Seiko Epson Corporation

Transmeta Corporation

Hitachi Micro Systems, Inc.

Other

Hitachi America, Ltd.

Seiko Corporation

Renesas Technology America, Inc.

Kevin Ray Iadonato

Sanjiv Garg

Trevor A Deosaran

Le Trong Nguyen

Johannes Wang

Kunio Uchiyama

Norio Nakagawa

Prasenjit Biswas

Gautam Dewan

A tag monitoring system for assigning tags to instructions embodied in software on a tangible computer-readable storage medium. A source supplies instructions to be executed by a functional unit. A queue having a plurality of slots containing tags which are used for tagging instructions. A register file stores information required for the execution of each instruction at a location in the register file defined by the tag assigned to that instruction. A control unit monitors the completion of executed instructions and advances the tags in the queue upon completion of an executed instruction. The register file also contains a plurality of read address enable ports and corresponding read output ports. Each of the slots from the queue is coupled to a corresponding one of the read address enable ports. Thus, the information for each instruction can be read out of the register file in program order.

System and method for assigning tags to control instruction processing in a superscalar processor

A system and method for performing register renaming of source registers in a processor having a variable advance instruction window for storing a group of instructions to be executed by the processor, wherein a new instruction is added to the variable advance instruction window when a location becomes available. A tag is assigned to each instruction in the variable advance instruction window. The tag of each instruction to leave the window is assigned to the next new instruction to be added to it. The results of instructions executed by the processor are stored in a temp buffer according to their corresponding tags to avoid output and anti-dependencies. The temp buffer therefore permits the processor to execute instructions out of order and in parallel. Data dependency checks for input dependencies are performed only for each new instruction added to the variable advance instruction window and register renaming is performed to avoid input dependencies.

System and method for register renaming

A register renaming system for out-of-order execution of a set of reduced instruction set computer instructions having addressable source and destination register fields, adapted for use in a computer having an instruction execution unit with a register file accessed by read address ports and for storing instruction operands. A data dependance check circuit is included for determining data dependencies between the instructions. A tag assignment circuit generates one or more tags to specify the location of operands, based on the data dependencies determined by the data dependance check circuit. A set of register file port multiplexers select the tags generated by the tag assignment circuit and pass the tags onto the read address ports of the register file for storing execution results.

Superscalar RISC instruction scheduling

An integrated structure layout of functional blocks and interconnections for an integrated circuit chip. Data dependency comparator blocks are arranged in rows and columns. This arrangement defines layout regions between adjacent ones of the data dependency comparator blocks in the rows. Tag assignment logic blocks are coupled to the data dependency comparator blocks to receive dependency information. The tag assignment logic blocks are positioned in one or more of the layout regions so as to be integrated with the data dependency comparator blocks to conserve area on the semiconductor chip and to spatially define a channel in and substantially orthogonal to one or more of the rows. Register file port multiplexer blocks are coupled to output lines of the tag assignment logic block adjacent to the orthogonal channel to receive tag information and to pass the tag information to address ports of a register file.

Integrated structure layout and layout of interconnections for an instruction execution unit of an integrated circuit chip

A tag monitoring system for assigning tags to instructions. A source supplies instructions to be executed by a functional unit. A register file stores information required for the execution of each instruction. A queue having a plurality of slots containing tags which are used for tagging the instructions. The tags are arranged in the queue in an order specified by the program order of their corresponding instructions. A control unit monitors the completion of executed instructions and advances the tags in the queue upon completion of an executed instruction. The register file stores an instruction's information at a location in the register file defined by the tag assigned to that instruction. The register file also contains a plurality of read address enable ports and corresponding read output ports. Each of the slots from the queue is coupled to a corresponding one of the read address enable ports. Thus, the information for each instruction can be read out of the register file in program order.

An FPU pipeline is synchronized with a CPU pipeline. Synchronization is achieved by having stalls and freezes in any one pipeline cause stalls and freezes in the other pipeline as well. Exceptions are kept precise even for long floating point operations. Precise exceptions are achieved by having a first execution stage of the FPU pipeline generate a busy signal, when a first floating point instruction enters a first execution stage of the FPU pipeline. When a second floating point instruction is decoded by the FPU pipeline before the first floating point instruction has finished executing in the first stage of the FPU pipeline, then both pipelines are stalled.

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San Jose, CA, United States of America

Kevin Ray Iadonato