Tracing speculatively executed instructions

摘要

A trace unit for generating items of trace data indicative of processing activities of a processor executing a stream of instructions, the stream of instructions comprising a plurality of groups of instructions, the processor executing at least some of the instructions speculatively is disclosed. The trace unit comprises: trace circuitry for monitoring a behaviour of the processor; storage circuitry for storing current trace control data for controlling the trace circuitry; a data store for storing at least some of the trace control data; the trace circuitry being configured to store the trace control data in the data store in response to detection of execution of the group of instructions; the trace circuitry being responsive to detecting the at least one processor cancelling at least one group of the speculatively executed instructions to retrieve at least some of the trace control data stored in the data store for the group of instructions executed before the cancelled speculatively executed instructions and to store the retrieved trace control data in the storage circuitry.