A method and apparatus for generating an optimized intermediate representation of source code for a computer program are described. An initial intermediate representation is extracted from the source code by organizing it as a plurality of basic blocks that each contain at least one program instruction ordered according to respective estimated profit values. A goal function that measures the degree of optimization of the program is calculated in accordance with its intermediate representation. The effect on the goal function of modifying the intermediate representation by moving an instruction from one of the basic blocks to each of its predecessors is tested iteratively and adopting the modified intermediate representation if it causes a reduction in the goal function.