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/*
* Copyright (c) 2020, Andreas Kling <kling@serenityos.org>
*
* SPDX-License-Identifier: BSD-2-Clause
*/
#include <AK/Format.h>
#include <AK/Platform.h>
#pragma once
namespace UserspaceEmulator {
template<typename T>
class ValueAndShadowReference;
template<typename T>
class ValueWithShadow {
public:
using ValueType = T;
ValueWithShadow(T value, T shadow)
: m_value(value)
, m_shadow(shadow)
{
}
ValueWithShadow(const ValueAndShadowReference<T>&);
T value() const { return m_value; }
T shadow() const { return m_shadow; }
bool is_uninitialized() const
{
if constexpr (sizeof(T) == 4)
return (m_shadow & 0x01010101) != 0x01010101;
if constexpr (sizeof(T) == 2)
return (m_shadow & 0x0101) != 0x0101;
if constexpr (sizeof(T) == 1)
return (m_shadow & 0x01) != 0x01;
}
void set_initialized()
{
if constexpr (sizeof(T) == 4)
m_shadow = 0x01010101;
if constexpr (sizeof(T) == 2)
m_shadow = 0x0101;
if constexpr (sizeof(T) == 1)
m_shadow = 0x01;
}
private:
T m_value;
T m_shadow;
};
template<typename T>
class ValueAndShadowReference {
public:
using ValueType = T;
ValueAndShadowReference(T& value, T& shadow)
: m_value(value)
, m_shadow(shadow)
{
}
bool is_uninitialized() const
{
if constexpr (sizeof(T) == 4)
return (m_shadow & 0x01010101) != 0x01010101;
if constexpr (sizeof(T) == 2)
return (m_shadow & 0x0101) != 0x0101;
if constexpr (sizeof(T) == 1)
return (m_shadow & 0x01) != 0x01;
}
void operator=(const ValueWithShadow<T>&);
T& value() { return m_value; }
T& shadow() { return m_shadow; }
const T& value() const { return m_value; }
const T& shadow() const { return m_shadow; }
private:
T& m_value;
T& m_shadow;
};
template<typename T>
ALWAYS_INLINE ValueWithShadow<T> shadow_wrap_as_initialized(T value)
{
if constexpr (sizeof(T) == 8)
return { value, 0x01010101'01010101LLU };
if constexpr (sizeof(T) == 4)
return { value, 0x01010101 };
if constexpr (sizeof(T) == 2)
return { value, 0x0101 };
if constexpr (sizeof(T) == 1)
return { value, 0x01 };
}
template<typename T, typename U>
ALWAYS_INLINE ValueWithShadow<T> shadow_wrap_with_taint_from(T value, const U& taint_a)
{
if (taint_a.is_uninitialized())
return { value, 0 };
return shadow_wrap_as_initialized(value);
}
template<typename T, typename U, typename V>
ALWAYS_INLINE ValueWithShadow<T> shadow_wrap_with_taint_from(T value, const U& taint_a, const V& taint_b)
{
if (taint_a.is_uninitialized() || taint_b.is_uninitialized())
return { value, 0 };
return shadow_wrap_as_initialized(value);
}
template<typename T, typename U, typename V, typename X>
ALWAYS_INLINE ValueWithShadow<T> shadow_wrap_with_taint_from(T value, const U& taint_a, const V& taint_b, const X& taint_c)
{
if (taint_a.is_uninitialized() || taint_b.is_uninitialized() || taint_c.is_uninitialized())
return { value, 0 };
return shadow_wrap_as_initialized(value);
}
template<typename T>
inline ValueWithShadow<T>::ValueWithShadow(const ValueAndShadowReference<T>& other)
: m_value(other.value())
, m_shadow(other.shadow())
{
}
template<typename T>
inline void ValueAndShadowReference<T>::operator=(const ValueWithShadow<T>& other)
{
m_value = other.value();
m_shadow = other.shadow();
}
}
template<typename T>
struct AK::Formatter<UserspaceEmulator::ValueWithShadow<T>> : AK::Formatter<T> {
void format(FormatBuilder& builder, UserspaceEmulator::ValueWithShadow<T> value)
{
return Formatter<T>::format(builder, value.value());
}
};
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