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execute as NDRange kernels if using a newer version of the Altera Offline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