SizeLimits.cpp

/*
 * Copyright (C) 2010 Google Inc. All rights reserved.
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 * modification, are permitted provided that the following conditions are
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 * in the documentation and/or other materials provided with the
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 * this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
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 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
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#include "wtf/Assertions.h"
#include "wtf/ContainerAnnotations.h"
#include "wtf/PassRefPtr.h"
#include "wtf/RefCounted.h"
#include "wtf/RefPtr.h"
#include "wtf/ThreadRestrictionVerifier.h"
#include "wtf/Vector.h"
#include "wtf/text/AtomicString.h"
#include "wtf/text/WTFString.h"
#include <memory>

namespace WTF {

#if DCHECK_IS_ON() || ENABLE(SECURITY_ASSERT)
// The debug/assertion version may get bigger.
struct SameSizeAsRefCounted {
  int a;
#if ENABLE(SECURITY_ASSERT)
  bool b;
#endif
#if DCHECK_IS_ON()
  bool c;
  ThreadRestrictionVerifier d;
#endif
};
#else
struct SameSizeAsRefCounted {
  int a;
  // Don't add anything here because this should stay small.
};
#endif
template <typename T, unsigned inlineCapacity = 0>
struct SameSizeAsVectorWithInlineCapacity;

template <typename T>
struct SameSizeAsVectorWithInlineCapacity<T, 0> {
  void* bufferPointer;
  unsigned capacity;
  unsigned size;
};

template <typename T, unsigned inlineCapacity>
struct SameSizeAsVectorWithInlineCapacity {
  SameSizeAsVectorWithInlineCapacity<T, 0> baseCapacity;
#if !defined(ANNOTATE_CONTIGUOUS_CONTAINER)
  AlignedBuffer<inlineCapacity * sizeof(T), WTF_ALIGN_OF(T)> inlineBuffer;
#endif
};

static_assert(sizeof(std::unique_ptr<int>) == sizeof(int*),
              "std::unique_ptr should stay small");
static_assert(sizeof(PassRefPtr<RefCounted<int>>) == sizeof(int*),
              "PassRefPtr should stay small");
static_assert(sizeof(RefCounted<int>) == sizeof(SameSizeAsRefCounted),
              "RefCounted should stay small");
static_assert(sizeof(RefPtr<RefCounted<int>>) == sizeof(int*),
              "RefPtr should stay small");
static_assert(sizeof(String) == sizeof(int*), "String should stay small");
static_assert(sizeof(AtomicString) == sizeof(String),
              "AtomicString should stay small");
static_assert(sizeof(Vector<int>) ==
                  sizeof(SameSizeAsVectorWithInlineCapacity<int>),
              "Vector should stay small");
static_assert(sizeof(Vector<int, 1>) ==
                  sizeof(SameSizeAsVectorWithInlineCapacity<int, 1>),
              "Vector should stay small");
static_assert(sizeof(Vector<int, 2>) ==
                  sizeof(SameSizeAsVectorWithInlineCapacity<int, 2>),
              "Vector should stay small");
static_assert(sizeof(Vector<int, 3>) ==
                  sizeof(SameSizeAsVectorWithInlineCapacity<int, 3>),
              "Vector should stay small");
}  // namespace WTF