Microsoft Corporation
REUSING FETCHED, FLUSHED INSTRUCTIONS AFTER AN INSTRUCTION PIPELINE FLUSH IN RESPONSE TO A HAZARD IN A PROCESSOR TO REDUCE INSTRUCTION RE-FETCHING

Abstract:

Reusing fetched, flushed instructions after an instruction pipeline flush in response to a hazard in a processor to reduce instruction re-fetching is disclosed. An instruction processing circuit is configured to detect fetched performance degrading instructions (PDIs) in a pre-execution stage in an instruction pipeline that may cause a precise interrupt that would cause flushing of the instruction pipeline. In response to detecting a PDI in an instruction pipeline, the instruction processing circuit is configured to capture the fetched PDI and/or its successor, younger fetched instructions that are processed in the instruction pipeline behind the PDI, in a pipeline refill circuit. If a later execution of the PDI in the instruction pipeline causes a flush of the instruction pipeline, the instruction processing circuit can inject the fetched PDI and/or its younger instructions previously captured from the pipeline refill circuit into the instruction pipeline to be processed without such instructions being re-fetched.