Unreachable.hpp

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/* Copyright 2022 Jan Stephan, Jeffrey Kelling
 * SPDX-License-Identifier: MPL-2.0
 */
 
#pragma once
 
#include "alpaka/core/config.hpp"
 
//! Before CUDA 11.5 nvcc is unable to correctly identify return statements in 'if constexpr' branches. It will issue
//! a false warning about a missing return statement unless it is told that the following code section is unreachable.
//!
//! \param x A dummy value for the expected return type of the calling function.
#if (ALPAKA_COMP_NVCC && ALPAKA_ARCH_PTX)
#    if ALPAKA_LANG_CUDA >= ALPAKA_VERSION_NUMBER(11, 3, 0)
#        define ALPAKA_UNREACHABLE(...) __builtin_unreachable()
#    else
#        define ALPAKA_UNREACHABLE(...) return __VA_ARGS__
#    endif
#elif ALPAKA_COMP_MSVC
#    define ALPAKA_UNREACHABLE(...) __assume(false)
#elif ALPAKA_COMP_GNUC || ALPAKA_COMP_CLANG
#    define ALPAKA_UNREACHABLE(...) __builtin_unreachable()
#else
#    define ALPAKA_UNREACHABLE(...)
#endif