Technical Reports (CIS)

Document Type

Technical Report

Date of this Version

January 2008


University of Pennsylvania Department of Computer and Information Science Technical Report No. MS-CIS-08-36


Recently proposed techniques like mini-graphs, CCA-subgraphs, and static strands exploit application-specific compound or fused instructions to reduce execution time, energy consumption, and/or processor complexity. To achieve their full potential, these techniques rely on static tools to identify common instruction sequences that make good fusion candidates. As a result, they also rely on ISA extension facilities that can encode these chosen instruction groups in a way that supports efficient execution on fusion-enabled hardware as well as compatibility across different implementations, including fusion-agnostic implementations.

This paper describes handle prefix outlining, the ISA extension scheme used by mini-graph processors. Handle prefix outlining can be thought of as a hybrid of the encoding scheme used by three previous instruction aggregation techniques: PRISC, static strands, and CCA-subgraphs. It combines the best features of each scheme to deliver both full compatibility and execution efficiency on fusion-enabled processors.


Instruction fusion, ISA extension, outlining



Date Posted: 16 December 2008