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ios/include/math/compiler.h

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+/*
+ * 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.
+ */
+
+#pragma once
+
+#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 {
+namespace 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> {
+};
+
+}
+}