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// Copyright 2020 the V8 project authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#include "src/heap/cppgc/object-allocator.h"
#include "src/base/logging.h"
#include "src/base/macros.h"
#include "src/heap/cppgc/free-list.h"
#include "src/heap/cppgc/globals.h"
#include "src/heap/cppgc/heap-object-header.h"
#include "src/heap/cppgc/heap-page.h"
#include "src/heap/cppgc/heap-space.h"
#include "src/heap/cppgc/heap-visitor.h"
#include "src/heap/cppgc/heap.h"
#include "src/heap/cppgc/object-start-bitmap.h"
#include "src/heap/cppgc/page-memory.h"
#include "src/heap/cppgc/stats-collector.h"
#include "src/heap/cppgc/sweeper.h"
namespace cppgc {
namespace internal {
namespace {
void MarkRangeAsYoung(BasePage* page, Address begin, Address end) {
#if defined(CPPGC_YOUNG_GENERATION)
DCHECK_LT(begin, end);
static constexpr auto kEntrySize = AgeTable::kEntrySizeInBytes;
const uintptr_t offset_begin = CagedHeap::OffsetFromAddress(begin);
const uintptr_t offset_end = CagedHeap::OffsetFromAddress(end);
const uintptr_t young_offset_begin = (begin == page->PayloadStart())
? RoundDown(offset_begin, kEntrySize)
: RoundUp(offset_begin, kEntrySize);
const uintptr_t young_offset_end = (end == page->PayloadEnd())
? RoundUp(offset_end, kEntrySize)
: RoundDown(offset_end, kEntrySize);
auto& age_table = page->heap()->caged_heap().local_data().age_table;
for (auto offset = young_offset_begin; offset < young_offset_end;
offset += AgeTable::kEntrySizeInBytes) {
age_table[offset] = AgeTable::Age::kYoung;
}
// Set to kUnknown the first and the last regions of the newly allocated
// linear buffer.
if (begin != page->PayloadStart() && !IsAligned(offset_begin, kEntrySize))
age_table[offset_begin] = AgeTable::Age::kUnknown;
if (end != page->PayloadEnd() && !IsAligned(offset_end, kEntrySize))
age_table[offset_end] = AgeTable::Age::kUnknown;
#endif
}
void AddToFreeList(NormalPageSpace* space, Address start, size_t size) {
auto& free_list = space->free_list();
free_list.Add({start, size});
NormalPage::From(BasePage::FromPayload(start))
->object_start_bitmap()
.SetBit(start);
}
void ReplaceLinearAllocationBuffer(NormalPageSpace* space,
StatsCollector* stats_collector,
Address new_buffer, size_t new_size) {
DCHECK_NOT_NULL(space);
DCHECK_NOT_NULL(stats_collector);
auto& lab = space->linear_allocation_buffer();
if (lab.size()) {
AddToFreeList(space, lab.start(), lab.size());
stats_collector->NotifyExplicitFree(lab.size());
}
lab.Set(new_buffer, new_size);
if (new_size) {
DCHECK_NOT_NULL(new_buffer);
stats_collector->NotifyAllocation(new_size);
auto* page = NormalPage::From(BasePage::FromPayload(new_buffer));
page->object_start_bitmap().ClearBit(new_buffer);
MarkRangeAsYoung(page, new_buffer, new_buffer + new_size);
}
}
void* AllocateLargeObject(PageBackend* page_backend, LargePageSpace* space,
StatsCollector* stats_collector, size_t size,
GCInfoIndex gcinfo) {
LargePage* page = LargePage::Create(page_backend, space, size);
space->AddPage(page);
auto* header = new (page->ObjectHeader())
HeapObjectHeader(HeapObjectHeader::kLargeObjectSizeInHeader, gcinfo);
stats_collector->NotifyAllocation(size);
MarkRangeAsYoung(page, page->PayloadStart(), page->PayloadEnd());
return header->Payload();
}
} // namespace
ObjectAllocator::ObjectAllocator(RawHeap* heap, PageBackend* page_backend,
StatsCollector* stats_collector)
: raw_heap_(heap),
page_backend_(page_backend),
stats_collector_(stats_collector) {}
void* ObjectAllocator::OutOfLineAllocate(NormalPageSpace* space, size_t size,
GCInfoIndex gcinfo) {
void* memory = OutOfLineAllocateImpl(space, size, gcinfo);
stats_collector_->NotifySafePointForConservativeCollection();
raw_heap_->heap()->AdvanceIncrementalGarbageCollectionOnAllocationIfNeeded();
return memory;
}
void* ObjectAllocator::OutOfLineAllocateImpl(NormalPageSpace* space,
size_t size, GCInfoIndex gcinfo) {
DCHECK_EQ(0, size & kAllocationMask);
DCHECK_LE(kFreeListEntrySize, size);
// 1. If this allocation is big enough, allocate a large object.
if (size >= kLargeObjectSizeThreshold) {
auto* large_space = LargePageSpace::From(
raw_heap_->Space(RawHeap::RegularSpaceType::kLarge));
return AllocateLargeObject(page_backend_, large_space, stats_collector_,
size, gcinfo);
}
// 2. Try to allocate from the freelist.
if (void* result = AllocateFromFreeList(space, size, gcinfo)) {
return result;
}
// 3. Lazily sweep pages of this heap until we find a freed area for
// this allocation or we finish sweeping all pages of this heap.
// TODO(chromium:1056170): Add lazy sweep.
// 4. Complete sweeping.
raw_heap_->heap()->sweeper().FinishIfRunning();
// 5. Add a new page to this heap.
auto* new_page = NormalPage::Create(page_backend_, space);
space->AddPage(new_page);
// 6. Set linear allocation buffer to new page.
ReplaceLinearAllocationBuffer(space, stats_collector_,
new_page->PayloadStart(),
new_page->PayloadSize());
// 7. Allocate from it. The allocation must succeed.
void* result = AllocateObjectOnSpace(space, size, gcinfo);
CHECK(result);
return result;
}
void* ObjectAllocator::AllocateFromFreeList(NormalPageSpace* space, size_t size,
GCInfoIndex gcinfo) {
const FreeList::Block entry = space->free_list().Allocate(size);
if (!entry.address) return nullptr;
ReplaceLinearAllocationBuffer(
space, stats_collector_, static_cast<Address>(entry.address), entry.size);
return AllocateObjectOnSpace(space, size, gcinfo);
}
void ObjectAllocator::ResetLinearAllocationBuffers() {
class Resetter : public HeapVisitor<Resetter> {
public:
explicit Resetter(StatsCollector* stats) : stats_collector_(stats) {}
bool VisitLargePageSpace(LargePageSpace*) { return true; }
bool VisitNormalPageSpace(NormalPageSpace* space) {
ReplaceLinearAllocationBuffer(space, stats_collector_, nullptr, 0);
return true;
}
private:
StatsCollector* stats_collector_;
} visitor(stats_collector_);
visitor.Traverse(raw_heap_);
}
ObjectAllocator::NoAllocationScope::NoAllocationScope(
ObjectAllocator& allocator)
: allocator_(allocator) {
allocator.no_allocation_scope_++;
}
ObjectAllocator::NoAllocationScope::~NoAllocationScope() {
allocator_.no_allocation_scope_--;
}
} // namespace internal
} // namespace cppgc
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