi_space() == this);
age_mark_ = mark;
// Mark all pages up to the one containing mark.
NewSpacePageIterator it(space_start(), mark);
while (it.has_next()) {
it.next()->SetFlag(MemoryChunk::NEW_SPACE_BELOW_AGE_MARK);
}
}
#ifdef DEBUG
void SemiSpace::Print() { }
void SemiSpace::Verify() {
bool is_from_space = (id_ == kFromSpace);
NewSpacePage* page = anchor_.next_page();
CHECK(anchor_.semi_space() == this);
while (page != &anchor_) {
CHECK(page->semi_space() == this);
CHECK(page->InNewSpace());
CHECK(page->IsFlagSet(is_from_space ? MemoryChunk::IN_FROM_SPACE
: MemoryChunk::IN_TO_SPACE));
CHECK(!page->IsFlagSet(is_from_space ? MemoryChunk::IN_TO_SPACE
: MemoryChunk::IN_FROM_SPACE));
CHECK(page->IsFlagSet(MemoryChunk::POINTERS_TO_HERE_ARE_INTERESTING));
if (!is_from_space) {
// The pointers-from-here-are-interesting flag isn't updated dynamically
// on from-space pages, so it might be out of sync with the marking state.
if (page->heap()->incremental_marking()->IsMarking()) {
CHECK(page->IsFlagSet(MemoryChunk::POINTERS_FROM_HERE_ARE_INTERESTING));
} else {
CHECK(!page->IsFlagSet(
MemoryChunk::POINTERS_FROM_HERE_ARE_INTERESTING));
}
// TODO(gc): Check that the live_bytes_count_ field matches the
// black marking on the page (if we make it match in new-space).
}
CHECK(page->IsFlagSet(MemoryChunk::SCAN_ON_SCAVENGE));
CHECK(page->prev_page()->next_page() == page);
page = page->next_page();
}
}
void SemiSpace::AssertValidRange(Address start, Address end) {
// Addresses belong to same semi-space
NewSpacePage* page = NewSpacePage::FromLimit(start);
NewSpacePage* end_page = NewSpacePage::FromLimit(end);
SemiSpace* space = page->semi_space();
CHECK_EQ(space, end_page->semi_space());
// Start address is before end address, either on same page,
// or end address is on a later page in the linked list of
// semi-space pages.
if (page == end_page) {
CHECK(start <= end);
} else {
while (page != end_page) {
page = page->next_page();
CHECK_NE(page, space->anchor());
}
}
}
#endif
// -----------------------------------------------------------------------------
// SemiSpaceIterator implementation.
SemiSpaceIterator::SemiSpaceIterator(NewSpace* space) {
Initialize(space->bottom(), space->top(), NULL);
}
SemiSpaceIterator::SemiSpaceIterator(NewSpace* space,
HeapObjectCallback size_func) {
Initialize(space->bottom(), space->top(), size_func);
}
SemiSpaceIterator::SemiSpaceIterator(NewSpace* space, Address start) {
Initialize(start, space->top(), NULL);
}
SemiSpaceIterator::SemiSpaceIterator(Address from, Address to) {
Initialize(from, to, NULL);
}
void SemiSpaceIterator::Initialize(Address start,
Address end,
HeapObjectCallback size_func) {
SemiSpace::AssertValidRange(start, end);
current_ = start;
limit_ = end;
size_func_ = size_func;
}
#ifdef DEBUG
// heap_histograms is shared, always clear it before using it.
static void ClearHistograms() {
Isolate* isolate = Isolate::Current();
// We reset the name each time, though it hasn't changed.
#define DEF_TYPE_NAME(name) isolate->heap_histograms()[name].set_name(#name);
INSTANCE_TYPE_LIST(DEF_TYPE_NAME)
#undef DEF_TYPE_NAME
#define CLEAR_HISTOGRAM(name) isolate->heap_histograms()[name].clear();
INSTANCE_TYPE_LIST(CLEAR_HISTOGRAM)
#undef CLEAR_HISTOGRAM
isolate->js_spill_information()->Clear();
}
static void ClearCodeKindStatistics() {
Isolate* isolate = Isolate::Current();
for (int i = 0; i < Code::NUMBER_OF_KINDS; i++) {
isolate->code_kind_statistics()[i] = 0;
}
}
static void ReportCodeKindStatistics() {
Isolate* isolate = Isolate::Current();
const char* table[Code::NUMBER_OF_KINDS] = { NULL };
#define CASE(name) \
case Code::name: table[Code::name] = #name; \
break
for (int i = 0; i < Code::NUMBER_OF_KINDS; i++) {
switch (static_cast<Code::Kind>(i)) {
CASE(FUNCTION);
CASE(OPTIMIZED_FUNCTION);
CASE(STUB);
CASE(BUILTIN);
CASE(LOAD_IC);
CASE(KEYED_LOAD_IC);
CASE(STORE_IC);
CASE(KEYED_STORE_IC);
CASE(CALL_IC);
CASE(KEYED_CALL_IC);
CASE(UNARY_OP_IC);
CASE(BINARY_OP_IC);
CASE(COMPARE_IC);
CASE(TO_BOOLEAN_IC);
}
}
#undef CASE
PrintF("\n Code kind histograms: \n");
for (int i = 0; i < Code::NUMBER_OF_KINDS; i++) {
if (isolate->code_kind_statistics()[i] > 0) {
PrintF(" %-20s: %10d bytes\n", table[i],
isolate->code_kind_statistics()[i]);
}
}
PrintF("\n");
}
static int CollectHistogramInfo(HeapObject* obj) {
Isolate* isolate = Isolate::Current();
InstanceType type = obj->map()->instance_type();
ASSERT(0 <= type && type <= LAST_TYPE);
ASSERT(isolate->heap_histograms()[type].name() != NULL);
isolate->heap_histograms()[type].increment_number(1);
isolate->heap_histograms()[type].increment_bytes(obj->Size());
if (FLAG_collect_heap_spill_statistics && obj->IsJSObject()) {
JSObject::cast(obj)->IncrementSpillStatistics(
isolate->js_spill_information());
}
return obj->Size();
}
static void ReportHistogram(bool print_spill) {
Isolate* isolate = Isolate::Current();
PrintF("\n Object Histogram:\n");
for (int i = 0; i <= LAST_TYPE; i++) {
if (isolate->heap_histograms()[i].number() > 0) {
PrintF(" %-34s%10d (%10d bytes)\n",
isolate->heap_histograms()[i].name(),
isolate->heap_histograms()[i].number(),
isolate->heap_histograms()[i].bytes());
}
}
PrintF("\n");
// Summarize string types.
int string_number = 0;
int string_bytes = 0;
#define INCREMENT(type, size, name, camel_name) \
string_number += isolate->heap_histograms()[type].number(); \
string_bytes += isolate->heap_histograms()[type].bytes();
STRING_TYPE_LIST(INCREMENT)
#undef INCREMENT
if (string_number > 0) {
PrintF(" %-34s%10d (%10d bytes)\n\n", "STRING_TYPE", string_number,
string_bytes);
}
if (FLAG_collect_heap_spill_statistics && print_spill) {
isolate->js_spill_information()->Print();
}
}
#endif // DEBUG
// Support for statistics gathering for --heap-stats and --log-gc.
void NewSpace::ClearHistograms() {
for (int i = 0; i <= LAST_TYPE; i++) {
allocated_histogram_[i].clear();
promoted_histogram_[i].clear();
}
}
// Because the copying collector does not touch garbage objects, we iterate
// the new space before a collection to get a histogram of allocated objects.
// This only happens when --log-gc flag is set.
void NewSpace::CollectStatistics() {
ClearHistograms();
SemiSpaceIterator it(this);
for (HeapObject* obj = it.Next(); obj != NULL; obj = it.Next())
RecordAllocation(obj);
}
static void DoReportStatistics(Isolate* isolate,
HistogramInfo* info, const char* description) {
LOG(isolate, HeapSampleBeginEvent("NewSpace", description));
// Lump all the string types together.
int string_number = 0;
int string_bytes = 0;
#define INCREMENT(type, size, name, camel_name) \
string_number += info[type].number(); \
string_bytes += info[type].bytes();
STRING_TYPE_LIST(INCREMENT)
#undef INCREMENT
if (string_number > 0) {
LOG(isolate,
HeapSampleItemEvent("STRING_TYPE", string_number, string_bytes));
}
// Then do the other types.
for (int i = FIRST_NONSTRING_TYPE; i <= LAST_TYPE; ++i) {
if (info[i].number() > 0) {
LOG(isolate,
HeapSampleItemEvent(info[i].name(), info[i].number(),
info[i].bytes()));
}
}
LOG(isolate, HeapSampleEndEvent("NewSpace", description));
}
void NewSpace::ReportStatistics() {
#ifdef DEBUG
if (FLAG_heap_stats) {
float pct = static_cast<float>(Available()) / Capacity();
PrintF(" capacity: %" V8_PTR_PREFIX "d"
", available: %" V8_PTR_PREFIX "d, %%%d\n",
Capacity(), Available(), static_cast<int>(pct*100));
PrintF("\n Object Histogram:\n");
for (int i = 0; i <= LAST_TYPE; i++) {
if (allocated_histogram_[i].number() > 0) {
PrintF(" %-34s%10d (%10d bytes)\n",
allocated_histogram_[i].name(),
allocated_histogram_[i].number(),
allocated_histogram_[i].bytes());
}
}
PrintF("\n");
}
#endif // DEBUG
if (FLAG_log_gc) {
Isolate* isolate = ISOLATE;
DoReportStatistics(isolate, allocated_histogram_, "allocated");
DoReportStatistics(isolate, promoted_histogram_, "promoted");
}
}
void NewSpace::RecordAllocation(HeapObject* obj) {
InstanceType type = obj->map()->instance_type();
ASSERT(0 <= type && type <= LAST_TYPE);
allocated_histogram_[type].increment_number(1);
allocated_histogram_[type].increment_bytes(obj->Size());
}
void NewSpace::RecordPromotion(HeapObject* obj) {
InstanceType type = obj->map()->instance_type();
ASSERT(0 <= type && type <= LAST_TYPE);
promoted_histogram_[type].increment_number(1);
promoted_histogram_[type].increment_bytes(obj->Size());
}
// -----------------------------------------------------------------------------
// Free lists for old object spaces implementation
void FreeListNode::set_size(Heap* heap, int size_in_bytes) {
ASSERT(size_in_bytes > 0);
ASSERT(IsAligned(size_in_bytes, kPointerSize));
// We write a map and possibly size information to the block. If the block
// is big enough to be a FreeSpace with at least one extra word (the next
// pointer), we set its map to be the free space map and its size to an
// appropriate array length for the desired size from HeapObject::Size().
// If the block is too small (eg, one or two words), to hold both a size
// field and a next pointer, we give it a filler map that gives it the
// correct size.
if (size_in_bytes > FreeSpace::kHeaderSize) {
set_map_no_write_barrier(heap->raw_unchecked_free_space_map());
// Can't use FreeSpace::cast because it fails during deserialization.
FreeSpace* this_as_free_space = reinterpret_cast<FreeSpace*>(this);
this_as_free_space->set_size(size_in_bytes);
} else if (size_in_bytes == kPointerSize) {
set_map_no_write_barrier(heap->raw_unchecked_one_pointer_filler_map());
} else if (size_in_bytes == 2 * kPointerSize) {
set_map_no_write_barrier(heap->raw_unchecked_two_pointer_filler_map());
} else {
UNREACHABLE();
}
// We would like to ASSERT(Size() == size_in_bytes) but this would fail during
// deserialization because the free space map is not done yet.
}
FreeListNode* FreeListNode::next() {
ASSERT(IsFreeListNode(this));
if (map() == HEAP->raw_unchecked_free_space_map()) {
ASSERT(map() == NULL || Size() >= kNextOffset + kPointerSize);
return reinterpret_cast<FreeListNode*>(
Memory::Address_at(address() + kNextOffset));
} else {
return reinterpret_cast<FreeListNode*>(
Memory::Address_at(address() + kPointerSize));
}
}
FreeListNode** FreeListNode::next_address() {
ASSERT(IsFreeListNode(this));
if (map() == HEAP->raw_unchecked_free_space_map()) {
ASSERT(Size() >= kNextOffset + kPointerSize);
return reinterpret_cast<FreeListNode**>(address() + kNextOffset);
} else {
return reinterpret_cast<FreeListNode**>(address() + kPointerSize);
}
}
void FreeListNode::set_next(FreeListNode* next) {
ASSERT(IsFreeListNode(this));
// While we are booting the VM the free space map will actually be null. So
// we have to make sure that we don't try to use it for anything at that
// stage.
if (map() == HEAP->raw_unchecked_free_space_map()) {
ASSERT(map() == NULL || Size() >= kNextOffset + kPointerSize);
Memory::Address_at(address() + kNextOffset) =
reinterpret_cast<Address>(next);
} else {
Memory::Address_at(address() + kPointerSize) =
reinterpret_cast<Address>(next);
}
}
FreeList::FreeList(PagedSpace* owner)
: owner_(owner), heap_(owner->heap()) {
Reset();
}
void FreeList::Reset() {
available_ = 0;
small_list_ = NULL;
medium_list_ = NULL;
large_list_ = NULL;
huge_list_ = NULL;
}
int FreeList::Free(Address start, int size_in_bytes) {
if (size_in_bytes == 0) return 0;
FreeListNode* node = FreeListNode::FromAddress(start);
node->set_size(heap_, size_in_bytes);
// Early return to drop too-small blocks on the floor.
if (size_in_bytes < kSmallListMin) return size_in_bytes;
// Insert other blocks at the head of a free list of the appropriate
// magnitude.
if (size_in_bytes <= kSmallListMax) {
node->set_next(small_list_);
small_list_ = node;
} else if (size_in_bytes <= kMediumListMax) {
node->set_next(medium_list_);
medium_list_ = node;
} else if (size_in_bytes <= kLargeListMax) {
node->set_next(large_list_);
large_list_ = node;
} else {
node->set_next(huge_list_);
huge_list_ = node;
}
available_ += size_in_bytes;
ASSERT(IsVeryLong() || available_ == SumFreeLists());
return 0;
}
FreeListNode* FreeList::PickNodeFromList(FreeListNode** list, int* node_size) {
FreeListNode* node = *list;
if (node == NULL) return NULL;
while (node != NULL &&
Page::FromAddress(node->address())->IsEvacuationCandidate()) {
available_ -= node->Size();
node = node->next();
}
if (node != NULL) {
*node_size = node->Size();
*list = node->next();
} else {
*list = NULL;
}
return node;
}
FreeListNode* FreeList::FindNodeFor(int size_in_bytes, int* node_size) {
FreeListNode* node = NULL;
if (size_in_bytes <= kSmallAllocationMax) {
node = PickNodeFromList(&small_list_, node_size);
if (node != NULL) return node;
}
if (size_in_bytes <= kMediumAllocationMax) {
node = PickNodeFromList(&medium_list_, node_size);
if (node != NULL) return node;
}
if (size_in_bytes <= kLargeAllocationMax) {
node = PickNodeFromList(&large_list_, node_size);
if (node != NULL) return node;
}
for (FreeListNode** cur = &huge_list_;
*cur != NULL;
cur = (*cur)->next_address()) {
FreeListNode* cur_node = *cur;
while (cur_node != NULL &&
Page::FromAddress(cur_node->address())->IsEvacuationCandidate()) {
available_ -= reinterpret_cast<FreeSpace*>(cur_node)->Size();
cur_node = cur_node->next();
}
*cur = cur_node;
if (cur_node == NULL) break;
ASSERT((*cur)->map() == HEAP->raw_unchecked_free_space_map());
FreeSpace* cur_as_free_space = reinterpret_cast<FreeSpace*>(*cur);
int size = cur_as_free_space->Size();
if (size >= size_in_bytes) {
// Large enough node found. Unlink it from the list.
node = *cur;
*node_size = size;
*cur = node->next();
break;
}
}
return node;
}
// Allocation on the old space free list. If it succeeds then a new linear
// allocation space has been set up with the top and limit of the space. If
// the allocation fails then NULL is returned, and the caller can perform a GC
// or allocate a new page before retrying.
HeapObject* FreeList::Allocate(int size_in_bytes) {
ASSERT(0 < size_in_bytes);
ASSERT(size_in_bytes <= kMaxBlockSize);
ASSERT(IsAligned(size_in_bytes, kPointerSize));
// Don't free list allocate if there is linear space available.
ASSERT(owner_->limit() - owner_->top() < size_in_bytes);
int new_node_size = 0;
FreeListNode* new_node = FindNodeFor(size_in_bytes, &new_node_size);
if (new_node == NULL) return NULL;
available_ -= new_node_size;
ASSERT(IsVeryLong() || available_ == SumFreeLists());
int bytes_left = new_node_size - size_in_bytes;
ASSERT(bytes_left >= 0);
int old_linear_size = static_cast<int>(owner_->limit() - owner_->top());
// Mark the old linear allocation area with a free space map so it can be
// skipped when scanning the heap. This also puts it back in the free list
// if it is big enough.
owner_->Free(owner_->top(), old_linear_size);
#ifdef DEBUG
for (int i = 0; i < size_in_bytes / kPointerSize; i++) {
reinterpret_cast<Object**>(new_node->address())[i] = Smi::FromInt(0);
}
#endif
owner_->heap()->incremental_marking()->OldSpaceStep(
size_in_bytes - old_linear_size);
// The old-space-step might have finished sweeping and restarted marking.
// Verify that it did not turn the page of the new node into an evacuation
// candidate.
ASSERT(!MarkCompactCollector::IsOnEvacuationCandidate(new_node));
const int kThreshold = IncrementalMarking::kAllocatedThreshold;
// Memory in the linear allocation area is counted as allocated. We may free
// a little of this again immediately - see below.
owner_->Allocate(new_node_size);
if (bytes_left > kThreshold &&
owner_->heap()->incremental_marking()->IsMarkingIncomplete() &&
FLAG_incremental_marking_steps) {
int linear_size = owner_->RoundSizeDownToObjectAlignment(kThreshold);
// We don't want to give too large linear areas to the allocator while
// incremental marking is going on, because we won't check again whether
// we want to do another increment until the linear area is used up.
owner_->Free(new_node->address() + size_in_bytes + linear_size,
new_node_size - size_in_bytes - linear_size);
owner_->SetTop(new_node->address() + size_in_bytes,
new_node->address() + size_in_bytes + linear_size);
} else if (bytes_left > 0) {
// Normally we give the rest of the node to the allocator as its new
// linear allocation area.
owner_->SetTop(new_node->address() + size_in_bytes,
new_node->address() + new_node_size);
} else {
// TODO(gc) Try not freeing linear allocation region when bytes_left
// are zero.
owner_->SetTop(NULL, NULL);
}
return new_node;
}
static intptr_t CountFreeListItemsInList(FreeListNode* n, Page* p) {
intptr_t sum = 0;
while (n != NULL) {
if (Page::FromAddress(n->address()) == p) {
FreeSpace* free_space = reinterpret_cast<FreeSpace*>(n);
sum += free_space->Size();
}
n = n->next();
}
return sum;
}
void FreeList::CountFreeListItems(Page* p, SizeStats* sizes) {
sizes->huge_size_ = CountFreeListItemsInList(huge_list_, p);
if (sizes->huge_size_ < p->area_size()) {
sizes->small_size_ = CountFreeListItemsInList(small_list_, p);
sizes->medium_size_ = CountFreeListItemsInList(medium_list_, p);
sizes->large_size_ = CountFreeListItemsInList(large_list_, p);
} else {
sizes->small_size_ = 0;
sizes->medium_size_ = 0;
sizes->large_size_ = 0;
}
}
static intptr_t EvictFreeListItemsInList(FreeListNode** n, Page* p) {
intptr_t sum = 0;
while (*n != NULL) {
if (Page::FromAddress((*n)->address()) == p) {
FreeSpace* free_space = reinterpret_cast<FreeSpace*>(*n);
sum += free_space->Size();
*n = (*n)->next();
} else {
n = (*n)->next_address();
}
}
return sum;
}
intptr_t FreeList::EvictFreeListItems(Page* p) {
intptr_t sum = EvictFreeListItemsInList(&huge_list_, p);
if (sum < p->area_size()) {
sum += EvictFreeListItemsInList(&small_list_, p) +
EvictFreeListItemsInList(&medium_list_, p) +
EvictFreeListItemsInList(&large_list_, p);
}
available_ -= static_cast<int>(sum);
return sum;
}
#ifdef DEBUG
intptr_t FreeList::SumFreeList(FreeListNode* cur) {
intptr_t sum = 0;
while (cur != NULL) {
ASSERT(cur->map() == HEAP->raw_unchecked_free_space_map());
FreeSpace* cur_as_free_space = reinterpret_cast<FreeSpace*>(cur);
sum += cur_as_free_space->Size();
cur = cur->next();
}
return sum;
}
static const int kVeryLongFreeList = 500;
int FreeList::FreeListLength(FreeListNode* cur) {
int length = 0;
while (cur != NULL) {
length++;
cur = cur->next();
if (length == kVeryLongFreeList) return length;
}
return length;
}
bool FreeList::IsVeryLong() {
if (FreeListLength(small_list_) == kVeryLongFreeList) return true;
if (FreeListLength(medium_list_) == kVeryLongFreeList) return true;
if (FreeListLength(large_list_) == kVeryLongFreeList) return true;
if (FreeListLength(huge_list_) == kVeryLongFreeList) return true;
return false;
}
// This can take a very long time because it is linear in the number of entries
// on the free list, so it should not be called if FreeListLength returns
// kVeryLongFreeList.
intptr_t FreeList::SumFreeLists() {
intptr_t sum = SumFreeList(small_list_);
sum += SumFreeList(medium_list_);
sum += SumFreeList(large_list_);
sum += SumFreeList(huge_list_);
return sum;
}
#endif
// -----------------------------------------------------------------------------
// OldSpace implementation
bool NewSpace::ReserveSpace(int bytes) {
// We can't reliably unpack a partial snapshot that needs more new space
// space than the minimum NewSpace size. The limit can be set lower than
// the end of new space either because there is more space on the next page
// or because we have lowered the limit in order to get periodic incremental
// marking. The most reliable way to ensure that there is linear space is
// to do the allocation, then rewind the limit.
ASSERT(bytes <= InitialCapacity());
MaybeObject* maybe = AllocateRaw(bytes);
Object* object = NULL;
if (!maybe->ToObject(&object)) return false;
HeapObject* allocation = HeapObject::cast(object);
Address top = allocation_info_.top;
if ((top - bytes) == allocation->address()) {
allocation_info_.top = allocation->address();
return true;
}
// There may be a borderline case here where the allocation succeeded, but
// the limit and top have moved on to a new page. In that case we try again.
return ReserveSpace(bytes);
}
void PagedSpace::PrepareForMarkCompact() {
// We don't have a linear allocation area while sweeping. It will be restored
// on the first allocation after the sweep.
// Mark the old linear allocation area with a free space map so it can be
// skipped when scanning the heap.
int old_linear_size = static_cast<int>(limit() - top());
Free(top(), old_linear_size);
SetTop(NULL, NULL);
// Stop lazy sweeping and clear marking bits for unswept pages.
if (first_unswept_page_ != NULL) {
Page* p = first_unswept_page_;
do {
// Do not use ShouldBeSweptLazily predicate here.
// New evacuation candidates were selected but they still have
// to be swept before collection starts.
if (!p->WasSwept()) {
Bitmap::Clear(p);
if (FLAG_gc_verbose) {
PrintF("Sweeping 0x%" V8PRIxPTR " lazily abandoned.\n",
reinterpret_cast<intptr_t>(p));
}
}
p = p->next_page();
} while (p != anchor());
}
first_unswept_page_ = Page::FromAddress(NULL);
unswept_free_bytes_ = 0;
// Clear the free list before a full GC---it will be rebuilt afterward.
free_list_.Reset();
}
bool PagedSpace::ReserveSpace(int size_in_bytes) {
ASSERT(size_in_bytes <= AreaSize());
ASSERT(size_in_bytes == RoundSizeDownToObjectAlignment(size_in_bytes));
Address current_top = allocation_info_.top;
Address new_top = current_top + size_in_bytes;
if (new_top <= allocation_info_.limit) return true;
HeapObject* new_area = free_list_.Allocate(size_in_bytes);
if (new_area == NULL) new_area = SlowAllocateRaw(size_in_bytes);
if (new_area == NULL) return false;
int old_linear_size = static_cast<int>(limit() - top());
// Mark the old linear allocation area with a free space so it can be
// skipped when scanning the heap. This also puts it back in the free list
// if it is big enough.
Free(top(), old_linear_size);
SetTop(new_area->address(), new_area->address() + size_in_bytes);
Allocate(size_in_bytes);
return true;
}
// You have to call this last, since the implementation from PagedSpace
// doesn't know that memory was 'promised' to large object space.
bool LargeObjectSpace::ReserveSpace(int bytes) {
return heap()->OldGenerationCapacityAvailable() >= bytes &&
(!heap()->incremental_marking()->IsStopped() ||
heap()->OldGenerationSpaceAvailable() >= bytes);
}
bool PagedSpace::AdvanceSweeper(intptr_t bytes_to_sweep) {
if (IsSweepingComplete()) return true;
intptr_t freed_bytes = 0;
Page* p = first_unswept_page_;
do {
Page* next_page = p->next_page();
if (ShouldBeSweptLazily(p)) {
if (FLAG_gc_verbose) {
PrintF("Sweeping 0x%" V8PRIxPTR " lazily advanced.\n",
reinterpret_cast<intptr_t>(p));
}
DecreaseUnsweptFreeBytes(p);
freed_bytes += MarkCompactCollector::SweepConservatively(this, p);
}
p = next_page;
} while (p != anchor() && freed_bytes < bytes_to_sweep);
if (p == anchor()) {
first_unswept_page_ = Page::FromAddress(NULL);
} else {
first_unswept_page_ = p;
}
heap()->LowerOldGenLimits(freed_bytes);
heap()->FreeQueuedChunks();
return IsSweepingComplete();
}
void PagedSpace::EvictEvacuationCandidatesFromFreeLists() {
if (allocation_info_.top >= allocation_info_.limit) return;
if (Page::FromAllocationTop(allocation_info_.top)->IsEvacuationCandidate()) {
// Create filler object to keep page iterable if it was iterable.
int remaining =
static_cast<int>(allocation_info_.limit - allocation_info_.top);
heap()->CreateFillerObjectAt(allocation_info_.top, remaining);
allocation_info_.top = NULL;
allocation_info_.limit = NULL;
}
}
HeapObject* PagedSpace::SlowAllocateRaw(int size_in_bytes) {
// Allocation in this space has failed.
// If there are unswept pages advance lazy sweeper then sweep one page before
// allocating a new page.
if (first_unswept_page_->is_valid()) {
AdvanceSweeper(size_in_bytes);
// Retry the free list allocation.
HeapObject* object = free_list_.Allocate(size_in_bytes);
if (object != NULL) return object;
}
// Free list allocation failed and there is no next page. Fail if we have
// hit the old generation size limit that should cause a garbage
// collection.
if (!heap()->always_allocate() &&
heap()->OldGenerationAllocationLimitReached()) {
return NULL;
}
// Try to expand the space and allocate in the new next page.
if (Expand()) {
return free_list_.Allocate(size_in_bytes);
}
// Last ditch, sweep all the remaining pages to try to find space. This may
// cause a pause.
if (!IsSweepingComplete()) {
AdvanceSweeper(kMaxInt);
// Retry the free list allocation.
HeapObject* object = free_list_.Allocate(size_in_bytes);
if (object != NULL) return object;
}
// Finally, fail.
return NULL;
}
#ifdef DEBUG
void PagedSpace::ReportCodeStatistics() {
Isolate* isolate = Isolate::Current();
CommentStatistic* comments_statistics =
isolate->paged_space_comments_statistics();
ReportCodeKindStatistics();
PrintF("Code comment statistics (\" [ comment-txt : size/ "
"count (average)\"):\n");
for (int i = 0; i <= CommentStatistic::kMaxComments; i++) {
const CommentStatistic& cs = comments_statistics[i];
if (cs.size > 0) {
PrintF(" %-30s: %10d/%6d (%d)\n", cs.comment, cs.size, cs.count,
cs.size/cs.count);
}
}
PrintF("\n");
}
void PagedSpace::ResetCodeStatistics() {
Isolate* isolate = Isolate::Current();
CommentStatistic* comments_statistics =
isolate->paged_space_comments_statistics();
ClearCodeKindStatistics();
for (int i = 0; i < CommentStatistic::kMaxComments; i++) {
comments_statistics[i].Clear();
}
comments_statistics[CommentStatistic::kMaxComments].comment = "Unknown";
comments_statistics[CommentStatistic::kMaxComments].size = 0;
comments_statistics[CommentStatistic::kMaxComments].count = 0;
}
// Adds comment to 'comment_statistics' table. Performance OK as long as
// 'kMaxComments' is small
static void EnterComment(Isolate* isolate, const char* comment, int delta) {
CommentStatistic* comments_statistics =
isolate->paged_space_comments_statistics();
// Do not count empty comments
if (delta <= 0) return;
CommentStatistic* cs = &comments_statistics[CommentStatistic::kMaxComments];
// Search for a free or matching entry in 'comments_statistics': 'cs'
// points to result.
for (int i = 0; i < CommentStatistic::kMaxComments; i++) {
if (comments_statistics[i].comment == NULL) {
cs = &comments_statistics[i];
cs->comment = comment;
break;
} else if (strcmp(comments_statistics[i].comment, comment) == 0) {
cs = &comments_statistics[i];
break;
}
}
// Update entry for 'comment'
cs->size += delta;
cs->count += 1;
}
// Call for each nested comment start (start marked with '[ xxx', end marked
// with ']'. RelocIterator 'it' must point to a comment reloc info.
static void CollectCommentStatistics(Isolate* isolate, RelocIterator* it) {
ASSERT(!it->done());
ASSERT(it->rinfo()->rmode() == RelocInfo::COMMENT);
const char* tmp = reinterpret_cast<const char*>(it->rinfo()->data());
if (tmp[0] != '[') {
// Not a nested comment; skip
return;
}
// Search for end of nested comment or a new nested comment
const char* const comment_txt =
reinterpret_cast<const char*>(it->rinfo()->data());
const byte* prev_pc = it->rinfo()->pc();
int flat_delta = 0;
it->next();
while (true) {
// All nested comments must be terminated properly, and therefore exit
// from loop.
ASSERT(!it->done());
if (it->rinfo()->rmode() == RelocInfo::COMMENT) {
const char* const txt =
reinterpret_cast<const char*>(it->rinfo()->data());
flat_delta += static_cast<int>(it->rinfo()->pc() - prev_pc);
if (txt[0] == ']') break; // End of nested comment
// A new comment
CollectCommentStatistics(isolate, it);
// Skip code that was covered with previous comment
prev_pc = it->rinfo()->pc();
}
it->next();
}
EnterComment(isolate, comment_txt, flat_delta);
}
// Collects code size statistics:
// - by code kind
// - by code comment
void PagedSpace::CollectCodeStatistics() {
Isolate* isolate = heap()->isolate();
HeapObjectIterator obj_it(this);
for (HeapObject* obj = obj_it.Next(); obj != NULL; obj = obj_it.Next()) {
if (obj->IsCode()) {
Code* code = Code::cast(obj);
isolate->code_kind_statistics()[code->kind()] += code->Size();
RelocIterator it(code);
int delta = 0;
const byte* prev_pc = code->instruction_start();
while (!it.done()) {
if (it.rinfo()->rmode() == RelocInfo::COMMENT) {
delta += static_cast<int>(it.rinfo()->pc() - prev_pc);
CollectCommentStatistics(isolate, &it);
prev_pc = it.rinfo()->pc();
}
it.next();
}
ASSERT(code->instruction_start() <= prev_pc &&
prev_pc <= code->instruction_end());
delta += static_cast<int>(code->instruction_end() - prev_pc);
EnterComment(isolate, "NoComment", delta);
}
}
}
void PagedSpace::ReportStatistics() {
int pct = static_cast<int>(Available() * 100 / Capacity());
PrintF(" capacity: %" V8_PTR_PREFIX "d"
", waste: %" V8_PTR_PREFIX "d"
", available: %" V8_PTR_PREFIX "d, %%%d\n",
Capacity(), Waste(), Available(), pct);
if (was_swept_conservatively_) return;
ClearHistograms();
HeapObjectIterator obj_it(this);
for (HeapObject* obj = obj_it.Next(); obj != NULL; obj = obj_it.Next())
CollectHistogramInfo(obj);
ReportHistogram(true);
}
#endif
// -----------------------------------------------------------------------------
// FixedSpace implementation
void FixedSpace::PrepareForMarkCompact() {
// Call prepare of the super class.
PagedSpace::PrepareForMarkCompact();
// During a non-compacting collection, everything below the linear
// allocation pointer except wasted top-of-page blocks is considered
// allocated and we will rediscover available bytes during the
// collection.
accounting_stats_.AllocateBytes(free_list_.available());
// Clear the free list before a full GC---it will be rebuilt afterward.
free_list_.Reset();
}
// -----------------------------------------------------------------------------
// MapSpace implementation
#ifdef DEBUG
void MapSpace::VerifyObject(HeapObject* object) {
// The object should be a map or a free-list node.
ASSERT(object->IsMap() || object->IsFreeSpace());
}
#endif
// -----------------------------------------------------------------------------
// GlobalPropertyCellSpace implementation
#ifdef DEBUG
void CellSpace::VerifyObject(HeapObject* object) {
// The object should be a global object property cell or a free-list node.
ASSERT(object->IsJSGlobalPropertyCell() ||
object->map() == heap()->two_pointer_filler_map());
}
#endif
// -----------------------------------------------------------------------------
// LargeObjectIterator
LargeObjectIterator::LargeObjectIterator(LargeObjectSpace* space) {
current_ = space->first_page_;
size_func_ = NULL;
}
LargeObjectIterator::LargeObjectIterator(LargeObjectSpace* space,
HeapObjectCallback size_func) {
current_ = space->first_page_;
size_func_ = size_func;
}
HeapObject* LargeObjectIterator::Next() {
if (current_ == NULL) return NULL;
HeapObject* object = current_->GetObject();
current_ = current_->next_page();
return object;
}
// -----------------------------------------------------------------------------
// LargeObjectSpace
static bool ComparePointers(void* key1, void* key2) {
return key1 == key2;
}
LargeObjectSpace::LargeObjectSpace(Heap* heap,
intptr_t max_capacity,
AllocationSpace id)
: Space(heap, id, NOT_EXECUTABLE), // Managed on a per-allocation basis
max_capacity_(max_capacity),
first_page_(NULL),
size_(0),
page_count_(0),
objects_size_(0),
chunk_map_(ComparePointers, 1024) {}
bool LargeObjectSpace::SetUp() {
first_page_ = NULL;
size_ = 0;
page_count_ = 0;
objects_size_ = 0;
chunk_map_.Clear();
return true;
}
void LargeObjectSpace::TearDown() {
while (first_page_ != NULL) {
LargePage* page = first_page_;
first_page_ = first_page_->next_page();
LOG(heap()->isolate(), DeleteEvent("LargeObjectChunk", page->address()));
ObjectSpace space = static_cast<ObjectSpace>(1 << identity());
heap()->isolate()->memory_allocator()->PerformAllocationCallback(
space, kAllocationActionFree, page->size());
heap()->isolate()->memory_allocator()->Free(page);
}
SetUp();
}
MaybeObject* LargeObjectSpace::AllocateRaw(int object_size,
Executability executable) {
// Check if we want to force a GC before growing the old space further.
// If so, fail the allocation.
if (!heap()->always_allocate() &&
heap()->OldGenerationAllocationLimitReached()) {
return Failure::RetryAfterGC(identity());
}
if (Size() + object_size > max_capacity_) {
return Failure::RetryAfterGC(identity());
}
LargePage* page = heap()->isolate()->memory_allocator()->
AllocateLargePage(object_size, this, executable);
if (page == NULL) return Failure::RetryAfterGC(identity());
ASSERT(page->area_size() >= object_size);
size_ += static_cast<int>(page->size());
objects_size_ += object_size;
page_count_++;
page->set_next_page(first_page_);
first_page_ = page;
// Register all MemoryChunk::kAlignment-aligned chunks covered by
// this large page in the chunk map.
uintptr_t base = reinterpret_cast<uintptr_t>(page) / MemoryChunk::kAlignment;
uintptr_t limit = base + (page->size() - 1) / MemoryChunk::kAlignment;
for (uintptr_t key = base; key <= limit; key++) {
HashMap::Entry* entry = chunk_map_.Lookup(reinterpret_cast<void*>(key),
static_cast<uint32_t>(key),
true);
ASSERT(entry != NULL);
entry->value = page;
}
HeapObject* object = page->GetObject();
#ifdef DEBUG
// Make the object consistent so the heap can be vefified in OldSpaceStep.
reinterpret_cast<Object**>(object->address())[0] =
heap()->fixed_array_map();
reinterpret_cast<Object**>(object->address())[1] = Smi::FromInt(0);
#endif
heap()->incremental_marking()->OldSpaceStep(object_size);
return object;
}
// GC support
MaybeObject* LargeObjectSpace::FindObject(Address a) {
LargePage* page = FindPage(a);
if (page != NULL) {
return page->GetObject();
}
return Failure::Exception();
}
LargePage* LargeObjectSpace::FindPage(Address a) {
uintptr_t key = reinterpret_cast<uintptr_t>(a) / MemoryChunk::kAlignment;
HashMap::Entry* e = chunk_map_.Lookup(reinterpret_cast<void*>(key),
static_cast<uint32_t>(key),
false);
if (e != NULL) {
ASSERT(e->value != NULL);
LargePage* page = reinterpret_cast<LargePage*>(e->value);
ASSERT(page->is_valid());
if (page->Contains(a)) {
return page;
}
}
return NULL;
}
void LargeObjectSpace::FreeUnmarkedObjects() {
LargePage* previous = NULL;
LargePage* current = first_page_;
while (current != NULL) {
HeapObject* object = current->GetObject();
// Can this large page contain pointers to non-trivial objects. No other
// pointer object is this big.
bool is_pointer_object = object->IsFixedArray();
MarkBit mark_bit = Marking::MarkBitFrom(object);
if (mark_bit.Get()) {
mark_bit.Clear();
MemoryChunk::IncrementLiveBytesFromGC(object->address(), -object->Size());
previous = current;
current = current->next_page();
} else {
LargePage* page = current;
// Cut the chunk out from the chunk list.
current = current->next_page();
if (previous == NULL) {
first_page_ = current;
} else {
previous->set_next_page(current);
}
// Free the chunk.
heap()->mark_compact_collector()->ReportDeleteIfNeeded(
object, heap()->isolate());
size_ -= static_cast<int>(page->size());
objects_size_ -= object->Size();
page_count_--;
// Remove entries belonging to this page.
// Use variable alignment to help pass length check (<= 80 characters)
// of single line in tools/presubmit.py.
const intptr_t alignment = MemoryChunk::kAlignment;
uintptr_t base = reinterpret_cast<uintptr_t>(page)/alignment;
uintptr_t limit = base + (page->size()-1)/alignment;
for (uintptr_t key = base; key <= limit; key++) {
chunk_map_.Remove(reinterpret_cast<void*>(key),
static_cast<uint32_t>(key));
}
if (is_pointer_object) {
heap()->QueueMemoryChunkForFree(page);
} else {
heap()->isolate()->memory_allocator()->Free(page);
}
}
}
heap()->FreeQueuedChunks();
}
bool LargeObjectSpace::Contains(HeapObject* object) {
Address address = object->address();
MemoryChunk* chunk = MemoryChunk::FromAddress(address);
bool owned = (chunk->owner() == this);
SLOW_ASSERT(!owned || !FindObject(address)->IsFailure());
return owned;
}
#ifdef DEBUG
// We do not assume that the large object iterator works, because it depends
// on the invariants we are checking during verification.
void LargeObjectSpace::Verify() {
for (LargePage* chunk = first_page_;
chunk != NULL;
chunk = chunk->next_page()) {
// Each chunk contains an object that starts at the large object page's
// object area start.
HeapObject* object = chunk->GetObject();
Page* page = Page::FromAddress(object->address());
ASSERT(object->address() == page->area_start());
// The first word should be a map, and we expect all map pointers to be
// in map space.
Map* map = object->map();
ASSERT(map->IsMap());
ASSERT(heap()->map_space()->Contains(map));
// We have only code, sequential strings, external strings
// (sequential strings that have been morphed into external
// strings), fixed arrays, and byte arrays in large object space.
ASSERT(object->IsCode() || object->IsSeqString() ||
object->IsExternalString() || object->IsFixedArray() ||
object->IsFixedDoubleArray() || object->IsByteArray());
// The object itself should look OK.
object->Verify();
// Byte arrays and strings don't have interior pointers.
if (object->IsCode()) {
VerifyPointersVisitor code_visitor;
object->IterateBody(map->instance_type(),
object->Size(),
&code_visitor);
} else if (object->IsFixedArray()) {
FixedArray* array = FixedArray::cast(object);
for (int j = 0; j < array->length(); j++) {
Object* element = array->get(j);
if (element->IsHeapObject()) {
HeapObject* element_object = HeapObject::cast(element);
ASSERT(heap()->Contains(element_object));
ASSERT(element_object->map()->IsMap());
}
}
}
}
}
void LargeObjectSpace::Print() {
LargeObjectIterator it(this);
for (HeapObject* obj = it.Next(); obj != NULL; obj = it.Next()) {
obj->Print();
}
}
void LargeObjectSpace::ReportStatistics() {
PrintF(" size: %" V8_PTR_PREFIX "d\n", size_);
int num_objects = 0;
ClearHistograms();
LargeObjectIterator it(this);
for (HeapObject* obj = it.Next(); obj != NULL; obj = it.Next()) {
num_objects++;
CollectHistogramInfo(obj);
}
PrintF(" number of objects %d, "
"size of objects %" V8_PTR_PREFIX "d\n", num_objects, objects_size_);
if (num_objects > 0) ReportHistogram(false);
}
void LargeObjectSpace::CollectCodeStatistics() {
Isolate* isolate = heap()->isolate();
LargeObjectIterator obj_it(this);
for (HeapObject* obj = obj_it.Next(); obj != NULL; obj = obj_it.Next()) {
if (obj->IsCode()) {
Code* code = Code::cast(obj);
isolate->code_kind_statistics()[code->kind()] += code->Size();
}
}
}
void Page::Print() {
// Make a best-effort to print the objects in the page.
PrintF("Page@%p in %s\n",
this->address(),
AllocationSpaceName(this->owner()->identity()));
printf(" --------------------------------------\n");
HeapObjectIterator objects(this, heap()->GcSafeSizeOfOldObjectFunction());
unsigned mark_size = 0;
for (HeapObject* object = objects.Next();
object != NULL;
object = objects.Next()) {
bool is_marked = Marking::MarkBitFrom(object).Get();
PrintF(" %c ", (is_marked ? '!' : ' ')); // Indent a little.
if (is_marked) {
mark_size += heap()->GcSafeSizeOfOldObjectFunction()(object);
}
object->ShortPrint();
PrintF("\n");
}
printf(" --------------------------------------\n");
printf(" Marked: %x, LiveCount: %x\n", mark_size, LiveBytes());
}
#endif // DEBUG
} } // namespace v8::internal
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