compiler/utils/scoped_arena_allocator.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_COMPILER_UTILS_SCOPED_ARENA_ALLOCATOR_H_
#define ART_COMPILER_UTILS_SCOPED_ARENA_ALLOCATOR_H_

#include "base/logging.h"
#include "base/macros.h"
#include "utils/arena_allocator.h"
#include "utils/debug_stack.h"
#include "globals.h"

namespace art {

class ArenaStack;
class ScopedArenaAllocator;

template <typename T>
class ScopedArenaAllocatorAdapter;

// Holds a list of Arenas for use by ScopedArenaAllocator stack.
class ArenaStack : private DebugStackRefCounter {
 public:
  explicit ArenaStack(ArenaPool* arena_pool);
  ~ArenaStack();

  void Reset();

  size_t PeakBytesAllocated() {
    return PeakStats()->BytesAllocated();
  }

  MemStats GetPeakStats() const;

 private:
  struct Peak;
  struct Current;
  template <typename Tag> struct TaggedStats : ArenaAllocatorStats { };
  struct StatsAndPool : TaggedStats<Peak>, TaggedStats<Current> {
    explicit StatsAndPool(ArenaPool* arena_pool) : pool(arena_pool) { }
    ArenaPool* const pool;
  };

  ArenaAllocatorStats* PeakStats() {
    return static_cast<TaggedStats<Peak>*>(&stats_and_pool_);
  }

  ArenaAllocatorStats* CurrentStats() {
    return static_cast<TaggedStats<Current>*>(&stats_and_pool_);
  }

  // Private - access via ScopedArenaAllocator or ScopedArenaAllocatorAdapter.
  void* Alloc(size_t bytes, ArenaAllocKind kind) ALWAYS_INLINE {
    if (UNLIKELY(running_on_valgrind_)) {
      return AllocValgrind(bytes, kind);
    }
    size_t rounded_bytes = RoundUp(bytes, 8);
    uint8_t* ptr = top_ptr_;
    if (UNLIKELY(static_cast<size_t>(top_end_ - ptr) < rounded_bytes)) {
      ptr = AllocateFromNextArena(rounded_bytes);
    }
    CurrentStats()->RecordAlloc(bytes, kind);
    top_ptr_ = ptr + rounded_bytes;
    return ptr;
  }

  uint8_t* AllocateFromNextArena(size_t rounded_bytes);
  void UpdatePeakStatsAndRestore(const ArenaAllocatorStats& restore_stats);
  void UpdateBytesAllocated();
  void* AllocValgrind(size_t bytes, ArenaAllocKind kind);

  StatsAndPool stats_and_pool_;
  Arena* bottom_arena_;
  Arena* top_arena_;
  uint8_t* top_ptr_;
  uint8_t* top_end_;

  const bool running_on_valgrind_;

  friend class ScopedArenaAllocator;
  template <typename T>
  friend class ScopedArenaAllocatorAdapter;

  DISALLOW_COPY_AND_ASSIGN(ArenaStack);
};

class ScopedArenaAllocator
    : private DebugStackReference, private DebugStackRefCounter, private ArenaAllocatorStats {
 public:
  // Create a ScopedArenaAllocator directly on the ArenaStack when the scope of
  // the allocator is not exactly a C++ block scope. For example, an optimization
  // pass can create the scoped allocator in Start() and destroy it in End().
  static ScopedArenaAllocator* Create(ArenaStack* arena_stack) {
    void* addr = arena_stack->Alloc(sizeof(ScopedArenaAllocator), kArenaAllocMisc);
    ScopedArenaAllocator* allocator = new(addr) ScopedArenaAllocator(arena_stack);
    allocator->mark_ptr_ = reinterpret_cast<uint8_t*>(addr);
    return allocator;
  }

  explicit ScopedArenaAllocator(ArenaStack* arena_stack);
  ~ScopedArenaAllocator();

  void Reset();

  void* Alloc(size_t bytes, ArenaAllocKind kind) ALWAYS_INLINE {
    DebugStackReference::CheckTop();
    return arena_stack_->Alloc(bytes, kind);
  }

  // ScopedArenaAllocatorAdapter is incomplete here, we need to define this later.
  ScopedArenaAllocatorAdapter<void> Adapter();

  // Allow a delete-expression to destroy but not deallocate allocators created by Create().
  static void operator delete(void* ptr) { UNUSED(ptr); }

 private:
  ArenaStack* const arena_stack_;
  Arena* mark_arena_;
  uint8_t* mark_ptr_;
  uint8_t* mark_end_;

  template <typename T>
  friend class ScopedArenaAllocatorAdapter;

  DISALLOW_COPY_AND_ASSIGN(ScopedArenaAllocator);
};

template <>
class ScopedArenaAllocatorAdapter<void>
    : private DebugStackReference, private DebugStackIndirectTopRef {
 public:
  typedef void value_type;
  typedef void* pointer;
  typedef const void* const_pointer;

  template <typename U>
  struct rebind {
    typedef ScopedArenaAllocatorAdapter<U> other;
  };

  explicit ScopedArenaAllocatorAdapter(ScopedArenaAllocator* arena_allocator)
      : DebugStackReference(arena_allocator),
        DebugStackIndirectTopRef(arena_allocator),
        arena_stack_(arena_allocator->arena_stack_) {
  }
  template <typename U>
  ScopedArenaAllocatorAdapter(const ScopedArenaAllocatorAdapter<U>& other)
      : DebugStackReference(other),
        DebugStackIndirectTopRef(other),
        arena_stack_(other.arena_stack_) {
  }
  ScopedArenaAllocatorAdapter(const ScopedArenaAllocatorAdapter& other) = default;
  ScopedArenaAllocatorAdapter& operator=(const ScopedArenaAllocatorAdapter& other) = default;
  ~ScopedArenaAllocatorAdapter() = default;

 private:
  ArenaStack* arena_stack_;

  template <typename U>
  friend class ScopedArenaAllocatorAdapter;
};

// Adapter for use of ScopedArenaAllocator in STL containers.
template <typename T>
class ScopedArenaAllocatorAdapter : private DebugStackReference, private DebugStackIndirectTopRef {
 public:
  typedef T value_type;
  typedef T* pointer;
  typedef T& reference;
  typedef const T* const_pointer;
  typedef const T& const_reference;
  typedef size_t size_type;
  typedef ptrdiff_t difference_type;

  template <typename U>
  struct rebind {
    typedef ScopedArenaAllocatorAdapter<U> other;
  };

  explicit ScopedArenaAllocatorAdapter(ScopedArenaAllocator* arena_allocator)
      : DebugStackReference(arena_allocator),
        DebugStackIndirectTopRef(arena_allocator),
        arena_stack_(arena_allocator->arena_stack_) {
  }
  template <typename U>
  ScopedArenaAllocatorAdapter(const ScopedArenaAllocatorAdapter<U>& other)
      : DebugStackReference(other),
        DebugStackIndirectTopRef(other),
        arena_stack_(other.arena_stack_) {
  }
  ScopedArenaAllocatorAdapter(const ScopedArenaAllocatorAdapter& other) = default;
  ScopedArenaAllocatorAdapter& operator=(const ScopedArenaAllocatorAdapter& other) = default;
  ~ScopedArenaAllocatorAdapter() = default;

  size_type max_size() const {
    return static_cast<size_type>(-1) / sizeof(T);
  }

  pointer address(reference x) const { return &x; }
  const_pointer address(const_reference x) const { return &x; }

  pointer allocate(size_type n, ScopedArenaAllocatorAdapter<void>::pointer hint = nullptr) {
    DCHECK_LE(n, max_size());
    DebugStackIndirectTopRef::CheckTop();
    return reinterpret_cast<T*>(arena_stack_->Alloc(n * sizeof(T), kArenaAllocSTL));
  }
  void deallocate(pointer p, size_type n) {
    DebugStackIndirectTopRef::CheckTop();
  }

  void construct(pointer p, const_reference val) {
    // Don't CheckTop(), allow reusing existing capacity of a vector/deque below the top.
    new (static_cast<void*>(p)) value_type(val);
  }
  void destroy(pointer p) {
    // Don't CheckTop(), allow reusing existing capacity of a vector/deque below the top.
    p->~value_type();
  }

 private:
  ArenaStack* arena_stack_;

  template <typename U>
  friend class ScopedArenaAllocatorAdapter;

  template <typename U>
  friend bool operator==(const ScopedArenaAllocatorAdapter<U>& lhs,
                         const ScopedArenaAllocatorAdapter<U>& rhs);
};

template <typename T>
inline bool operator==(const ScopedArenaAllocatorAdapter<T>& lhs,
                       const ScopedArenaAllocatorAdapter<T>& rhs) {
  return lhs.arena_stack_ == rhs.arena_stack_;
}

template <typename T>
inline bool operator!=(const ScopedArenaAllocatorAdapter<T>& lhs,
                       const ScopedArenaAllocatorAdapter<T>& rhs) {
  return !(lhs == rhs);
}

inline ScopedArenaAllocatorAdapter<void> ScopedArenaAllocator::Adapter() {
  return ScopedArenaAllocatorAdapter<void>(this);
}

}  // namespace art

#endif  // ART_COMPILER_UTILS_SCOPED_ARENA_ALLOCATOR_H_