VCG - visualization of compiler graphs

The VCG tool allows the visualization of graphs that occur typically as data structures in programs. We describe the design concepts of the tool, its specification language and its usage. The tool supports the partitioning of edges and nodes into edge classes and nested subgraphs, the folding of regions, and the management of priorities of edges

VCG - visualization of compiler graphs

The VCG tool allows the visualization of graphs that occur typically as data structures in programs. We describe the design concepts of the tool, its specification language and its usage. The tool supports the partitioning of edges and nodes into edge classes and nested subgraphs, the folding of regions, and the management of priorities of edges

Generating program analyzers

In this work the automatic generation of program analyzers from concise specifications is presented. It focuses on provably correct and complex interprocedural analyses for real world sized imperative programs. Thus, a powerful and flexible specification mechanism is required, enabling both correctness proofs and efficient implementations. The generation process relies on the theory of data flow analysis and on abstract interpretation. The theory of data flow analysis provides methods to efficiently implement analyses. Abstract interpretation provides the relation to the semantics of the programming language. This allows the systematic derivation of efficient provably correct, and terminating analyses. The approach has been implemented in the program analyzer generator PAG. It addresses analyses ranging from "simple\u27; intraprocedural bit vector frameworks to complex interprocedural alias analyses. A high level specialized functional language is used as specification mechanism enabling elegant and concise specifications even for complex analyses. Additionally, it allows the automatic selection of efficient implementations for the underlying abstract datatypes, such as balanced binary trees, binary decision diagrams, bit vectors, and arrays. For the interprocedural analysis the functional approach, the call string approach, and a novel approach especially targeting on the precise analysis of loops can be chosen. In this work the implementation of PAG as well as a large number of applications of PAG are presented.Diese Arbeit befaßt sich mit der automatischen Generierung von Programmanalysatoren aus prägnanten Spezifikationen. Dabei wird besonderer Wert auf die Generierung von beweisbar korrekten und komplexen interprozeduralen Analysen für imperative Programme realer Größe gelegt. Um dies zu erreichen, ist ein leistungsfähiger und flexibler Spezifikationsmechanismus erforderlich, der sowohl Korrektheitsbeweise, als auch effiziente Implementierungen ermöglicht. Die Generierung basiert auf den Theorien der Datenflußanalyse und der abstrakten Interpretation. Die Datenflußanalyse liefert Methoden zur effizienten Implementierung von Analysen. Die abstrakte Interpretation stellt den Bezug zur Semantik der Programmiersprache her und ermöglicht dadurch die systematische Ableitung beweisbar korrekter und terminierender Analysen. Dieser Ansatz wurde im Programmanalysatorgenerator PAG implementiert, der sowohl für einfache intraprozedurale Bitvektor- Analysen, als auch für komplexe interprozedurale Alias-Analysen geeignet ist. Als Spezifikationsmechanismus wird dabei eine spezialisierte funktionale Sprache verwendet, die es ermöglicht, auch komplexe Analysen kurz und prägnant zu spezifizieren. Darüberhinaus ist es möglich, für die zugrunde liegenden abstrakten Bereiche automatisch effiziente Implementierungen auszuwählen, z.B. balancierte binäre Bäume, Binary Decision Diagrams, Bitvektoren oder Felder. Für die interprozedurale Analyse stehen folgende Möglichkeiten zur Auswahl: der funktionale Ansatz, der Call-String-Ansatz und ein neuer Ansatz, der besonders auf die präzise Analyse von Schleifen abzielt. Diese Arbeit beschreibt sowohl die Implementierung von PAG, als auch eine große Anzahl von Anwendungen

Graph layout using subgraph isomorphisms

Today, graphs are used for many things. In engineering, graphs are used to design circuits in very large scale integration. In computer science, graphs are used in the representation of the structure of software. They show information such as the flow of data through the program (known as the data flow graph [1]) or the information about the calling sequence of programs (known as the call graph [145]). These graphs consist of many classes of graphs and may occupy a large area and involve a large number of vertices and edges. The manual layout of graphs is a tedious and error prone task. Algorithms for graph layout exist but tend to only produce a 'good' layout when they are applied to specific classes of small graphs. In this thesis, research is presented into a new automatic graph layout technique. Within many graphs, common structures exist. These are structures that produce 'good' layouts that are instantly recognisable and, when combined, can be used to improve the layout of the graphs. In this thesis common structures are given that are present in call graphs. A method of using subgraph isomorphism to detect these common structures is also presented. The method is known as the ANHOF method. This method is implemented in the ANHOF system, and is used to improve the layout of call graphs. The resulting layouts are an improvement over layouts from other algorithms because these common structures are evident and the number of edge crossings, clusters and aspect ratio are improved

CLAX - A Visualized Compiler

The CLAX compiler was developed in the project COMPARE as reconfigurable demonstration compiler. Its various optimization phases are visualized and animated by the graph layout tool VCG. Visualization allows to understand and to improve the behavior of the algorithms of the compiler phases. We present a tour through the CLAX compiler and demonstrate the newest extensions of the VCG tool, that help to explore large compiler data structures