EFFICIENT WAY TO RESET SPECULATIVE SOURCE READY IN SCHEDULER FOR DIRECT AND NESTED DEPENDENT INSTRUCTIONS

摘要

The present invention relates to an apparatus and a method to cancel instructions and reset a source-ready state. According to an embodiment of the present invention, a method to process a plurality of instructions comprises the steps of: speculatively waking up a source of a dependent instruction by a producer instruction of the dependent instruction; speculatively waking up, by the dependent instruction, a source of a nested dependent instruction depending on the dependent instruction; setting a source ready bit of the source of the dependent instruction, and setting a source ready bit of the source of the nested dependent instruction to indicate that the source of the dependent instruction and the source of the nested dependent instruction are ready for access; setting a cancel timer of the source of the dependent instruction and setting a cancel timer of the source of the nested dependent instruction based on a cancel time at which a cancel is expected to be asserted for the producer instruction, wherein the cancel timers start to count down when the source ready bits are set; and simultaneously canceling the dependent instruction and the nested dependent instruction if the cancel timer of the source of the dependent instruction and the cancel timer of the source of the nested dependent instruction expire and the producer instruction is canceled. According to an embodiment of the present invention, it is possible to enable a simple structure and save power and time.