Cart (Loading....) | Create Account
Close category search window
 

Unroll-based copy elimination for enhanced pipeline scheduling

Sign In

Cookies must be enabled to login.After enabling cookies , please use refresh or reload or ctrl+f5 on the browser for the login options.

Formats Non-Member Member
$31 $13
Learn how you can qualify for the best price for this item!
Become an IEEE Member or Subscribe to
IEEE Xplore for exclusive pricing!
close button

puzzle piece

IEEE membership options for an individual and IEEE Xplore subscriptions for an organization offer the most affordable access to essential journal articles, conference papers, standards, eBooks, and eLearning courses.

Learn more about:

IEEE membership

IEEE Xplore subscriptions

4 Author(s)
Suhyun Kim ; Sch. of Electr. Eng. & Comput. Sci., Seoul Nat. Univ., South Korea ; Soo-Mook Moon ; Jinpyo Park ; Ebcioglu, K.

Enhanced pipeline scheduling (EPS) is a software pipelining technique which can achieve a variable initiation interval (II) for loops with control flow via its code motion pipelining. EPS, however, leaves behind many renaming copy instructions that cannot be coalesced due to interferences. These copies take resources and, more seriously, they may cause a stall if they rename a multilatency instruction whose latency is longer than the II aimed for by EPS. This paper proposes a code transformation technique based on loop unrolling which makes those copies coalescible. Two unique features of the technique are its method of determining the precise unroll amount, based on an idea of extended live ranges, and its insertion of special bookkeeping copies at loop exits. The proposed technique enables EPS to avoid a serious slowdown from latency handling and resource pressure, while keeping its variable II and other advantages. In fact, renaming through copies, followed by unroll-based copy elimination, is EPS's solution to the cross-iteration register overwrite problem in software pipelining. It works for loops with arbitrary control flow that EPS must deal with, as well as for straightline loops. Our empirical study performed on a VLIW testbed with a two-cycle load latency shows that 86 percent of the otherwise uncoalescible copies in innermost loops become coalescible when unrolled 2.2 times on average. In addition, it is demonstrated that the unroll amount obtained is precise and the most efficient. The unrolled version of the VLIW code includes fewer no-op VLIW caused by stalls, improving the performance by a geometric mean of 18 percent on a 16-ALU machine.

Published in:

Computers, IEEE Transactions on  (Volume:51 ,  Issue: 9 )

Date of Publication:

Sep 2002

Need Help?


IEEE Advancing Technology for Humanity About IEEE Xplore | Contact | Help | Terms of Use | Nondiscrimination Policy | Site Map | Privacy & Opting Out of Cookies

A not-for-profit organization, IEEE is the world's largest professional association for the advancement of technology.
© Copyright 2014 IEEE - All rights reserved. Use of this web site signifies your agreement to the terms and conditions.