System and method for jump-evaluated trace designation

摘要

A computer-implemented system and method are provided to designate traces of original instructions of an executable file at run time based on evaluations of control flow through jump instructions. Such designation typically increases the opportunities for dynamic optimization based on loop unrolling and other modifications of the control-flow structure of the executable file. The target of a jump instruction is designated as the start of a trace if the number of times that control has passed to it through any one or more jump instructions of a predetermined type of jump instruction reaches a predetermined start-trace threshold. The trace is ended if the number of times that control has passed through jump instructions of one of a variety of particular types of jump instructions reaches an end-trace threshold that is predetermined for each such type of jump instruction. The invention includes an instruction emulator, a start-end designator, a trace translator and optimizer, and a backpatch manager. The instruction emulator emulates original instructions that have not been translated. The start-end designator designates the start and end of traces. The trace translator and optimizer translates and optimizes traces designated by the start-end designator. The backpatch manager backpatches jump instructions in translated instructions so that they jump to target instructions that have been translated, when present.