Microsoft Corporation
Instruction dispatch for superscalar processors

Abstract:

The present disclosure relates to instruction dispatch mechanisms for superscalar processors having a plurality of functional units for executing operations simultaneously. Each particular functional unit of the plurality of functional units may be configured to output a capability vector indicating a set of operations that the particular functional unit is currently available to perform. As instructions are received in an issue queue, the functional unit to execute the instruction is selected by comparing capabilities required by the instruction to the asserted capabilities of each of the functional units. A functional unit may reset or de-assert a particular functionality while performing an operation and then re-assert the capability when the instruction is completed. A result of the operation may be stored in a skid buffer for at least as long as the chain execution time in order to avoid resource hazards are a write port of the vector register file.