DevTools: Move to Userland/DevTools/

Userland/DevTools/UserspaceEmulator/ValueWithShadow.h

@@ -0,0 +1,171 @@
+/*
+ * Copyright (c) 2020, Andreas Kling <kling@serenityos.org>
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright notice, this
+ *    list of conditions and the following disclaimer.
+ *
+ * 2. Redistributions in binary form must reproduce the above copyright notice,
+ *    this list of conditions and the following disclaimer in the documentation
+ *    and/or other materials provided with the distribution.
+ *
+ * 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 HOLDER OR CONTRIBUTORS BE LIABLE
+ * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
+ * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
+ * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
+ * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#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());
+    }
+};