A method and apparatus for power reduction in a processor controlled by
multiple-instruction control words. A multiple-instruction control word
comprises a number of ordered fields, with each ordered field containing
an instruction for an element of the processor. The sequence of
instructions for a loop is compressed by identifying a set of aligned
fields that contain NOP instructions in all of the control words of the
sequence. The sequence of control words is then modified by removing the
fields of the identified aligned set containing NOP instructions and
adding an identifier that identifies the set of fields removed. The
sequence of control words is processed by fetching the identifier at the
start the loop, then, for each control word in the sequence, fetching a
control word and reconstructing the corresponding uncompressed control
word by inserting NOP instructions into the compressed control word as
indicated by the identifier. The identifier may be a bit mask and may
used to disable memory units and processing elements for the duration of
the loop to reduce power consumption by the processor.