Reservation station early age indicator generation

A method comprising:

• storing instruction operations in a plurality of entries of a reservation station of a processor until being issued for execution by one of the one or more execution units;
• and
• determining in a first clock cycle a plurality of early age indicators for subsets of entries of the plurality of entries, wherein each early age indicator indicates which entry of a given subset has an oldest ready instruction operation;
• and
• storing the plurality of early age indicators in a plurality of registers during the first clock cycle;
• accessing the plurality of registers to determine in a second clock cycle which entry of all entries in the reservation station has an oldest ready instruction operation without reconsidering entries which were excluded by the early age indicators.

A computing system comprising:

• a memory;
• and
• a processor comprising:
• an execution unit;
• a dispatch unit;
• and
• a reservation station comprising:
• a plurality of entries, each of the plurality of entries being configured to store an instruction operation prior to issuance to an execution unit;
• control logic configured to:
• determine in a first clock cycle a plurality of early age indicators for subsets of entries of the plurality of entries, wherein each early age indicator indicates which entry of a given subset has an oldest ready instruction operation;
• store the plurality of early age indicators in a plurality of registers during the first clock cycle;
• access the plurality of registers to determine in a second clock cycle, based on the determined plurality of early age indicators which entry of all entries in the reservation station has an oldest ready instruction operation without reconsidering entries which were excluded by the early age indicators;
• wherein the reservation station is configured to keep each instruction operation in an entry into which the instruction operation was originally written until issuance to an execution unit;
• and
• wherein the dispatch unit is configured to write an instruction operation to any of the plurality of entries of the reservation station.