Semantics and implementation of a generalized forall statement for parallel languages

Abstract

In this paper we present a generalized forall statement for parallel languages. The forall statement occurs in many (data) parallel languages and specifies which computations can be performed independently. Many different definitions of such a construct can be found in literature, with different conditions and execution models. We will show how forall constructs of a wide class of parallel languages can be mapped to this generalized forall statement. In addition, the forall statement we propose has the ability to spawn more complex independent activities than can be found in these languages. Denotational semantics are used to define the meaning of the forall and define only one possible program state change. It is shown that it is easy to use and that it is feasible to implement this forall efficiently.