Target Code Selection by Tilling AST with the Use of Tree Pattern Pushdown Automaton

A new and simple method for target code selection by tilling an abstract syntax tree is presented. As it is usual, tree patterns corresponding to target machine instructions are matched in the abstract syntax tree. Matching tree patterns is performed with the use of tree pattern pushdown automaton, which accepts all tree patterns matching the abstract syntax tree in the linear postfix bar notation and represents a full index of the abstract syntax tree for tree patterns. The use of the index allows to match patterns quickly, in time depending on the size of patterns and not depending on the size of the tree. The selection of a particular target instruction corresponds to a modification of the abstract syntax tree and also a corresponding incremental modification of the index is performed. A reference to a fully functional prototype is provided

Code Generation = A* + BURS

A system called BURS that is based on term rewrite systems and a search algorithm A* are combined to produce a code generator that generates optimal code. The theory underlying BURS is re-developed, formalised and explained in this work. The search algorithm uses a cost heuristic that is derived from the termrewrite system to direct the search. The advantage of using a search algorithm is that we need to compute only those costs that may be part of an optimal rewrite sequence

On Tree Pattern Matching by Pushdown Automata

Tree pattern matching is an important operation in Computer Science on which a number of tasks such as mechanical theorem proving, term-rewriting, symbolic computation and non-procedural programming languages are based on. Work has begun on a systematic approach to the construction of tree pattern matchers by deterministic pushdown automata which read subject trees in prefix notation. The method is analogous to the construction of string pattern matchers: for given patterns, a non-deterministic pushdown automaton is created and then it is determinised. In this first paper, we present the proposed non-deterministic pushdown automaton which will serve as a basis for the determinisation process, and prove its correctness.

Taxonomies of regular tree algorithms

Algorithms for acceptance, pattern matching and parsing of regular trees and the tree automata used in these algorithms have many applications, including instruction selection in compilers, implementation of term rewriting systems, and model checking. Many such tree algorithms and constructions for such tree automata appear in the literature, but some deficiencies existed, including: inaccessibility of theory and algorithms; difficulty of comparing algorithms due to variations in presentation style and level of formality; and lack of reference to the theory in many publications. An algorithm taxonomy is an effective means of bringing order to such a field. We report on two taxonomies of regular tree algorithms that we have constructed to deal with the deficiencies. The complete work has been presented in the PhD thesis of the first author

Survey on Instruction Selection: An Extensive and Modern Literature Review

Instruction selection is one of three optimisation problems involved in the code generator backend of a compiler. The instruction selector is responsible of transforming an input program from its target-independent representation into a target-specific form by making best use of the available machine instructions. Hence instruction selection is a crucial part of efficient code generation. Despite on-going research since the late 1960s, the last, comprehensive survey on the field was written more than 30 years ago. As new approaches and techniques have appeared since its publication, this brings forth a need for a new, up-to-date review of the current body of literature. This report addresses that need by performing an extensive review and categorisation of existing research. The report therefore supersedes and extends the previous surveys, and also attempts to identify where future research should be directed.Comment: Major changes: - Merged simulation chapter with macro expansion chapter - Addressed misunderstandings of several approaches - Completely rewrote many parts of the chapters; strengthened the discussion of many approaches - Revised the drawing of all trees and graphs to put the root at the top instead of at the bottom - Added appendix for listing the approaches in a table See doc for more inf

View-based abstraction : enhancing maintainability and modularity in the presence of implementation dependencies

Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 1997.Includes bibliographical references (p. 173-177).by Luis H. Rodriguez, Jr.Ph.D

Estudo e desenvolvimento de sistemas de geração de back-ends do processo de compilação

O back-end de um compilador agrupa todo um conjunto de tarefas cuja implementação é intrinsecamente dependente das características do processador para o qual se pretende gerar código. A rápida evolução da industria dos processadores e microcontroladores levou esta área de desenvolvimento de software a realizar fortes investimentos na pesquisa de meios que permitissem dar uma resposta rápida e de qualidade à procura verificada. É dentro deste contexto que surge o tema e o trabalho desenvolvido ao longo desta tese de mestrado, que pretende de alguma forma sintetizar o que já se encontra feito e propor algumas soluções, que apesar de individualmente não serem originais permitem, quando em conjunto, vislumbrar alternativas aos sistemas já concebidos e avançar um pouco mais na área de investigação dos geradores de código final e optimizadores. O trabalho aqui descrito é extremamente abrangente para uma qualquer tese, cobrindo todas as áreas do processo de compilação a partir da análise semântica até à geração do código máquina, passando pela apresentação de modelos de compiladores, representação da informação, sistemas de análise de fluxo de controlo e de dados, alocação de registos local e global, selecção de instruções e geração de selectores, optimização de código a vários níveis, etc. É ainda de referir que do trabalho desenvolvido resultou o Back-End Development System, que como o nome indica é um sistema de apoio ao desenvolvimento das tarefas de back-end de um compilador. The back-end of a compiler gathers a group of tasks, whose implementation is directly dependent on the features of the processor for which machine code is intended to be generated. The fast evolution of processors and micro-controllers industry lead this area of software development to perform strong investments in the research of means, which would give a fast and proper answer to the demand. It is within this context that the theme and the work carried on through this thesis emerges. The aim of this work is to synthesise what has already been done and to give some solutions which, although individually not original, when put together, they allow alternatives to the pre-established systems and move on a little further in the research of generators of final code and optimisers. This work is extremely wide-ranging, covering all areas of the compiling process, going from the semantic analyses till the generation of machine code. It also contains the presentation of models of compilers, representation of information, control and data flow analysis, local and global registers allocation, instructions selection and generation of selectors, code optimisation at several levels, etc. It is also important to refer that from the development work emerged the Back-End Development System, which, as the name itself indicates, is a software system to support development of back-end tasks of a compiler