// Protocol Buffers - Google's data interchange format

// Copyright 2008 Google Inc.  All rights reserved.

// https://developers.google.com/protocol-buffers/

//

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// 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.

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// in the documentation and/or other materials provided with the

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// 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

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// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT

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// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

// This file provides alignment utilities for use in arenas.

//

// `ArenaAlign` contains a single `align` data member and provides

// the below functions which operate on the given alignment.

//

//   Ceil(size_t n)      - rounds `n` up to the nearest `align` boundary.

//   Floor(size_t n)     - rounds `n` down to the nearest `align` boundary.

//   Padded(size_t n)    - returns the unaligned size to align 'n' bytes. (1)

//   Ceil(T* P)          - rounds `p` up to the nearest `align` boundary. (2)

//   IsAligned(size_t n) - returns true if `n` is aligned to `align`

//   IsAligned(T* p)     - returns true if `p` is aligned to `align`

//   CheckAligned(T* p)  - returns `p`. Checks alignment of `p` in debug.

//

// 1) `Padded(n)` returns the minimum size needed to align an object of size 'n'

//    into a memory area that is default aligned. For example, allocating 'n'

//    bytes aligned at 32 bytes requires a size of 'n + 32 - 8' to align at 32

//    bytes for any 8 byte boundary.

//

// 2) There is an optimized `CeilDefaultAligned(T*)` method which is equivalent

//    to `Ceil(ArenaAlignDefault::CheckAlign(p))` but more efficiently

//    implemented as a 'check only' for ArenaAlignDefault.

//

// These classes allow for generic arena logic using 'alignment policies'.

//

// For example:

//

//  template <Align>

//  void* NaiveAlloc(size_t n, Align align) {

//    ABSL_ASSERT(align.IsAligned(n));

//    const size_t required = align.Padded(n);

//    if (required <= static_cast<size_t>(ptr_ - limit_)) {

//      uint8_t* ptr = align.CeilDefaultAligned(ptr_);

//      ptr_ = ptr + n;

//      return ptr;

//    }

//    return nullptr;

//  }

//

//  void CallSites() {

//    void *p1 = NaiveAlloc(n, ArenaAlignDefault());

//    void *p2 = NaiveAlloc(n, ArenaAlignAs(32));

//  }

//

#ifndef GOOGLE_PROTOBUF_ARENA_ALIGN_H__

#define GOOGLE_PROTOBUF_ARENA_ALIGN_H__

#include <cstddef>

#include <cstdint>

#include "absl/log/absl_check.h"

#include "absl/numeric/bits.h"

// Must be included last.

#include "google/protobuf/port_def.inc"

namespace google {

namespace protobuf {

namespace internal {

struct ArenaAlignDefault {

  PROTOBUF_EXPORT static constexpr size_t align = 8;  // NOLINT

  static constexpr bool IsAligned(size_t n) { return (n & (align - 1)) == 0U; }

  template <typename T>

  static inline PROTOBUF_ALWAYS_INLINE bool IsAligned(T* ptr) {

    return (reinterpret_cast<uintptr_t>(ptr) & (align - 1)) == 0U;

  }

Unexecuted instantiation: bool google::protobuf::internal::ArenaAlignDefault::IsAligned<void>(void*)

Unexecuted instantiation: bool google::protobuf::internal::ArenaAlignDefault::IsAligned<char>(char*)

  static inline PROTOBUF_ALWAYS_INLINE constexpr size_t Ceil(size_t n) {

    return (n + align - 1) & -align;

  }

  static inline PROTOBUF_ALWAYS_INLINE constexpr size_t Floor(size_t n) {

    return (n & ~(align - 1));

  }

  static inline PROTOBUF_ALWAYS_INLINE size_t Padded(size_t n) {

    ABSL_ASSERT(IsAligned(n));

    return n;

  }

  template <typename T>

  static inline PROTOBUF_ALWAYS_INLINE T* Ceil(T* ptr) {

    uintptr_t intptr = reinterpret_cast<uintptr_t>(ptr);

    return reinterpret_cast<T*>((intptr + align - 1) & -align);

  }

  template <typename T>

  static inline PROTOBUF_ALWAYS_INLINE T* CeilDefaultAligned(T* ptr) {

    ABSL_ASSERT(IsAligned(ptr));

    return ptr;

  }

  // Address sanitizer enabled alignment check

  template <typename T>

  static inline PROTOBUF_ALWAYS_INLINE T* CheckAligned(T* ptr) {

    ABSL_ASSERT(IsAligned(ptr));

    return ptr;

  }

};

struct ArenaAlign {

  static constexpr bool IsDefault() { return false; };

  size_t align;

  constexpr bool IsAligned(size_t n) const { return (n & (align - 1)) == 0U; }

  template <typename T>

  bool IsAligned(T* ptr) const {

    return (reinterpret_cast<uintptr_t>(ptr) & (align - 1)) == 0U;

  }

  constexpr size_t Ceil(size_t n) const { return (n + align - 1) & -align; }

  constexpr size_t Floor(size_t n) const { return (n & ~(align - 1)); }

  constexpr size_t Padded(size_t n) const {

    // TODO(mvels): there are direct callers of AllocateAligned() that violate

    // `size` being a multiple of `align`: that should be an error / assert.

    //  ABSL_ASSERT(IsAligned(n));

    ABSL_ASSERT(ArenaAlignDefault::IsAligned(align));

    return n + align - ArenaAlignDefault::align;

  }

  template <typename T>

  T* Ceil(T* ptr) const {

    uintptr_t intptr = reinterpret_cast<uintptr_t>(ptr);

    return reinterpret_cast<T*>((intptr + align - 1) & -align);

  }

Unexecuted instantiation: char* google::protobuf::internal::ArenaAlign::Ceil<char>(char*) const

Unexecuted instantiation: void* google::protobuf::internal::ArenaAlign::Ceil<void>(void*) const

  template <typename T>

  T* CeilDefaultAligned(T* ptr) const {

    ABSL_ASSERT(ArenaAlignDefault::IsAligned(ptr));

    return Ceil(ptr);

  }

Unexecuted instantiation: void* google::protobuf::internal::ArenaAlign::CeilDefaultAligned<void>(void*) const

Unexecuted instantiation: char* google::protobuf::internal::ArenaAlign::CeilDefaultAligned<char>(char*) const

  // Address sanitizer enabled alignment check

  template <typename T>

  T* CheckAligned(T* ptr) const {

    ABSL_ASSERT(IsAligned(ptr));

    return ptr;

  }

};

inline ArenaAlign ArenaAlignAs(size_t align) {

  // align must be a non zero power of 2 >= 8

  ABSL_DCHECK_NE(align, 0U);

  ABSL_DCHECK(absl::has_single_bit(align)) << "Invalid alignment " << align;

  return ArenaAlign{align};

}

template <bool, size_t align>

struct AlignFactory {

  static_assert(align > ArenaAlignDefault::align, "Not over-aligned");

  static_assert((align & (align - 1)) == 0U, "Not power of 2");

  static constexpr ArenaAlign Create() { return ArenaAlign{align}; }

};

template <size_t align>

struct AlignFactory<true, align> {

  static_assert(align <= ArenaAlignDefault::align, "Over-aligned");

  static_assert((align & (align - 1)) == 0U, "Not power of 2");

  static constexpr ArenaAlignDefault Create() { return ArenaAlignDefault{}; }

};

// Returns an `ArenaAlignDefault` instance for `align` less than or equal to the

// default alignment, and `AlignAs(align)` for over-aligned values of `align`.

// The purpose is to take advantage of invoking functions accepting a template

// overloaded 'Align align` argument reducing the alignment operations on

// `ArenaAlignDefault` implementations to no-ops.

template <size_t align>

inline constexpr auto ArenaAlignAs() {

  return AlignFactory<align <= ArenaAlignDefault::align, align>::Create();

}

// Returns ArenaAlignAs<alignof(T)>

template <typename T>

inline constexpr auto ArenaAlignOf() {

  return ArenaAlignAs<alignof(T)>();

}

}  // namespace internal

}  // namespace protobuf

}  // namespace google

#include "google/protobuf/port_undef.inc"

#endif  // GOOGLE_PROTOBUF_ARENA_ALIGN_H__