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// Copyright 2011 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.
#ifndef V8_HEAP_SPACES_H_
#define V8_HEAP_SPACES_H_
#include <atomic>
#include <memory>
#include "src/base/iterator.h"
#include "src/base/macros.h"
#include "src/common/globals.h"
#include "src/heap/allocation-observer.h"
#include "src/heap/base-space.h"
#include "src/heap/base/active-system-pages.h"
#include "src/heap/basic-memory-chunk.h"
#include "src/heap/free-list.h"
#include "src/heap/linear-allocation-area.h"
#include "src/heap/list.h"
#include "src/heap/main-allocator.h"
#include "src/heap/memory-chunk-layout.h"
#include "src/heap/memory-chunk.h"
#include "src/heap/page.h"
#include "src/heap/slot-set.h"
#include "src/objects/objects.h"
#include "src/utils/allocation.h"
#include "src/utils/utils.h"
#include "testing/gtest/include/gtest/gtest_prod.h" // nogncheck
namespace v8 {
namespace internal {
namespace heap {
class HeapTester;
class TestCodePageAllocatorScope;
} // namespace heap
class AllocationObserver;
class FreeList;
class Heap;
class Isolate;
class LargeObjectSpace;
class LargePage;
class ObjectIterator;
class PagedSpaceBase;
class SemiSpace;
// Some assertion macros used in the debugging mode.
#define DCHECK_OBJECT_SIZE(size) \
DCHECK((0 < size) && (size <= kMaxRegularHeapObjectSize))
#define DCHECK_CODEOBJECT_SIZE(size) \
DCHECK((0 < size) && (size <= MemoryChunkLayout::MaxRegularCodeObjectSize()))
template <typename Enum, typename Callback>
void ForAll(Callback callback) {
for (int i = 0; i < static_cast<int>(Enum::kNumValues); i++) {
callback(static_cast<Enum>(i), i);
}
}
// ----------------------------------------------------------------------------
// Space is the abstract superclass for all allocation spaces that are not
// sealed after startup (i.e. not ReadOnlySpace).
class V8_EXPORT_PRIVATE Space : public BaseSpace {
public:
static inline void MoveExternalBackingStoreBytes(
ExternalBackingStoreType type, Space* from, Space* to, size_t amount);
Space(Heap* heap, AllocationSpace id, std::unique_ptr<FreeList> free_list)
: BaseSpace(heap, id), free_list_(std::move(free_list)) {}
~Space() override = default;
Space(const Space&) = delete;
Space& operator=(const Space&) = delete;
// Returns size of objects. Can differ from the allocated size
// (e.g. see OldLargeObjectSpace).
virtual size_t SizeOfObjects() const { return Size(); }
// Return the available bytes without growing.
virtual size_t Available() const = 0;
virtual std::unique_ptr<ObjectIterator> GetObjectIterator(Heap* heap) = 0;
inline void IncrementExternalBackingStoreBytes(ExternalBackingStoreType type,
size_t amount);
inline void DecrementExternalBackingStoreBytes(ExternalBackingStoreType type,
size_t amount);
// Returns amount of off-heap memory in-use by objects in this Space.
virtual size_t ExternalBackingStoreBytes(
ExternalBackingStoreType type) const {
return external_backing_store_bytes_[static_cast<int>(type)];
}
virtual MemoryChunk* first_page() { return memory_chunk_list_.front(); }
virtual MemoryChunk* last_page() { return memory_chunk_list_.back(); }
virtual const MemoryChunk* first_page() const {
return memory_chunk_list_.front();
}
virtual const MemoryChunk* last_page() const {
return memory_chunk_list_.back();
}
virtual heap::List<MemoryChunk>& memory_chunk_list() {
return memory_chunk_list_;
}
virtual Page* InitializePage(MemoryChunk* chunk) { UNREACHABLE(); }
FreeList* free_list() { return free_list_.get(); }
Address FirstPageAddress() const {
DCHECK_NOT_NULL(first_page());
return first_page()->address();
}
#ifdef DEBUG
virtual void Print() = 0;
#endif
protected:
// The List manages the pages that belong to the given space.
heap::List<MemoryChunk> memory_chunk_list_;
// Tracks off-heap memory used by this space.
std::atomic<size_t> external_backing_store_bytes_[static_cast<int>(
ExternalBackingStoreType::kNumValues)] = {0};
std::unique_ptr<FreeList> free_list_;
};
static_assert(sizeof(std::atomic<intptr_t>) == kSystemPointerSize);
// -----------------------------------------------------------------------------
// Interface for heap object iterator to be implemented by all object space
// object iterators.
class V8_EXPORT_PRIVATE ObjectIterator : public Malloced {
public:
// Note: The destructor can not be marked as `= default` as this causes
// the compiler on C++20 to define it as `constexpr` resulting in the
// compiler producing warnings about undefined inlines for Next()
// on classes inheriting from it.
virtual ~ObjectIterator() {}
virtual Tagged<HeapObject> Next() = 0;
};
template <class PAGE_TYPE>
class PageIteratorImpl
: public base::iterator<std::forward_iterator_tag, PAGE_TYPE> {
public:
explicit PageIteratorImpl(PAGE_TYPE* p) : p_(p) {}
PageIteratorImpl(const PageIteratorImpl<PAGE_TYPE>& other) : p_(other.p_) {}
PAGE_TYPE* operator*() { return p_; }
bool operator==(const PageIteratorImpl<PAGE_TYPE>& rhs) const {
return rhs.p_ == p_;
}
bool operator!=(const PageIteratorImpl<PAGE_TYPE>& rhs) const {
return rhs.p_ != p_;
}
inline PageIteratorImpl<PAGE_TYPE>& operator++();
inline PageIteratorImpl<PAGE_TYPE> operator++(int);
private:
PAGE_TYPE* p_;
};
using PageIterator = PageIteratorImpl<Page>;
using ConstPageIterator = PageIteratorImpl<const Page>;
using LargePageIterator = PageIteratorImpl<LargePage>;
using ConstLargePageIterator = PageIteratorImpl<const LargePage>;
class PageRange {
public:
using iterator = PageIterator;
PageRange(Page* begin, Page* end) : begin_(begin), end_(end) {}
inline explicit PageRange(Page* page);
iterator begin() { return iterator(begin_); }
iterator end() { return iterator(end_); }
private:
Page* begin_;
Page* end_;
};
class ConstPageRange {
public:
using iterator = ConstPageIterator;
ConstPageRange(const Page* begin, const Page* end)
: begin_(begin), end_(end) {}
inline explicit ConstPageRange(const Page* page);
iterator begin() { return iterator(begin_); }
iterator end() { return iterator(end_); }
private:
const Page* begin_;
const Page* end_;
};
// -----------------------------------------------------------------------------
// A space has a circular list of pages. The next page can be accessed via
// Page::next_page() call.
// LocalAllocationBuffer represents a linear allocation area that is created
// from a given {AllocationResult} and can be used to allocate memory without
// synchronization.
//
// The buffer is properly closed upon destruction and reassignment.
// Example:
// {
// AllocationResult result = ...;
// LocalAllocationBuffer a(heap, result, size);
// LocalAllocationBuffer b = a;
// CHECK(!a.IsValid());
// CHECK(b.IsValid());
// // {a} is invalid now and cannot be used for further allocations.
// }
// // Since {b} went out of scope, the LAB is closed, resulting in creating a
// // filler object for the remaining area.
class LocalAllocationBuffer {
public:
// Indicates that a buffer cannot be used for allocations anymore. Can result
// from either reassigning a buffer, or trying to construct it from an
// invalid {AllocationResult}.
static LocalAllocationBuffer InvalidBuffer() {
return LocalAllocationBuffer(
nullptr, LinearAllocationArea(kNullAddress, kNullAddress));
}
// Creates a new LAB from a given {AllocationResult}. Results in
// InvalidBuffer if the result indicates a retry.
static inline LocalAllocationBuffer FromResult(Heap* heap,
AllocationResult result,
intptr_t size);
~LocalAllocationBuffer() { CloseAndMakeIterable(); }
LocalAllocationBuffer(const LocalAllocationBuffer& other) = delete;
V8_EXPORT_PRIVATE LocalAllocationBuffer(LocalAllocationBuffer&& other)
V8_NOEXCEPT;
LocalAllocationBuffer& operator=(const LocalAllocationBuffer& other) = delete;
V8_EXPORT_PRIVATE LocalAllocationBuffer& operator=(
LocalAllocationBuffer&& other) V8_NOEXCEPT;
V8_WARN_UNUSED_RESULT inline AllocationResult AllocateRawAligned(
int size_in_bytes, AllocationAlignment alignment);
V8_WARN_UNUSED_RESULT inline AllocationResult AllocateRawUnaligned(
int size_in_bytes);
inline bool IsValid() { return allocation_info_.top() != kNullAddress; }
// Try to merge LABs, which is only possible when they are adjacent in memory.
// Returns true if the merge was successful, false otherwise.
inline bool TryMerge(LocalAllocationBuffer* other);
inline bool TryFreeLast(Tagged<HeapObject> object, int object_size);
// Close a LAB, effectively invalidating it. Returns the unused area.
V8_EXPORT_PRIVATE LinearAllocationArea CloseAndMakeIterable();
void MakeIterable();
Address top() const { return allocation_info_.top(); }
Address limit() const { return allocation_info_.limit(); }
private:
V8_EXPORT_PRIVATE LocalAllocationBuffer(
Heap* heap, LinearAllocationArea allocation_info) V8_NOEXCEPT;
Heap* heap_;
LinearAllocationArea allocation_info_;
};
class V8_EXPORT_PRIVATE SpaceWithLinearArea : public Space {
public:
// Creates this space with a new MainAllocator instance.
SpaceWithLinearArea(
Heap* heap, AllocationSpace id, std::unique_ptr<FreeList> free_list,
CompactionSpaceKind compaction_space_kind,
MainAllocator::SupportsExtendingLAB supports_extending_lab);
// Creates this space with a new MainAllocator instance and passes
// `allocation_info` to its constructor.
SpaceWithLinearArea(
Heap* heap, AllocationSpace id, std::unique_ptr<FreeList> free_list,
CompactionSpaceKind compaction_space_kind,
MainAllocator::SupportsExtendingLAB supports_extending_lab,
LinearAllocationArea& allocation_info);
// Creates this space and uses the existing `allocator`. It doesn't create a
// new MainAllocator instance.
SpaceWithLinearArea(Heap* heap, AllocationSpace id,
std::unique_ptr<FreeList> free_list,
CompactionSpaceKind compaction_space_kind,
MainAllocator* allocator);
MainAllocator* main_allocator() { return allocator_; }
V8_WARN_UNUSED_RESULT V8_INLINE AllocationResult
AllocateRaw(int size_in_bytes, AllocationAlignment alignment,
AllocationOrigin origin = AllocationOrigin::kRuntime);
protected:
// Sets up a linear allocation area that fits the given number of bytes.
// Returns false if there is not enough space and the caller has to retry
// after collecting garbage.
// Writes to `max_aligned_size` the actual number of bytes used for checking
// that there is enough space.
virtual bool EnsureAllocation(int size_in_bytes,
AllocationAlignment alignment,
AllocationOrigin origin,
int* out_max_aligned_size) = 0;
virtual void FreeLinearAllocationArea() = 0;
virtual void UpdateInlineAllocationLimit() = 0;
// TODO(chromium:1480975): Move the LAB out of the space.
MainAllocator* allocator_;
base::Optional<MainAllocator> owned_allocator_;
friend class MainAllocator;
};
class V8_EXPORT_PRIVATE SpaceIterator : public Malloced {
public:
explicit SpaceIterator(Heap* heap);
virtual ~SpaceIterator();
bool HasNext();
Space* Next();
private:
Heap* heap_;
int current_space_; // from enum AllocationSpace.
};
// Iterates over all memory chunks in the heap (across all spaces).
class MemoryChunkIterator {
public:
explicit MemoryChunkIterator(Heap* heap) : space_iterator_(heap) {}
V8_INLINE bool HasNext();
V8_INLINE MemoryChunk* Next();
private:
SpaceIterator space_iterator_;
MemoryChunk* current_chunk_ = nullptr;
};
} // namespace internal
} // namespace v8
#endif // V8_HEAP_SPACES_H_
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