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.

// 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.