| // 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 <typename T> |
| 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(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<typename T> |
| class ZoneList: public List<T, ZoneListAllocationPolicy> { |
| 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<T, ZoneListAllocationPolicy>(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_; |
| }; |
| |
| |
| } } // namespace v8::internal |
| |
| #endif // V8_ZONE_H_ |