sycl::nd_item#
template <int Dimensions = 1>
class nd_item;
The sycl::nd_item class identifies an instance of the function object
executing at each point in an sycl::nd_range<int Dimensions>
passed to a parallel_for call. It encapsulates enough
information to identify the work-item's local and global ids,
the work-group id and also provides access to the sycl::group
and sycl::sub_group classes. Instances of the
sycl::nd_item<int Dimensions> class are not user-constructible
and are passed by the runtime to each instance of the function object.
See also
SYCL Specification Section 4.9.1.5
Member functions#
get_global_id#
sycl::id<Dimensions> get_global_id() const;
Return the constituent global id representing the work-item’s position in the global iteration space.
size_t get_global_id(int dimension) const;
Return the constituent element of the global id representing
the work-item’s position in the sycl::nd_range in the given
dimension.
get_global_linear_id#
size_t get_global_linear_id() const;
Return the constituent global id as a linear index value, representing the work-item’s position in the global iteration space. The linear address is calculated from the multi-dimensional index by first subtracting the offset and then following SYCL Specification Section 3.11.1.
get_local_id#
sycl::id<Dimensions> get_local_id() const;
Return the constituent local id representing the work-item’s position within the current work-group.
size_t get_local_id(int dimension) const;
Return the constituent element of the local id representing the
work-item’s position within the current
work-group in the given dimension.
get_local_linear_id#
size_t get_local_linear_id() const;
Return the constituent local id as a linear index value, representing the work-item’s position within the current work-group. The linear address is calculated from the multi-dimensional index following SYCL Specification Section 3.11.1.
get_group#
sycl::group<Dimensions> get_group() const;
Return the constituent work-group, group representing the work-group's
position within the overall nd-range.
size_t get_group(int dimension) const;
Return the constituent element of the group sycl::id representing
the work-group’s position within the overall sycl::nd_range in
the given dimension.
get_sub_group#
sycl::sub_group get_sub_group() const;
Return a sycl::sub_group representing the sub-group
to which the work-item belongs.
get_group_linear_id#
size_t get_group_linear_id() const;
Return the group id as a linear index value. Calculating a linear address from a multi-dimensional index follows SYCL Specification Section 3.11.1.
get_group_range#
sycl::range<Dimensions> get_group_range() const;
Returns the number of work-groups in the iteration space.
size_t get_group_range(int dimension) const;
Return the number of work-groups for dimension in
the iteration space.
get_global_range#
sycl::range<Dimensions> get_global_range() const;
Returns a sycl::range representing the dimensions
of the global iteration space.
size_t get_global_range(int dimension) const;
Return the same value as get_global_range().get(dimension).
get_local_range#
sycl::range<Dimensions> get_local_range() const;
Returns a sycl::range representing the dimensions
of the current work-group.
size_t get_local_range(int dimension) const;
Return the same value as get_local_range().get(dimension).
get_offset#
sycl::id<Dimensions> get_offset() const;
// Deprecated in SYCL 2020.
Deprecated in SYCL 2020.
Returns an id representing the n-dimensional offset
provided to the constructor of the sycl::nd_range
and that is added by the runtime to the global id of
each work-item.
get_nd_range#
sycl::nd_range<Dimensions> get_nd_range() const;
Returns the sycl::nd_range of the current execution.
async_work_group_copy#
template <typename DataT>
sycl::device_event async_work_group_copy(sycl::local_ptr<DataT> dest,
sycl::global_ptr<DataT> src,
size_t numElements) const;
template <typename DataT>
sycl::device_event async_work_group_copy(sycl::global_ptr<DataT> dest,
sycl::local_ptr<DataT> src,
size_t numElements) const;
template <typename DataT>
sycl::device_event async_work_group_copy(sycl::local_ptr<DataT> dest,
sycl::global_ptr<DataT> src,
size_t numElements, size_t srcStride) const;
template <typename DataT>
sycl::device_event async_work_group_copy(sycl::global_ptr<DataT> dest,
sycl::local_ptr<DataT> src,
size_t numElements, size_t destStride) const;
All four async_work_group_copy functions listed above are deprecated
in SYCL 2020. Has the same effect as the overload taking
sycl::decorated_local_ptr and sycl::decorated_global_ptr
except that the dest and src parameters are
sycl::multi_ptr with sycl::access::decorated::legacy.
template <typename DestDataT, typename SrcDataT>
sycl::device_event async_work_group_copy(sycl::decorated_global_ptr<DestDataT> dest,
sycl::decorated_local_ptr<SrcDataT> src,
size_t numElements) const;
template <typename DestDataT, typename SrcDataT>
sycl::device_event async_work_group_copy(sycl::decorated_local_ptr<DestDataT> dest,
sycl::decorated_global_ptr<SrcDataT> src,
size_t numElements, size_t srcStride) const;
template <typename DestDataT, SrcDataT>
sycl::device_event async_work_group_copy(sycl::decorated_global_ptr<DestDataT> dest,
sycl::decorated_local_ptr<SrcDataT> src,
size_t numElements, size_t destStride) const;
All three functions above are available only when:
(std::is_same_v<DestDataT, std::remove_const_t<SrcDataT>> == true)
Permitted types for DataT are all scalar and vector types.
Asynchronously copies a number of elements specified by
numElements from the source pointer src to destination pointer
dest with a destination stride specified by destStride
and returns a sycl::device_event which can be used to wait
on the completion of the copy.
wait_for#
template <typename... EventTN> void wait_for(EventTN... events) const;
Permitted type for EventTN is sycl::device_event. Waits for the
asynchronous operations associated with each
sycl::device_event to complete.