Lookup table for Virtual Registers including renaming



  • ISA reg numbers are in rows
  • Virtual (including renamed) reg numbers are in columns
  • from both the bottom and the right are multi-issue (unary) "Set1, Set2" signals
  • where these cross they are ANDed to set a Latch in a given cell
    • at no time will there be more than one cell set per row
    • OR per column
  • there being only one per column a "reset" signal can be per column
  • for regfile port "lookup" the per-column Set1/Set2 wires may be re-used
    • they may be binary or unary as preferred
    • read and write ports are all numbered
  • a "request virtual-to-real regfile port redirection" signal is along the bottom
    • this is ANDed with the Latch
    • that is MUXed with the per-column Set1/Set2 wires
    • ANDs which accumulate in Great Big ORs fire per-row outputs

in this way any "virtual" read or write request to a register file port may be translated to a "real" request. the actual regfile data transfers on respective associated broadcast buses are external and do not need routing through this Matrix: the Matrix simply provides name translation, nothing else.

note that if regfile port IDs are encoded in binary, an entire column can light up like a Mythbusters Christmas tree with XOR gates unless the EN is carefully arranged.