Stmicroelectronics S.a.

Stmicroelectronics Gmbh

Isabelle Sename

Andrew Cofler

Laurent Wojcieszak

Renaud Ayrignac

Bruno Bernard

Arnaud Dehamel

Stephane Bouvier

The disclosure relates to a method for executing by a processor an instruction for saving/restoring several internal registers of the processor. The method comprises breaking down the saving/restoring instruction to generate micro-instructions for saving/restoring the content of a register, executing each of the micro-instructions, initializing a progress status of the saving/restoration of the registers, updating the progress status of the saving/restoration upon each generation of a micro-instruction for saving/restoring a register, saving the progress status in the event of an interruption in the saving/restoration of the registers to execute a higher-priority task, and restoring the progress status when the saving/restoration of the registers is resumed.

Method and device for saving and restoring a set of registers of a microprocessor in an interruptible manner

A method for debugging a multitask program executed by a processor includes interrupting the processor during the execution of a task of the program, and activating a debugging mode of the processor, wherein the instructions executed by the processor are supplied by an external emulator. The method comprises steps during which: the processor sends an activation message to the external emulator every time the debugging mode is activated, and upon receiving the activation message, the external emulator sends an acknowledgement message to the processor containing at least one portion of the activation message received.

Method and device for debugging a program executed by a multitask processor

A computer system with enhanced integrated debug facilities is described. According to one aspect, step-by-step execution of an instruction sequence is implemented where each instruction is guarded. If, after guard resolution, the instruction is committed, a divert routine is executed. If the instruction is not committed, the next instruction in the sequence is executed. According to another aspect, a stall state can be set at the decode unit either by reading stall attributes associated with debug instructions, or responsive to a stall command from an on-chip emulation unit.

Computer system with a debug facility for a pipelined processor using predicated execution

A computer system is provided with precise and non-precise watch modes. The computer system is a pipelined system in which the fate of an instruction is determined at the decode stage. Once instructions have been decoded, it is not possible for them to be 'killed' later in the pipeline. According to the precise watch mode, instructions are held at the decode stage until the guard value has been resolved to determine whether or not that instruction is committed. Actions of the decode unit are determined in dependence on whether or not the instruction is committed when the guard has been resolved. According to a non-precise watch mode, instructions continue to be decoded and executed normally until a breakpoint instruction has had its guard resolved. At that point, an on-chip emulator can take over operations of the processor in a divert mode. The computer system can take into account different intrusion levels while implementing the watch modes.

Computer system with two debug watch modes for controlling execution of guarded instructions upon breakpoint detection

A computer system for executing instructions having assigned guard indicators, comprises instruction supply circuitry, pipelined execution units for receiving instructions from the supply circuitry together with at least one guard indicator selected from a set of guard indicators, the execution unit including a master guard value store containing master values for the guard indicators, and circuitry for resolving the guard values in the execution pipeline and providing a signal to indicate whether the pipeline is committed to the execution of the instruction, and an emulator having watch circuitry for effecting a watch on selected instructions supplied to the execution pipeline and synchronising circuitry for correlating resolution of the guard indicator of each selected instruction with a program count for that instruction.

Computer system with debug facility

A computer system includes instruction fetch circuitry, decode circuitry to decode instructions and identify any registers to be used and dispatch circuitry to dispatch instructions to one or more execution units, said system including emulator circuitry for debug operations which is arranged to watch data values in one or more selected registers modified during execution of the instructions, the computer circuitry further comprising a register watch store for identifying one or more registers to be watched, comparator circuitry for comparing registers identified by said decode circuitry with registers identified in said register watch store and providing a hit signal for hits in the comparison, and instruction insertion circuitry responsive to hit signals to insert in the instruction sequence to an execution unit a store instruction to store in a location accessible by the emulation circuitry the data value in a data register identified by a hit signal after execution of the instruction using the data register.

Computer register watch

A computer system includes instruction fetch circuitry for dispatching fetched instructions to a pipelined execution unit, data memory access circuitry and emulator circuitry for use in debug operations, said emulator circuitry including error indicating circuitry to indicate an error in a data memory access operation, snoop circuitry for snooping memory access operation in said data memory access circuitry, synchronising means for synchronising snooped data memory access addresses with respective program counts for the instructions associated with said access addresses, memory mapped storage circuitry responsive to a data memory access error to indicate the data memory address associated with the error, whereby the emulator circuitry may use the data memory address in a subsequent operation to obtain from the synchronising means the specific program count associated with the memory access operation in which the error occurred.

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Grenoble, France

Isabelle Sename