Skip to content

HTTPS clone URL

Subversion checkout URL

You can clone with
or
.
Download ZIP
tree: 9dc621f83a
Fetching contributors…

Cannot retrieve contributors at this time

2636 lines (2155 sloc) 83.744 kB
// Copyright 2006-2008 the V8 project authors. All rights reserved.
// Redistribution and use in source and binary forms, with or without
// modification, are permitted provided that the following conditions are
// met:
//
// * Redistributions of source code must retain the above copyright
// notice, this list of conditions and the following disclaimer.
// * Redistributions in binary form must reproduce the above
// copyright notice, this list of conditions and the following
// disclaimer in the documentation and/or other materials provided
// with the distribution.
// * Neither the name of Google Inc. nor the names of its
// contributors may be used to endorse or promote products derived
// from this software without specific prior written permission.
//
// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
#include "v8.h"
#include "macro-assembler.h"
#include "mark-compact.h"
#include "platform.h"
namespace v8 {
namespace internal {
// For contiguous spaces, top should be in the space (or at the end) and limit
// should be the end of the space.
#define ASSERT_SEMISPACE_ALLOCATION_INFO(info, space) \
ASSERT((space).low() <= (info).top \
&& (info).top <= (space).high() \
&& (info).limit == (space).high())
// ----------------------------------------------------------------------------
// HeapObjectIterator
HeapObjectIterator::HeapObjectIterator(PagedSpace* space) {
Initialize(space->bottom(), space->top(), NULL);
}
HeapObjectIterator::HeapObjectIterator(PagedSpace* space,
HeapObjectCallback size_func) {
Initialize(space->bottom(), space->top(), size_func);
}
HeapObjectIterator::HeapObjectIterator(PagedSpace* space, Address start) {
Initialize(start, space->top(), NULL);
}
HeapObjectIterator::HeapObjectIterator(PagedSpace* space, Address start,
HeapObjectCallback size_func) {
Initialize(start, space->top(), size_func);
}
void HeapObjectIterator::Initialize(Address cur, Address end,
HeapObjectCallback size_f) {
cur_addr_ = cur;
end_addr_ = end;
end_page_ = Page::FromAllocationTop(end);
size_func_ = size_f;
Page* p = Page::FromAllocationTop(cur_addr_);
cur_limit_ = (p == end_page_) ? end_addr_ : p->AllocationTop();
#ifdef DEBUG
Verify();
#endif
}
bool HeapObjectIterator::HasNextInNextPage() {
if (cur_addr_ == end_addr_) return false;
Page* cur_page = Page::FromAllocationTop(cur_addr_);
cur_page = cur_page->next_page();
ASSERT(cur_page->is_valid());
cur_addr_ = cur_page->ObjectAreaStart();
cur_limit_ = (cur_page == end_page_) ? end_addr_ : cur_page->AllocationTop();
ASSERT(cur_addr_ < cur_limit_);
#ifdef DEBUG
Verify();
#endif
return true;
}
#ifdef DEBUG
void HeapObjectIterator::Verify() {
Page* p = Page::FromAllocationTop(cur_addr_);
ASSERT(p == Page::FromAllocationTop(cur_limit_));
ASSERT(p->Offset(cur_addr_) <= p->Offset(cur_limit_));
}
#endif
// -----------------------------------------------------------------------------
// PageIterator
PageIterator::PageIterator(PagedSpace* space, Mode mode) : space_(space) {
prev_page_ = NULL;
switch (mode) {
case PAGES_IN_USE:
stop_page_ = space->AllocationTopPage();
break;
case PAGES_USED_BY_MC:
stop_page_ = space->MCRelocationTopPage();
break;
case ALL_PAGES:
#ifdef DEBUG
// Verify that the cached last page in the space is actually the
// last page.
for (Page* p = space->first_page_; p->is_valid(); p = p->next_page()) {
if (!p->next_page()->is_valid()) {
ASSERT(space->last_page_ == p);
}
}
#endif
stop_page_ = space->last_page_;
break;
}
}
// -----------------------------------------------------------------------------
// Page
#ifdef DEBUG
Page::RSetState Page::rset_state_ = Page::IN_USE;
#endif
// -----------------------------------------------------------------------------
// MemoryAllocator
//
int MemoryAllocator::capacity_ = 0;
int MemoryAllocator::size_ = 0;
VirtualMemory* MemoryAllocator::initial_chunk_ = NULL;
// 270 is an estimate based on the static default heap size of a pair of 256K
// semispaces and a 64M old generation.
const int kEstimatedNumberOfChunks = 270;
List<MemoryAllocator::ChunkInfo> MemoryAllocator::chunks_(
kEstimatedNumberOfChunks);
List<int> MemoryAllocator::free_chunk_ids_(kEstimatedNumberOfChunks);
int MemoryAllocator::max_nof_chunks_ = 0;
int MemoryAllocator::top_ = 0;
void MemoryAllocator::Push(int free_chunk_id) {
ASSERT(max_nof_chunks_ > 0);
ASSERT(top_ < max_nof_chunks_);
free_chunk_ids_[top_++] = free_chunk_id;
}
int MemoryAllocator::Pop() {
ASSERT(top_ > 0);
return free_chunk_ids_[--top_];
}
bool MemoryAllocator::Setup(int capacity) {
capacity_ = RoundUp(capacity, Page::kPageSize);
// Over-estimate the size of chunks_ array. It assumes the expansion of old
// space is always in the unit of a chunk (kChunkSize) except the last
// expansion.
//
// Due to alignment, allocated space might be one page less than required
// number (kPagesPerChunk) of pages for old spaces.
//
// Reserve two chunk ids for semispaces, one for map space, one for old
// space, and one for code space.
max_nof_chunks_ = (capacity_ / (kChunkSize - Page::kPageSize)) + 5;
if (max_nof_chunks_ > kMaxNofChunks) return false;
size_ = 0;
ChunkInfo info; // uninitialized element.
for (int i = max_nof_chunks_ - 1; i >= 0; i--) {
chunks_.Add(info);
free_chunk_ids_.Add(i);
}
top_ = max_nof_chunks_;
return true;
}
void MemoryAllocator::TearDown() {
for (int i = 0; i < max_nof_chunks_; i++) {
if (chunks_[i].address() != NULL) DeleteChunk(i);
}
chunks_.Clear();
free_chunk_ids_.Clear();
if (initial_chunk_ != NULL) {
LOG(DeleteEvent("InitialChunk", initial_chunk_->address()));
delete initial_chunk_;
initial_chunk_ = NULL;
}
ASSERT(top_ == max_nof_chunks_); // all chunks are free
top_ = 0;
capacity_ = 0;
size_ = 0;
max_nof_chunks_ = 0;
}
void* MemoryAllocator::AllocateRawMemory(const size_t requested,
size_t* allocated,
Executability executable) {
if (size_ + static_cast<int>(requested) > capacity_) return NULL;
void* mem = OS::Allocate(requested, allocated, executable == EXECUTABLE);
int alloced = *allocated;
size_ += alloced;
Counters::memory_allocated.Increment(alloced);
return mem;
}
void MemoryAllocator::FreeRawMemory(void* mem, size_t length) {
OS::Free(mem, length);
Counters::memory_allocated.Decrement(length);
size_ -= length;
ASSERT(size_ >= 0);
}
void* MemoryAllocator::ReserveInitialChunk(const size_t requested) {
ASSERT(initial_chunk_ == NULL);
initial_chunk_ = new VirtualMemory(requested);
CHECK(initial_chunk_ != NULL);
if (!initial_chunk_->IsReserved()) {
delete initial_chunk_;
initial_chunk_ = NULL;
return NULL;
}
// We are sure that we have mapped a block of requested addresses.
ASSERT(initial_chunk_->size() == requested);
LOG(NewEvent("InitialChunk", initial_chunk_->address(), requested));
size_ += requested;
return initial_chunk_->address();
}
static int PagesInChunk(Address start, size_t size) {
// The first page starts on the first page-aligned address from start onward
// and the last page ends on the last page-aligned address before
// start+size. Page::kPageSize is a power of two so we can divide by
// shifting.
return (RoundDown(start + size, Page::kPageSize)
- RoundUp(start, Page::kPageSize)) >> Page::kPageSizeBits;
}
Page* MemoryAllocator::AllocatePages(int requested_pages, int* allocated_pages,
PagedSpace* owner) {
if (requested_pages <= 0) return Page::FromAddress(NULL);
size_t chunk_size = requested_pages * Page::kPageSize;
// There is not enough space to guarantee the desired number pages can be
// allocated.
if (size_ + static_cast<int>(chunk_size) > capacity_) {
// Request as many pages as we can.
chunk_size = capacity_ - size_;
requested_pages = chunk_size >> Page::kPageSizeBits;
if (requested_pages <= 0) return Page::FromAddress(NULL);
}
void* chunk = AllocateRawMemory(chunk_size, &chunk_size, owner->executable());
if (chunk == NULL) return Page::FromAddress(NULL);
LOG(NewEvent("PagedChunk", chunk, chunk_size));
*allocated_pages = PagesInChunk(static_cast<Address>(chunk), chunk_size);
if (*allocated_pages == 0) {
FreeRawMemory(chunk, chunk_size);
LOG(DeleteEvent("PagedChunk", chunk));
return Page::FromAddress(NULL);
}
int chunk_id = Pop();
chunks_[chunk_id].init(static_cast<Address>(chunk), chunk_size, owner);
return InitializePagesInChunk(chunk_id, *allocated_pages, owner);
}
Page* MemoryAllocator::CommitPages(Address start, size_t size,
PagedSpace* owner, int* num_pages) {
ASSERT(start != NULL);
*num_pages = PagesInChunk(start, size);
ASSERT(*num_pages > 0);
ASSERT(initial_chunk_ != NULL);
ASSERT(InInitialChunk(start));
ASSERT(InInitialChunk(start + size - 1));
if (!initial_chunk_->Commit(start, size, owner->executable() == EXECUTABLE)) {
return Page::FromAddress(NULL);
}
Counters::memory_allocated.Increment(size);
// So long as we correctly overestimated the number of chunks we should not
// run out of chunk ids.
CHECK(!OutOfChunkIds());
int chunk_id = Pop();
chunks_[chunk_id].init(start, size, owner);
return InitializePagesInChunk(chunk_id, *num_pages, owner);
}
bool MemoryAllocator::CommitBlock(Address start,
size_t size,
Executability executable) {
ASSERT(start != NULL);
ASSERT(size > 0);
ASSERT(initial_chunk_ != NULL);
ASSERT(InInitialChunk(start));
ASSERT(InInitialChunk(start + size - 1));
if (!initial_chunk_->Commit(start, size, executable)) return false;
Counters::memory_allocated.Increment(size);
return true;
}
bool MemoryAllocator::UncommitBlock(Address start, size_t size) {
ASSERT(start != NULL);
ASSERT(size > 0);
ASSERT(initial_chunk_ != NULL);
ASSERT(InInitialChunk(start));
ASSERT(InInitialChunk(start + size - 1));
if (!initial_chunk_->Uncommit(start, size)) return false;
Counters::memory_allocated.Decrement(size);
return true;
}
Page* MemoryAllocator::InitializePagesInChunk(int chunk_id, int pages_in_chunk,
PagedSpace* owner) {
ASSERT(IsValidChunk(chunk_id));
ASSERT(pages_in_chunk > 0);
Address chunk_start = chunks_[chunk_id].address();
Address low = RoundUp(chunk_start, Page::kPageSize);
#ifdef DEBUG
size_t chunk_size = chunks_[chunk_id].size();
Address high = RoundDown(chunk_start + chunk_size, Page::kPageSize);
ASSERT(pages_in_chunk <=
((OffsetFrom(high) - OffsetFrom(low)) / Page::kPageSize));
#endif
Address page_addr = low;
for (int i = 0; i < pages_in_chunk; i++) {
Page* p = Page::FromAddress(page_addr);
p->opaque_header = OffsetFrom(page_addr + Page::kPageSize) | chunk_id;
p->is_normal_page = 1;
page_addr += Page::kPageSize;
}
// Set the next page of the last page to 0.
Page* last_page = Page::FromAddress(page_addr - Page::kPageSize);
last_page->opaque_header = OffsetFrom(0) | chunk_id;
return Page::FromAddress(low);
}
Page* MemoryAllocator::FreePages(Page* p) {
if (!p->is_valid()) return p;
// Find the first page in the same chunk as 'p'
Page* first_page = FindFirstPageInSameChunk(p);
Page* page_to_return = Page::FromAddress(NULL);
if (p != first_page) {
// Find the last page in the same chunk as 'prev'.
Page* last_page = FindLastPageInSameChunk(p);
first_page = GetNextPage(last_page); // first page in next chunk
// set the next_page of last_page to NULL
SetNextPage(last_page, Page::FromAddress(NULL));
page_to_return = p; // return 'p' when exiting
}
while (first_page->is_valid()) {
int chunk_id = GetChunkId(first_page);
ASSERT(IsValidChunk(chunk_id));
// Find the first page of the next chunk before deleting this chunk.
first_page = GetNextPage(FindLastPageInSameChunk(first_page));
// Free the current chunk.
DeleteChunk(chunk_id);
}
return page_to_return;
}
void MemoryAllocator::DeleteChunk(int chunk_id) {
ASSERT(IsValidChunk(chunk_id));
ChunkInfo& c = chunks_[chunk_id];
// We cannot free a chunk contained in the initial chunk because it was not
// allocated with AllocateRawMemory. Instead we uncommit the virtual
// memory.
if (InInitialChunk(c.address())) {
// TODO(1240712): VirtualMemory::Uncommit has a return value which
// is ignored here.
initial_chunk_->Uncommit(c.address(), c.size());
Counters::memory_allocated.Decrement(c.size());
} else {
LOG(DeleteEvent("PagedChunk", c.address()));
FreeRawMemory(c.address(), c.size());
}
c.init(NULL, 0, NULL);
Push(chunk_id);
}
Page* MemoryAllocator::FindFirstPageInSameChunk(Page* p) {
int chunk_id = GetChunkId(p);
ASSERT(IsValidChunk(chunk_id));
Address low = RoundUp(chunks_[chunk_id].address(), Page::kPageSize);
return Page::FromAddress(low);
}
Page* MemoryAllocator::FindLastPageInSameChunk(Page* p) {
int chunk_id = GetChunkId(p);
ASSERT(IsValidChunk(chunk_id));
Address chunk_start = chunks_[chunk_id].address();
size_t chunk_size = chunks_[chunk_id].size();
Address high = RoundDown(chunk_start + chunk_size, Page::kPageSize);
ASSERT(chunk_start <= p->address() && p->address() < high);
return Page::FromAddress(high - Page::kPageSize);
}
#ifdef DEBUG
void MemoryAllocator::ReportStatistics() {
float pct = static_cast<float>(capacity_ - size_) / capacity_;
PrintF(" capacity: %d, used: %d, available: %%%d\n\n",
capacity_, size_, static_cast<int>(pct*100));
}
#endif
// -----------------------------------------------------------------------------
// PagedSpace implementation
PagedSpace::PagedSpace(int max_capacity,
AllocationSpace id,
Executability executable)
: Space(id, executable) {
max_capacity_ = (RoundDown(max_capacity, Page::kPageSize) / Page::kPageSize)
* Page::kObjectAreaSize;
accounting_stats_.Clear();
allocation_info_.top = NULL;
allocation_info_.limit = NULL;
mc_forwarding_info_.top = NULL;
mc_forwarding_info_.limit = NULL;
}
bool PagedSpace::Setup(Address start, size_t size) {
if (HasBeenSetup()) return false;
int num_pages = 0;
// Try to use the virtual memory range passed to us. If it is too small to
// contain at least one page, ignore it and allocate instead.
int pages_in_chunk = PagesInChunk(start, size);
if (pages_in_chunk > 0) {
first_page_ = MemoryAllocator::CommitPages(RoundUp(start, Page::kPageSize),
Page::kPageSize * pages_in_chunk,
this, &num_pages);
} else {
int requested_pages = Min(MemoryAllocator::kPagesPerChunk,
max_capacity_ / Page::kObjectAreaSize);
first_page_ =
MemoryAllocator::AllocatePages(requested_pages, &num_pages, this);
if (!first_page_->is_valid()) return false;
}
// We are sure that the first page is valid and that we have at least one
// page.
ASSERT(first_page_->is_valid());
ASSERT(num_pages > 0);
accounting_stats_.ExpandSpace(num_pages * Page::kObjectAreaSize);
ASSERT(Capacity() <= max_capacity_);
// Sequentially initialize remembered sets in the newly allocated
// pages and cache the current last page in the space.
for (Page* p = first_page_; p->is_valid(); p = p->next_page()) {
p->ClearRSet();
last_page_ = p;
}
// Use first_page_ for allocation.
SetAllocationInfo(&allocation_info_, first_page_);
return true;
}
bool PagedSpace::HasBeenSetup() {
return (Capacity() > 0);
}
void PagedSpace::TearDown() {
first_page_ = MemoryAllocator::FreePages(first_page_);
ASSERT(!first_page_->is_valid());
accounting_stats_.Clear();
}
#ifdef ENABLE_HEAP_PROTECTION
void PagedSpace::Protect() {
Page* page = first_page_;
while (page->is_valid()) {
MemoryAllocator::ProtectChunkFromPage(page);
page = MemoryAllocator::FindLastPageInSameChunk(page)->next_page();
}
}
void PagedSpace::Unprotect() {
Page* page = first_page_;
while (page->is_valid()) {
MemoryAllocator::UnprotectChunkFromPage(page);
page = MemoryAllocator::FindLastPageInSameChunk(page)->next_page();
}
}
#endif
void PagedSpace::ClearRSet() {
PageIterator it(this, PageIterator::ALL_PAGES);
while (it.has_next()) {
it.next()->ClearRSet();
}
}
Object* PagedSpace::FindObject(Address addr) {
// Note: this function can only be called before or after mark-compact GC
// because it accesses map pointers.
ASSERT(!MarkCompactCollector::in_use());
if (!Contains(addr)) return Failure::Exception();
Page* p = Page::FromAddress(addr);
ASSERT(IsUsed(p));
Address cur = p->ObjectAreaStart();
Address end = p->AllocationTop();
while (cur < end) {
HeapObject* obj = HeapObject::FromAddress(cur);
Address next = cur + obj->Size();
if ((cur <= addr) && (addr < next)) return obj;
cur = next;
}
UNREACHABLE();
return Failure::Exception();
}
bool PagedSpace::IsUsed(Page* page) {
PageIterator it(this, PageIterator::PAGES_IN_USE);
while (it.has_next()) {
if (page == it.next()) return true;
}
return false;
}
void PagedSpace::SetAllocationInfo(AllocationInfo* alloc_info, Page* p) {
alloc_info->top = p->ObjectAreaStart();
alloc_info->limit = p->ObjectAreaEnd();
ASSERT(alloc_info->VerifyPagedAllocation());
}
void PagedSpace::MCResetRelocationInfo() {
// Set page indexes.
int i = 0;
PageIterator it(this, PageIterator::ALL_PAGES);
while (it.has_next()) {
Page* p = it.next();
p->mc_page_index = i++;
}
// Set mc_forwarding_info_ to the first page in the space.
SetAllocationInfo(&mc_forwarding_info_, first_page_);
// All the bytes in the space are 'available'. We will rediscover
// allocated and wasted bytes during GC.
accounting_stats_.Reset();
}
int PagedSpace::MCSpaceOffsetForAddress(Address addr) {
#ifdef DEBUG
// The Contains function considers the address at the beginning of a
// page in the page, MCSpaceOffsetForAddress considers it is in the
// previous page.
if (Page::IsAlignedToPageSize(addr)) {
ASSERT(Contains(addr - kPointerSize));
} else {
ASSERT(Contains(addr));
}
#endif
// If addr is at the end of a page, it belongs to previous page
Page* p = Page::IsAlignedToPageSize(addr)
? Page::FromAllocationTop(addr)
: Page::FromAddress(addr);
int index = p->mc_page_index;
return (index * Page::kPageSize) + p->Offset(addr);
}
// Slow case for reallocating and promoting objects during a compacting
// collection. This function is not space-specific.
HeapObject* PagedSpace::SlowMCAllocateRaw(int size_in_bytes) {
Page* current_page = TopPageOf(mc_forwarding_info_);
if (!current_page->next_page()->is_valid()) {
if (!Expand(current_page)) {
return NULL;
}
}
// There are surely more pages in the space now.
ASSERT(current_page->next_page()->is_valid());
// We do not add the top of page block for current page to the space's
// free list---the block may contain live objects so we cannot write
// bookkeeping information to it. Instead, we will recover top of page
// blocks when we move objects to their new locations.
//
// We do however write the allocation pointer to the page. The encoding
// of forwarding addresses is as an offset in terms of live bytes, so we
// need quick access to the allocation top of each page to decode
// forwarding addresses.
current_page->mc_relocation_top = mc_forwarding_info_.top;
SetAllocationInfo(&mc_forwarding_info_, current_page->next_page());
return AllocateLinearly(&mc_forwarding_info_, size_in_bytes);
}
bool PagedSpace::Expand(Page* last_page) {
ASSERT(max_capacity_ % Page::kObjectAreaSize == 0);
ASSERT(Capacity() % Page::kObjectAreaSize == 0);
if (Capacity() == max_capacity_) return false;
ASSERT(Capacity() < max_capacity_);
// Last page must be valid and its next page is invalid.
ASSERT(last_page->is_valid() && !last_page->next_page()->is_valid());
int available_pages = (max_capacity_ - Capacity()) / Page::kObjectAreaSize;
if (available_pages <= 0) return false;
int desired_pages = Min(available_pages, MemoryAllocator::kPagesPerChunk);
Page* p = MemoryAllocator::AllocatePages(desired_pages, &desired_pages, this);
if (!p->is_valid()) return false;
accounting_stats_.ExpandSpace(desired_pages * Page::kObjectAreaSize);
ASSERT(Capacity() <= max_capacity_);
MemoryAllocator::SetNextPage(last_page, p);
// Sequentially clear remembered set of new pages and and cache the
// new last page in the space.
while (p->is_valid()) {
p->ClearRSet();
last_page_ = p;
p = p->next_page();
}
return true;
}
#ifdef DEBUG
int PagedSpace::CountTotalPages() {
int count = 0;
for (Page* p = first_page_; p->is_valid(); p = p->next_page()) {
count++;
}
return count;
}
#endif
void PagedSpace::Shrink() {
// Release half of free pages.
Page* top_page = AllocationTopPage();
ASSERT(top_page->is_valid());
// Loop over the pages from the top page to the end of the space to count
// the number of pages to keep and find the last page to keep.
int free_pages = 0;
int pages_to_keep = 0; // Of the free pages.
Page* last_page_to_keep = top_page;
Page* current_page = top_page->next_page();
// Loop over the pages to the end of the space.
while (current_page->is_valid()) {
#if defined(ANDROID)
// Free all chunks if possible
#else
// Advance last_page_to_keep every other step to end up at the midpoint.
if ((free_pages & 0x1) == 1) {
pages_to_keep++;
last_page_to_keep = last_page_to_keep->next_page();
}
#endif
free_pages++;
current_page = current_page->next_page();
}
// Free pages after last_page_to_keep, and adjust the next_page link.
Page* p = MemoryAllocator::FreePages(last_page_to_keep->next_page());
MemoryAllocator::SetNextPage(last_page_to_keep, p);
// Since pages are only freed in whole chunks, we may have kept more
// than pages_to_keep. Count the extra pages and cache the new last
// page in the space.
last_page_ = last_page_to_keep;
while (p->is_valid()) {
pages_to_keep++;
last_page_ = p;
p = p->next_page();
}
// The difference between free_pages and pages_to_keep is the number of
// pages actually freed.
ASSERT(pages_to_keep <= free_pages);
int bytes_freed = (free_pages - pages_to_keep) * Page::kObjectAreaSize;
accounting_stats_.ShrinkSpace(bytes_freed);
ASSERT(Capacity() == CountTotalPages() * Page::kObjectAreaSize);
}
bool PagedSpace::EnsureCapacity(int capacity) {
if (Capacity() >= capacity) return true;
// Start from the allocation top and loop to the last page in the space.
Page* last_page = AllocationTopPage();
Page* next_page = last_page->next_page();
while (next_page->is_valid()) {
last_page = MemoryAllocator::FindLastPageInSameChunk(next_page);
next_page = last_page->next_page();
}
// Expand the space until it has the required capacity or expansion fails.
do {
if (!Expand(last_page)) return false;
ASSERT(last_page->next_page()->is_valid());
last_page =
MemoryAllocator::FindLastPageInSameChunk(last_page->next_page());
} while (Capacity() < capacity);
return true;
}
#ifdef DEBUG
void PagedSpace::Print() { }
#endif
#ifdef DEBUG
// We do not assume that the PageIterator works, because it depends on the
// invariants we are checking during verification.
void PagedSpace::Verify(ObjectVisitor* visitor) {
// The allocation pointer should be valid, and it should be in a page in the
// space.
ASSERT(allocation_info_.VerifyPagedAllocation());
Page* top_page = Page::FromAllocationTop(allocation_info_.top);
ASSERT(MemoryAllocator::IsPageInSpace(top_page, this));
// Loop over all the pages.
bool above_allocation_top = false;
Page* current_page = first_page_;
while (current_page->is_valid()) {
if (above_allocation_top) {
// We don't care what's above the allocation top.
} else {
// Unless this is the last page in the space containing allocated
// objects, the allocation top should be at a constant offset from the
// object area end.
Address top = current_page->AllocationTop();
if (current_page == top_page) {
ASSERT(top == allocation_info_.top);
// The next page will be above the allocation top.
above_allocation_top = true;
} else {
ASSERT(top == current_page->ObjectAreaEnd() - page_extra_);
}
// It should be packed with objects from the bottom to the top.
Address current = current_page->ObjectAreaStart();
while (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();
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 and
// have their remembered set bits set if required as determined
// by the visitor.
int size = object->Size();
if (object->IsCode()) {
Code::cast(object)->ConvertICTargetsFromAddressToObject();
object->IterateBody(map->instance_type(), size, visitor);
Code::cast(object)->ConvertICTargetsFromObjectToAddress();
} else {
object->IterateBody(map->instance_type(), size, visitor);
}
current += size;
}
// The allocation pointer should not be in the middle of an object.
ASSERT(current == top);
}
current_page = current_page->next_page();
}
}
#endif
// -----------------------------------------------------------------------------
// NewSpace implementation
bool NewSpace::Setup(Address start, int size) {
// Setup 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();
int maximum_semispace_capacity = Heap::SemiSpaceSize();
ASSERT(initial_semispace_capacity <= maximum_semispace_capacity);
ASSERT(IsPowerOf2(maximum_semispace_capacity));
maximum_capacity_ = maximum_semispace_capacity;
capacity_ = initial_semispace_capacity;
// Allocate and setup the histogram arrays if necessary.
#if defined(DEBUG) || defined(ENABLE_LOGGING_AND_PROFILING)
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
#endif
ASSERT(size == 2 * maximum_capacity_);
ASSERT(IsAddressAligned(start, size, 0));
if (!to_space_.Setup(start, capacity_, maximum_capacity_)) {
return false;
}
if (!from_space_.Setup(start + maximum_capacity_,
capacity_,
maximum_capacity_)) {
return false;
}
start_ = start;
address_mask_ = ~(size - 1);
object_mask_ = address_mask_ | kHeapObjectTag;
object_expected_ = reinterpret_cast<uintptr_t>(start) | kHeapObjectTag;
allocation_info_.top = to_space_.low();
allocation_info_.limit = to_space_.high();
mc_forwarding_info_.top = NULL;
mc_forwarding_info_.limit = NULL;
ASSERT_SEMISPACE_ALLOCATION_INFO(allocation_info_, to_space_);
return true;
}
void NewSpace::TearDown() {
#if defined(DEBUG) || defined(ENABLE_LOGGING_AND_PROFILING)
if (allocated_histogram_) {
DeleteArray(allocated_histogram_);
allocated_histogram_ = NULL;
}
if (promoted_histogram_) {
DeleteArray(promoted_histogram_);
promoted_histogram_ = NULL;
}
#endif
start_ = NULL;
capacity_ = 0;
allocation_info_.top = NULL;
allocation_info_.limit = NULL;
mc_forwarding_info_.top = NULL;
mc_forwarding_info_.limit = NULL;
to_space_.TearDown();
from_space_.TearDown();
}
#ifdef ENABLE_HEAP_PROTECTION
void NewSpace::Protect() {
MemoryAllocator::Protect(ToSpaceLow(), Capacity());
MemoryAllocator::Protect(FromSpaceLow(), Capacity());
}
void NewSpace::Unprotect() {
MemoryAllocator::Unprotect(ToSpaceLow(), Capacity(),
to_space_.executable());
MemoryAllocator::Unprotect(FromSpaceLow(), Capacity(),
from_space_.executable());
}
#endif
void NewSpace::Flip() {
SemiSpace tmp = from_space_;
from_space_ = to_space_;
to_space_ = tmp;
}
bool NewSpace::Grow() {
ASSERT(capacity_ < maximum_capacity_);
// TODO(1240712): Failure to double the from space can result in
// semispaces of different sizes. In the event of that failure, the
// to space doubling should be rolled back before returning false.
if (!to_space_.Grow() || !from_space_.Grow()) return false;
capacity_ = to_space_.Capacity() + from_space_.Capacity();
allocation_info_.limit = to_space_.high();
ASSERT_SEMISPACE_ALLOCATION_INFO(allocation_info_, to_space_);
return true;
}
void NewSpace::ResetAllocationInfo() {
allocation_info_.top = to_space_.low();
allocation_info_.limit = to_space_.high();
ASSERT_SEMISPACE_ALLOCATION_INFO(allocation_info_, to_space_);
}
void NewSpace::MCResetRelocationInfo() {
mc_forwarding_info_.top = from_space_.low();
mc_forwarding_info_.limit = from_space_.high();
ASSERT_SEMISPACE_ALLOCATION_INFO(mc_forwarding_info_, from_space_);
}
void NewSpace::MCCommitRelocationInfo() {
// Assumes that the spaces have been flipped so that mc_forwarding_info_ is
// valid allocation info for the to space.
allocation_info_.top = mc_forwarding_info_.top;
allocation_info_.limit = to_space_.high();
ASSERT_SEMISPACE_ALLOCATION_INFO(allocation_info_, to_space_);
}
#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_.low();
while (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();
ASSERT(map->IsMap());
ASSERT(Heap::map_space()->Contains(map));
// The object should not be code or a map.
ASSERT(!object->IsMap());
ASSERT(!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;
}
// The allocation pointer should not be in the middle of an object.
ASSERT(current == top());
}
#endif
bool SemiSpace::Commit() {
ASSERT(!is_committed());
if (!MemoryAllocator::CommitBlock(start_, capacity_, executable())) {
return false;
}
committed_ = true;
return true;
}
bool SemiSpace::Uncommit() {
ASSERT(is_committed());
if (!MemoryAllocator::UncommitBlock(start_, capacity_)) {
return false;
}
committed_ = false;
return true;
}
// -----------------------------------------------------------------------------
// SemiSpace implementation
bool 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.
capacity_ = initial_capacity;
maximum_capacity_ = maximum_capacity;
committed_ = false;
start_ = start;
address_mask_ = ~(maximum_capacity - 1);
object_mask_ = address_mask_ | kHeapObjectTag;
object_expected_ = reinterpret_cast<uintptr_t>(start) | kHeapObjectTag;
age_mark_ = start_;
return Commit();
}
void SemiSpace::TearDown() {
start_ = NULL;
capacity_ = 0;
}
bool SemiSpace::Grow() {
// Commit 50% extra space but only up to maximum capacity.
int extra = RoundUp(capacity_ / 2, OS::AllocateAlignment());
if (capacity_ + extra > maximum_capacity_) {
extra = maximum_capacity_ - capacity_;
}
if (!MemoryAllocator::CommitBlock(high(), extra, executable())) {
return false;
}
capacity_ += extra;
return true;
}
#ifdef DEBUG
void SemiSpace::Print() { }
void SemiSpace::Verify() { }
#endif
// -----------------------------------------------------------------------------
// SemiSpaceIterator implementation.
SemiSpaceIterator::SemiSpaceIterator(NewSpace* space) {
Initialize(space, space->bottom(), space->top(), NULL);
}
SemiSpaceIterator::SemiSpaceIterator(NewSpace* space,
HeapObjectCallback size_func) {
Initialize(space, space->bottom(), space->top(), size_func);
}
SemiSpaceIterator::SemiSpaceIterator(NewSpace* space, Address start) {
Initialize(space, start, space->top(), NULL);
}
void SemiSpaceIterator::Initialize(NewSpace* space, Address start,
Address end,
HeapObjectCallback size_func) {
ASSERT(space->ToSpaceContains(start));
ASSERT(space->ToSpaceLow() <= end
&& end <= space->ToSpaceHigh());
space_ = &space->to_space_;
current_ = start;
limit_ = end;
size_func_ = size_func;
}
#ifdef DEBUG
// A static array of histogram info for each type.
static HistogramInfo heap_histograms[LAST_TYPE+1];
static JSObject::SpillInformation js_spill_information;
// heap_histograms is shared, always clear it before using it.
static void ClearHistograms() {
// We reset the name each time, though it hasn't changed.
#define DEF_TYPE_NAME(name) heap_histograms[name].set_name(#name);
INSTANCE_TYPE_LIST(DEF_TYPE_NAME)
#undef DEF_TYPE_NAME
#define CLEAR_HISTOGRAM(name) heap_histograms[name].clear();
INSTANCE_TYPE_LIST(CLEAR_HISTOGRAM)
#undef CLEAR_HISTOGRAM
js_spill_information.Clear();
}
static int code_kind_statistics[Code::NUMBER_OF_KINDS];
static void ClearCodeKindStatistics() {
for (int i = 0; i < Code::NUMBER_OF_KINDS; i++) {
code_kind_statistics[i] = 0;
}
}
static void ReportCodeKindStatistics() {
const char* table[Code::NUMBER_OF_KINDS];
#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(STUB);
CASE(BUILTIN);
CASE(LOAD_IC);
CASE(KEYED_LOAD_IC);
CASE(STORE_IC);
CASE(KEYED_STORE_IC);
CASE(CALL_IC);
}
}
#undef CASE
PrintF("\n Code kind histograms: \n");
for (int i = 0; i < Code::NUMBER_OF_KINDS; i++) {
if (code_kind_statistics[i] > 0) {
PrintF(" %-20s: %10d bytes\n", table[i], code_kind_statistics[i]);
}
}
PrintF("\n");
}
static int CollectHistogramInfo(HeapObject* obj) {
InstanceType type = obj->map()->instance_type();
ASSERT(0 <= type && type <= LAST_TYPE);
ASSERT(heap_histograms[type].name() != NULL);
heap_histograms[type].increment_number(1);
heap_histograms[type].increment_bytes(obj->Size());
if (FLAG_collect_heap_spill_statistics && obj->IsJSObject()) {
JSObject::cast(obj)->IncrementSpillStatistics(&js_spill_information);
}
return obj->Size();
}
static void ReportHistogram(bool print_spill) {
PrintF("\n Object Histogram:\n");
for (int i = 0; i <= LAST_TYPE; i++) {
if (heap_histograms[i].number() > 0) {
PrintF(" %-33s%10d (%10d bytes)\n",
heap_histograms[i].name(),
heap_histograms[i].number(),
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 += heap_histograms[type].number(); \
string_bytes += heap_histograms[type].bytes();
STRING_TYPE_LIST(INCREMENT)
#undef INCREMENT
if (string_number > 0) {
PrintF(" %-33s%10d (%10d bytes)\n\n", "STRING_TYPE", string_number,
string_bytes);
}
if (FLAG_collect_heap_spill_statistics && print_spill) {
js_spill_information.Print();
}
}
#endif // DEBUG
// Support for statistics gathering for --heap-stats and --log-gc.
#if defined(DEBUG) || defined(ENABLE_LOGGING_AND_PROFILING)
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 (1) when compiled with DEBUG and the --heap-stats flag is
// set, or when compiled with ENABLE_LOGGING_AND_PROFILING and the --log-gc
// flag is set.
void NewSpace::CollectStatistics() {
ClearHistograms();
SemiSpaceIterator it(this);
while (it.has_next()) RecordAllocation(it.next());
}
#ifdef ENABLE_LOGGING_AND_PROFILING
static void DoReportStatistics(HistogramInfo* info, const char* description) {
LOG(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(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(HeapSampleItemEvent(info[i].name(), info[i].number(),
info[i].bytes()));
}
}
LOG(HeapSampleEndEvent("NewSpace", description));
}
#endif // ENABLE_LOGGING_AND_PROFILING
void NewSpace::ReportStatistics() {
#ifdef DEBUG
if (FLAG_heap_stats) {
float pct = static_cast<float>(Available()) / Capacity();
PrintF(" capacity: %d, available: %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(" %-33s%10d (%10d bytes)\n",
allocated_histogram_[i].name(),
allocated_histogram_[i].number(),
allocated_histogram_[i].bytes());
}
}
PrintF("\n");
}
#endif // DEBUG
#ifdef ENABLE_LOGGING_AND_PROFILING
if (FLAG_log_gc) {
DoReportStatistics(allocated_histogram_, "allocated");
DoReportStatistics(promoted_histogram_, "promoted");
}
#endif // ENABLE_LOGGING_AND_PROFILING
}
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());
}
#endif // defined(DEBUG) || defined(ENABLE_LOGGING_AND_PROFILING)
// -----------------------------------------------------------------------------
// Free lists for old object spaces implementation
void FreeListNode::set_size(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 ByteArray with at least one extra word (the next
// pointer), we set its map to be the byte array 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 > ByteArray::kAlignedSize) {
set_map(Heap::raw_unchecked_byte_array_map());
ByteArray::cast(this)->set_length(ByteArray::LengthFor(size_in_bytes));
} else if (size_in_bytes == kPointerSize) {
set_map(Heap::raw_unchecked_one_pointer_filler_map());
} else if (size_in_bytes == 2 * kPointerSize) {
set_map(Heap::raw_unchecked_two_pointer_filler_map());
} else {
UNREACHABLE();
}
ASSERT(Size() == size_in_bytes);
}
Address FreeListNode::next() {
ASSERT(map() == Heap::raw_unchecked_byte_array_map() ||
map() == Heap::raw_unchecked_two_pointer_filler_map());
if (map() == Heap::raw_unchecked_byte_array_map()) {
ASSERT(Size() >= kNextOffset + kPointerSize);
return Memory::Address_at(address() + kNextOffset);
} else {
return Memory::Address_at(address() + kPointerSize);
}
}
void FreeListNode::set_next(Address next) {
ASSERT(map() == Heap::raw_unchecked_byte_array_map() ||
map() == Heap::raw_unchecked_two_pointer_filler_map());
if (map() == Heap::raw_unchecked_byte_array_map()) {
ASSERT(Size() >= kNextOffset + kPointerSize);
Memory::Address_at(address() + kNextOffset) = next;
} else {
Memory::Address_at(address() + kPointerSize) = next;
}
}
OldSpaceFreeList::OldSpaceFreeList(AllocationSpace owner) : owner_(owner) {
Reset();
}
void OldSpaceFreeList::Reset() {
available_ = 0;
for (int i = 0; i < kFreeListsLength; i++) {
free_[i].head_node_ = NULL;
}
needs_rebuild_ = false;
finger_ = kHead;
free_[kHead].next_size_ = kEnd;
}
void OldSpaceFreeList::RebuildSizeList() {
ASSERT(needs_rebuild_);
int cur = kHead;
for (int i = cur + 1; i < kFreeListsLength; i++) {
if (free_[i].head_node_ != NULL) {
free_[cur].next_size_ = i;
cur = i;
}
}
free_[cur].next_size_ = kEnd;
needs_rebuild_ = false;
}
int OldSpaceFreeList::Free(Address start, int size_in_bytes) {
#ifdef DEBUG
for (int i = 0; i < size_in_bytes; i += kPointerSize) {
Memory::Address_at(start + i) = kZapValue;
}
#endif
FreeListNode* node = FreeListNode::FromAddress(start);
node->set_size(size_in_bytes);
// We don't use the freelists in compacting mode. This makes it more like a
// GC that only has mark-sweep-compact and doesn't have a mark-sweep
// collector.
if (FLAG_always_compact) {
return size_in_bytes;
}
// Early return to drop too-small blocks on the floor (one or two word
// blocks cannot hold a map pointer, a size field, and a pointer to the
// next block in the free list).
if (size_in_bytes < kMinBlockSize) {
return size_in_bytes;
}
// Insert other blocks at the head of an exact free list.
int index = size_in_bytes >> kPointerSizeLog2;
node->set_next(free_[index].head_node_);
free_[index].head_node_ = node->address();
available_ += size_in_bytes;
needs_rebuild_ = true;
return 0;
}
Object* OldSpaceFreeList::Allocate(int size_in_bytes, int* wasted_bytes) {
ASSERT(0 < size_in_bytes);
ASSERT(size_in_bytes <= kMaxBlockSize);
ASSERT(IsAligned(size_in_bytes, kPointerSize));
if (needs_rebuild_) RebuildSizeList();
int index = size_in_bytes >> kPointerSizeLog2;
// Check for a perfect fit.
if (free_[index].head_node_ != NULL) {
FreeListNode* node = FreeListNode::FromAddress(free_[index].head_node_);
// If this was the last block of its size, remove the size.
if ((free_[index].head_node_ = node->next()) == NULL) RemoveSize(index);
available_ -= size_in_bytes;
*wasted_bytes = 0;
ASSERT(!FLAG_always_compact); // We only use the freelists with mark-sweep.
return node;
}
// Search the size list for the best fit.
int prev = finger_ < index ? finger_ : kHead;
int cur = FindSize(index, &prev);
ASSERT(index < cur);
if (cur == kEnd) {
// No large enough size in list.
*wasted_bytes = 0;
return Failure::RetryAfterGC(size_in_bytes, owner_);
}
ASSERT(!FLAG_always_compact); // We only use the freelists with mark-sweep.
int rem = cur - index;
int rem_bytes = rem << kPointerSizeLog2;
FreeListNode* cur_node = FreeListNode::FromAddress(free_[cur].head_node_);
ASSERT(cur_node->Size() == (cur << kPointerSizeLog2));
FreeListNode* rem_node = FreeListNode::FromAddress(free_[cur].head_node_ +
size_in_bytes);
// Distinguish the cases prev < rem < cur and rem <= prev < cur
// to avoid many redundant tests and calls to Insert/RemoveSize.
if (prev < rem) {
// Simple case: insert rem between prev and cur.
finger_ = prev;
free_[prev].next_size_ = rem;
// If this was the last block of size cur, remove the size.
if ((free_[cur].head_node_ = cur_node->next()) == NULL) {
free_[rem].next_size_ = free_[cur].next_size_;
} else {
free_[rem].next_size_ = cur;
}
// Add the remainder block.
rem_node->set_size(rem_bytes);
rem_node->set_next(free_[rem].head_node_);
free_[rem].head_node_ = rem_node->address();
} else {
// If this was the last block of size cur, remove the size.
if ((free_[cur].head_node_ = cur_node->next()) == NULL) {
finger_ = prev;
free_[prev].next_size_ = free_[cur].next_size_;
}
if (rem_bytes < kMinBlockSize) {
// Too-small remainder is wasted.
rem_node->set_size(rem_bytes);
available_ -= size_in_bytes + rem_bytes;
*wasted_bytes = rem_bytes;
return cur_node;
}
// Add the remainder block and, if needed, insert its size.
rem_node->set_size(rem_bytes);
rem_node->set_next(free_[rem].head_node_);
free_[rem].head_node_ = rem_node->address();
if (rem_node->next() == NULL) InsertSize(rem);
}
available_ -= size_in_bytes;
*wasted_bytes = 0;
return cur_node;
}
#ifdef DEBUG
bool OldSpaceFreeList::Contains(FreeListNode* node) {
for (int i = 0; i < kFreeListsLength; i++) {
Address cur_addr = free_[i].head_node_;
while (cur_addr != NULL) {
FreeListNode* cur_node = FreeListNode::FromAddress(cur_addr);
if (cur_node == node) return true;
cur_addr = cur_node->next();
}
}
return false;
}
#endif
FixedSizeFreeList::FixedSizeFreeList(AllocationSpace owner, int object_size)
: owner_(owner), object_size_(object_size) {
Reset();
}
void FixedSizeFreeList::Reset() {
available_ = 0;
head_ = NULL;
}
void FixedSizeFreeList::Free(Address start) {
#ifdef DEBUG
for (int i = 0; i < object_size_; i += kPointerSize) {
Memory::Address_at(start + i) = kZapValue;
}
#endif
ASSERT(!FLAG_always_compact); // We only use the freelists with mark-sweep.
FreeListNode* node = FreeListNode::FromAddress(start);
node->set_size(object_size_);
node->set_next(head_);
head_ = node->address();
available_ += object_size_;
}
Object* FixedSizeFreeList::Allocate() {
if (head_ == NULL) {
return Failure::RetryAfterGC(object_size_, owner_);
}
ASSERT(!FLAG_always_compact); // We only use the freelists with mark-sweep.
FreeListNode* node = FreeListNode::FromAddress(head_);
head_ = node->next();
available_ -= object_size_;
return node;
}
// -----------------------------------------------------------------------------
// OldSpace implementation
void OldSpace::PrepareForMarkCompact(bool will_compact) {
if (will_compact) {
// Reset relocation info. During a compacting collection, everything in
// the space is considered 'available' and we will rediscover live data
// and waste during the collection.
MCResetRelocationInfo();
ASSERT(Available() == Capacity());
} else {
// During a non-compacting collection, everything below the linear
// allocation pointer is considered allocated (everything above is
// available) and we will rediscover available and wasted bytes during
// the collection.
accounting_stats_.AllocateBytes(free_list_.available());
accounting_stats_.FillWastedBytes(Waste());
}
// Clear the free list before a full GC---it will be rebuilt afterward.
free_list_.Reset();
}
void OldSpace::MCCommitRelocationInfo() {
// Update fast allocation info.
allocation_info_.top = mc_forwarding_info_.top;
allocation_info_.limit = mc_forwarding_info_.limit;
ASSERT(allocation_info_.VerifyPagedAllocation());
// The space is compacted and we haven't yet built free lists or
// wasted any space.
ASSERT(Waste() == 0);
ASSERT(AvailableFree() == 0);
// Build the free list for the space.
int computed_size = 0;
PageIterator it(this, PageIterator::PAGES_USED_BY_MC);
while (it.has_next()) {
Page* p = it.next();
// Space below the relocation pointer is allocated.
computed_size += p->mc_relocation_top - p->ObjectAreaStart();
if (it.has_next()) {
// Free the space at the top of the page. We cannot use
// p->mc_relocation_top after the call to Free (because Free will clear
// remembered set bits).
int extra_size = p->ObjectAreaEnd() - p->mc_relocation_top;
if (extra_size > 0) {
int wasted_bytes = free_list_.Free(p->mc_relocation_top, extra_size);
// The bytes we have just "freed" to add to the free list were
// already accounted as available.
accounting_stats_.WasteBytes(wasted_bytes);
}
}
}
// Make sure the computed size - based on the used portion of the pages in
// use - matches the size obtained while computing forwarding addresses.
ASSERT(computed_size == Size());
}
// Slow case for normal allocation. Try in order: (1) allocate in the next
// page in the space, (2) allocate off the space's free list, (3) expand the
// space, (4) fail.
HeapObject* OldSpace::SlowAllocateRaw(int size_in_bytes) {
// Linear allocation in this space has failed. If there is another page
// in the space, move to that page and allocate there. This allocation
// should succeed (size_in_bytes should not be greater than a page's
// object area size).
Page* current_page = TopPageOf(allocation_info_);
if (current_page->next_page()->is_valid()) {
return AllocateInNextPage(current_page, size_in_bytes);
}
// There is no next page in this space. Try free list allocation.
int wasted_bytes;
Object* result = free_list_.Allocate(size_in_bytes, &wasted_bytes);
accounting_stats_.WasteBytes(wasted_bytes);
if (!result->IsFailure()) {
accounting_stats_.AllocateBytes(size_in_bytes);
return HeapObject::cast(result);
}
// 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.
ASSERT(!current_page->next_page()->is_valid());
if (Expand(current_page)) {
return AllocateInNextPage(current_page, size_in_bytes);
}
// Finally, fail.
return NULL;
}
// Add the block at the top of the page to the space's free list, set the
// allocation info to the next page (assumed to be one), and allocate
// linearly there.
HeapObject* OldSpace::AllocateInNextPage(Page* current_page,
int size_in_bytes) {
ASSERT(current_page->next_page()->is_valid());
// Add the block at the top of this page to the free list.
int free_size = current_page->ObjectAreaEnd() - allocation_info_.top;
if (free_size > 0) {
int wasted_bytes = free_list_.Free(allocation_info_.top, free_size);
accounting_stats_.WasteBytes(wasted_bytes);
}
SetAllocationInfo(&allocation_info_, current_page->next_page());
return AllocateLinearly(&allocation_info_, size_in_bytes);
}
#ifdef DEBUG
struct CommentStatistic {
const char* comment;
int size;
int count;
void Clear() {
comment = NULL;
size = 0;
count = 0;
}
};
// must be small, since an iteration is used for lookup
const int kMaxComments = 64;
static CommentStatistic comments_statistics[kMaxComments+1];
void PagedSpace::ReportCodeStatistics() {
ReportCodeKindStatistics();
PrintF("Code comment statistics (\" [ comment-txt : size/ "
"count (average)\"):\n");
for (int i = 0; i <= 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() {
ClearCodeKindStatistics();
for (int i = 0; i < kMaxComments; i++) comments_statistics[i].Clear();
comments_statistics[kMaxComments].comment = "Unknown";
comments_statistics[kMaxComments].size = 0;
comments_statistics[kMaxComments].count = 0;
}
// Adds comment to 'comment_statistics' table. Performance OK sa long as
// 'kMaxComments' is small
static void EnterComment(const char* comment, int delta) {
// Do not count empty comments
if (delta <= 0) return;
CommentStatistic* cs = &comments_statistics[kMaxComments];
// Search for a free or matching entry in 'comments_statistics': 'cs'
// points to result.
for (int i = 0; i < 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(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 += it->rinfo()->pc() - prev_pc;
if (txt[0] == ']') break; // End of nested comment
// A new comment
CollectCommentStatistics(it);
// Skip code that was covered with previous comment
prev_pc = it->rinfo()->pc();
}
it->next();
}
EnterComment(comment_txt, flat_delta);
}
// Collects code size statistics:
// - by code kind
// - by code comment
void PagedSpace::CollectCodeStatistics() {
HeapObjectIterator obj_it(this);
while (obj_it.has_next()) {
HeapObject* obj = obj_it.next();
if (obj->IsCode()) {
Code* code = Code::cast(obj);
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 += it.rinfo()->pc() - prev_pc;
CollectCommentStatistics(&it);
prev_pc = it.rinfo()->pc();
}
it.next();
}
ASSERT(code->instruction_start() <= prev_pc &&
prev_pc <= code->relocation_start());
delta += code->relocation_start() - prev_pc;
EnterComment("NoComment", delta);
}
}
}
void OldSpace::ReportStatistics() {
int pct = Available() * 100 / Capacity();
PrintF(" capacity: %d, waste: %d, available: %d, %%%d\n",
Capacity(), Waste(), Available(), pct);
// Report remembered set statistics.
int rset_marked_pointers = 0;
int rset_marked_arrays = 0;
int rset_marked_array_elements = 0;
int cross_gen_pointers = 0;
int cross_gen_array_elements = 0;
PageIterator page_it(this, PageIterator::PAGES_IN_USE);
while (page_it.has_next()) {
Page* p = page_it.next();
for (Address rset_addr = p->RSetStart();
rset_addr < p->RSetEnd();
rset_addr += kIntSize) {
int rset = Memory::int_at(rset_addr);
if (rset != 0) {
// Bits were set
int intoff = rset_addr - p->address();
int bitoff = 0;
for (; bitoff < kBitsPerInt; ++bitoff) {
if ((rset & (1 << bitoff)) != 0) {
int bitpos = intoff*kBitsPerByte + bitoff;
Address slot = p->OffsetToAddress(bitpos << kObjectAlignmentBits);
Object** obj = reinterpret_cast<Object**>(slot);
if (*obj == Heap::raw_unchecked_fixed_array_map()) {
rset_marked_arrays++;
FixedArray* fa = FixedArray::cast(HeapObject::FromAddress(slot));
rset_marked_array_elements += fa->length();
// Manually inline FixedArray::IterateBody
Address elm_start = slot + FixedArray::kHeaderSize;
Address elm_stop = elm_start + fa->length() * kPointerSize;
for (Address elm_addr = elm_start;
elm_addr < elm_stop; elm_addr += kPointerSize) {
// Filter non-heap-object pointers
Object** elm_p = reinterpret_cast<Object**>(elm_addr);
if (Heap::InNewSpace(*elm_p))
cross_gen_array_elements++;
}
} else {
rset_marked_pointers++;
if (Heap::InNewSpace(*obj))
cross_gen_pointers++;
}
}
}
}
}
}
pct = rset_marked_pointers == 0 ?
0 : cross_gen_pointers * 100 / rset_marked_pointers;
PrintF(" rset-marked pointers %d, to-new-space %d (%%%d)\n",
rset_marked_pointers, cross_gen_pointers, pct);
PrintF(" rset_marked arrays %d, ", rset_marked_arrays);
PrintF(" elements %d, ", rset_marked_array_elements);
pct = rset_marked_array_elements == 0 ? 0
: cross_gen_array_elements * 100 / rset_marked_array_elements;
PrintF(" pointers to new space %d (%%%d)\n", cross_gen_array_elements, pct);
PrintF(" total rset-marked bits %d\n",
(rset_marked_pointers + rset_marked_arrays));
pct = (rset_marked_pointers + rset_marked_array_elements) == 0 ? 0
: (cross_gen_pointers + cross_gen_array_elements) * 100 /
(rset_marked_pointers + rset_marked_array_elements);
PrintF(" total rset pointers %d, true cross generation ones %d (%%%d)\n",
(rset_marked_pointers + rset_marked_array_elements),
(cross_gen_pointers + cross_gen_array_elements),
pct);
ClearHistograms();
HeapObjectIterator obj_it(this);
while (obj_it.has_next()) { CollectHistogramInfo(obj_it.next()); }
ReportHistogram(true);
}
// Dump the range of remembered set words between [start, end) corresponding
// to the pointers starting at object_p. The allocation_top is an object
// pointer which should not be read past. This is important for large object
// pages, where some bits in the remembered set range do not correspond to
// allocated addresses.
static void PrintRSetRange(Address start, Address end, Object** object_p,
Address allocation_top) {
Address rset_address = start;
// If the range starts on on odd numbered word (eg, for large object extra
// remembered set ranges), print some spaces.
if ((reinterpret_cast<uintptr_t>(start) / kIntSize) % 2 == 1) {
PrintF(" ");
}
// Loop over all the words in the range.
while (rset_address < end) {
uint32_t rset_word = Memory::uint32_at(rset_address);
int bit_position = 0;
// Loop over all the bits in the word.
while (bit_position < kBitsPerInt) {
if (object_p == reinterpret_cast<Object**>(allocation_top)) {
// Print a bar at the allocation pointer.
PrintF("|");
} else if (object_p > reinterpret_cast<Object**>(allocation_top)) {
// Do not dereference object_p past the allocation pointer.
PrintF("#");
} else if ((rset_word & (1 << bit_position)) == 0) {
// Print a dot for zero bits.
PrintF(".");
} else if (Heap::InNewSpace(*object_p)) {
// Print an X for one bits for pointers to new space.
PrintF("X");
} else {
// Print a circle for one bits for pointers to old space.
PrintF("o");
}
// Print a space after every 8th bit except the last.
if (bit_position % 8 == 7 && bit_position != (kBitsPerInt - 1)) {
PrintF(" ");
}
// Advance to next bit.
bit_position++;
object_p++;
}
// Print a newline after every odd numbered word, otherwise a space.
if ((reinterpret_cast<uintptr_t>(rset_address) / kIntSize) % 2 == 1) {
PrintF("\n");
} else {
PrintF(" ");
}
// Advance to next remembered set word.
rset_address += kIntSize;
}
}
void PagedSpace::DoPrintRSet(const char* space_name) {
PageIterator it(this, PageIterator::PAGES_IN_USE);
while (it.has_next()) {
Page* p = it.next();
PrintF("%s page 0x%x:\n", space_name, p);
PrintRSetRange(p->RSetStart(), p->RSetEnd(),
reinterpret_cast<Object**>(p->ObjectAreaStart()),
p->AllocationTop());
PrintF("\n");
}
}
void OldSpace::PrintRSet() { DoPrintRSet("old"); }
#endif
// -----------------------------------------------------------------------------
// FixedSpace implementation
void FixedSpace::PrepareForMarkCompact(bool will_compact) {
if (will_compact) {
// Reset relocation info.
MCResetRelocationInfo();
// During a compacting collection, everything in the space is considered
// 'available' (set by the call to MCResetRelocationInfo) and we will
// rediscover live and wasted bytes during the collection.
ASSERT(Available() == Capacity());
} else {
// 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();
}
void FixedSpace::MCCommitRelocationInfo() {
// Update fast allocation info.
allocation_info_.top = mc_forwarding_info_.top;
allocation_info_.limit = mc_forwarding_info_.limit;
ASSERT(allocation_info_.VerifyPagedAllocation());
// The space is compacted and we haven't yet wasted any space.
ASSERT(Waste() == 0);
// Update allocation_top of each page in use and compute waste.
int computed_size = 0;
PageIterator it(this, PageIterator::PAGES_USED_BY_MC);
while (it.has_next()) {
Page* page = it.next();
Address page_top = page->AllocationTop();
computed_size += page_top - page->ObjectAreaStart();
if (it.has_next()) {
accounting_stats_.WasteBytes(page->ObjectAreaEnd() - page_top);
}
}
// Make sure the computed size - based on the used portion of the
// pages in use - matches the size we adjust during allocation.
ASSERT(computed_size == Size());
}
// Slow case for normal allocation. Try in order: (1) allocate in the next
// page in the space, (2) allocate off the space's free list, (3) expand the
// space, (4) fail.
HeapObject* FixedSpace::SlowAllocateRaw(int size_in_bytes) {
ASSERT_EQ(object_size_in_bytes_, size_in_bytes);
// Linear allocation in this space has failed. If there is another page
// in the space, move to that page and allocate there. This allocation
// should succeed.
Page* current_page = TopPageOf(allocation_info_);
if (current_page->next_page()->is_valid()) {
return AllocateInNextPage(current_page, size_in_bytes);
}
// There is no next page in this space. Try free list allocation.
// The fixed space free list implicitly assumes that all free blocks
// are of the fixed size.
if (size_in_bytes == object_size_in_bytes_) {
Object* result = free_list_.Allocate();
if (!result->IsFailure()) {
accounting_stats_.AllocateBytes(size_in_bytes);
return HeapObject::cast(result);
}
}
// 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.
ASSERT(!current_page->next_page()->is_valid());
if (Expand(current_page)) {
return AllocateInNextPage(current_page, size_in_bytes);
}
// Finally, fail.
return NULL;
}
// Move to the next page (there is assumed to be one) and allocate there.
// The top of page block is always wasted, because it is too small to hold a
// map.
HeapObject* FixedSpace::AllocateInNextPage(Page* current_page,
int size_in_bytes) {
ASSERT(current_page->next_page()->is_valid());
ASSERT(current_page->ObjectAreaEnd() - allocation_info_.top == page_extra_);
ASSERT_EQ(object_size_in_bytes_, size_in_bytes);
accounting_stats_.WasteBytes(page_extra_);
SetAllocationInfo(&allocation_info_, current_page->next_page());
return AllocateLinearly(&allocation_info_, size_in_bytes);
}
#ifdef DEBUG
void FixedSpace::ReportStatistics() {
int pct = Available() * 100 / Capacity();
PrintF(" capacity: %d, waste: %d, available: %d, %%%d\n",
Capacity(), Waste(), Available(), pct);
// Report remembered set statistics.
int rset_marked_pointers = 0;
int cross_gen_pointers = 0;
PageIterator page_it(this, PageIterator::PAGES_IN_USE);
while (page_it.has_next()) {
Page* p = page_it.next();
for (Address rset_addr = p->RSetStart();
rset_addr < p->RSetEnd();
rset_addr += kIntSize) {
int rset = Memory::int_at(rset_addr);
if (rset != 0) {
// Bits were set
int intoff = rset_addr - p->address();
int bitoff = 0;
for (; bitoff < kBitsPerInt; ++bitoff) {
if ((rset & (1 << bitoff)) != 0) {
int bitpos = intoff*kBitsPerByte + bitoff;
Address slot = p->OffsetToAddress(bitpos << kObjectAlignmentBits);
Object** obj = reinterpret_cast<Object**>(slot);
rset_marked_pointers++;
if (Heap::InNewSpace(*obj))
cross_gen_pointers++;
}
}
}
}
}
pct = rset_marked_pointers == 0 ?
0 : cross_gen_pointers * 100 / rset_marked_pointers;
PrintF(" rset-marked pointers %d, to-new-space %d (%%%d)\n",
rset_marked_pointers, cross_gen_pointers, pct);
ClearHistograms();
HeapObjectIterator obj_it(this);
while (obj_it.has_next()) { CollectHistogramInfo(obj_it.next()); }
ReportHistogram(false);
}
void FixedSpace::PrintRSet() { DoPrintRSet(name_); }
#endif
// -----------------------------------------------------------------------------
// MapSpace implementation
void MapSpace::PrepareForMarkCompact(bool will_compact) {
// Call prepare of the super class.
FixedSpace::PrepareForMarkCompact(will_compact);
if (will_compact) {
// Initialize map index entry.
int page_count = 0;
PageIterator it(this, PageIterator::ALL_PAGES);
while (it.has_next()) {
ASSERT_MAP_PAGE_INDEX(page_count);
Page* p = it.next();
ASSERT(p->mc_page_index == page_count);
page_addresses_[page_count++] = p->address();
}
}
}
#ifdef DEBUG
void MapSpace::VerifyObject(HeapObject* object) {
// The object should be a map or a free-list node.
ASSERT(object->IsMap() || object->IsByteArray());
}
#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_chunk_;
size_func_ = NULL;
}
LargeObjectIterator::LargeObjectIterator(LargeObjectSpace* space,
HeapObjectCallback size_func) {
current_ = space->first_chunk_;
size_func_ = size_func;
}
HeapObject* LargeObjectIterator::next() {
ASSERT(has_next());
HeapObject* object = current_->GetObject();
current_ = current_->next();
return object;
}
// -----------------------------------------------------------------------------
// LargeObjectChunk
LargeObjectChunk* LargeObjectChunk::New(int size_in_bytes,
size_t* chunk_size,
Executability executable) {
size_t requested = ChunkSizeFor(size_in_bytes);
void* mem = MemoryAllocator::AllocateRawMemory(requested,
chunk_size,
executable);
if (mem == NULL) return NULL;
LOG(NewEvent("LargeObjectChunk", mem, *chunk_size));
if (*chunk_size < requested) {
MemoryAllocator::FreeRawMemory(mem, *chunk_size);
LOG(DeleteEvent("LargeObjectChunk", mem));
return NULL;
}
return reinterpret_cast<LargeObjectChunk*>(mem);
}
int LargeObjectChunk::ChunkSizeFor(int size_in_bytes) {
int os_alignment = OS::AllocateAlignment();
if (os_alignment < Page::kPageSize)
size_in_bytes += (Page::kPageSize - os_alignment);
return size_in_bytes + Page::kObjectStartOffset;
}
// -----------------------------------------------------------------------------
// LargeObjectSpace
LargeObjectSpace::LargeObjectSpace(AllocationSpace id)
: Space(id, NOT_EXECUTABLE), // Managed on a per-allocation basis
first_chunk_(NULL),
size_(0),
page_count_(0) {}
bool LargeObjectSpace::Setup() {
first_chunk_ = NULL;
size_ = 0;
page_count_ = 0;
return true;
}
void LargeObjectSpace::TearDown() {
while (first_chunk_ != NULL) {
LargeObjectChunk* chunk = first_chunk_;
first_chunk_ = first_chunk_->next();
LOG(DeleteEvent("LargeObjectChunk", chunk->address()));
MemoryAllocator::FreeRawMemory(chunk->address(), chunk->size());
}
size_ = 0;
page_count_ = 0;
}
#ifdef ENABLE_HEAP_PROTECTION
void LargeObjectSpace::Protect() {
LargeObjectChunk* chunk = first_chunk_;
while (chunk != NULL) {
MemoryAllocator::Protect(chunk->address(), chunk->size());
chunk = chunk->next();
}
}
void LargeObjectSpace::Unprotect() {
LargeObjectChunk* chunk = first_chunk_;
while (chunk != NULL) {
bool is_code = chunk->GetObject()->IsCode();
MemoryAllocator::Unprotect(chunk->address(), chunk->size(),
is_code ? EXECUTABLE : NOT_EXECUTABLE);
chunk = chunk->next();
}
}
#endif
Object* LargeObjectSpace::AllocateRawInternal(int requested_size,
int object_size,
Executability executable) {
ASSERT(0 < object_size && object_size <= requested_size);
// 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(requested_size, identity());
}
size_t chunk_size;
LargeObjectChunk* chunk =
LargeObjectChunk::New(requested_size, &chunk_size, executable);
if (chunk == NULL) {
return Failure::RetryAfterGC(requested_size, identity());
}
size_ += chunk_size;
page_count_++;
chunk->set_next(first_chunk_);
chunk->set_size(chunk_size);
first_chunk_ = chunk;
// Set the object address and size in the page header and clear its
// remembered set.
Page* page = Page::FromAddress(RoundUp(chunk->address(), Page::kPageSize));
Address object_address = page->ObjectAreaStart();
// Clear the low order bit of the second word in the page to flag it as a
// large object page. If the chunk_size happened to be written there, its
// low order bit should already be clear.
ASSERT((chunk_size & 0x1) == 0);
page->is_normal_page &= ~0x1;
page->ClearRSet();
int extra_bytes = requested_size - object_size;
if (extra_bytes > 0) {
// The extra memory for the remembered set should be cleared.
memset(object_address + object_size, 0, extra_bytes);
}
return HeapObject::FromAddress(object_address);
}
Object* LargeObjectSpace::AllocateRawCode(int size_in_bytes) {
ASSERT(0 < size_in_bytes);
return AllocateRawInternal(size_in_bytes,
size_in_bytes,
EXECUTABLE);
}
Object* LargeObjectSpace::AllocateRawFixedArray(int size_in_bytes) {
ASSERT(0 < size_in_bytes);
int extra_rset_bytes = ExtraRSetBytesFor(size_in_bytes);
return AllocateRawInternal(size_in_bytes + extra_rset_bytes,
size_in_bytes,
NOT_EXECUTABLE);
}
Object* LargeObjectSpace::AllocateRaw(int size_in_bytes) {
ASSERT(0 < size_in_bytes);
return AllocateRawInternal(size_in_bytes,
size_in_bytes,
NOT_EXECUTABLE);
}
// GC support
Object* LargeObjectSpace::FindObject(Address a) {
for (LargeObjectChunk* chunk = first_chunk_;
chunk != NULL;
chunk = chunk->next()) {
Address chunk_address = chunk->address();
if (chunk_address <= a && a < chunk_address + chunk->size()) {
return chunk->GetObject();
}
}
return Failure::Exception();
}
void LargeObjectSpace::ClearRSet() {
ASSERT(Page::is_rset_in_use());
LargeObjectIterator it(this);
while (it.has_next()) {
HeapObject* object = it.next();
// We only have code, sequential strings, or fixed arrays in large
// object space, and only fixed arrays need remembered set support.
if (object->IsFixedArray()) {
// Clear the normal remembered set region of the page;
Page* page = Page::FromAddress(object->address());
page->ClearRSet();
// Clear the extra remembered set.
int size = object->Size();
int extra_rset_bytes = ExtraRSetBytesFor(size);
memset(object->address() + size, 0, extra_rset_bytes);
}
}
}
void LargeObjectSpace::IterateRSet(ObjectSlotCallback copy_object_func) {
ASSERT(Page::is_rset_in_use());
static void* lo_rset_histogram = StatsTable::CreateHistogram(
"V8.RSetLO",
0,
// Keeping this histogram's buckets the same as the paged space histogram.
Page::kObjectAreaSize / kPointerSize,
30);
LargeObjectIterator it(this);
while (it.has_next()) {
// We only have code, sequential strings, or fixed arrays in large
// object space, and only fixed arrays can possibly contain pointers to
// the young generation.
HeapObject* object = it.next();
if (object->IsFixedArray()) {
// Iterate the normal page remembered set range.
Page* page = Page::FromAddress(object->address());
Address object_end = object->address() + object->Size();
int count = Heap::IterateRSetRange(page->ObjectAreaStart(),
Min(page->ObjectAreaEnd(), object_end),
page->RSetStart(),
copy_object_func);
// Iterate the extra array elements.
if (object_end > page->ObjectAreaEnd()) {
count += Heap::IterateRSetRange(page->ObjectAreaEnd(), object_end,
object_end, copy_object_func);
}
if (lo_rset_histogram != NULL) {
StatsTable::AddHistogramSample(lo_rset_histogram, count);
}
}
}
}
void LargeObjectSpace::FreeUnmarkedObjects() {
LargeObjectChunk* previous = NULL;
LargeObjectChunk* current = first_chunk_;
while (current != NULL) {
HeapObject* object = current->GetObject();
if (object->IsMarked()) {
object->ClearMark();
MarkCompactCollector::tracer()->decrement_marked_count();
previous = current;
current = current->next();
} else {
Address chunk_address = current->address();
size_t chunk_size = current->size();
// Cut the chunk out from the chunk list.
current = current->next();
if (previous == NULL) {
first_chunk_ = current;
} else {
previous->set_next(current);
}
// Free the chunk.
if (object->IsCode()) {
LOG(CodeDeleteEvent(object->address()));
}
size_ -= chunk_size;
page_count_--;
MemoryAllocator::FreeRawMemory(chunk_address, chunk_size);
LOG(DeleteEvent("LargeObjectChunk", chunk_address));
}
}
}
bool LargeObjectSpace::Contains(HeapObject* object) {
Address address = object->address();
Page* page = Page::FromAddress(address);
SLOW_ASSERT(!page->IsLargeObjectPage()
|| !FindObject(address)->IsFailure());
return page->IsLargeObjectPage();
}
#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 (LargeObjectChunk* chunk = first_chunk_;
chunk != NULL;
chunk = chunk->next()) {
// 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->ObjectAreaStart());
// 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, fixed arrays, and byte arrays
// in large object space.
ASSERT(object->IsCode() || object->IsSeqString()
|| object->IsFixedArray() || 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;
Code::cast(object)->ConvertICTargetsFromAddressToObject();
object->IterateBody(map->instance_type(),
object->Size(),
&code_visitor);
Code::cast(object)->ConvertICTargetsFromObjectToAddress();
} else if (object->IsFixedArray()) {
// We loop over fixed arrays ourselves, rather then using the visitor,
// because the visitor doesn't support the start/offset iteration
// needed for IsRSetSet.
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());
if (Heap::InNewSpace(element_object)) {
ASSERT(Page::IsRSetSet(object->address(),
FixedArray::kHeaderSize + j * kPointerSize));
}
}
}
}
}
}
void LargeObjectSpace::Print() {
LargeObjectIterator it(this);
while (it.has_next()) {
it.next()->Print();
}
}
void LargeObjectSpace::ReportStatistics() {
PrintF(" size: %d\n", size_);
int num_objects = 0;
ClearHistograms();
LargeObjectIterator it(this);
while (it.has_next()) {
num_objects++;
CollectHistogramInfo(it.next());
}
PrintF(" number of objects %d\n", num_objects);
if (num_objects > 0) ReportHistogram(false);
}
void LargeObjectSpace::CollectCodeStatistics() {
LargeObjectIterator obj_it(this);
while (obj_it.has_next()) {
HeapObject* obj = obj_it.next();
if (obj->IsCode()) {
Code* code = Code::cast(obj);
code_kind_statistics[code->kind()] += code->Size();
}
}
}
void LargeObjectSpace::PrintRSet() {
LargeObjectIterator it(this);
while (it.has_next()) {
HeapObject* object = it.next();
if (object->IsFixedArray()) {
Page* page = Page::FromAddress(object->address());
Address allocation_top = object->address() + object->Size();
PrintF("large page 0x%x:\n", page);
PrintRSetRange(page->RSetStart(), page->RSetEnd(),
reinterpret_cast<Object**>(object->address()),
allocation_top);
int extra_array_bytes = object->Size() - Page::kObjectAreaSize;
int extra_rset_bits = RoundUp(extra_array_bytes / kPointerSize,
kBitsPerInt);
PrintF("------------------------------------------------------------"
"-----------\n");
PrintRSetRange(allocation_top,
allocation_top + extra_rset_bits / kBitsPerByte,
reinterpret_cast<Object**>(object->address()
+ Page::kObjectAreaSize),
allocation_top);
PrintF("\n");
}
}
}
#endif // DEBUG
} } // namespace v8::internal
Jump to Line
Something went wrong with that request. Please try again.