graphics/graphics-path/src/main/cpp/math/compiler.h

/*
 * Copyright (C) 2017 The Android Open Source Project
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

#ifndef PATH_MATH_COMPILER_H
#define PATH_MATH_COMPILER_H

#include <type_traits>

#if defined (WIN32)

#ifdef max
#undef max
#endif

#ifdef min
#undef min
#endif

#ifdef far
#undef far
#endif

#ifdef near
#undef near
#endif

#endif

// compatibility with non-clang compilers...
#ifndef __has_attribute
#define __has_attribute(x) 0
#endif
#ifndef __has_builtin
#define __has_builtin(x) 0
#endif

#if __has_builtin(__builtin_expect)
#   ifdef __cplusplus
#      define MATH_LIKELY( exp )    (__builtin_expect( !!(exp), true ))
#      define MATH_UNLIKELY( exp )  (__builtin_expect( !!(exp), false ))
#   else
#      define MATH_LIKELY( exp )    (__builtin_expect( !!(exp), 1 ))
#      define MATH_UNLIKELY( exp )  (__builtin_expect( !!(exp), 0 ))
#   endif
#else
#   define MATH_LIKELY( exp )    (exp)
#   define MATH_UNLIKELY( exp )  (exp)
#endif

#if __has_attribute(unused)
#   define MATH_UNUSED __attribute__((unused))
#else
#   define MATH_UNUSED
#endif

#if __has_attribute(pure)
#   define MATH_PURE __attribute__((pure))
#else
#   define MATH_PURE
#endif

#ifdef _MSC_VER
#   define MATH_EMPTY_BASES __declspec(empty_bases)

// MSVC does not support loop unrolling hints
#   define MATH_NOUNROLL

// Sadly, MSVC does not support __builtin_constant_p
#   ifndef MAKE_CONSTEXPR
#       define MAKE_CONSTEXPR(e) (e)
#   endif

// About value initialization, the C++ standard says:
//   if T is a class type with a default constructor that is neither user-provided nor deleted
//   (that is, it may be a class with an implicitly-defined or defaulted default constructor),
//   the object is zero-initialized and then it is default-initialized
//   if it has a non-trivial default constructor;
// Unfortunately, MSVC always calls the default constructor, even if it is trivial, which
// breaks constexpr-ness. To workaround this, we're always zero-initializing TVecN<>
#   define MATH_CONSTEXPR_INIT {}
#   define MATH_DEFAULT_CTOR {}
#   define MATH_DEFAULT_CTOR_CONSTEXPR constexpr
#   define CONSTEXPR_IF_NOT_MSVC // when declared constexpr, msvc fails with
                                 // "failure was caused by cast of object of dynamic type"

#else // _MSC_VER

#   define MATH_EMPTY_BASES
// C++11 allows pragmas to be specified as part of defines using the _Pragma syntax.
#   define MATH_NOUNROLL _Pragma("nounroll")

#   ifndef MAKE_CONSTEXPR
#       define MAKE_CONSTEXPR(e) __builtin_constant_p(e) ? (e) : (e)
#   endif

#   define MATH_CONSTEXPR_INIT
#   define MATH_DEFAULT_CTOR = default;
#   define MATH_DEFAULT_CTOR_CONSTEXPR
#   define CONSTEXPR_IF_NOT_MSVC constexpr

#endif // _MSC_VER

namespace filament::math {

// MSVC 2019 16.4 doesn't seem to like it when we specialize std::is_arithmetic for
// filament::math::half, so we're forced to create our own is_arithmetic here and specialize it
// inside of half.h.
template<typename T>
struct is_arithmetic : std::integral_constant<bool,
        std::is_integral<T>::value || std::is_floating_point<T>::value> {
};

} // filament::math

#endif // PATH_MATH_COMPILER_H