Automatic Static Cost Analysis for Parallel Programs

Abstract. Static analysis of the evaluation cost of programs is an extensively studied problem that has many important applications. However, most automatic methods for static cost analysis are limited to sequential evaluation while programs are increasingly evaluated on modern multicore and multiprocessor hardware. This article introduces the first automatic analysis for deriving bounds on the worst-case evaluation cost of parallel first-order functional programs. The analysis is performed by a novel type system for amortized resource analysis. The main innovation is a technique that separates the reasoning about sizes of data structures and evaluation cost within the same framework. The cost semantics of parallel programs is based on call-by-value evaluation and the standard cost measures work and depth. A soundness proof of the type system establishes the correctness of the derived cost bounds with respect to the cost semantics. The derived bounds are multivariate resource polynomials which depend on the sizes of the arguments of a function. Type inference can be reduced to linear programming and is fully automatic. A prototype implementation of the analysis system has been developed to experimentally evaluate the effectiveness of the approach. The experiments show that the analysis infers bounds for realistic example programs such as quick sort for lists of lists, matrix multiplication, and an implementation of sets with lists. The derived bounds are often asymptotically tight and the constant factors are close to the optimal ones

Automatic Static Cost Analysis for Parallel Programs

Abstract Static analysis of the evaluation cost of programs is an extensively studied problem that has many important applications. However, most automatic methods for static cost analysis are limited to sequential evaluation while programs are increasingly evaluated on modern multicore and multiprocessor hardware. This article introduces the first automatic analysis for deriving bounds on the worst-case evaluation cost of parallel first-order functional programs. The analysis is performed by a novel type system for amortized resource analysis. The main innovation is a technique that separates the reasoning about sizes of data structures and evaluation cost within the same framework. The cost semantics of parallel programs is based on call-by-value evaluation and the standard cost measures work and depth. A soundness proof of the type system establishes the correctness of the derived cost bounds with respect to the cost semantics. The derived bounds are multivariate resource polynomials which depend on the sizes of the arguments of a function. Type inference can be reduced to linear programming and is fully automatic. A prototype implementation of the analysis system has been developed to experimentally evaluate the effectiveness of the approach. The experiments show that the analysis infers bounds for realistic example programs such as quick sort for lists of lists, matrix multiplication, and an implementation of sets with lists. The derived bounds are often asymptotically tight and the constant factors are close to the optimal ones

Automatic Static Cost Analysis for Parallel Programs

Abstract Static analysis of the evaluation cost of programs is an extensively studied problem that has many important applications. However, most automatic methods for static cost analysis are limited to sequential evaluation while programs are increasingly evaluated on modern multicore and multiprocessor hardware. This article introduces the first automatic analysis for deriving bounds on the worst-case evaluation cost of parallel first-order functional programs. The analysis is performed by a novel type system for amortized resource analysis. The main innovation is a technique that separates the reasoning about sizes of data structures and evaluation cost within the same framework. The cost semantics of parallel programs is based on call-by-value evaluation and the standard cost measures work and depth. A soundness proof of the type system establishes the correctness of the derived cost bounds with respect to the cost semantics. The derived bounds are multivariate resource polynomials which depend on the sizes of the arguments of a function. Type inference can be reduced to linear programming and is fully automatic. A prototype implementation of the analysis system has been developed to experimentally evaluate the effectiveness of the approach. The experiments show that the analysis infers bounds for realistic example programs such as quick sort for lists of lists, matrix multiplication, and an implementation of sets with lists. The derived bounds are often asymptotically tight and the constant factors are close to the optimal ones

An overview of the ciao multiparadigm language and program development environment and its design philosophy

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

Enhancing the performance of Decoupled Software Pipeline through Backward Slicing

The rapidly increasing number of cores available in multicore processors does not necessarily lead directly to a commensurate increase in performance: programs written in conventional languages, such as C, need careful restructuring, preferably automatically, before the benefits can be observed in improved run-times. Even then, much depends upon the intrinsic capacity of the original program for concurrent execution. The subject of this paper is the performance gains from the combined effect of the complementary techniques of the Decoupled Software Pipeline (DSWP) and (backward) slicing. DSWP extracts threadlevel parallelism from the body of a loop by breaking it into stages which are then executed pipeline style: in effect cutting across the control chain. Slicing, on the other hand, cuts the program along the control chain, teasing out finer threads that depend on different variables (or locations). parts that depend on different variables. The main contribution of this paper is to demonstrate that the application of DSWP, followed by slicing offers notable improvements over DSWP alone, especially when there is a loop-carried dependence that prevents the application of the simpler DOALL optimization. Experimental results show an improvement of a factor of ?1.6 for DSWP + slicing over DSWP alone and a factor of ?2.4 for DSWP + slicing over the original sequential code

A practical application of sharing and freeness inference

Abstract is not available