Monitoring memory locations to identify whether data stored at the memory locations has been modified

A method comprising:

• storing indications of a first set of memory locations of a shared memory in address storage circuitry;
• providing a capacity indicator to indicate whether a capacity of the address storage circuitry has been reached;
• monitoring the first set of memory locations and a second set of memory locations of the shared memory, identified in further storage circuitry, to identify whether data stored at either the first set of memory locations or the second set of memory locations has been modified;
• in response to determining that the data has been modified, generating an indication that the data has been modified;
• receiving at processing circuitry the indication that the data has been modified;
• and
• executing a monitor-address instruction that specifies an address of a new memory location in the shared memory to:
• determine, based on the capacity indicator, whether the capacity of the address storage circuitry has been reached;
• in response to determining that the capacity of the address storage circuitry has not been reached, update the address storage circuitry to indicate that the new memory location is to be monitored by the monitoring circuitry;
• and
• in response to determining that the capacity of the address storage circuitry has been reached, update the further storage circuitry to indicate that the new memory location is to be monitored;
• wherein the processing circuitry supports instructions in an instruction set architecture and the instructions include the monitor-address instruction.

A computer program to control a host data processing apparatus to provide an instruction execution environment for execution of target code, the computer program comprising:

• address storage program logic to maintain an address storage structure in a memory or in registers of the host data processing apparatus to store indications of a first set of memory locations of a shared memory;
• capacity indicating program logic to maintain a capacity indicator in the memory or the registers to indicate whether a capacity of the address storage structure has been reached;
• monitoring program logic to monitor the first set of memory locations and a second set of memory locations of the shared memory, identified in a further storage structure maintained in the memory or the registers, to identify whether data stored at either the first set of memory locations or the second set of memory locations has been modified, wherein the monitoring program logic is responsive to determining that the data has been modified to generate an indication that the data has been modified;
• and
• instruction decoding program logic to decode instructions of the target code to control the host data processing apparatus to perform data processing;
• wherein the instruction decoding program logic is responsive to a monitor-address instruction that specifies an address of a new memory location in the shared memory to:
• determine, based on the capacity indicator, whether the capacity of the address storage structure has been reached;
• in response to determining that the capacity of the address storage structure has not been reached, update the address storage structure to indicate that the new memory location is to be monitored by the monitoring logic;
• and
• in response to determining that the capacity of the address structure circuitry has been reached, update the further storage structure to indicate that the new memory location is to be monitored by the monitoring logic;
• wherein the instruction decoding program logic supports instructions in an instruction set architecture and the instructions include the monitor-address instruction.