Eligibility for Parallelizing

An MP taskloop pragma suggests to the compiler that, unless otherwise disallowed, the specified for loop should be parallelized.

For loops with irregular control flow and unknown loop iteration increment are not eligible for parallelization. For example, for loops containing setjmp, longjmp, exit, abort, return, goto, labels, and break should not be considered as candidates for parallelization.

Of particular importance is to note that for loops with inter-iteration dependencies can be eligible for explicit parallelization. This means that if a MP taskloop pragma is specified for such a loop the compiler will simply honor it, unless the for loop is disqualified. It is the user's responsibility to make sure that such explicit parallelization will not lead to incorrect results.

If both the serial_loop or serial_loop_nested and taskloop pragmas are specified for a for loop, the last one specified will prevail.

Consider the following example:

The i loop will not be parallelized but the j loop might be.