Abstract: One embodiment of the present invention provides a system that performs register file checkpointing to support speculative execution within a processor. During operation, the system commences speculative execution of a program from a point of speculation, at which the outcome of a long latency instruction is speculatively predicted. During this speculative execution, registers are updated by checkpointing an old value of the register, if the register has not already been checkpointed, and then updating the architectural state of the register with the new value. In this way, only registers that are updated during the speculative execution are checkpointed, instead of checkpointing all of the architectural registers prior to commencing speculative execution.

Abstract: One embodiment of the present invention provides a system that dynamically allocates physical registers in a windowed processor architecture. The system includes a physical register file and a register map that maps architectural registers defined within an executing program to physical registers within the physical register file. The system also includes a window allocation mechanism that allocates a new name space for a register window without allocating physical registers for the register window, thereby allowing the physical registers to be dynamically allocated as needed instead of being allocated at window initialization time.