PACWON: A parallelizing compiler for workstations on a network Dibyendu Das 1 , P.P. Das * Department of Computer Science and Engineering, Indian Institute of Technology, Kharagpur 721302, India Received 23 September 1996; received in revised form 8 July 1997; accepted 12 September 1997 Abstract The current in¯ux of networked workstations has prompted people to use this platform as a multiprocessing en- vironment. In addition, tools like the Parallel Virtual Machine (PVM) has fuelled the growth even further. In this work we present the design and some possible future strategies for automatically parallelizing sequential programs using a compilation tool called PACWON for a network of workstations (NOW). The sequential programs are written using a subset of C ± without pointers and structures. The target language is C embedded with PVM library calls. The au- tomatically parallelized programs are run on a NOW environment. Ó 1998 Elsevier Science B.V. All rights reserved. Keywords: Parallelizing compiler; Network of workstations; Parallel virtual machine; Clustering; Block graphs; Cloning 1. Introduction The current computing world is relying heavily on networked machines, especially workstations. A number of workstations on a medium/fast net- work provide ample opportunities for parall- elization. Hence, such an environment is projected as a probable high performance computing envi- ronment of the future. However, high startup times for communication and communication la- tency restrict such an environment from exploiting ®ne-grained parallelism. In addition, heterogeneity of the individual systems poses a lot of problems. Developing programs for such an environment by hand is not time and cost optimal and so auto- matic tools can be of great aid to a programmer ± particularly tools meant for automatic parall- elization. Work on parallelizing compilers/tools for a network of workstations (NOW) environment has concentrated mainly on loop parallelization [10,15,20]. The strategies applied mostly follow the Journal of Systems Architecture 45 (1998) 157±176 * Corresponding author. E-mail: ppdas@cse.litkgp.ernet.in 1 E-mail: deedee@cse.iitkgp.ernet.in 1383-7621/97/$ ± see front matter Ó 1998 Elsevier Science B.V. All rights reserved. PII: S 1 3 8 3 - 7 6 2 1 ( 9 7 ) 0 0 0 7 8 - 7