llvm/clang-tools-extra/docs/clang-tidy/checks/altera/id-dependent-backward-branch.rst

.. title:: clang-tidy - altera-id-dependent-backward-branch

altera-id-dependent-backward-branch
===================================

Finds ID-dependent variables and fields that are used within loops. This causes
branches to occur inside the loops, and thus leads to performance degradation.

.. code-block:: c++

  // The following code will produce a warning because this ID-dependent
  // variable is used in a loop condition statement.
  int ThreadID = get_local_id(0);

  // The following loop will produce a warning because the loop condition
  // statement depends on an ID-dependent variable.
  for (int i = 0; i < ThreadID; ++i) {
    std::cout << i << std::endl;
  }

  // The following loop will not produce a warning, because the ID-dependent
  // variable is not used in the loop condition statement.
  for (int i = 0; i < 100; ++i) {
    std::cout << ThreadID << std::endl;
  }

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>`_.