Moved zones and zone related stuff in its own directory.

src/zone.h

-// Copyright 2012 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_ZONE_H_
-#define V8_ZONE_H_
-
-#include <limits>
-
-#include "src/base/accounting-allocator.h"
-#include "src/base/hashmap.h"
-#include "src/base/logging.h"
-#include "src/globals.h"
-#include "src/list.h"
-#include "src/splay-tree.h"
-
-namespace v8 {
-namespace internal {
-
-// Forward declarations.
-class Segment;
-
-
-// The Zone supports very fast allocation of small chunks of
-// memory. The chunks cannot be deallocated individually, but instead
-// the Zone supports deallocating all chunks in one fast
-// operation. The Zone is used to hold temporary data structures like
-// the abstract syntax tree, which is deallocated after compilation.
-//
-// Note: There is no need to initialize the Zone; the first time an
-// allocation is attempted, a segment of memory will be requested
-// through a call to malloc().
-//
-// Note: The implementation is inherently not thread safe. Do not use
-// from multi-threaded code.
-class Zone final {
- public:
-  explicit Zone(base::AccountingAllocator* allocator);
-  ~Zone();
-
-  // Allocate 'size' bytes of memory in the Zone; expands the Zone by
-  // allocating new segments of memory on demand using malloc().
-  void* New(size_t size);
-
-  template <typename T>
-  T* NewArray(size_t length) {
-    DCHECK_LT(length, std::numeric_limits<size_t>::max() / sizeof(T));
-    return static_cast<T*>(New(length * sizeof(T)));
-  }
-
-  // Deletes all objects and free all memory allocated in the Zone. Keeps one
-  // small (size <= kMaximumKeptSegmentSize) segment around if it finds one.
-  void DeleteAll();
-
-  // Deletes the last small segment kept around by DeleteAll(). You
-  // may no longer allocate in the Zone after a call to this method.
-  void DeleteKeptSegment();
-
-  // Returns true if more memory has been allocated in zones than
-  // the limit allows.
-  bool excess_allocation() const {
-    return segment_bytes_allocated_ > kExcessLimit;
-  }
-
-  size_t allocation_size() const { return allocation_size_; }
-
-  base::AccountingAllocator* allocator() const { return allocator_; }
-
- private:
-  // All pointers returned from New() have this alignment.  In addition, if the
-  // object being allocated has a size that is divisible by 8 then its alignment
-  // will be 8. ASan requires 8-byte alignment.
-#ifdef V8_USE_ADDRESS_SANITIZER
-  static const size_t kAlignment = 8;
-  STATIC_ASSERT(kPointerSize <= 8);
-#else
-  static const size_t kAlignment = kPointerSize;
-#endif
-
-  // Never allocate segments smaller than this size in bytes.
-  static const size_t kMinimumSegmentSize = 8 * KB;
-
-  // Never allocate segments larger than this size in bytes.
-  static const size_t kMaximumSegmentSize = 1 * MB;
-
-  // Never keep segments larger than this size in bytes around.
-  static const size_t kMaximumKeptSegmentSize = 64 * KB;
-
-  // Report zone excess when allocation exceeds this limit.
-  static const size_t kExcessLimit = 256 * MB;
-
-  // The number of bytes allocated in this zone so far.
-  size_t allocation_size_;
-
-  // The number of bytes allocated in segments.  Note that this number
-  // includes memory allocated from the OS but not yet allocated from
-  // the zone.
-  size_t segment_bytes_allocated_;
-
-  // Expand the Zone to hold at least 'size' more bytes and allocate
-  // the bytes. Returns the address of the newly allocated chunk of
-  // memory in the Zone. Should only be called if there isn't enough
-  // room in the Zone already.
-  Address NewExpand(size_t size);
-
-  // Creates a new segment, sets it size, and pushes it to the front
-  // of the segment chain. Returns the new segment.
-  inline Segment* NewSegment(size_t size);
-
-  // Deletes the given segment. Does not touch the segment chain.
-  inline void DeleteSegment(Segment* segment, size_t size);
-
-  // The free region in the current (front) segment is represented as
-  // the half-open interval [position, limit). The 'position' variable
-  // is guaranteed to be aligned as dictated by kAlignment.
-  Address position_;
-  Address limit_;
-
-  base::AccountingAllocator* allocator_;
-
-  Segment* segment_head_;
-};
-
-
-// ZoneObject is an abstraction that helps define classes of objects
-// allocated in the Zone. Use it as a base class; see ast.h.
-class ZoneObject {
- public:
-  // Allocate a new ZoneObject of 'size' bytes in the Zone.
-  void* operator new(size_t size, Zone* zone) { return zone->New(size); }
-
-  // Ideally, the delete operator should be private instead of
-  // public, but unfortunately the compiler sometimes synthesizes
-  // (unused) destructors for classes derived from ZoneObject, which
-  // require the operator to be visible. MSVC requires the delete
-  // operator to be public.
-
-  // ZoneObjects should never be deleted individually; use
-  // Zone::DeleteAll() to delete all zone objects in one go.
-  void operator delete(void*, size_t) { UNREACHABLE(); }
-  void operator delete(void* pointer, Zone* zone) { UNREACHABLE(); }
-};
-
-
-// The ZoneScope is used to automatically call DeleteAll() on a
-// Zone when the ZoneScope is destroyed (i.e. goes out of scope)
-class ZoneScope final {
- public:
-  explicit ZoneScope(Zone* zone) : zone_(zone) { }
-  ~ZoneScope() { zone_->DeleteAll(); }
-
-  Zone* zone() const { return zone_; }
-
- private:
-  Zone* zone_;
-};
-
-
-// The ZoneAllocationPolicy is used to specialize generic data
-// structures to allocate themselves and their elements in the Zone.
-class ZoneAllocationPolicy final {
- public:
-  explicit ZoneAllocationPolicy(Zone* zone) : zone_(zone) { }
-  void* New(size_t size) { return zone()->New(size); }
-  static void Delete(void* pointer) {}
-  Zone* zone() const { return zone_; }
-
- private:
-  Zone* zone_;
-};
-
-
-// ZoneLists are growable lists with constant-time access to the
-// elements. The list itself and all its elements are allocated in the
-// Zone. ZoneLists cannot be deleted individually; you can delete all
-// objects in the Zone by calling Zone::DeleteAll().
-template <typename T>
-class ZoneList final : public List<T, ZoneAllocationPolicy> {
- public:
-  // Construct a new ZoneList with the given capacity; the length is
-  // always zero. The capacity must be non-negative.
-  ZoneList(int capacity, Zone* zone)
-      : List<T, ZoneAllocationPolicy>(capacity, ZoneAllocationPolicy(zone)) { }
-
-  void* operator new(size_t size, Zone* zone) { return zone->New(size); }
-
-  // Construct a new ZoneList by copying the elements of the given ZoneList.
-  ZoneList(const ZoneList<T>& other, Zone* zone)
-      : List<T, ZoneAllocationPolicy>(other.length(),
-                                      ZoneAllocationPolicy(zone)) {
-    AddAll(other, zone);
-  }
-
-  // We add some convenience wrappers so that we can pass in a Zone
-  // instead of a (less convenient) ZoneAllocationPolicy.
-  void Add(const T& element, Zone* zone) {
-    List<T, ZoneAllocationPolicy>::Add(element, ZoneAllocationPolicy(zone));
-  }
-  void AddAll(const List<T, ZoneAllocationPolicy>& other, Zone* zone) {
-    List<T, ZoneAllocationPolicy>::AddAll(other, ZoneAllocationPolicy(zone));
-  }
-  void AddAll(const Vector<T>& other, Zone* zone) {
-    List<T, ZoneAllocationPolicy>::AddAll(other, ZoneAllocationPolicy(zone));
-  }
-  void InsertAt(int index, const T& element, Zone* zone) {
-    List<T, ZoneAllocationPolicy>::InsertAt(index, element,
-                                            ZoneAllocationPolicy(zone));
-  }
-  Vector<T> AddBlock(T value, int count, Zone* zone) {
-    return List<T, ZoneAllocationPolicy>::AddBlock(value, count,
-                                                   ZoneAllocationPolicy(zone));
-  }
-  void Allocate(int length, Zone* zone) {
-    List<T, ZoneAllocationPolicy>::Allocate(length, ZoneAllocationPolicy(zone));
-  }
-  void Initialize(int capacity, Zone* zone) {
-    List<T, ZoneAllocationPolicy>::Initialize(capacity,
-                                              ZoneAllocationPolicy(zone));
-  }
-
-  void operator delete(void* pointer) { UNREACHABLE(); }
-  void operator delete(void* pointer, Zone* zone) { UNREACHABLE(); }
-};
-
-
-// A zone splay tree.  The config type parameter encapsulates the
-// different configurations of a concrete splay tree (see splay-tree.h).
-// The tree itself and all its elements are allocated in the Zone.
-template <typename Config>
-class ZoneSplayTree final : public SplayTree<Config, ZoneAllocationPolicy> {
- public:
-  explicit ZoneSplayTree(Zone* zone)
-      : SplayTree<Config, ZoneAllocationPolicy>(ZoneAllocationPolicy(zone)) {}
-  ~ZoneSplayTree() {
-    // Reset the root to avoid unneeded iteration over all tree nodes
-    // in the destructor.  For a zone-allocated tree, nodes will be
-    // freed by the Zone.
-    SplayTree<Config, ZoneAllocationPolicy>::ResetRoot();
-  }
-
-  void* operator new(size_t size, Zone* zone) { return zone->New(size); }
-
-  void operator delete(void* pointer) { UNREACHABLE(); }
-  void operator delete(void* pointer, Zone* zone) { UNREACHABLE(); }
-};
-
-typedef base::TemplateHashMapImpl<void*, void*, ZoneAllocationPolicy>
-    ZoneHashMap;
-
-}  // namespace internal
-}  // namespace v8
-
-#endif  // V8_ZONE_H_