Abstract: A compiling method compiles an object program to be executed by a processor having a plurality of execution units operable in parallel. In the method a first availability chain is created from a producer instruction (p1), scheduled for execution by a first one of the execution units (20: AGU), to a first consumer instruction (c1), scheduled for execution by a second one of the execution units (22: EXU) and requiring a value produced by the said producer instruction. The first availability chain comprises at least one move instruction (mv1-mv3) for moving the required value from a first point (20: ARF) accessible by the first execution unit to a second point (22: DRF) accessible by the second execution unit.