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.. title:: clang-tidy - altera-single-work-item-barrier
altera-single-work-item-barrier
===============================
Finds OpenCL kernel functions that call a barrier function but do not call
an ID function (``get_local_id``, ``get_local_id``, ``get_group_id``, or
``get_local_linear_id``).
These kernels may be viable single work-item kernels, but will be forced to
execute as NDRange kernels if using a newer version of the Altera Offline
Compiler (>= v17.01).
If using an older version of the Altera Offline Compiler, these kernel
functions will be treated as single work-item kernels, which could be
inefficient or lead to errors if NDRange semantics were intended.
Based on the `Altera SDK for OpenCL: Best Practices Guide
<https://www.altera.com/en_US/pdfs/literature/hb/opencl-sdk/aocl_optimization_guide.pdf>`_.
Examples:
.. code-block:: c++
// error: function calls barrier but does not call an ID function.
void __kernel barrier_no_id(__global int * foo, int size) {
for (int i = 0; i < 100; i++) {
foo[i] += 5;
}
barrier(CLK_GLOBAL_MEM_FENCE);
}
// ok: function calls barrier and an ID function.
void __kernel barrier_with_id(__global int * foo, int size) {
for (int i = 0; i < 100; i++) {
int tid = get_global_id(0);
foo[tid] += 5;
}
barrier(CLK_GLOBAL_MEM_FENCE);
}
// ok with AOC Version 17.01: the reqd_work_group_size turns this into
// an NDRange.
__attribute__((reqd_work_group_size(2,2,2)))
void __kernel barrier_with_id(__global int * foo, int size) {
for (int i = 0; i < 100; i++) {
foo[tid] += 5;
}
barrier(CLK_GLOBAL_MEM_FENCE);
}
Options
-------
.. option:: AOCVersion
Defines the version of the Altera Offline Compiler. Defaults to ``1600``
(corresponding to version 16.00).
|
