Constant Propagation for Loops with Factored Use-Def Chains

• Main Authors: Hsun-Her Wang, 王勳和
• Other Authors: Chung Yung
• Format: Others
• Language: en_US
• Published: 2002
• Online Access: http://ndltd.ncl.edu.tw/handle/98870057345470435322

碩士 === 國立東華大學 === 資訊工程學系 === 90 === Constant propagation analysis is the optimization based on data- ow analysis which is a static analysis of providing global information about how a proce- dure manipulates its data. Compiler can generate more e cient codes when performing constant propagation within a procedure. Constant propagation can be regarded as a code reduction technique that determines whether all as- signments to a particular variable is a constant and provides the same constant value to some particular points. In this thesis, we develop a new approach of constant propagation with a focus on the constant propagation problems within loops. We combine the idea from Wegman and Zadeck's SCC algorithm of nding conditional constants and the idea from the method by Wolfe et al. of nding linear induction variables[Wol96] with loops. The method we applied is based on Factored Use-Def (FUD) chains, which is a demand-driven representation of the popular Static Single Assignment (SSA) form. We develop a new approach that nds the constants of the loops in a program. We have implemented this algorithm and we present experiments comparing our approach with the SCC method.