UNIFIED MULTI-FUNCTION OPERATION SCHEDULER FOR OUT-OF-ORDER EXECUTION IN A SUPERSCALAR PROCESSOR

摘要

A superscalar processor (200) includes a scheduler (280) which selects operations for out-of-order execution. The scheduler (280) contains storage and control logic which is partitioned into entries (540) corresponding to operations. The scheduler (280) uses the entries to issue operations to execution units (251 to 257) for parallel pipelined execution, to provide operands as required for execution, and as a reorder buffer keeping the results of operations until the results are committed. The scheduler (280) is tightly coupled to execution units (251 to 257) and provides a wide parallel path which minimizes pipeline bottlenecks and hold ups into and out of the execution units (251 to 257). The scheduler (280) monitors entries to determine when all operands required for execution of an operation are available and provides required operands to the execution units (251 to 257). The operands can be from a register file (290), a scheduler entry, or an execution unit (251 to 257). Scan chains (530, 532, 534, 536 and 538) link the entries together and identify operations and operands for execution.