A result forwarding mechanism for asynchronous pipelined systems

Modern, fast microprocessors are deeply pipelined to enhance their performance. Thus they cannot afford to wait for each instruction to complete before starting the next. When inter-instruction dependencies are encountered it is essential that data are forwarded from their point of production to where they are needed as rapidly as possible. This has been a problem in asynchronous processors because of the lack of synchronisation between the units producing and consuming the data. This paper presents a solution to this problem. The mechanism described allows the depth of speculative execution to be increased, improving memory efficiency by hiding the load latency yet still allowing precise exceptions.