System and method using partial trap barrier instruction to provide trap barrier class-based selective stall of instruction processing pipeline

摘要

A new “partial trap barrier” instruction can be inserted in an instruction stream to cut off trap shadows of instructions of a respective one of a plurality of particular classes associated with each instruction. Several criteria may be used to assign instructions to trap barrier classes, including (i) explicit encoding of a trap barrier value which is contained in the respective instructions; (ii) resource(s) of the processor which is or are used in their execution, and (iii) where the instructions are located in the instruction stream in relation to the partial trap barrier instructions in the instruction stream. When the processor executes a partial trap barrier instruction in a particular class, while an earlier instruction in the same class is casting its trap shadow, the processor will stall the pipeline in connection with an instruction of the same class after the partial trap barrier instruction in the pipeline, as well as instructions in the instruction stream subsequent thereto. When the earlier instruction's trap shadow terminates, the processor can resume processing of the stalled and subsequent instructions. However, if no instruction in the instruction stream enters the pipeline prior to termination of the earlier instruction's trap shadow, the pipeline will not stall.