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// Copyright 2017 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#ifndef BASE_NUMERICS_SAFE_MATH_CLANG_GCC_IMPL_H_
#define BASE_NUMERICS_SAFE_MATH_CLANG_GCC_IMPL_H_
#include <cassert>
#include <limits>
#include <type_traits>
#include "base/numerics/safe_conversions.h"
#if !defined(__native_client__) && (defined(__ARMEL__) || defined(__arch64__))
#include "base/numerics/safe_math_arm_impl.h"
#define BASE_HAS_ASSEMBLER_SAFE_MATH (1)
#else
#define BASE_HAS_ASSEMBLER_SAFE_MATH (0)
#endif
namespace base {
namespace internal {
// These are the non-functioning boilerplate implementations of the optimized
// safe math routines.
#if !BASE_HAS_ASSEMBLER_SAFE_MATH
template <typename T, typename U>
struct CheckedMulFastAsmOp {
static const bool is_supported = false;
template <typename V>
static constexpr bool Do(T, U, V*) {
// Force a compile failure if instantiated.
return CheckOnFailure::template HandleFailure<bool>();
}
};
template <typename T, typename U>
struct ClampedAddFastAsmOp {
static const bool is_supported = false;
template <typename V>
static constexpr V Do(T, U) {
// Force a compile failure if instantiated.
return CheckOnFailure::template HandleFailure<V>();
}
};
template <typename T, typename U>
struct ClampedSubFastAsmOp {
static const bool is_supported = false;
template <typename V>
static constexpr V Do(T, U) {
// Force a compile failure if instantiated.
return CheckOnFailure::template HandleFailure<V>();
}
};
template <typename T, typename U>
struct ClampedMulFastAsmOp {
static const bool is_supported = false;
template <typename V>
static constexpr V Do(T, U) {
// Force a compile failure if instantiated.
return CheckOnFailure::template HandleFailure<V>();
}
};
#endif // BASE_HAS_ASSEMBLER_SAFE_MATH
#undef BASE_HAS_ASSEMBLER_SAFE_MATH
template <typename T, typename U>
struct CheckedAddFastOp {
static const bool is_supported = true;
template <typename V>
__attribute__((always_inline)) static constexpr bool Do(T x, U y, V* result) {
return !__builtin_add_overflow(x, y, result);
}
};
template <typename T, typename U>
struct CheckedSubFastOp {
static const bool is_supported = true;
template <typename V>
__attribute__((always_inline)) static constexpr bool Do(T x, U y, V* result) {
return !__builtin_sub_overflow(x, y, result);
}
};
template <typename T, typename U>
struct CheckedMulFastOp {
#if defined(__clang__)
// TODO(jschuh): Get the Clang runtime library issues sorted out so we can
// support full-width, mixed-sign multiply builtins.
// https://crbug.com/613003
// We can support intptr_t, uintptr_t, or a smaller common type.
static const bool is_supported =
(IsTypeInRangeForNumericType<intptr_t, T>::value &&
IsTypeInRangeForNumericType<intptr_t, U>::value) ||
(IsTypeInRangeForNumericType<uintptr_t, T>::value &&
IsTypeInRangeForNumericType<uintptr_t, U>::value);
#else
static const bool is_supported = true;
#endif
template <typename V>
__attribute__((always_inline)) static constexpr bool Do(T x, U y, V* result) {
return CheckedMulFastAsmOp<T, U>::is_supported
? CheckedMulFastAsmOp<T, U>::Do(x, y, result)
: !__builtin_mul_overflow(x, y, result);
}
};
template <typename T, typename U>
struct ClampedAddFastOp {
static const bool is_supported = ClampedAddFastAsmOp<T, U>::is_supported;
template <typename V>
__attribute__((always_inline)) static V Do(T x, U y) {
return ClampedAddFastAsmOp<T, U>::template Do<V>(x, y);
}
};
template <typename T, typename U>
struct ClampedSubFastOp {
static const bool is_supported = ClampedSubFastAsmOp<T, U>::is_supported;
template <typename V>
__attribute__((always_inline)) static V Do(T x, U y) {
return ClampedSubFastAsmOp<T, U>::template Do<V>(x, y);
}
};
template <typename T, typename U>
struct ClampedMulFastOp {
static const bool is_supported = ClampedMulFastAsmOp<T, U>::is_supported;
template <typename V>
__attribute__((always_inline)) static V Do(T x, U y) {
return ClampedMulFastAsmOp<T, U>::template Do<V>(x, y);
}
};
template <typename T>
struct ClampedNegFastOp {
static const bool is_supported = std::is_signed<T>::value;
__attribute__((always_inline)) static T Do(T value) {
// Use this when there is no assembler path available.
if (!ClampedSubFastAsmOp<T, T>::is_supported) {
T result;
return !__builtin_sub_overflow(T(0), value, &result)
? result
: std::numeric_limits<T>::max();
}
// Fallback to the normal subtraction path.
return ClampedSubFastOp<T, T>::template Do<T>(T(0), value);
}
};
} // namespace internal
} // namespace base
#endif // BASE_NUMERICS_SAFE_MATH_CLANG_GCC_IMPL_H_
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