A loop remainder mask instruction indicates a current iteration count of a loop as a first operand, an iteration limit of a loop as a second operand, and a destination. The loop contains iterations and each iteration includes a data element of the array. A processor receives the loop remainder mask instruction, decodes the instruction for execution, and stores a result of the execution in the destination. The result indicates a number of data elements of the array past an end of a preceding portion of the array that are to be handled separately from the preceding portion, the end of the preceding portion being where the current iteration count is recorded.