runtime/gc/space/region_space.h - LeafOS-Project/android_art - Gitiles

 /*
  * Copyright (C) 2014 The Android Open Source Project
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
  * You may obtain a copy of the License at
  *
  *      http://www.apache.org/licenses/LICENSE-2.0
  *
  * Unless required by applicable law or agreed to in writing, software
  * distributed under the License is distributed on an "AS IS" BASIS,
  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  * See the License for the specific language governing permissions and
  * limitations under the License.
  */

 #ifndef ART_RUNTIME_GC_SPACE_REGION_SPACE_H_
 #define ART_RUNTIME_GC_SPACE_REGION_SPACE_H_

 #include "base/macros.h"
 #include "base/mutex.h"
 #include "space.h"
 #include "thread.h"

 namespace art {
 namespace gc {

 namespace accounting {
 class ReadBarrierTable;
 }  // namespace accounting

 namespace space {

 // A space that consists of equal-sized regions.
 class RegionSpace FINAL : public ContinuousMemMapAllocSpace {
  public:
   typedef void(*WalkCallback)(void *start, void *end, size_t num_bytes, void* callback_arg);

   SpaceType GetType() const OVERRIDE {
     return kSpaceTypeRegionSpace;
   }

   // Create a region space mem map with the requested sizes. The requested base address is not
   // guaranteed to be granted, if it is required, the caller should call Begin on the returned
   // space to confirm the request was granted.
   static MemMap* CreateMemMap(const std::string& name, size_t capacity, uint8_t* requested_begin);
   static RegionSpace* Create(const std::string& name, MemMap* mem_map);

   // Allocate `num_bytes`, returns null if the space is full.
   mirror::Object* Alloc(Thread* self,
                         size_t num_bytes,
                         /* out */ size_t* bytes_allocated,
                         /* out */ size_t* usable_size,
                         /* out */ size_t* bytes_tl_bulk_allocated)
       OVERRIDE REQUIRES(!region_lock_);
   // Thread-unsafe allocation for when mutators are suspended, used by the semispace collector.
   mirror::Object* AllocThreadUnsafe(Thread* self,
                                     size_t num_bytes,
                                     /* out */ size_t* bytes_allocated,
                                     /* out */ size_t* usable_size,
                                     /* out */ size_t* bytes_tl_bulk_allocated)
       OVERRIDE REQUIRES(Locks::mutator_lock_) REQUIRES(!region_lock_);
   // The main allocation routine.
   template<bool kForEvac>
   ALWAYS_INLINE mirror::Object* AllocNonvirtual(size_t num_bytes,
                                                 /* out */ size_t* bytes_allocated,
                                                 /* out */ size_t* usable_size,
                                                 /* out */ size_t* bytes_tl_bulk_allocated)
       REQUIRES(!region_lock_);
   // Allocate/free large objects (objects that are larger than the region size).
   template<bool kForEvac>
   mirror::Object* AllocLarge(size_t num_bytes,
                              /* out */ size_t* bytes_allocated,
                              /* out */ size_t* usable_size,
                              /* out */ size_t* bytes_tl_bulk_allocated) REQUIRES(!region_lock_);
   template<bool kForEvac>
   void FreeLarge(mirror::Object* large_obj, size_t bytes_allocated) REQUIRES(!region_lock_);

   // Return the storage space required by obj.
   size_t AllocationSize(mirror::Object* obj, size_t* usable_size) OVERRIDE
       REQUIRES_SHARED(Locks::mutator_lock_) REQUIRES(!region_lock_) {
     return AllocationSizeNonvirtual(obj, usable_size);
   }
   size_t AllocationSizeNonvirtual(mirror::Object* obj, size_t* usable_size)
       REQUIRES_SHARED(Locks::mutator_lock_) REQUIRES(!region_lock_);

   size_t Free(Thread*, mirror::Object*) OVERRIDE {
     UNIMPLEMENTED(FATAL);
     return 0;
   }
   size_t FreeList(Thread*, size_t, mirror::Object**) OVERRIDE {
     UNIMPLEMENTED(FATAL);
     return 0;
   }
   accounting::ContinuousSpaceBitmap* GetLiveBitmap() const OVERRIDE {
     return mark_bitmap_.get();
   }
   accounting::ContinuousSpaceBitmap* GetMarkBitmap() const OVERRIDE {
     return mark_bitmap_.get();
   }

   void Clear() OVERRIDE REQUIRES(!region_lock_);

   // Change the non growth limit capacity to new capacity by shrinking or expanding the map.
   // Currently, only shrinking is supported.
   // Unlike implementations of this function in other spaces, we need to pass
   // new capacity as argument here as region space doesn't have any notion of
   // growth limit.
   void ClampGrowthLimit(size_t new_capacity) REQUIRES(!region_lock_);

   void Dump(std::ostream& os) const;
   void DumpRegions(std::ostream& os) REQUIRES(!region_lock_);
   // Dump region containing object `obj`. Precondition: `obj` is in the region space.
   void DumpRegionForObject(std::ostream& os, mirror::Object* obj) REQUIRES(!region_lock_);
   void DumpNonFreeRegions(std::ostream& os) REQUIRES(!region_lock_);

   size_t RevokeThreadLocalBuffers(Thread* thread) REQUIRES(!region_lock_);
   void RevokeThreadLocalBuffersLocked(Thread* thread) REQUIRES(region_lock_);
   size_t RevokeAllThreadLocalBuffers()
       REQUIRES(!Locks::runtime_shutdown_lock_, !Locks::thread_list_lock_, !region_lock_);
   void AssertThreadLocalBuffersAreRevoked(Thread* thread) REQUIRES(!region_lock_);
   void AssertAllThreadLocalBuffersAreRevoked()
       REQUIRES(!Locks::runtime_shutdown_lock_, !Locks::thread_list_lock_, !region_lock_);

   enum class RegionType : uint8_t {
     kRegionTypeAll,              // All types.
     kRegionTypeFromSpace,        // From-space. To be evacuated.
     kRegionTypeUnevacFromSpace,  // Unevacuated from-space. Not to be evacuated.
     kRegionTypeToSpace,          // To-space.
     kRegionTypeNone,             // None.
   };

   enum class RegionState : uint8_t {
     kRegionStateFree,            // Free region.
     kRegionStateAllocated,       // Allocated region.
     kRegionStateLarge,           // Large allocated (allocation larger than the region size).
     kRegionStateLargeTail,       // Large tail (non-first regions of a large allocation).
   };

   template<RegionType kRegionType> uint64_t GetBytesAllocatedInternal() REQUIRES(!region_lock_);
   template<RegionType kRegionType> uint64_t GetObjectsAllocatedInternal() REQUIRES(!region_lock_);
   uint64_t GetBytesAllocated() REQUIRES(!region_lock_) {
     return GetBytesAllocatedInternal<RegionType::kRegionTypeAll>();
   }
   uint64_t GetObjectsAllocated() REQUIRES(!region_lock_) {
     return GetObjectsAllocatedInternal<RegionType::kRegionTypeAll>();
   }
   uint64_t GetBytesAllocatedInFromSpace() REQUIRES(!region_lock_) {
     return GetBytesAllocatedInternal<RegionType::kRegionTypeFromSpace>();
   }
   uint64_t GetObjectsAllocatedInFromSpace() REQUIRES(!region_lock_) {
     return GetObjectsAllocatedInternal<RegionType::kRegionTypeFromSpace>();
   }
   uint64_t GetBytesAllocatedInUnevacFromSpace() REQUIRES(!region_lock_) {
     return GetBytesAllocatedInternal<RegionType::kRegionTypeUnevacFromSpace>();
   }
   uint64_t GetObjectsAllocatedInUnevacFromSpace() REQUIRES(!region_lock_) {
     return GetObjectsAllocatedInternal<RegionType::kRegionTypeUnevacFromSpace>();
   }
   size_t GetMaxPeakNumNonFreeRegions() const {
     return max_peak_num_non_free_regions_;
   }
   size_t GetNumRegions() const {
     return num_regions_;
   }

   bool CanMoveObjects() const OVERRIDE {
     return true;
   }

   bool Contains(const mirror::Object* obj) const {
     const uint8_t* byte_obj = reinterpret_cast<const uint8_t*>(obj);
     return byte_obj >= Begin() && byte_obj < Limit();
   }

   RegionSpace* AsRegionSpace() OVERRIDE {
     return this;
   }

   // Go through all of the blocks and visit the continuous objects.
   template <typename Visitor>
   ALWAYS_INLINE void Walk(Visitor&& visitor) REQUIRES(Locks::mutator_lock_) {
     WalkInternal<false /* kToSpaceOnly */>(visitor);
   }
   template <typename Visitor>
   ALWAYS_INLINE void WalkToSpace(Visitor&& visitor)
       REQUIRES(Locks::mutator_lock_) {
     WalkInternal<true /* kToSpaceOnly */>(visitor);
   }

   accounting::ContinuousSpaceBitmap::SweepCallback* GetSweepCallback() OVERRIDE {
     return nullptr;
   }
   void LogFragmentationAllocFailure(std::ostream& os, size_t failed_alloc_bytes) OVERRIDE
       REQUIRES_SHARED(Locks::mutator_lock_) REQUIRES(!region_lock_);

   // Object alignment within the space.
   static constexpr size_t kAlignment = kObjectAlignment;
   // The region size.
   static constexpr size_t kRegionSize = 256 * KB;

   bool IsInFromSpace(mirror::Object* ref) {
     if (HasAddress(ref)) {
       Region* r = RefToRegionUnlocked(ref);
       return r->IsInFromSpace();
     }
     return false;
   }

   bool IsInNewlyAllocatedRegion(mirror::Object* ref) {
     if (HasAddress(ref)) {
       Region* r = RefToRegionUnlocked(ref);
       return r->IsNewlyAllocated();
     }
     return false;
   }

   bool IsInUnevacFromSpace(mirror::Object* ref) {
     if (HasAddress(ref)) {
       Region* r = RefToRegionUnlocked(ref);
       return r->IsInUnevacFromSpace();
     }
     return false;
   }

   bool IsInToSpace(mirror::Object* ref) {
     if (HasAddress(ref)) {
       Region* r = RefToRegionUnlocked(ref);
       return r->IsInToSpace();
     }
     return false;
   }

   // If `ref` is in the region space, return the type of its region;
   // otherwise, return `RegionType::kRegionTypeNone`.
   RegionType GetRegionType(mirror::Object* ref) {
     if (HasAddress(ref)) {
       return GetRegionTypeUnsafe(ref);
     }
     return RegionType::kRegionTypeNone;
   }

   // Unsafe version of RegionSpace::GetRegionType.
   // Precondition: `ref` is in the region space.
   RegionType GetRegionTypeUnsafe(mirror::Object* ref) {
     DCHECK(HasAddress(ref)) << ref;
     Region* r = RefToRegionUnlocked(ref);
     return r->Type();
   }

   // Determine which regions to evacuate and tag them as
   // from-space. Tag the rest as unevacuated from-space.
   void SetFromSpace(accounting::ReadBarrierTable* rb_table, bool force_evacuate_all)
       REQUIRES(!region_lock_);

   size_t FromSpaceSize() REQUIRES(!region_lock_);
   size_t UnevacFromSpaceSize() REQUIRES(!region_lock_);
   size_t ToSpaceSize() REQUIRES(!region_lock_);
   void ClearFromSpace(/* out */ uint64_t* cleared_bytes, /* out */ uint64_t* cleared_objects)
       REQUIRES(!region_lock_);

   void AddLiveBytes(mirror::Object* ref, size_t alloc_size) {
     Region* reg = RefToRegionUnlocked(ref);
     reg->AddLiveBytes(alloc_size);
   }

   void AssertAllRegionLiveBytesZeroOrCleared() REQUIRES(!region_lock_) {
     if (kIsDebugBuild) {
       MutexLock mu(Thread::Current(), region_lock_);
       for (size_t i = 0; i < num_regions_; ++i) {
         Region* r = &regions_[i];
         size_t live_bytes = r->LiveBytes();
         CHECK(live_bytes == 0U || live_bytes == static_cast<size_t>(-1)) << live_bytes;
       }
     }
   }

   void RecordAlloc(mirror::Object* ref) REQUIRES(!region_lock_);
   bool AllocNewTlab(Thread* self, size_t min_bytes) REQUIRES(!region_lock_);

   uint32_t Time() {
     return time_;
   }

  private:
   RegionSpace(const std::string& name, MemMap* mem_map);

   template<bool kToSpaceOnly, typename Visitor>
   ALWAYS_INLINE void WalkInternal(Visitor&& visitor) NO_THREAD_SAFETY_ANALYSIS;

   class Region {
    public:
     Region()
         : idx_(static_cast<size_t>(-1)),
           begin_(nullptr), top_(nullptr), end_(nullptr),
           state_(RegionState::kRegionStateAllocated), type_(RegionType::kRegionTypeToSpace),
           objects_allocated_(0), alloc_time_(0), live_bytes_(static_cast<size_t>(-1)),
           is_newly_allocated_(false), is_a_tlab_(false), thread_(nullptr) {}

     void Init(size_t idx, uint8_t* begin, uint8_t* end) {
       idx_ = idx;
       begin_ = begin;
       top_.StoreRelaxed(begin);
       end_ = end;
       state_ = RegionState::kRegionStateFree;
       type_ = RegionType::kRegionTypeNone;
       objects_allocated_.StoreRelaxed(0);
       alloc_time_ = 0;
       live_bytes_ = static_cast<size_t>(-1);
       is_newly_allocated_ = false;
       is_a_tlab_ = false;
       thread_ = nullptr;
       DCHECK_LT(begin, end);
       DCHECK_EQ(static_cast<size_t>(end - begin), kRegionSize);
     }

     RegionState State() const {
       return state_;
     }

     RegionType Type() const {
       return type_;
     }

     void Clear(bool zero_and_release_pages);

     ALWAYS_INLINE mirror::Object* Alloc(size_t num_bytes,
                                         /* out */ size_t* bytes_allocated,
                                         /* out */ size_t* usable_size,
                                         /* out */ size_t* bytes_tl_bulk_allocated);

     bool IsFree() const {
       bool is_free = (state_ == RegionState::kRegionStateFree);
       if (is_free) {
         DCHECK(IsInNoSpace());
         DCHECK_EQ(begin_, Top());
         DCHECK_EQ(objects_allocated_.LoadRelaxed(), 0U);
       }
       return is_free;
     }

     // Given a free region, declare it non-free (allocated).
     void Unfree(RegionSpace* region_space, uint32_t alloc_time)
         REQUIRES(region_space->region_lock_);

     // Given a free region, declare it non-free (allocated) and large.
     void UnfreeLarge(RegionSpace* region_space, uint32_t alloc_time)
         REQUIRES(region_space->region_lock_);

     // Given a free region, declare it non-free (allocated) and large tail.
     void UnfreeLargeTail(RegionSpace* region_space, uint32_t alloc_time)
         REQUIRES(region_space->region_lock_);

     void MarkAsAllocated(RegionSpace* region_space, uint32_t alloc_time)
         REQUIRES(region_space->region_lock_);

     void SetNewlyAllocated() {
       is_newly_allocated_ = true;
     }

     // Non-large, non-large-tail allocated.
     bool IsAllocated() const {
       return state_ == RegionState::kRegionStateAllocated;
     }

     // Large allocated.
     bool IsLarge() const {
       bool is_large = (state_ == RegionState::kRegionStateLarge);
       if (is_large) {
         DCHECK_LT(begin_ + kRegionSize, Top());
       }
       return is_large;
     }

     // Large-tail allocated.
     bool IsLargeTail() const {
       bool is_large_tail = (state_ == RegionState::kRegionStateLargeTail);
       if (is_large_tail) {
         DCHECK_EQ(begin_, Top());
       }
       return is_large_tail;
     }

     size_t Idx() const {
       return idx_;
     }

     bool IsNewlyAllocated() const {
       return is_newly_allocated_;
     }

     bool IsInFromSpace() const {
       return type_ == RegionType::kRegionTypeFromSpace;
     }

     bool IsInToSpace() const {
       return type_ == RegionType::kRegionTypeToSpace;
     }

     bool IsInUnevacFromSpace() const {
       return type_ == RegionType::kRegionTypeUnevacFromSpace;
     }

     bool IsInNoSpace() const {
       return type_ == RegionType::kRegionTypeNone;
     }

     // Set this region as evacuated from-space. At the end of the
     // collection, RegionSpace::ClearFromSpace will clear and reclaim
     // the space used by this region, and tag it as unallocated/free.
     void SetAsFromSpace() {
       DCHECK(!IsFree() && IsInToSpace());
       type_ = RegionType::kRegionTypeFromSpace;
       live_bytes_ = static_cast<size_t>(-1);
     }

     // Set this region as unevacuated from-space. At the end of the
     // collection, RegionSpace::ClearFromSpace will preserve the space
     // used by this region, and tag it as to-space (see
     // Region::SetUnevacFromSpaceAsToSpace below).
     void SetAsUnevacFromSpace() {
       DCHECK(!IsFree() && IsInToSpace());
       type_ = RegionType::kRegionTypeUnevacFromSpace;
       live_bytes_ = 0U;
     }

     // Set this region as to-space. Used by RegionSpace::ClearFromSpace.
     // This is only valid if it is currently an unevac from-space region.
     void SetUnevacFromSpaceAsToSpace() {
       DCHECK(!IsFree() && IsInUnevacFromSpace());
       type_ = RegionType::kRegionTypeToSpace;
     }

     // Return whether this region should be evacuated. Used by RegionSpace::SetFromSpace.
     ALWAYS_INLINE bool ShouldBeEvacuated();

     void AddLiveBytes(size_t live_bytes) {
       DCHECK(IsInUnevacFromSpace());
       DCHECK(!IsLargeTail());
       DCHECK_NE(live_bytes_, static_cast<size_t>(-1));
       // For large allocations, we always consider all bytes in the
       // regions live.
       live_bytes_ += IsLarge() ? Top() - begin_ : live_bytes;
       DCHECK_LE(live_bytes_, BytesAllocated());
     }

     bool AllAllocatedBytesAreLive() const {
       return LiveBytes() == static_cast<size_t>(Top() - Begin());
     }

     size_t LiveBytes() const {
       return live_bytes_;
     }

     size_t BytesAllocated() const;

     size_t ObjectsAllocated() const;

     uint8_t* Begin() const {
       return begin_;
     }

     ALWAYS_INLINE uint8_t* Top() const {
       return top_.LoadRelaxed();
     }

     void SetTop(uint8_t* new_top) {
       top_.StoreRelaxed(new_top);
     }

     uint8_t* End() const {
       return end_;
     }

     bool Contains(mirror::Object* ref) const {
       return begin_ <= reinterpret_cast<uint8_t*>(ref) && reinterpret_cast<uint8_t*>(ref) < end_;
     }

     void Dump(std::ostream& os) const;

     void RecordThreadLocalAllocations(size_t num_objects, size_t num_bytes) {
       DCHECK(IsAllocated());
       DCHECK_EQ(objects_allocated_.LoadRelaxed(), 0U);
       DCHECK_EQ(Top(), end_);
       objects_allocated_.StoreRelaxed(num_objects);
       top_.StoreRelaxed(begin_ + num_bytes);
       DCHECK_LE(Top(), end_);
     }

    private:
     size_t idx_;                        // The region's index in the region space.
     uint8_t* begin_;                    // The begin address of the region.
     // Note that `top_` can be higher than `end_` in the case of a
     // large region, where an allocated object spans multiple regions
     // (large region + one or more large tail regions).
     Atomic<uint8_t*> top_;              // The current position of the allocation.
     uint8_t* end_;                      // The end address of the region.
     RegionState state_;                 // The region state (see RegionState).
     RegionType type_;                   // The region type (see RegionType).
     Atomic<size_t> objects_allocated_;  // The number of objects allocated.
     uint32_t alloc_time_;               // The allocation time of the region.
     // Note that newly allocated and evacuated regions use -1 as
     // special value for `live_bytes_`.
     size_t live_bytes_;                 // The live bytes. Used to compute the live percent.
     bool is_newly_allocated_;           // True if it's allocated after the last collection.
     bool is_a_tlab_;                    // True if it's a tlab.
     Thread* thread_;                    // The owning thread if it's a tlab.

     friend class RegionSpace;
   };

   Region* RefToRegion(mirror::Object* ref) REQUIRES(!region_lock_) {
     MutexLock mu(Thread::Current(), region_lock_);
     return RefToRegionLocked(ref);
   }

   Region* RefToRegionUnlocked(mirror::Object* ref) NO_THREAD_SAFETY_ANALYSIS {
     // For a performance reason (this is frequently called via
     // RegionSpace::IsInFromSpace, etc.) we avoid taking a lock here.
     // Note that since we only change a region from to-space to (evac)
     // from-space during a pause (in RegionSpace::SetFromSpace) and
     // from (evac) from-space to free (after GC is done), as long as
     // `ref` is a valid reference into an allocated region, it's safe
     // to access the region state without the lock.
     return RefToRegionLocked(ref);
   }

   Region* RefToRegionLocked(mirror::Object* ref) REQUIRES(region_lock_) {
     DCHECK(HasAddress(ref));
     uintptr_t offset = reinterpret_cast<uintptr_t>(ref) - reinterpret_cast<uintptr_t>(Begin());
     size_t reg_idx = offset / kRegionSize;
     DCHECK_LT(reg_idx, num_regions_);
     Region* reg = &regions_[reg_idx];
     DCHECK_EQ(reg->Idx(), reg_idx);
     DCHECK(reg->Contains(ref));
     return reg;
   }

   // Return the object location following `obj` in the region space
   // (i.e., the object location at `obj + obj->SizeOf()`).
   //
   // Note that unless
   // - the region containing `obj` is fully used; and
   // - `obj` is not the last object of that region;
   // the returned location is not guaranteed to be a valid object.
   mirror::Object* GetNextObject(mirror::Object* obj)
       REQUIRES_SHARED(Locks::mutator_lock_);

   void AdjustNonFreeRegionLimit(size_t new_non_free_region_index) REQUIRES(region_lock_) {
     DCHECK_LT(new_non_free_region_index, num_regions_);
     non_free_region_index_limit_ = std::max(non_free_region_index_limit_,
                                             new_non_free_region_index + 1);
     VerifyNonFreeRegionLimit();
   }

   void SetNonFreeRegionLimit(size_t new_non_free_region_index_limit) REQUIRES(region_lock_) {
     DCHECK_LE(new_non_free_region_index_limit, num_regions_);
     non_free_region_index_limit_ = new_non_free_region_index_limit;
     VerifyNonFreeRegionLimit();
   }

   // Implementation of this invariant:
   // for all `i >= non_free_region_index_limit_`, `regions_[i].IsFree()` is true.
   void VerifyNonFreeRegionLimit() REQUIRES(region_lock_) {
     if (kIsDebugBuild && non_free_region_index_limit_ < num_regions_) {
       for (size_t i = non_free_region_index_limit_; i < num_regions_; ++i) {
         CHECK(regions_[i].IsFree());
       }
     }
   }

   Region* AllocateRegion(bool for_evac) REQUIRES(region_lock_);

   Mutex region_lock_ DEFAULT_MUTEX_ACQUIRED_AFTER;

   uint32_t time_;                  // The time as the number of collections since the startup.
   size_t num_regions_;             // The number of regions in this space.
   // The number of non-free regions in this space.
   size_t num_non_free_regions_ GUARDED_BY(region_lock_);

   // The number of evac regions allocated during collection. 0 when GC not running.
   size_t num_evac_regions_ GUARDED_BY(region_lock_);

   // Maintain the maximum of number of non-free regions collected just before
   // reclaim in each GC cycle. At this moment in cycle, highest number of
   // regions are in non-free.
   size_t max_peak_num_non_free_regions_;

   // The pointer to the region array.
   std::unique_ptr<Region[]> regions_ GUARDED_BY(region_lock_);

   // The upper-bound index of the non-free regions. Used to avoid scanning all regions in
   // RegionSpace::SetFromSpace and RegionSpace::ClearFromSpace.
   //
   // Invariant (verified by RegionSpace::VerifyNonFreeRegionLimit):
   //   for all `i >= non_free_region_index_limit_`, `regions_[i].IsFree()` is true.
   size_t non_free_region_index_limit_ GUARDED_BY(region_lock_);

   Region* current_region_;         // The region currently used for allocation.
   Region* evac_region_;            // The region currently used for evacuation.
   Region full_region_;             // The dummy/sentinel region that looks full.

   // Mark bitmap used by the GC.
   std::unique_ptr<accounting::ContinuousSpaceBitmap> mark_bitmap_;

   DISALLOW_COPY_AND_ASSIGN(RegionSpace);
 };

 std::ostream& operator<<(std::ostream& os, const RegionSpace::RegionState& value);
 std::ostream& operator<<(std::ostream& os, const RegionSpace::RegionType& value);

 }  // namespace space
 }  // namespace gc
 }  // namespace art

 #endif  // ART_RUNTIME_GC_SPACE_REGION_SPACE_H_
	/*
	* Copyright (C) 2014 The Android Open Source Project
	*
	* Licensed under the Apache License, Version 2.0 (the "License");
	* you may not use this file except in compliance with the License.
	* You may obtain a copy of the License at
	*
	* http://www.apache.org/licenses/LICENSE-2.0
	*
	* Unless required by applicable law or agreed to in writing, software
	* distributed under the License is distributed on an "AS IS" BASIS,
	* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
	* See the License for the specific language governing permissions and
	* limitations under the License.
	*/

	#ifndef ART_RUNTIME_GC_SPACE_REGION_SPACE_H_
	#define ART_RUNTIME_GC_SPACE_REGION_SPACE_H_

	#include "base/macros.h"
	#include "base/mutex.h"
	#include "space.h"
	#include "thread.h"

	namespace art {
	namespace gc {

	namespace accounting {
	class ReadBarrierTable;
	} // namespace accounting

	namespace space {

	// A space that consists of equal-sized regions.
	class RegionSpace FINAL : public ContinuousMemMapAllocSpace {
	public:
	typedef void(WalkCallback)(void start, void end, size_t num_bytes, void callback_arg);

	SpaceType GetType() const OVERRIDE {
	return kSpaceTypeRegionSpace;
	}

	// Create a region space mem map with the requested sizes. The requested base address is not
	// guaranteed to be granted, if it is required, the caller should call Begin on the returned
	// space to confirm the request was granted.
	static MemMap* CreateMemMap(const std::string& name, size_t capacity, uint8_t* requested_begin);
	static RegionSpace* Create(const std::string& name, MemMap* mem_map);

	// Allocate `num_bytes`, returns null if the space is full.
	mirror::Object* Alloc(Thread* self,
	size_t num_bytes,
	/* out / size_t bytes_allocated,
	/* out / size_t usable_size,
	/* out / size_t bytes_tl_bulk_allocated)
	OVERRIDE REQUIRES(!region_lock_);
	// Thread-unsafe allocation for when mutators are suspended, used by the semispace collector.
	mirror::Object* AllocThreadUnsafe(Thread* self,
	size_t num_bytes,
	/* out / size_t bytes_allocated,
	/* out / size_t usable_size,
	/* out / size_t bytes_tl_bulk_allocated)
	OVERRIDE REQUIRES(Locks::mutator_lock_) REQUIRES(!region_lock_);
	// The main allocation routine.
	template<bool kForEvac>
	ALWAYS_INLINE mirror::Object* AllocNonvirtual(size_t num_bytes,
	/* out / size_t bytes_allocated,
	/* out / size_t usable_size,
	/* out / size_t bytes_tl_bulk_allocated)
	REQUIRES(!region_lock_);
	// Allocate/free large objects (objects that are larger than the region size).
	template<bool kForEvac>
	mirror::Object* AllocLarge(size_t num_bytes,
	/* out / size_t bytes_allocated,
	/* out / size_t usable_size,
	/* out / size_t bytes_tl_bulk_allocated) REQUIRES(!region_lock_);
	template<bool kForEvac>
	void FreeLarge(mirror::Object* large_obj, size_t bytes_allocated) REQUIRES(!region_lock_);

	// Return the storage space required by obj.
	size_t AllocationSize(mirror::Object* obj, size_t* usable_size) OVERRIDE
	REQUIRES_SHARED(Locks::mutator_lock_) REQUIRES(!region_lock_) {
	return AllocationSizeNonvirtual(obj, usable_size);
	}
	size_t AllocationSizeNonvirtual(mirror::Object* obj, size_t* usable_size)
	REQUIRES_SHARED(Locks::mutator_lock_) REQUIRES(!region_lock_);

	size_t Free(Thread, mirror::Object) OVERRIDE {
	UNIMPLEMENTED(FATAL);
	return 0;
	}
	size_t FreeList(Thread, size_t, mirror::Object*) OVERRIDE {
	UNIMPLEMENTED(FATAL);
	return 0;
	}
	accounting::ContinuousSpaceBitmap* GetLiveBitmap() const OVERRIDE {
	return mark_bitmap_.get();
	}
	accounting::ContinuousSpaceBitmap* GetMarkBitmap() const OVERRIDE {
	return mark_bitmap_.get();
	}

	void Clear() OVERRIDE REQUIRES(!region_lock_);

	// Change the non growth limit capacity to new capacity by shrinking or expanding the map.
	// Currently, only shrinking is supported.
	// Unlike implementations of this function in other spaces, we need to pass
	// new capacity as argument here as region space doesn't have any notion of
	// growth limit.
	void ClampGrowthLimit(size_t new_capacity) REQUIRES(!region_lock_);

	void Dump(std::ostream& os) const;
	void DumpRegions(std::ostream& os) REQUIRES(!region_lock_);
	// Dump region containing object `obj`. Precondition: `obj` is in the region space.
	void DumpRegionForObject(std::ostream& os, mirror::Object* obj) REQUIRES(!region_lock_);
	void DumpNonFreeRegions(std::ostream& os) REQUIRES(!region_lock_);

	size_t RevokeThreadLocalBuffers(Thread* thread) REQUIRES(!region_lock_);
	void RevokeThreadLocalBuffersLocked(Thread* thread) REQUIRES(region_lock_);
	size_t RevokeAllThreadLocalBuffers()
	REQUIRES(!Locks::runtime_shutdown_lock_, !Locks::thread_list_lock_, !region_lock_);
	void AssertThreadLocalBuffersAreRevoked(Thread* thread) REQUIRES(!region_lock_);
	void AssertAllThreadLocalBuffersAreRevoked()
	REQUIRES(!Locks::runtime_shutdown_lock_, !Locks::thread_list_lock_, !region_lock_);

	enum class RegionType : uint8_t {
	kRegionTypeAll, // All types.
	kRegionTypeFromSpace, // From-space. To be evacuated.
	kRegionTypeUnevacFromSpace, // Unevacuated from-space. Not to be evacuated.
	kRegionTypeToSpace, // To-space.
	kRegionTypeNone, // None.
	};

	enum class RegionState : uint8_t {
	kRegionStateFree, // Free region.
	kRegionStateAllocated, // Allocated region.
	kRegionStateLarge, // Large allocated (allocation larger than the region size).
	kRegionStateLargeTail, // Large tail (non-first regions of a large allocation).
	};

	template<RegionType kRegionType> uint64_t GetBytesAllocatedInternal() REQUIRES(!region_lock_);
	template<RegionType kRegionType> uint64_t GetObjectsAllocatedInternal() REQUIRES(!region_lock_);
	uint64_t GetBytesAllocated() REQUIRES(!region_lock_) {
	return GetBytesAllocatedInternal<RegionType::kRegionTypeAll>();
	}
	uint64_t GetObjectsAllocated() REQUIRES(!region_lock_) {
	return GetObjectsAllocatedInternal<RegionType::kRegionTypeAll>();
	}
	uint64_t GetBytesAllocatedInFromSpace() REQUIRES(!region_lock_) {
	return GetBytesAllocatedInternal<RegionType::kRegionTypeFromSpace>();
	}
	uint64_t GetObjectsAllocatedInFromSpace() REQUIRES(!region_lock_) {
	return GetObjectsAllocatedInternal<RegionType::kRegionTypeFromSpace>();
	}
	uint64_t GetBytesAllocatedInUnevacFromSpace() REQUIRES(!region_lock_) {
	return GetBytesAllocatedInternal<RegionType::kRegionTypeUnevacFromSpace>();
	}
	uint64_t GetObjectsAllocatedInUnevacFromSpace() REQUIRES(!region_lock_) {
	return GetObjectsAllocatedInternal<RegionType::kRegionTypeUnevacFromSpace>();
	}
	size_t GetMaxPeakNumNonFreeRegions() const {
	return max_peak_num_non_free_regions_;
	}
	size_t GetNumRegions() const {
	return num_regions_;
	}

	bool CanMoveObjects() const OVERRIDE {
	return true;
	}

	bool Contains(const mirror::Object* obj) const {
	const uint8_t* byte_obj = reinterpret_cast<const uint8_t*>(obj);
	return byte_obj >= Begin() && byte_obj < Limit();
	}

	RegionSpace* AsRegionSpace() OVERRIDE {
	return this;
	}

	// Go through all of the blocks and visit the continuous objects.
	template <typename Visitor>
	ALWAYS_INLINE void Walk(Visitor&& visitor) REQUIRES(Locks::mutator_lock_) {
	WalkInternal<false /* kToSpaceOnly */>(visitor);
	}
	template <typename Visitor>
	ALWAYS_INLINE void WalkToSpace(Visitor&& visitor)
	REQUIRES(Locks::mutator_lock_) {
	WalkInternal<true /* kToSpaceOnly */>(visitor);
	}

	accounting::ContinuousSpaceBitmap::SweepCallback* GetSweepCallback() OVERRIDE {
	return nullptr;
	}
	void LogFragmentationAllocFailure(std::ostream& os, size_t failed_alloc_bytes) OVERRIDE
	REQUIRES_SHARED(Locks::mutator_lock_) REQUIRES(!region_lock_);

	// Object alignment within the space.
	static constexpr size_t kAlignment = kObjectAlignment;
	// The region size.
	static constexpr size_t kRegionSize = 256 * KB;

	bool IsInFromSpace(mirror::Object* ref) {
	if (HasAddress(ref)) {
	Region* r = RefToRegionUnlocked(ref);
	return r->IsInFromSpace();
	}
	return false;
	}

	bool IsInNewlyAllocatedRegion(mirror::Object* ref) {
	if (HasAddress(ref)) {
	Region* r = RefToRegionUnlocked(ref);
	return r->IsNewlyAllocated();
	}
	return false;
	}

	bool IsInUnevacFromSpace(mirror::Object* ref) {
	if (HasAddress(ref)) {
	Region* r = RefToRegionUnlocked(ref);
	return r->IsInUnevacFromSpace();
	}
	return false;
	}

	bool IsInToSpace(mirror::Object* ref) {
	if (HasAddress(ref)) {
	Region* r = RefToRegionUnlocked(ref);
	return r->IsInToSpace();
	}
	return false;
	}

	// If `ref` is in the region space, return the type of its region;
	// otherwise, return `RegionType::kRegionTypeNone`.
	RegionType GetRegionType(mirror::Object* ref) {
	if (HasAddress(ref)) {
	return GetRegionTypeUnsafe(ref);
	}
	return RegionType::kRegionTypeNone;
	}

	// Unsafe version of RegionSpace::GetRegionType.
	// Precondition: `ref` is in the region space.
	RegionType GetRegionTypeUnsafe(mirror::Object* ref) {
	DCHECK(HasAddress(ref)) << ref;
	Region* r = RefToRegionUnlocked(ref);
	return r->Type();
	}

	// Determine which regions to evacuate and tag them as
	// from-space. Tag the rest as unevacuated from-space.
	void SetFromSpace(accounting::ReadBarrierTable* rb_table, bool force_evacuate_all)
	REQUIRES(!region_lock_);

	size_t FromSpaceSize() REQUIRES(!region_lock_);
	size_t UnevacFromSpaceSize() REQUIRES(!region_lock_);
	size_t ToSpaceSize() REQUIRES(!region_lock_);
	void ClearFromSpace(/* out / uint64_t cleared_bytes, /* out / uint64_t cleared_objects)
	REQUIRES(!region_lock_);

	void AddLiveBytes(mirror::Object* ref, size_t alloc_size) {
	Region* reg = RefToRegionUnlocked(ref);
	reg->AddLiveBytes(alloc_size);
	}

	void AssertAllRegionLiveBytesZeroOrCleared() REQUIRES(!region_lock_) {
	if (kIsDebugBuild) {
	MutexLock mu(Thread::Current(), region_lock_);
	for (size_t i = 0; i < num_regions_; ++i) {
	Region* r = &regions_[i];
	size_t live_bytes = r->LiveBytes();
	CHECK(live_bytes == 0U \|\| live_bytes == static_cast<size_t>(-1)) << live_bytes;
	}
	}
	}

	void RecordAlloc(mirror::Object* ref) REQUIRES(!region_lock_);
	bool AllocNewTlab(Thread* self, size_t min_bytes) REQUIRES(!region_lock_);

	uint32_t Time() {
	return time_;
	}

	private:
	RegionSpace(const std::string& name, MemMap* mem_map);

	template<bool kToSpaceOnly, typename Visitor>
	ALWAYS_INLINE void WalkInternal(Visitor&& visitor) NO_THREAD_SAFETY_ANALYSIS;

	class Region {
	public:
	Region()
	: idx_(static_cast<size_t>(-1)),
	begin_(nullptr), top_(nullptr), end_(nullptr),
	state_(RegionState::kRegionStateAllocated), type_(RegionType::kRegionTypeToSpace),
	objects_allocated_(0), alloc_time_(0), live_bytes_(static_cast<size_t>(-1)),
	is_newly_allocated_(false), is_a_tlab_(false), thread_(nullptr) {}

	void Init(size_t idx, uint8_t* begin, uint8_t* end) {
	idx_ = idx;
	begin_ = begin;
	top_.StoreRelaxed(begin);
	end_ = end;
	state_ = RegionState::kRegionStateFree;
	type_ = RegionType::kRegionTypeNone;
	objects_allocated_.StoreRelaxed(0);
	alloc_time_ = 0;
	live_bytes_ = static_cast<size_t>(-1);
	is_newly_allocated_ = false;
	is_a_tlab_ = false;
	thread_ = nullptr;
	DCHECK_LT(begin, end);
	DCHECK_EQ(static_cast<size_t>(end - begin), kRegionSize);
	}

	RegionState State() const {
	return state_;
	}

	RegionType Type() const {
	return type_;
	}

	void Clear(bool zero_and_release_pages);

	ALWAYS_INLINE mirror::Object* Alloc(size_t num_bytes,
	/* out / size_t bytes_allocated,
	/* out / size_t usable_size,
	/* out / size_t bytes_tl_bulk_allocated);

	bool IsFree() const {
	bool is_free = (state_ == RegionState::kRegionStateFree);
	if (is_free) {
	DCHECK(IsInNoSpace());
	DCHECK_EQ(begin_, Top());
	DCHECK_EQ(objects_allocated_.LoadRelaxed(), 0U);
	}
	return is_free;
	}

	// Given a free region, declare it non-free (allocated).
	void Unfree(RegionSpace* region_space, uint32_t alloc_time)
	REQUIRES(region_space->region_lock_);

	// Given a free region, declare it non-free (allocated) and large.
	void UnfreeLarge(RegionSpace* region_space, uint32_t alloc_time)
	REQUIRES(region_space->region_lock_);

	// Given a free region, declare it non-free (allocated) and large tail.
	void UnfreeLargeTail(RegionSpace* region_space, uint32_t alloc_time)
	REQUIRES(region_space->region_lock_);

	void MarkAsAllocated(RegionSpace* region_space, uint32_t alloc_time)
	REQUIRES(region_space->region_lock_);

	void SetNewlyAllocated() {
	is_newly_allocated_ = true;
	}

	// Non-large, non-large-tail allocated.
	bool IsAllocated() const {
	return state_ == RegionState::kRegionStateAllocated;
	}

	// Large allocated.
	bool IsLarge() const {
	bool is_large = (state_ == RegionState::kRegionStateLarge);
	if (is_large) {
	DCHECK_LT(begin_ + kRegionSize, Top());
	}
	return is_large;
	}

	// Large-tail allocated.
	bool IsLargeTail() const {
	bool is_large_tail = (state_ == RegionState::kRegionStateLargeTail);
	if (is_large_tail) {
	DCHECK_EQ(begin_, Top());
	}
	return is_large_tail;
	}

	size_t Idx() const {
	return idx_;
	}

	bool IsNewlyAllocated() const {
	return is_newly_allocated_;
	}

	bool IsInFromSpace() const {
	return type_ == RegionType::kRegionTypeFromSpace;
	}

	bool IsInToSpace() const {
	return type_ == RegionType::kRegionTypeToSpace;
	}

	bool IsInUnevacFromSpace() const {
	return type_ == RegionType::kRegionTypeUnevacFromSpace;
	}

	bool IsInNoSpace() const {
	return type_ == RegionType::kRegionTypeNone;
	}

	// Set this region as evacuated from-space. At the end of the
	// collection, RegionSpace::ClearFromSpace will clear and reclaim
	// the space used by this region, and tag it as unallocated/free.
	void SetAsFromSpace() {
	DCHECK(!IsFree() && IsInToSpace());
	type_ = RegionType::kRegionTypeFromSpace;
	live_bytes_ = static_cast<size_t>(-1);
	}

	// Set this region as unevacuated from-space. At the end of the
	// collection, RegionSpace::ClearFromSpace will preserve the space
	// used by this region, and tag it as to-space (see
	// Region::SetUnevacFromSpaceAsToSpace below).
	void SetAsUnevacFromSpace() {
	DCHECK(!IsFree() && IsInToSpace());
	type_ = RegionType::kRegionTypeUnevacFromSpace;
	live_bytes_ = 0U;
	}

	// Set this region as to-space. Used by RegionSpace::ClearFromSpace.
	// This is only valid if it is currently an unevac from-space region.
	void SetUnevacFromSpaceAsToSpace() {
	DCHECK(!IsFree() && IsInUnevacFromSpace());
	type_ = RegionType::kRegionTypeToSpace;
	}

	// Return whether this region should be evacuated. Used by RegionSpace::SetFromSpace.
	ALWAYS_INLINE bool ShouldBeEvacuated();

	void AddLiveBytes(size_t live_bytes) {
	DCHECK(IsInUnevacFromSpace());
	DCHECK(!IsLargeTail());
	DCHECK_NE(live_bytes_, static_cast<size_t>(-1));
	// For large allocations, we always consider all bytes in the
	// regions live.
	live_bytes_ += IsLarge() ? Top() - begin_ : live_bytes;
	DCHECK_LE(live_bytes_, BytesAllocated());
	}

	bool AllAllocatedBytesAreLive() const {
	return LiveBytes() == static_cast<size_t>(Top() - Begin());
	}

	size_t LiveBytes() const {
	return live_bytes_;
	}

	size_t BytesAllocated() const;

	size_t ObjectsAllocated() const;

	uint8_t* Begin() const {
	return begin_;
	}

	ALWAYS_INLINE uint8_t* Top() const {
	return top_.LoadRelaxed();
	}

	void SetTop(uint8_t* new_top) {
	top_.StoreRelaxed(new_top);
	}

	uint8_t* End() const {
	return end_;
	}

	bool Contains(mirror::Object* ref) const {
	return begin_ <= reinterpret_cast<uint8_t>(ref) && reinterpret_cast<uint8_t>(ref) < end_;
	}

	void Dump(std::ostream& os) const;

	void RecordThreadLocalAllocations(size_t num_objects, size_t num_bytes) {
	DCHECK(IsAllocated());
	DCHECK_EQ(objects_allocated_.LoadRelaxed(), 0U);
	DCHECK_EQ(Top(), end_);
	objects_allocated_.StoreRelaxed(num_objects);
	top_.StoreRelaxed(begin_ + num_bytes);
	DCHECK_LE(Top(), end_);
	}

	private:
	size_t idx_; // The region's index in the region space.
	uint8_t* begin_; // The begin address of the region.
	// Note that `top_` can be higher than `end_` in the case of a
	// large region, where an allocated object spans multiple regions
	// (large region + one or more large tail regions).
	Atomic<uint8_t*> top_; // The current position of the allocation.
	uint8_t* end_; // The end address of the region.
	RegionState state_; // The region state (see RegionState).
	RegionType type_; // The region type (see RegionType).
	Atomic<size_t> objects_allocated_; // The number of objects allocated.
	uint32_t alloc_time_; // The allocation time of the region.
	// Note that newly allocated and evacuated regions use -1 as
	// special value for `live_bytes_`.
	size_t live_bytes_; // The live bytes. Used to compute the live percent.
	bool is_newly_allocated_; // True if it's allocated after the last collection.
	bool is_a_tlab_; // True if it's a tlab.
	Thread* thread_; // The owning thread if it's a tlab.

	friend class RegionSpace;
	};

	Region* RefToRegion(mirror::Object* ref) REQUIRES(!region_lock_) {
	MutexLock mu(Thread::Current(), region_lock_);
	return RefToRegionLocked(ref);
	}

	Region* RefToRegionUnlocked(mirror::Object* ref) NO_THREAD_SAFETY_ANALYSIS {
	// For a performance reason (this is frequently called via
	// RegionSpace::IsInFromSpace, etc.) we avoid taking a lock here.
	// Note that since we only change a region from to-space to (evac)
	// from-space during a pause (in RegionSpace::SetFromSpace) and
	// from (evac) from-space to free (after GC is done), as long as
	// `ref` is a valid reference into an allocated region, it's safe
	// to access the region state without the lock.
	return RefToRegionLocked(ref);
	}

	Region* RefToRegionLocked(mirror::Object* ref) REQUIRES(region_lock_) {
	DCHECK(HasAddress(ref));
	uintptr_t offset = reinterpret_cast<uintptr_t>(ref) - reinterpret_cast<uintptr_t>(Begin());
	size_t reg_idx = offset / kRegionSize;
	DCHECK_LT(reg_idx, num_regions_);
	Region* reg = &regions_[reg_idx];
	DCHECK_EQ(reg->Idx(), reg_idx);
	DCHECK(reg->Contains(ref));
	return reg;
	}

	// Return the object location following `obj` in the region space
	// (i.e., the object location at `obj + obj->SizeOf()`).
	//
	// Note that unless
	// - the region containing `obj` is fully used; and
	// - `obj` is not the last object of that region;
	// the returned location is not guaranteed to be a valid object.
	mirror::Object* GetNextObject(mirror::Object* obj)
	REQUIRES_SHARED(Locks::mutator_lock_);

	void AdjustNonFreeRegionLimit(size_t new_non_free_region_index) REQUIRES(region_lock_) {
	DCHECK_LT(new_non_free_region_index, num_regions_);
	non_free_region_index_limit_ = std::max(non_free_region_index_limit_,
	new_non_free_region_index + 1);
	VerifyNonFreeRegionLimit();
	}

	void SetNonFreeRegionLimit(size_t new_non_free_region_index_limit) REQUIRES(region_lock_) {
	DCHECK_LE(new_non_free_region_index_limit, num_regions_);
	non_free_region_index_limit_ = new_non_free_region_index_limit;
	VerifyNonFreeRegionLimit();
	}

	// Implementation of this invariant:
	// for all `i >= non_free_region_index_limit_`, `regions_[i].IsFree()` is true.
	void VerifyNonFreeRegionLimit() REQUIRES(region_lock_) {
	if (kIsDebugBuild && non_free_region_index_limit_ < num_regions_) {
	for (size_t i = non_free_region_index_limit_; i < num_regions_; ++i) {
	CHECK(regions_[i].IsFree());
	}
	}
	}

	Region* AllocateRegion(bool for_evac) REQUIRES(region_lock_);

	Mutex region_lock_ DEFAULT_MUTEX_ACQUIRED_AFTER;

	uint32_t time_; // The time as the number of collections since the startup.
	size_t num_regions_; // The number of regions in this space.
	// The number of non-free regions in this space.
	size_t num_non_free_regions_ GUARDED_BY(region_lock_);

	// The number of evac regions allocated during collection. 0 when GC not running.
	size_t num_evac_regions_ GUARDED_BY(region_lock_);

	// Maintain the maximum of number of non-free regions collected just before
	// reclaim in each GC cycle. At this moment in cycle, highest number of
	// regions are in non-free.
	size_t max_peak_num_non_free_regions_;

	// The pointer to the region array.
	std::unique_ptr<Region[]> regions_ GUARDED_BY(region_lock_);

	// The upper-bound index of the non-free regions. Used to avoid scanning all regions in
	// RegionSpace::SetFromSpace and RegionSpace::ClearFromSpace.
	//
	// Invariant (verified by RegionSpace::VerifyNonFreeRegionLimit):
	// for all `i >= non_free_region_index_limit_`, `regions_[i].IsFree()` is true.
	size_t non_free_region_index_limit_ GUARDED_BY(region_lock_);

	Region* current_region_; // The region currently used for allocation.
	Region* evac_region_; // The region currently used for evacuation.
	Region full_region_; // The dummy/sentinel region that looks full.

	// Mark bitmap used by the GC.
	std::unique_ptr<accounting::ContinuousSpaceBitmap> mark_bitmap_;

	DISALLOW_COPY_AND_ASSIGN(RegionSpace);
	};

	std::ostream& operator<<(std::ostream& os, const RegionSpace::RegionState& value);
	std::ostream& operator<<(std::ostream& os, const RegionSpace::RegionType& value);

	} // namespace space
	} // namespace gc
	} // namespace art

	#endif // ART_RUNTIME_GC_SPACE_REGION_SPACE_H_