Strict and nonstrict independent and-parallelism in logic programs: Correctness, efficiency, and compile-time conditions

Hermenegildo, Manuel V.; Rossi, Francesca

doi:10.1016/0743-1066(93)00007-f

Cited by 61 publications

(120 citation statements)

References 15 publications

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“…This optimization is performed as a source-to-source transformation, in which the input program is annotated with parallel expressions. The parallelization algorithms, or annotators [71], exploit parallelism under certain independence conditions, which allow guaranteeing interesting correctness and no-slowdown properties for the parallelized programs [54,31]. This process is made more complex by the presence of variables shared among goals and pointers among data structures at runtime.…”

Section: High Performance With Less Effortmentioning

confidence: 99%

An Overview of the Ciao Multiparadigm Language and Program Development Environment and Its Design Philosophy

Hermenegildo¹,

Bueno²,

Carro³

et al. 2008

Concurrency, Graphs and Models

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Abstract. We describe some of the novel aspects and motivations behind the design and implementation of the Ciao multiparadigm programming system. An important aspect of Ciao is that it provides the programmer with a large number of useful features from different programming paradigms and styles, and that the use of each of these features can be turned on and off at will for each program module. Thus, a given module may be using e.g. higher order functions and constraints, while another module may be using objects, predicates, and concurrency. Furthermore, the language is designed to be extensible in a simple and modular way. Another important aspect of Ciao is its programming environment, which provides a powerful preprocessor (with an associated assertion language) capable of statically finding non-trivial bugs, verifying that programs comply with specifications, and performing many types of program optimizations. Such optimizations produce code that is highly competitive with other dynamic languages or, when the highest levéis of optimization are used, even that of static languages, all while retaining the interactive development environment of a dynamic language. The environment also includes a powerful auto-documenter. The paper provides an informal overview of the language and program development environment. It aims at illustrating the design philosophy rather than at being exhaustive, which would be impossible in the format of a paper, pointing instead to the existing literature on the system.

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Section: High Performance With Less Effortmentioning

confidence: 99%

An Overview of the Ciao Multiparadigm Language and Program Development Environment and Its Design Philosophy

Hermenegildo¹,

Bueno²,

Carro³

et al. 2008

Concurrency, Graphs and Models

Self Cite

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show abstract

“…One of the more widely used approaches is illustrated in the following figure (representing the parallelization of " [24,27,7]:…”

Section: Notions Of Independencementioning

confidence: 99%

Automatic parallelization of irregular and pointer-based computations: Perspectives from logic and constraint programming

Hermenegildo

1997

Euro-Par'97 Parallel Processing

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Abstract. Irregular computations pose some of the most interesting and challenging problems in automatic parallelization. Irregularity appears in certain kinds of numerical problems and is pervasive in symbolic applications. Such computations often use dynamic data structures which make heavy use of pointers. This complicates all the steps of a parallelizing compiler, from independence detection to task partitioning and placement. In the past decade there has been significant progress in the development of parallelizing compilers for logic programming and, more recently, constraint programming. The typical applications of these paradigms frequently involve irregular computations, which arguably makes the techniques used in these compilers potentially interesting. In this paper we introduce in a tutorial way some of the problems faced by parallelizing compilers for logic and constraint programs. These include the need for inter-procedural pointer aliasing analysis for independence detection and having to manage speculative and irregular computations through task granularity control and dynamic task allocation. We also provide pointers to some of the progress made in these áreas. In the associated talk we demónstrate representatives of several generations of these parallelizing compilers.

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“…A correct parallelization has been defined as one that preserves during andparallel execution some key properties, typically correctness and no-slowdown [14]. The preservation of these properties is ensured by executing in parallel goals which meet some notion of independence, meaning that the goals to be executed in parallel do not interfere with each other in some particular sense.…”

Section: Introductionmentioning

confidence: 99%

“…It should be noted that some proposals exploit andparallelism between goals which do not meet this condition, but on which other restrictions are imposed which also ensure no-slowdown and correctness. Examples of such restrictions are determinism and non-failure [14] (determinism is exploited for example in [24]) and absence of conflicts due to the binding of shared variables (as in non-strict independent and-parallelism [14]). Another interesting issue is at what level of granularity the notion of independence is applied: at the goal level, at the binding level, etc.…”

Section: Introductionmentioning

confidence: 99%

“…One of the best understood sufficient conditions for ensuring that goals meet the efficiency and correctness criteria for parallelization is strict independence [14], which entails the absence of shared variables at runtime between any two goals being parallelized. It should be noted that some proposals exploit andparallelism between goals which do not meet this condition, but on which other restrictions are imposed which also ensure no-slowdown and correctness.…”

Section: Introductionmentioning

confidence: 99%

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Annotation Algorithms for Unrestricted Independent And-Parallelism in Logic Programs

Casas

Carro

Hermenegildo

2008

Logic-Based Program Synthesis and Transformation

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Abstract. We present two new algorithms which perform automatic parallelization via source-to-source transformations. The objective is to exploit goal-level, unrestricted independent and-parallelism. The proposed algorithms use as targets new parallel execution primitives which are simpler and more flexible than the well-known &/2 parallel operator. This makes it possible to generate better parallel expressions by exposing more potential parallelism among the literals of a clause than is possible with &/2. The difference between the two algorithms stems from whether the order of the solutions obtained is preserved or not. We also report on a preliminary evaluation of an implementation of our approach. We compare the performance obtained to that of previous annotation algorithms and show that relevant improvements can be obtained.

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Strict and nonstrict independent and-parallelism in logic programs: Correctness, efficiency, and compile-time conditions

Cited by 61 publications

References 15 publications

An Overview of the Ciao Multiparadigm Language and Program Development Environment and Its Design Philosophy

An Overview of the Ciao Multiparadigm Language and Program Development Environment and Its Design Philosophy

Automatic parallelization of irregular and pointer-based computations: Perspectives from logic and constraint programming

Annotation Algorithms for Unrestricted Independent And-Parallelism in Logic Programs

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