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Compiler transformations for effectively exploiting a zero overhead loop buffer
Author(s) -
Uh GangRyung,
Wang Yuhong,
Whalley David,
Jinturkar Sanjay,
Paek Yunheung,
Cao Vincent,
Burns Chris
Publication year - 2004
Publication title -
software: practice and experience
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.437
H-Index - 70
eISSN - 1097-024X
pISSN - 0038-0644
DOI - 10.1002/spe.642
Subject(s) - computer science , loop unrolling , compiler , overhead (engineering) , parallel computing , loop fission , cache , code (set theory) , loop tiling , loop (graph theory) , digital signal processing , code generation , optimizing compiler , stencil , buffer overflow , loop optimization , loop fusion , embedded system , computer hardware , operating system , programming language , key (lock) , computational science , mathematics , set (abstract data type) , combinatorics
Abstract A Zero Overhead Loop Buffer (ZOLB) is an architectural feature that is commonly found in DSP processors. This buffer can be viewed as a compiler managed cache that contains a sequence of instructions that will be executed a specified number of times without incurring any loop overhead. Unlike loop unrolling, a loop buffer can be used to minimize loop overhead without the penalty of increasing code size. In addition, a ZOLB requires relatively little space and power, which are both important considerations for most DSP applications. This paper describes strategies for generating code to effectively use a ZOLB. We have found that many common code improving transformations used by optimizing compilers on conventional architectures can be easily used to (1) allow more loops to be placed in a ZOLB, (2) further reduce loop overhead of the loops placed in a ZOLB, and (3) avoid redundant loading of ZOLB loops. The results given in this paper demonstrate that this architectural feature can often be exploited with substantial improvements in execution time and slight reductions in code size for various signal processing applications. Copyright © 2004 John Wiley & Sons, Ltd.