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Miku AuahDark
97 lines
2.3 KiB
C++
97 lines
2.3 KiB
C++
#ifndef OPTHELPERS_H
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#define OPTHELPERS_H
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#include <cstdint>
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#include <utility>
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#include <memory>
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#ifdef __has_builtin
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#define HAS_BUILTIN __has_builtin
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#else
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#define HAS_BUILTIN(x) (0)
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#endif
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#ifdef __has_cpp_attribute
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#define HAS_ATTRIBUTE __has_cpp_attribute
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#else
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#define HAS_ATTRIBUTE(x) (0)
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#endif
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#ifdef __GNUC__
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#define force_inline [[gnu::always_inline]] inline
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#define NOINLINE [[gnu::noinline]]
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#elif defined(_MSC_VER)
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#define force_inline __forceinline
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#define NOINLINE __declspec(noinline)
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#else
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#define force_inline inline
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#define NOINLINE
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#endif
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/* Unlike the likely attribute, ASSUME requires the condition to be true or
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* else it invokes undefined behavior. It's essentially an assert without
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* actually checking the condition at run-time, allowing for stronger
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* optimizations than the likely attribute.
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*/
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#if HAS_BUILTIN(__builtin_assume)
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#define ASSUME __builtin_assume
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#elif defined(_MSC_VER)
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#define ASSUME __assume
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#elif __has_attribute(assume)
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#define ASSUME(x) [[assume(x)]]
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#elif HAS_BUILTIN(__builtin_unreachable)
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#define ASSUME(x) do { if(x) break; __builtin_unreachable(); } while(0)
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#else
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#define ASSUME(x) (static_cast<void>(0))
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#endif
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/* This shouldn't be needed since unknown attributes are ignored, but older
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* versions of GCC choke on the attribute syntax in certain situations.
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*/
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#if HAS_ATTRIBUTE(likely)
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#define LIKELY [[likely]]
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#define UNLIKELY [[unlikely]]
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#else
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#define LIKELY
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#define UNLIKELY
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#endif
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namespace al {
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template<typename T>
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constexpr std::underlying_type_t<T> to_underlying(T e) noexcept
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{ return static_cast<std::underlying_type_t<T>>(e); }
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[[noreturn]] inline void unreachable()
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{
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#if HAS_BUILTIN(__builtin_unreachable)
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__builtin_unreachable();
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#else
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ASSUME(false);
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#endif
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}
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template<std::size_t alignment, typename T>
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force_inline constexpr auto assume_aligned(T *ptr) noexcept
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{
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#ifdef __cpp_lib_assume_aligned
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return std::assume_aligned<alignment,T>(ptr);
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#elif HAS_BUILTIN(__builtin_assume_aligned)
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return static_cast<T*>(__builtin_assume_aligned(ptr, alignment));
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#elif defined(_MSC_VER)
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constexpr std::size_t alignment_mask{(1<<alignment) - 1};
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if((reinterpret_cast<std::uintptr_t>(ptr)&alignment_mask) == 0)
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return ptr;
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__assume(0);
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#elif defined(__ICC)
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__assume_aligned(ptr, alignment);
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return ptr;
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#else
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return ptr;
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#endif
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}
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} // namespace al
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#endif /* OPTHELPERS_H */
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