Processor having plurality of functional units for orderly retiring outstanding operations based upon its associated tags

A computer processor comprising:

• means, responsive to an input stream containing instructions, for converting each one of said instructions in the input stream to one or a series of operations;
• a plurality of functional units wherein each said functional unit executes at least some of the operations, each said operation that is executed by one of said functional units having one or normal termination and abnormal termination;
• means, coupled to said plurality of functional units, for communicating each of the operations to at least those of the functional units that are required to execute that operation, an operation so communicated being designated an outstanding operation;
• means for limiting the number of said outstanding operations to a predefined maximum;
• means, coupled to said first-mentioned communicating means and said plurality of functional units, for assigning a tag to each said outstanding operation, the tags being assigned in a sequential manner;
• means, coupled to said first-mentioned communicating means and said plurality of functional units, for maintaining, for each said outstanding operation, information regarding which ones of said functional units have terminated that operation and whether each said termination was normal or abnormal;
• means, associated with each said functional unit and coupled to said maintaining means, for determining with respect to each said operation communicated to it for execution when the functional unit has terminated the operation and whether the termination was normal, and for communicating the termination information, so determined, to said maintaining means along with the tag of the operation;
• means, coupled to said maintaining means, for communicating an indication of said outstanding operations to the functional units;
• means, coupled to said maintaining means and responsive to the termination information from the functional units, for retiring normally terminated operations in order;
• means, coupled to the functional units and responsive to information that one of said outstanding operations terminated abnormally, for instructing said functional units to flush at least said one of said outstanding operations and all later outstanding operations;
• means, associated with the functional units, for flushing all said outstanding operations specified by said instructing means;
• and
• means for causing said tag assigning means to commence assigning further tags beginning with the tag that was associated with the oldest outstanding operation that was flushed.