Speculative software management of datapath-width for energy optimization

Gilles Pokam, Olivier Rochecouste, André Seznec, François Bodin
2004 Proceedings of the 2004 ACM SIGPLAN/SIGBED conference on Languages, compilers, and tools - LCTES '04  
This paper evaluates managing the processor's datapathwidth at the compiler level by means of exploiting dynamic narrow-width operands. We capitalize on the large occurrence of these operands in multimedia programs to build static narrow-width regions that may be directly exposed to the compiler. We propose to augment the ISA with instructions directly exposing the datapath and the register widths to the compiler. Simple exception management allows this exposition to be only speculative. In
more » ... way, we permit the software to speculatively accommodate the execution of a program on a narrower datapath-width in order to save energy. For this purpose, we introduce a novel register file organization, the byte-slice register file, which allows the width of the register file to be dynamically reconfigured, providing both static and dynamic energy savings. We show that by combining the advantages of the byte-slice register file with the advantages provided by clock-gating the datapath on a per-region basis, up to 17% of the datapath dynamic energy can be saved, while a 22% reduction of the register file static energy is achieved.
doi:10.1145/997163.997175 dblp:conf/lctrts/PokamRSB04 fatcat:ywf7dmx27vhabjizcbdnmvamte