Data processing apparatus and method for performing hazard detection

A method of detecting occurrence of at least one hazard condition in respect of a series of access requests issued by processing circuitry for handling by one or more slave devices, said series of access requests including one or more write access requests, each write access request specifying a write operation to be performed by an addressed slave device from said one or more slave devices, and each issued write access request being a pending write access request until the write operation has been completed by the addressed slave device, the method comprising the steps of:

• providing a pending write access history storage comprising at least one buffer and at least one counter for keeping a record of each pending write access request;
• responsive to receipt of a write access request to be issued by the processing circuitry, performing an update process to identify that write access request as a pending write access request in one of said at least one buffers and, if the identity of another pending write access request is overwritten by that update process, to increment a count value in said at least one counter;
• on completion of each write access request by the addressed slave device, performing a further update process to remove the record of that completed write access request from the pending write access history storage;
• and
• responsive to at least a subset of the access requests to be issued by the processing circuitry, referencing the pending write access history storage in order to determine whether said at least one hazard condition occurs.

A data processing apparatus for coupling to one or more slave device means, the data processing apparatus comprising:

• processing means for issuing a series of access requests for handling by said one or more slave device means, said series of access requests including one or more write access requests, each write access request specifying a write operation to be performed by an addressed slave device means from said one or more slave device means, and each issued write access request being a pending write access request until the write operation has been completed by the addressed slave device means;
• and
• hazard detection means for detecting occurrence of at least one hazard condition in respect of the series of access requests issued by the processing means;
• said hazard detection means comprising:
• a pending write access history storage means comprising at least one buffer means and at least one counter means for keeping a record of each pending write access request;
• update means, responsive to receipt of a write access request to be issued by the processing means, for performing an update process to identify that write access request as a pending write access request in one of said at least one buffer means and, if the identity of another pending write access request is overwritten by that update process, for incrementing a count value in said at least one counter means;
• on completion of each write access request by the addressed slave device means, the update means for performing a further update process to remove the record of that completed write access request from the pending write access history storage means;
• and
• hazard checking means, responsive to at least a subset of the access requests to be issued by the processing means, for referencing the pending write access history storage means in order to determine whether said at least one hazard condition occurs.