Microprocessor in which multiple instructions are executed in one clock

Abstract

A microprocessor having a memory coprocessor (10) connected to a MEM interface (16) and a register coprocessor (12) connected to a REG interface (14). The REG interface (14) and MEM interface (16) are connected to independent read and write ports of a register file (6). An Instruction Sequencer (7) also connected to an independent write port of the register file, to the REG interface and to the MEM interface. An Instruction Cache (9) supplies the instruction sequencer with at least two instruction words per clock (7). Single-cycle coprocessors (4) are connected to the REG interface (14) and a multiple-cycle coprocessors (2) are connected to the REG interface (14). An Address Generation Unit (3) is connected to the MEM interface (16) for executing load-effective-address instructions and address computations for loads and stores to thereby perform effective address calculations in parallel with instruction execution by the single-cycle coprocessor. The Instruction Sequencer (7) decodes incoming instruction words form the Cache, and issues up to three instructions on the REG interface (14), the MEM interface (16), and/or the branch logic within the Instruction Sequencer. The instruction sequencer includes means for detecting dependencies between the instructions to thereby prevent collisions between instructions. A local register cache (5) is provided connected to the MEM interface. The local register cache maintains a stack of multiple word local register sets, such that one each call the local registers are transferred from the register file (6) to the Local Register Cache (5) to thereby allocate the local registers in the register file for the called procedure and on a return the words are transferred back into the register file to the calling procedure.