Register Requirement for Exploiting Loops' Maximum Instruction-Level Parallelism

Jian Wang, Andreas Krall and M. Anton Ertl

Institut für Computersprachen
Technische Universität Wien
Argentinierstraße 8
A-1040 Wien, Austria
{jian,andi}@complang.tuwien.ac.at

Abstract

This paper studies the interaction between register requirement and loops' maximum Instruction-Level Parallelism (ILP). First, we present the minimum data dependence graph (MinDDG) of a loop to represent the maximum ILP available in the loop. Then we analyze the influence of register requirement on the data dependence graph and the MinDDG, and on the basis of which we present an approach to estimate the upper bound on register requirement for exposing loops' maximum ILP. Finally, the preliminary experimental results are given to verify our approach.