Abstract: A data processing apparatus is provided having a hierarchy of layers comprising at least two data processing layers, each data processing layer configured to receive data and to generate processed data for passing to a next lower layer in said hierarchy, according to a protocol specific to that data processing layer. Each data processing layer is configured intermittently to add synchronization information to its processed data, the synchronization information providing semantic information required to interpret the processed data. Each data processing layer is further configured to output its synchronization information in response to a synchronization request signal received from a lower layer in said hierarchy, and at least one data processing layer is configured, when outputting its synchronization information, to issue its synchronization request signal to a higher layer in the hierarchy.

Abstract: A data processing apparatus is disclosed that comprises monitoring circuitry for monitoring accesses to a plurality of addressable locations within said data processing apparatus that occur between start and end events said monitoring circuitry comprising: an address location store for storing data identifying said plurality of addressable locations to be monitored and a monitoring data store; said monitoring circuitry being responsive to detection of said start event to detect accesses to said plurality of addressable locations and to store monitoring data relating to a summary of said detected accesses in said monitoring data store; and said monitoring circuitry being responsive to detection of said end event to stop collecting said monitoring data; said monitoring circuit being responsive to detection of a flush event to output said stored monitoring data and to flush said monitoring data store.

Abstract: An integrated circuit 2 is provided with a data source 6 in the form of a processor executing program instructions connected via a bus interconnect 16 to a trace output device 8. The trace output device 8 is memory mapped. Different memory addresses that are mapped to the trace output device 8 are associated with different priority levels. Trace data written to at least one memory address has a first level of priority in which it is either accepted or the transfer is stalled until the data can be processed by the trace output device 8. Another level of priority associated with a different memory address is such that the data is always accepted but is discarded if the trace output device 8 does not have the ability to process, e.g. store that data at that time.

Abstract: A data processing apparatus is provided having a hierarchy of layers comprising at least two data processing layers, each data processing layer configured to receive data and to generate processed data for passing to a next lower layer in said hierarchy, according to a protocol specific to that data processing layer. Each data processing layer is configured intermittently to add synchronization information to its processed data, the synchronization information providing semantic information required to interpret the processed data. Each data processing layer is further configured to output its synchronization information in response to a synchronization request signal received from a lower layer in said hierarchy, and at least one data processing layer is configured, when outputting its synchronization information, to issue its synchronization request signal to a higher layer in the hierarchy.

Abstract: An integrated circuit 2 is provided with a data source 6 in the form of a processor executing program instructions connected via a bus interconnect 16 to a trace output device 8. The trace output device 8 is memory mapped. Different memory addresses that are mapped to the trace output device 8 are associated with different priority levels. Trace data written to at least one memory address has a first level of priority in which it is either accepted or the transfer is stalled until the data can be processed by the trace output device 8. Another level of priority associated with a different memory address is such that the data is always accepted but is discarded if the trace output device 8 does not have the ability to process, e.g. store that data at that time.

Abstract: An asymmetric multiprocessor apparatus 2 is provided in which respective slave diagnostic units 20, 22, 24 are associated with corresponding execution mechanisms 6, 8, 10. A master diagnostic unit 26 tracks the migration of thread execution between the different execution mechanisms 6, 8, 10 so that the execution of a given thread can be followed by the diagnostic mechanisms 20, 22, 24, 26 and this information provided to the programmer. The execution mechanisms 6, 8, 10 can be diverse such as a general purpose processor 6, a DMA unit 12, a coprocessor, an VLIW processor, a digital signal processor 8 and a hardware accelerator 10. The asymmetric multiprocessor apparatus 2 will also typically include an asymmetric memory hierarchy such as including two or more of a global memory, a shared memory 16, a private memory 18 and a cache memory 14.

Abstract: A method of compiling a computer program to improve trace efficiency is disclosed. The computer program comprises a plurality of trace operations for triggering output of trace data generated by said computer program, and the method of compiling comprises the steps of: transforming said computer program into code forming an intermediate version of said computer program; analysing said transformed code; replacing at least some of said trace operations with modified trace operations; transforming said code into code suitable for execution on a data processing system; and generating translation data relating said modified trace operations to said trace operations they replaced.

Abstract: A data processing apparatus is disclosed that comprises monitoring circuitry for monitoring accesses to a plurality of addressable locations within said data processing apparatus that occur between start and end events said monitoring circuitry comprising: an address location store for storing data identifying said plurality of addressable locations to be monitored and a monitoring data store; said monitoring circuitry being responsive to detection of said start event to detect accesses to said plurality of addressable locations and to store monitoring data relating to a summary of said detected accesses in said monitoring data store; and said monitoring circuitry being responsive to detection of said end event to stop collecting said monitoring data; said monitoring circuit being responsive to detection of a flush event to output said stored monitoring data and to flush said monitoring data store.

Abstract: A data processing apparatus is provided comprising a memory, memory management unit and identification circuitry for identifying a predetermined type of data access transaction within a plurality of received data access transactions. The memory management unit is responsive to the predetermined type of data access transaction to both permit completion of a data access and to cause an exception to be raised despite completion of the data access having been permitted.

Abstract: A diagnostic method is described for generating diagnostic data relating to processing of an instruction stream, wherein said instruction stream has been compiled from a source instruction stream to include multiple threads, said method comprising the steps of: (i) initiating a diagnostic procedure in which at least a portion of said instruction stream is executed; (ii) controlling a scheduling order for executing instructions within said at least a portion of said instruction stream to cause execution of a sequence of thread portions, said sequence being determined in response to one or more rules, at least one of said rules defining an order of execution of said thread portions to follow an order of said source instruction stream. In this way, the diagnostic method can generate a debug view of a parallelised program which is the same as, or at least similar to, a debug view which would be provided when debugging the original non-parallelised program.

Abstract: A diagnostic method for outputting diagnostic data relating to processing of instruction streams stemming from a computer program, at least some of said instructions streams comprising multiple threads is disclosed. The method comprises the steps of: (i) receiving diagnostic data; (ii) reordering said received diagnostic data in dependence upon reordering data, said reordering data comprising data relating to said computer program; and (iii) outputting said reordered diagnostic data. In general, the instructions streams are processed by a plurality of processing units arranged to process at least some of said instructions in parallel, said diagnostic data being received from said plurality of processing units.

Abstract: An asymmetric multiprocessor apparatus 2 is provided in which respective slave diagnostic units 20, 22, 24 are associated with corresponding execution mechanisms 6, 8, 10. A master diagnostic unit 26 tracks the migration of thread execution between the different execution mechanisms 6, 8, 10 so that the execution of a given thread can be followed by the diagnostic mechanisms 20, 22, 24, 26 and this information provided to the programmer. The execution mechanisms 6, 8, 10 can be diverse such as a general purpose processor 6, a DMA unit 12, a coprocessor, an VLIW processor, a digital signal processor 8 and a hardware accelerator 10. The asymmetric multiprocessor apparatus 2 will also typically include an asymmetric memory hierarchy such as including two or more of a global memory, a shared memory 16, a private memory 18 and a cache memory 14.