Work-in-Progress: Register File Management for PRET Machines

PREcision Timed (PRET) machines often use multithreading to achieve high CPU resources utilisation and time-determinism. Multithreading enables sharing most of the pipeline resources between threads, except the register file (RF), which is used to store thread context. Traditional multithreading on PRET machines uses large RF. We propose a register file management (RFM) technique suitable for multithreaded PRET machines, reducing the RF size. Our RFM has software-controlled RF partitions for each thread with support for runtime repartitioning. We evaluate the design on the PRET uRISC processor with a 55% average reduction of FPGA resource utilisation and show performance tradeoff on a selection of TACLeBench benchmarks.