The invention provides a method of processing a sequence of operands to produce compiled code for a target data processor, the method comprising the steps of: automatically analysing a source code to produce a fist representation of that code in single static assignment form; transforming the first representation into a second representation by unlooping Φ nodes within the single static assignment form so as to create code suitable for tree pattern matching to be performed thereon; performing tree pattern matching on the second representation of the code; and re-looping the Φ nodes.