// 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. #ifndef V8_ZONE_H_ #define V8_ZONE_H_ namespace v8 { namespace internal { // Zone scopes are in one of two modes. Either they delete the zone // on exit or they do not. enum ZoneScopeMode { DELETE_ON_EXIT, DONT_DELETE_ON_EXIT }; // 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 { public: // Allocate 'size' bytes of memory in the Zone; expands the Zone by // allocating new segments of memory on demand using malloc(). static inline void* New(int size); template static inline T* NewArray(int length); // Delete all objects and free all memory allocated in the Zone. static void DeleteAll(); // Returns true if more memory has been allocated in zones than // the limit allows. static inline bool excess_allocation(); static inline void adjust_segment_bytes_allocated(int delta); private: // All pointers returned from New() have this alignment. static const int kAlignment = kPointerSize; // Never allocate segments smaller than this size in bytes. static const int kMinimumSegmentSize = 8 * KB; // Never allocate segments larger than this size in bytes. static const int kMaximumSegmentSize = 1 * MB; // Never keep segments larger than this size in bytes around. static const int kMaximumKeptSegmentSize = 64 * KB; // Report zone excess when allocation exceeds this limit. static int zone_excess_limit_; // The number of bytes allocated in segments. Note that this number // includes memory allocated from the OS but not yet allocated from // the zone. static int segment_bytes_allocated_; // The Zone is intentionally a singleton; you should not try to // allocate instances of the class. Zone() { UNREACHABLE(); } // 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. static Address NewExpand(int 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. static Address position_; static Address limit_; }; // 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) { return Zone::New(static_cast(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(); } }; class AssertNoZoneAllocation { public: AssertNoZoneAllocation() : prev_(allow_allocation_) { allow_allocation_ = false; } ~AssertNoZoneAllocation() { allow_allocation_ = prev_; } static bool allow_allocation() { return allow_allocation_; } private: bool prev_; static bool allow_allocation_; }; // The ZoneListAllocationPolicy is used to specialize the GenericList // implementation to allocate ZoneLists and their elements in the // Zone. class ZoneListAllocationPolicy { public: // Allocate 'size' bytes of memory in the zone. static void* New(int size) { return Zone::New(size); } // De-allocation attempts are silently ignored. static void Delete(void* p) { } }; // 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 class ZoneList: public List { public: // Construct a new ZoneList with the given capacity; the length is // always zero. The capacity must be non-negative. explicit ZoneList(int capacity) : List(capacity) { } }; // ZoneScopes keep track of the current parsing and compilation // nesting and cleans up generated ASTs in the Zone when exiting the // outer-most scope. class ZoneScope BASE_EMBEDDED { public: explicit ZoneScope(ZoneScopeMode mode) : mode_(mode) { nesting_++; } virtual ~ZoneScope() { if (ShouldDeleteOnExit()) Zone::DeleteAll(); --nesting_; } bool ShouldDeleteOnExit() { return nesting_ == 1 && mode_ == DELETE_ON_EXIT; } // For ZoneScopes that do not delete on exit by default, call this // method to request deletion on exit. void DeleteOnExit() { mode_ = DELETE_ON_EXIT; } static int nesting() { return nesting_; } private: ZoneScopeMode mode_; static int nesting_; }; // A zone splay tree. The config type parameter encapsulates the // different configurations of a concrete splay tree: // // typedef Key: the key type // typedef Value: the value type // static const kNoKey: the dummy key used when no key is set // static const kNoValue: the dummy value used to initialize nodes // int (Compare)(Key& a, Key& b) -> {-1, 0, 1}: comparison function // template class ZoneSplayTree : public ZoneObject { public: typedef typename Config::Key Key; typedef typename Config::Value Value; class Locator; ZoneSplayTree() : root_(NULL) { } // Inserts the given key in this tree with the given value. Returns // true if a node was inserted, otherwise false. If found the locator // is enabled and provides access to the mapping for the key. bool Insert(const Key& key, Locator* locator); // Looks up the key in this tree and returns true if it was found, // otherwise false. If the node is found the locator is enabled and // provides access to the mapping for the key. bool Find(const Key& key, Locator* locator); // Finds the mapping with the greatest key less than or equal to the // given key. bool FindGreatestLessThan(const Key& key, Locator* locator); // Find the mapping with the greatest key in this tree. bool FindGreatest(Locator* locator); // Finds the mapping with the least key greater than or equal to the // given key. bool FindLeastGreaterThan(const Key& key, Locator* locator); // Find the mapping with the least key in this tree. bool FindLeast(Locator* locator); // Remove the node with the given key from the tree. bool Remove(const Key& key); bool is_empty() { return root_ == NULL; } // Perform the splay operation for the given key. Moves the node with // the given key to the top of the tree. If no node has the given // key, the last node on the search path is moved to the top of the // tree. void Splay(const Key& key); class Node : public ZoneObject { public: Node(const Key& key, const Value& value) : key_(key), value_(value), left_(NULL), right_(NULL) { } Key key() { return key_; } Value value() { return value_; } Node* left() { return left_; } Node* right() { return right_; } private: friend class ZoneSplayTree; friend class Locator; Key key_; Value value_; Node* left_; Node* right_; }; // A locator provides access to a node in the tree without actually // exposing the node. class Locator { public: explicit Locator(Node* node) : node_(node) { } Locator() : node_(NULL) { } const Key& key() { return node_->key_; } Value& value() { return node_->value_; } void set_value(const Value& value) { node_->value_ = value; } inline void bind(Node* node) { node_ = node; } private: Node* node_; }; template void ForEach(Callback* callback); private: Node* root_; }; } } // namespace v8::internal #endif // V8_ZONE_H_