Instruction scheduling

The compiler phase that orders instructions on a pipelined, superscalar, or VLIW architecture so as to maximise the number of function units operating in parallel and to minimise the time they spend waiting for each other.
Examples are filling a delay slot; interspersing floating-point instructions with integer instructions to keep both units operating; making adjacent instructions independent, e.g. one which writes a register and another which reads from it; separating memory writes to avoid filling the write buffer.
Norman P. Jouppi and David W. Wall, “Available Instruction-Level Parallelism for Superscalar and Superpipelined Processors” (, Proceedings of the Third International Conference on Architectural Support for Programming Languages and Operating Systems, pp. 272–282, 1989.
[The SPARC Architecture Manual, v8, ISBN 0-13-825001-4]


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