void PopulateDefaultStreamExecutor(SP_StreamExecutor* se) {
  *se = {SP_STREAMEXECUTOR_STRUCT_SIZE};
  se->allocate = Allocate;
  se->deallocate = Deallocate;
  se->host_memory_allocate = HostMemoryAllocate;
  se->host_memory_deallocate = HostMemoryDeallocate;
  se->get_allocator_stats = GetAllocatorStats;
  se->device_memory_usage = DeviceMemoryUsage;
  se->create_stream = CreateStream;
  se->destroy_stream = DestroyStream;

  TF_VALIDATE_NOT_NULL(SP_StreamExecutor, se, deallocate);
  TF_VALIDATE_NOT_NULL(SP_StreamExecutor, se, get_allocator_stats);
  TF_VALIDATE_NOT_NULL(SP_StreamExecutor, se, host_memory_allocate);
  TF_VALIDATE_NOT_NULL(SP_StreamExecutor, se, host_memory_deallocate);
  if (platform.supports_unified_memory) {
    TF_VALIDATE_NOT_NULL(SP_StreamExecutor, se, unified_memory_allocate);

  // Memory allocated in this manner is required for use in asynchronous memcpy
  // operations, such as `memcpy_dtoh`.
  void* (*host_memory_allocate)(const SP_Device* device, uint64_t size);

  // Deallocates a region of host memory allocated by `host_memory_allocate`.
  void (*host_memory_deallocate)(const SP_Device* device, void* mem);

  // Allocates unified memory space of the given size, if supported. Unified

TEST_F(StreamExecutorTest, HostMemoryAllocate) {
  static bool allocate_called = false;
  static bool deallocate_called = false;
  se_.host_memory_allocate = [](const SP_Device* const device, uint64_t size) {
    allocate_called = true;
    return malloc(size);
  };
  se_.host_memory_deallocate = [](const SP_Device* const device, void* mem) {
    free(mem);
    deallocate_called = true;
  };