rocm-systems/projects/rocshmem/src/ipc_policy.hpp

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#ifndef LIBRARY_SRC_IPC_POLICY_HPP_
#define LIBRARY_SRC_IPC_POLICY_HPP_

#include <hip/hip_runtime.h>
#include <mpi.h>

#include <atomic>
#include <vector>

#include "config.h"  // NOLINT(build/include_subdir)
#include "memory/hip_allocator.hpp"
#include "util.hpp"

namespace rocshmem {

class Backend;
class Context;

class IpcOnImpl {
  using HEAP_BASES_T = std::vector<char *, StdAllocatorHIP<char *>>;

 public:
  uint32_t shm_size{0};

  char **ipc_bases{nullptr};

  __host__ void ipcHostInit(int my_pe, const HEAP_BASES_T &heap_bases,
                            MPI_Comm thread_comm);

  __device__ bool isIpcAvailable(int my_pe, int target_pe) {
    return my_pe / shm_size == target_pe / shm_size;
  }
  __device__ void ipcGpuInit(Backend *gpu_backend, Context *ctx, int thread_id);

  __device__ void ipcCopy(void *dst, void *src, size_t size);

  __device__ void ipcCopy_wg(void *dst, void *src, size_t size);

  __device__ void ipcCopy_wave(void *dst, void *src, size_t size);

  __device__ void ipcFence() { __threadfence(); }

  template <typename T>
  __device__ T ipcAMOFetchAdd(T *val, T value) {
    return __hip_atomic_fetch_add(val, value, __ATOMIC_RELAXED,
                                  __HIP_MEMORY_SCOPE_AGENT);
  }

  template <typename T>
  __device__ T ipcAMOFetchCas(T *val, T cond, T value) {
    __hip_atomic_compare_exchange_strong(val, &cond, value, __ATOMIC_RELAXED,
                                         __ATOMIC_RELAXED,
                                         __HIP_MEMORY_SCOPE_AGENT);
    return cond;
  }

  template <typename T>
  __device__ void ipcAMOAdd(T *val, T value) {
    __hip_atomic_fetch_add(val, value, __ATOMIC_RELAXED,
                           __HIP_MEMORY_SCOPE_AGENT);
  }

  template <typename T>
  __device__ void ipcAMOCas(T *val, T cond, T value) {
    __hip_atomic_compare_exchange_strong(val, &cond, value, __ATOMIC_RELAXED,
                                         __ATOMIC_RELAXED,
                                         __HIP_MEMORY_SCOPE_AGENT);
  }

  template <typename T>
  __device__ void ipcAMOSet(T *val, T value) {
    __hip_atomic_store(val, value, __ATOMIC_RELAXED, __HIP_MEMORY_SCOPE_AGENT);
  }

  __device__ void zero_byte_read(int pe) {
    int local_pe = pe % shm_size;
    uint32_t *pe_ipc_base = reinterpret_cast<uint32_t *>(ipc_bases[local_pe]);
    volatile uint32_t read_value = __hip_atomic_load(
        pe_ipc_base, __ATOMIC_SEQ_CST, __HIP_MEMORY_SCOPE_SYSTEM);
  }
};

// clang-format off
NOWARN(-Wunused-parameter,
class IpcOffImpl {
  using HEAP_BASES_T = std::vector<char *, StdAllocatorHIP<char *>>;

 public:
  uint32_t shm_size{0};

  char **ipc_bases{nullptr};

  __host__ void ipcHostInit(int my_pe, const HEAP_BASES_T &heap_bases,
                            MPI_Comm thread_comm) {}

  __device__ bool isIpcAvailable(int my_pe, int target_pe) { return false; }

  __device__ void ipcGpuInit(Backend *roc_shmem_handle, Context *ctx,
                             int thread_id) {}

  __device__ void ipcCopy(void *dst, void *src, size_t size) {}

  __device__ void ipcCopy_wg(void *dst, void *src, size_t size) {}

  __device__ void ipcCopy_wave(void *dst, void *src, size_t size) {}

  __device__ void ipcFence() {}

  template <typename T>
  __device__ T ipcAMOFetchAdd(T *val, T value) {
    return T();
  }

  template <typename T>
  __device__ T ipcAMOFetchCas(T *val, T cond, T value) {
    return T();
  }

  template <typename T>
  __device__ void ipcAMOAdd(T *val, T value) {}

  template <typename T>
  __device__ void ipcAMOSet(T *val, T value) {}

  template <typename T>
  __device__ void ipcAMOCas(T *val, T cond, T value) {}

  __device__ void zero_byte_read(int pe) {}
};
)
// clang-format on

/*
 * Select which one of our IPC policies to use at compile time.
 */
#ifdef USE_IPC
typedef IpcOnImpl IpcImpl;
#else
typedef IpcOffImpl IpcImpl;
#endif

}  // namespace rocshmem

#endif  // LIBRARY_SRC_IPC_POLICY_HPP_