Inline function expansion is an optimization that may improve program performance by removing calling sequences and enlarging the scope of other optimizations. Unfortunately it also has the drawback of enlarging programs. This might impair executable programs performance. In order to get rid of this annoying effect, we present, an easy to implement, inlining optimization that minimizes code size growth by combining a compile-time algorithm deciding when expansion should occur with different expansion frameworks describing how they should be performed. We present the experimental measures that have driven the design of inline function expansion. We conclude with measurements showing that our optimization succeeds in producing faster codes while avoiding code size increase.

Keywords: Compilation, Optimization, Inlining, Functional languages.

In this paper we present a new program analysis method which we call Storage Use Analysis. This analysis deduces how objects are used by the program and allows the optimization of their allocation. This analysis can be applied to both statically typed languages (e.g. ML) and latently typed languages (e.g. Scheme). It handles side-effects, higher order functions, separate compilation and does not require cps transformation. We show the application of our analysis to two important optimizations: stack allocation and unboxing. The first optimization replaces some heap allocations by stack allocations for user and system data storage (e.g. lists, vectors, procedures). The second optimization avoids boxing some objects. This analysis and associated optimizations have been implemented in the Bigloo Scheme/ML compiler. Experimental results show that for many allocation intensive programs we get a significant speedup. In particular, numerically intensive programs are almost 20 times faster because floating point numbers are unboxed and no longer heap allocated.

We present Bigloo, a highly portable and optimizing compiler. Bigloo is the first compiler for strict functional languages that can efficiently compile several languages: Bigloo is the first compiler for full Scheme and full ML, and for these two languages, Bigloo is one of the most efficient compiler now available (Bigloo is available by anonymous ftp on ftp.inria.fr). This high level of performance is achieved by numerous high-level optimizations. Some of those are classical optimizations adapted to higher-order functional languages (e.g. inlining), other optimization schemes are specific to Bigloo (e.g. a new refined closure analysis, an original optimization of imperative variables, and intensive use of higher-order control flow analysis). All these optimizations share the same design guideline: the reduction of heap allocation.

This paper introduces the concepts of wide classes and widening as extensions to the object model of class-based languages such as Java and Smalltalk. Widening allows an object to be temporarily widened, that is transformed into an instance of a subclass, a wide class, and, later on, to be shrunk, that is reshaped to its original class. Wide classes share the main properties of plain classes: they have a name, a superclass, they may be instantiated, they have an associated class predicate and an associated type that may be used to override function definitions.

Widening is also useful to implement transient data storage for long-lasting computations. In particular, it helps reducing software data retention. This phenomenon arises when the actual data structures used in a program fail to reflect time-dependent properties of values and can cause excessive memory consumption during the execution.

Wide classes may be implemented for any dynamically-typed class-based programming language with very few modifications to the existing runtime system. We describe the simple and efficient implementation strategy used in the Bigloo runtime system.

Keywords: language implementation, dynamic inheritance, dynamic type checking, instance modification.

Cet article présente Rgc, un générateur d'analyseurs lexicaux rapides, développé pour Scheme. Nous ne décrivons pas ici une maquette mais un produit final efficace. Par ses performances, il est en concurrence directe avec le logiciel Flex. Après mesures, il apparaît que Rgc est entre 5 et 10 % plus rapide que Flex et entre 250 et 260 % plus rapide que Lex. Pour obtenir ce niveau de performance, nous avons réalisé un compilateur spécialisé restreint Scheme!>C. De plus, puisque Scheme ne possède pas de primitives rapides de lecture il s'est avéré indispensable de programmer les requêtes systèmes et la gestion des tampons en C. Le code est donc composé de 90% de Scheme et 10% de C.

Memory is the performance bottleneck of modern architectures. Keeping memory consumption as low as possible enables fast and unobtrusive applications. But it is not easy to estimate the memory use of programs implemented in functional languages, due to both the complex translations of some high level constructs, and the use of automatic memory managers.

To help understand memory allocation behavior of Scheme programs, we have designed two complementary tools. The first one reports on frequency of allocation, heap configurations and on memory reclamation. The second tracks down memory leaks. We have applied these tools to our Scheme compiler, the largest Scheme program we have been developing. This has allowed us to drastically reduce the amount of memory consumed during its bootstrap process, without requiring much development time.

Development tools will be neglected unless they are both conveniently accessible and easy to use. In order to avoid this pitfall, we have carefully designed the user interface of these two tools. Their integration into a real programming environment for Scheme is detailed in the paper.

The Bee is an integrated development environment for the Scheme programming language. It provides the user with a connection between Scheme and the C programming language, a symbolic debugger, a profiler, an interpreter, an optimizing compiler that delivers stand alone executables, a source file browser, a project manager, user libraries and online documentation. This article details the facilities of the Bee, its user interface and presents an overview of the implementation of its main components.