Electrical Engineering
      and Computer Sciences

Electrical Engineering and Computer Sciences

COLLEGE OF ENGINEERING

UC Berkeley

Improving Energy Efficiency and Reducing Code Size with RISC-V Compressed

Andrew Waterman

EECS Department
University of California, Berkeley
Technical Report No. UCB/EECS-2011-63
May 13, 2011

http://www.eecs.berkeley.edu/Pubs/TechRpts/2011/EECS-2011-63.pdf

Delivering the instruction stream can be the largest source of energy consumption in a processor, yet loosely-encoded RISC instruction sets are wasteful of instruction bandwidth. Aiming to improve the performance and energy efficiency of the RISC-V ISA, this thesis proposes RISC-V Compressed (RVC), a variable-length instruction set extension. RVC is a superset of the RISC-V ISA, encoding the most frequent instructions in half the size of a RISC- V instruction; the remaining functionality is still accessible with full-length instructions. RVC programs are 25% smaller than RISC-V programs, fetch 25% fewer instruction bits than RISC- V programs, and incur fewer instruction cache misses. Its code size is competitive with other compressed RISCs. RVC is expected to improve the performance and energy per operation of RISC-V.

Advisor: David A. Patterson and Krste Asanović


BibTeX citation:

@mastersthesis{Waterman:EECS-2011-63,
    Author = {Waterman, Andrew},
    Title = {Improving Energy Efficiency and Reducing Code Size with RISC-V Compressed},
    School = {EECS Department, University of California, Berkeley},
    Year = {2011},
    Month = {May},
    URL = {http://www.eecs.berkeley.edu/Pubs/TechRpts/2011/EECS-2011-63.html},
    Number = {UCB/EECS-2011-63},
    Abstract = {Delivering the instruction stream can be the largest source of energy consumption in a processor, yet loosely-encoded RISC instruction sets are wasteful of instruction bandwidth. Aiming to improve the performance and energy efficiency of the RISC-V ISA, this thesis proposes RISC-V Compressed (RVC), a variable-length instruction set extension. RVC is a superset of the RISC-V ISA, encoding the most frequent instructions in half the size of a RISC- V instruction; the remaining functionality is still accessible with full-length instructions. RVC programs are 25% smaller than RISC-V programs, fetch 25% fewer instruction bits than RISC- V programs, and incur fewer instruction cache misses. Its code size is competitive with other compressed RISCs. RVC is expected to improve the performance and energy per operation of RISC-V.}
}

EndNote citation:

%0 Thesis
%A Waterman, Andrew
%T Improving Energy Efficiency and Reducing Code Size with RISC-V Compressed
%I EECS Department, University of California, Berkeley
%D 2011
%8 May 13
%@ UCB/EECS-2011-63
%U http://www.eecs.berkeley.edu/Pubs/TechRpts/2011/EECS-2011-63.html
%F Waterman:EECS-2011-63