V-Pascal: An automatic vectorizing compiler for Pascal with no language extensions

Abstract

An automatic vectorizing compiler called V-Pascal is described in detail. The compiler has been designed and implemented with a view to vectorizing Pascal source programs. Using the mechanism of vector indirect addressing, it reduces multiply nestedfor loops to equivalent single loops, which are then executed by vector mode with sufficiently long vector lengths. TheD matrix, which is an adjacency matrix giving dependences between intermediate code nodes, plays an important role in the V-Pascal compiler. It is demonstrated that, in some cases, the V-Pascal compiler yields object code that runs faster than the Fortran counterpart. This paper mainly presents the basic constituents of the Version 1 of the V-Pascal compiler. Version 2 includes higher functions such as vectorization ofwhile-do loops and recursive procedures, vectorization of character string manipulations and relational database operations (written in Pascal), and automatic parallel decomposition for multiprocessor environments.