Register File Having a Plurality of Sub-Register Files

An out-of-order processor comprising:

• a register file, the register file comprising:
• a plurality of sub-register files, each sub-register file comprising at least one physical register;
• and
• a plurality of buffers, each buffer being associated with a sub-register file and arranged to:
• receive and store write operations destined for the associated sub-register file;
• receive and store a write value for each write operation stored in the buffer;
• once a write value for a particular write operation has been received, that write operation becomes a waiting write operation;
• determine, each clock cycle, if there is at least one waiting write operation in the buffer;
• and if there is at least one waiting write operation in the buffer, select one of the waiting write operations and issue the selected write operation to the associated sub-register file;
• and
• a decoding and renaming stage, the decoding and renaming stage being configured to:
• receive a fetched instruction;
• assign any architectural register referred to in a write operation of the fetched instruction a sub-register file and a physical register of the assigned sub-register file;
• and
• rename the architectural register with an indicator of the assigned sub-register file and an indicator of the assigned physical register.

A method of reading and writing to a register file of an out-of-order processor, the register file comprising a plurality of sub-register files, each sub-register file comprising at least one physical register, the method comprising:

• receiving at one of a plurality of buffers a write operation destined for an associated sub-register file;
• storing the received write operation in the buffer;
• receiving at the buffer a write value for the write operation;
• storing the received write value in the buffer in association with the write operation making the write operation a waiting write operation;
• each clock cycle, determining if there are any waiting write operations in the buffer;
• and
• if there is at least one waiting write operation in the buffer, selecting one of the waiting write operations and issuing it to the associated sub-register file.