FACILITATING RAPID PROGRESS WHILE SPECULATIVELY EXECUTING CODE IN SCOUT MODE

摘要

A processor that facilitates rapid progress while speculatively executing instructions in scout mode. During normal operation, the processor executes instructions in a normal execution mode. Upon encountering a stall condition, the processor executes the instructions in a scout mode, wherein the instructions are speculatively executed to prefetch future loads, but wherein results are not committed to the architectural state of the processor. While speculatively executing the instructions in scout mode, the processor maintains dependency information for each register indicating whether or not a value in the register depends on an unresolved data-dependency. If an instruction to be executed in scout mode depends on an unresolved data dependency, the processor executes the instruction as a NOOP so that the instruction executes rapidly without tying up computational resources. The processor also propagates dependency information indicating an unresolved data dependency to a destination register for the instruction.