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36 #ifndef GMX_GPU_UTILS_SYCL_KERNEL_UTILS_H
37 #define GMX_GPU_UTILS_SYCL_KERNEL_UTILS_H
42 * \brief SYCL kernel helper functions.
44 * \author Andrey Alekseenko <al42and@gmail.com>
47 /*! \brief Access mode to use for atomic accessors.
49 * Intel DPCPP compiler has \c sycl::atomic_ref, but has no \c sycl::atomic_fetch_add for floats.
50 * However, \c atomic_ref can not be constructed from \c sycl::atomic, so we can not use
51 * atomic accessors. Thus, we use \c mode::read_write accessors and \c atomic_ref.
53 * hipSYCL does not have \c sycl::atomic_ref, but has \c sycl::atomic_fetch_add for floats, which
54 * requires using atomic accessors. Thus, we use \c mode::atomic accessors.
56 * The \ref atomicFetchAdd function could be used for doing operations on such accessors.
58 static constexpr auto mode_atomic = GMX_SYCL_DPCPP ? cl::sycl::access::mode::read_write :
59 /* GMX_SYCL_HIPSYCL */ cl::sycl::access::mode::atomic;
61 /*! \brief Convenience wrapper to do atomic addition to a global buffer.
63 * Skips sub-normal values.
65 * The implementation differences between DPCPP and hipSYCL are explained in \ref mode_atomic.
67 template<class IndexType>
68 static inline void atomicFetchAdd(DeviceAccessor<float, mode_atomic> acc, const IndexType idx, const float val)
71 sycl_2020::atomic_ref<float, sycl_2020::memory_order::relaxed, sycl_2020::memory_scope::device, cl::sycl::access::address_space::global_space>
72 fout_atomic(acc[idx]);
73 fout_atomic.fetch_add(val);
74 #elif GMX_SYCL_HIPSYCL
75 # ifdef SYCL_DEVICE_ONLY
76 /* While there is support for float atomics on device, the host implementation uses
77 * Clang's __atomic_fetch_add intrinsic, that, at least in Clang 11, does not support
78 * floats. Luckily, we don't want to run on host. */
79 acc[idx].fetch_add(val);
81 GMX_ASSERT(false, "hipSYCL host codepath not supported");
82 GMX_UNUSED_VALUE(val);
83 GMX_UNUSED_VALUE(acc);
84 GMX_UNUSED_VALUE(idx);
92 __device__ static inline float shift_left(sycl_2020::sub_group, float var, sycl_2020::sub_group::linear_id_type delta)
94 // No sycl::sub_group::shift_left / shuffle_down in hipSYCL yet
95 # ifdef SYCL_DEVICE_ONLY
96 # if defined(HIPSYCL_PLATFORM_CUDA) && defined(__HIPSYCL_ENABLE_CUDA_TARGET__)
97 static const unsigned int sc_cudaFullWarpMask = 0xffffffff;
98 return __shfl_down_sync(sc_cudaFullWarpMask, var, delta);
99 # elif defined(HIPSYCL_PLATFORM_ROCM) && defined(__HIPSYCL_ENABLE_HIP_TARGET__)
100 // Do we need more ifdefs? https://github.com/ROCm-Developer-Tools/HIP/issues/1491
101 return __shfl_down(var, delta);
103 # error "Unsupported hipSYCL target"
106 // Should never be called
107 GMX_UNUSED_VALUE(var);
108 GMX_UNUSED_VALUE(delta);
113 __host__ static inline float shift_left(sycl_2020::sub_group, float, sycl_2020::sub_group::linear_id_type)
115 // Should never be called
120 static inline float shift_left(sycl_2020::sub_group sg, float var, sycl_2020::sub_group::linear_id_type delta)
122 return sg.shuffle_down(var, delta);
127 __device__ static inline float shift_right(sycl_2020::sub_group,
129 sycl_2020::sub_group::linear_id_type delta)
131 // No sycl::sub_group::shift_right / shuffle_up in hipSYCL yet
132 # ifdef SYCL_DEVICE_ONLY
133 # if defined(HIPSYCL_PLATFORM_CUDA) && defined(__HIPSYCL_ENABLE_CUDA_TARGET__)
134 static const unsigned int sc_cudaFullWarpMask = 0xffffffff;
135 return __shfl_up_sync(sc_cudaFullWarpMask, var, delta);
136 # elif defined(HIPSYCL_PLATFORM_ROCM) && defined(__HIPSYCL_ENABLE_HIP_TARGET__)
137 // Do we need more ifdefs? https://github.com/ROCm-Developer-Tools/HIP/issues/1491
138 return __shfl_up(var, delta);
140 # error "Unsupported hipSYCL target"
143 // Should never be called
145 GMX_UNUSED_VALUE(var);
146 GMX_UNUSED_VALUE(delta);
150 __host__ static inline float shift_right(sycl_2020::sub_group, float, sycl_2020::sub_group::linear_id_type)
152 // Should never be called
157 static inline float shift_right(sycl_2020::sub_group sg, float var, sycl_2020::sub_group::linear_id_type delta)
159 return sg.shuffle_up(var, delta);
162 } // namespace sycl_2020
164 #endif /* GMX_GPU_UTILS_SYCL_KERNEL_UTILS_H */