According to one embodiment of the invention, an apparatus is provided which includes a first register to hold an initial value of a first index associated with a looping instruction to be executed for a number of iterations, a second register to hold an initial value of a second index associated with the respective looping instruction, and a third register to hold data indicating non-linear variation pattern associated with the second index. For each iteration, actual increment of the first index and actual increment of the second index are set based on a target increment and the data indicating the non-linear variation pattern associated with the second index.