Compiler Construction

In traditional university compiler syllabus, all phases of compiler is studied in detail in each unit before moving on to the next one. This makes the students lose the big picture of the subject. The course format should be updated in such a way which incrementally introduced through ten compilers of increasingly complexity. The first phase of compiler is syntax analyzer of any simple language. The last one is a complete compiler of a Pascal-like language. Students from this course learn how to build compilers faster than the usual.

In traditional university compiler syllabus, all phases of compiler is studied in detail in each unit before moving on to the next one. This makes the students lose the big picture of the subject. The course format should be updated in such a way which incrementally introduced through ten compilers of increasingly complexity. The first phase of compiler is syntax analyzer of any simple language. The last one is a complete compiler of a Pascal-like language. Students from this course learn how to build compilers faster than the usual.

During language evolution, compiler construction is usually performed along two dimensions: defining new abstract syntax tree (AST) classes, or adding new operations. In order to facilitate such changes, two software design patterns (i.e., the inheritance pattern and the visitor pattern) are widely used to help modularize the language constructs. However, as each design pattern is only suitable for one dimension of extension, neither of these two patterns can independently fulfill the evolution needs during the compiler construction process. In this paper, we analyze two dimensions of concerns in compiler construction and develop a paradigm allowing compiler evolution across these two dimensions using both object-orientation and aspect-orientation. Moreover, this approach provides an ability to perform pattern transformation based on pluggable aspects. A simple implementation of an expression language and its possible extension is demonstrated using Java and AspectJ.

The use of object-oriented techniques and concepts, like encapsulation and inheritance, greatly improves language specifications towards better modularity, reusability and extensibility. Additional improvements can be achieved with aspect-oriented techniques since semantic aspects also crosscut many language constructs. Indeed, aspect-oriented constructs have been already added to some language specifications. The LISA compiler construction system follows an object-oriented approach and has already implemented mechanisms for inheritance, modularity and extensibility. Adding aspects to LISA will lead to more reusable language specifications. In the paper, aspect-oriented attribute grammars are introduced, and the underlying ideas are incorporated into AspectLISA, an aspect-oriented compiler generator based on attribute grammars.

We are developing an optimizing compiler for a dialect of the LISP language. The current target architecture is the S-I, a multiprocessing supercomputer designed at Lawrence Livermore National Laboratory. While LISP is usually thought of as a language primarily for symbolic processing and list manipulation, this compiler is also intended to compete with the S-1 PASCAL and FORTIG~.N compilers for quality of compiled numerical code. The S-1 is designed for extremely high-speed signal processing as well as for symbolic computation; it provides primitive operations on vectors of floating-point and complex numbers. The LISP compiler is designed to exploit the architecture heavily. The compiler is structurally and conceptually similar to the BLISS-11 compiler and the compilers produced by PQO:. In particular, the TNBIND technique has been borrowed and extended. Particularly interesting properties of the compiler are: • Extensive use of source-to-source transformations. • Use of an intermediate form that is expression-oriented rather than statement-oriented. • Exploitation of tail-recursive function calls to represent complex control structures. • Efficient compilation of code that can manipulate procedural objects that require heap-aUocated environments, • Smooth run-time interfacing between the "numerical world" and "LISP pointer world", including automatic stack allocation of objects that ordinarily must be hcap-allocated. Each of these techniques has been used before, but we believe their synthesis to be original and unique. The compiler is table-driven to a great extent, more so than BLISS-11 but less so than a ~ compiler. We expect to be able to to redirect the compiler to other target architectures such as the VAX or PDP-10 with relatively little effort. Permission to copy without fee all or part of this material is granted provided that the copies are not made or distributed for direct commercial advantage, the ACM copyright notice and the title of the publication and its date appear, and notice is given that copying is by permission of the Association for Computing Machinery. To copy otherwiae, or to republish, requires a fee and/or specific permission.

Design of general/special purpose supercomputing VLSI systems for numeric algorithm execution involves tackling two important aspects, namely their computational and communication complexities. Development of software tools for designing such systems ...

The following work uses the writing of one of the most outstanding personalities of the Byzantine Empire, Michael Psellos (1018-1078?), as a conduit into the world of Byzantine astrology. The focus of the article is his celebrated chronicle, The Chronographia, which documents his life and experiences as an influential courtier at the Byzantine court in the eleventh century. Psellos was at the forefront of political life in the Empire and its fluctuating fortunes but somehow managed to combine these duties with a prodigious scholarly vocation. He taught extensively in both public and private capacities-he was appointed Consul of the Philosophers at the University of Constantinople-and was at the forefront of intellectual activity, touching on everything from theology to law, military strategy to esoterica. Psellos' writings on esoteric subjects of all sorts, including astrology and other related divinatory practices, are a true treasure trove of information for historians of astrology and practising astrologers alike. This article looks at a number of astrological and divinatory episodes in The Chronographia before the investigation broadens out to consider Psellos' relationship to astrology in detail in a variety of other sources. This context is very important because The Chronographia is an imperial commission and, like many of his contemporaries both before and after, Psellos had to toe the line of official disapproval of astrology. It is quite clear, however, that Psellos' curiosity and attraction to the subject is barely concealed beneath the surface text. For those who are unfamiliar with Byzantine history, the astrological episodes in The Chronographia throw much light on the niche occupied by astrology and astrologers in Byzantine culture. It may well surprise those readers who are accustomed to hearing of the achievements and activities of astrologers in the adjoining Arabic empire to be introduced to astrological activity in a Byzantine context which, if not as equally prolific, is never devoid of interest and relevance for historians of astrology. This work aims to offer a small corrective to the accepted notion of a moribund astrological culture in Byzantium. For all the work done by their Arabic counterparts in the Abbasid Dynasty, it still remains true that Hellenistic astrology was preserved and transmitted to posterity by the Byzantines.

The following work uses the writing of one of the most outstanding personalities of the Byzantine Empire, Michael Psellos (1018-1078?), as a conduit into the world of Byzantine astrology. The focus of the article is his celebrated chronicle, The Chronographia, which documents his life and experiences as an influential courtier at the Byzantine court in the eleventh century. Psellos was at the forefront of political life in the Empire and its fluctuating fortunes but somehow managed to combine these duties with a prodigious scholarly vocation. He taught extensively in both public and private capacities-he was appointed Consul of the Philosophers at the University of Constantinople-and was at the forefront of intellectual activity, touching on everything from theology to law, military strategy to esoterica. Psellos' writings on esoteric subjects of all sorts, including astrology and other related divinatory practices, are a true treasure trove of information for historians of astrology and practising astrologers alike. This article looks at a number of astrological and divinatory episodes in The Chronographia before the investigation broadens out to consider Psellos' relationship to astrology in detail in a variety of other sources. This context is very important because The Chronographia is an imperial commission and, like many of his contemporaries both before and after, Psellos had to toe the line of official disapproval of astrology. It is quite clear, however, that Psellos' curiosity and attraction to the subject is barely concealed beneath the surface text. For those who are unfamiliar with Byzantine history, the astrological episodes in The Chronographia throw much light on the niche occupied by astrology and astrologers in Byzantine culture. It may well surprise those readers who are accustomed to hearing of the achievements and activities of astrologers in the adjoining Arabic empire to be introduced to astrological activity in a Byzantine context which, if not as equally prolific, is never devoid of interest and relevance for historians of astrology. This work aims to offer a small corrective to the accepted notion of a moribund astrological culture in Byzantium. For all the work done by their Arabic counterparts in the Abbasid Dynasty, it still remains true that Hellenistic astrology was preserved and transmitted to posterity by the Byzantines.

İstanbul, as one of the most significant coastal cities of Turkey, has very unique cultural, historical, ecological and social dynamics. As the economic centre of the country, the city has been exposed to human attraction throughout centuries. However, in recent decades Istanbul has been experiencing rapid growths in population; this has instigated dramatic changes regarding the urban patterns, as well as the coastline of the city. Although some legal regulations had been arranged as a precaution to protect the uniqueness of the city's coastal areas, these efforts of conserving the coastline have been overruled by unforeseen planning actions, which resulted in more deformation in the last decades. In this paper, we aim to determine the coastline changes in İstanbul between 1852 and 2011 and unravel their correlation with the legal regulations implemented. As evidence for this argument, we will utilise historical maps and aerial photographs, these resources will be assessed with GIS overlapping technique to identify the differences in coastal lines. The coastlines in these zones have been grouped as 'natural, deformed or artificial' according to its physical characteristics. As a result, visuals are compared to show the change in the coastline's characteristics, and the relation of these changes to regulations will be discussed in each analysed year. The findings are expected to be used for further research on the assessment of lost or degraded change in coastal lines between 1852 and 2011.

İstanbul, as one of the most significant coastal cities of Turkey, has very unique cultural, historical, ecological and social dynamics. As the economic centre of the country, the city has been exposed to human attraction throughout centuries. However, in recent decades Istanbul has been experiencing rapid growths in population; this has instigated dramatic changes regarding the urban patterns, as well as the coastline of the city. Although some legal regulations had been arranged as a precaution to protect the uniqueness of the city's coastal areas, these efforts of conserving the coastline have been overruled by unforeseen planning actions, which resulted in more deformation in the last decades. In this paper, we aim to determine the coastline changes in İstanbul between 1852 and 2011 and unravel their correlation with the legal regulations implemented. As evidence for this argument, we will utilise historical maps and aerial photographs, these resources will be assessed with GIS overlapping technique to identify the differences in coastal lines. The coastlines in these zones have been grouped as 'natural, deformed or artificial' according to its physical characteristics. As a result, visuals are compared to show the change in the coastline's characteristics, and the relation of these changes to regulations will be discussed in each analysed year. The findings are expected to be used for further research on the assessment of lost or degraded change in coastal lines between 1852 and 2011.

Niklaus Wirth is not only a master of language design but also a pioneer of compiler construction. For four decades he has refined his techniques for building simple, efficient and reliable compilers. This paper tries to collect some general principles behind his work. It is not a paper about new compilation techniques but a reflection about Wirth's way to write compilers.

Leo, .I., A general context-free parsing algorithm running in linear time on every LR(k) grammar without using lookahead, Theoretical Computer Scic 2s; 82 :'13?1) ;tLiiti A new general context-free parsing algorithm is pre<.ented which runs in linear time and space on every LR( k) grammar without using any lookahead and without making use of the LR property. Most of the existing implementations of tabular parsing algorithms, including those using lookahead, can easily be adapted to this new algorithm without a noteworthy loss of efficiency. For some natural right recursive grammars both the time and space complexity will be improved from n( n') to O(n). This makes this algorithm not only of theoretical but probably of practical interest as well.

Dynamic languages, such as JavaScript, employ string-to-code primitives to turn dynamically generated text into executable code at run-time. These features make standard static analysis extremely hard if not impossible because its essential data structures, i.e., the control-flow graph and the system of recursive equations associated with the program to analyze, are themselves dynamically mutating objects. Nevertheless, assembling code at run-time by manipulating strings, such as by eval in JavaScript, has been always strongly discouraged since it is often recognized that "eval is evil", leading static analyzers to not consider such statements or ignoring their effects. Unfortunately, the lack of formal approaches to analyze string-to-code statements pose a perfect habitat for malicious code, that is surely evil and do not respect good practice rules, allowing them to hide malicious intents as strings to be converted to code and making static analyses blind to the real malicious aim of the code. Hence, the need to handle string-to-code statements approximating what they can execute, and therefore allowing the analysis to continue (even in presence of dynamically generated program statements) with an acceptable degree of precision, should be clear. In order to reach this goal, we propose a static analysis allowing us to collect string values and to soundly over-approximate and analyze the code potentially executed by a string-to-code statement.

TABLE OF CONTENTS I. INTRODUCTION 1 II. REVIEW OF THE LITERATURE % III. THE METAX METALANGUAGES I'* A. Developmental Rationale B. Bootstrapping C. The HETAX9 Metalanguage 1. Compiler definition commands 2. Elmentary syntactical commands 3. Metasyntactic elements 4. Semantic commands 5. Output operators 6-Error processing D. The METAX9 Pseudo-Machine 1. Primitive operations 2. Control stack 3. Symbol table structure 4.

We present a parsing technique which is a hybrid of Earley's method and the LR(k) methods. The new method retains the ability of Earley's method to parse using arbitrary context-free grammars. However, by using precomputed LR(k) sets of items, we obtain much faster recognition speeds while also reducing memory requirements.

In this paper, we argue firstly that researchers in critical computing should address the specific information and communication technology (ICT) needs and activities of those agencies concerned with emancipatory issues. Secondly, we argue that a critical perspective, explicitly foregrounding empowerment and emancipatory concerns, forms a basis for emphasising the practice of individuals, groups and organsations , rather than purely focusing on organisational form in social action. We discuss this context of social action, identifying some relevant ICT-related challenges. We identify three themes that highlight factors that differentiate ICT support for social action groups from the setting of conventional business and service organisations: Free / Libre Open-Source Software, techniques and technologies for engagement through storytelling, and learning and evaluation in social action.

For predicated code a number of predicate analysis systems have been developed like PHG, PQA or PAS. In optimizing compilers for (fully) predicated architectures like the Itanium® 2 processor, the primary application for such systems is global register allocation. This paper classifies predicated live ranges into four types, develops strategies based on classical dataflow analysis to allocate register candidates for all classes efficiently, and shows that the simplest strategy can achieve the performance potential provided by a PQSbased implementation. The gain achieved in the Intel® production compiler for the CINT2006 integer benchmarks is up to 37.6% and 4.48% in the geomean.

For predicated code a number of predicate analysis systems have been developed like PHG, PQA or PAS. In optimizing compilers for (fully) predicated architectures like the Itanium® 2 processor, the primary application for such systems is global register allocation. This paper classifies predicated live ranges into four types, develops strategies based on classical dataflow analysis to allocate register candidates for all classes efficiently, and shows that the simplest strategy can achieve the performance potential provided by a PQSbased implementation. The gain achieved in the Intel® production compiler for the CINT2006 integer benchmarks is up to 37.6% and 4.48% in the geomean.

The implementation of a parallel functional language is discussed. 2DTprograms are composed of local SPMD-computations and global transformations of 2-dimensional data structures leading to a coarse grain computecommunicate scheme. The implementation is made up of virtual processes doing the local computations and abstract processors emulating several virtual processes and taking care of communication. Code and data structures which are common to virtual processes are shared and allocated to abstract processes in order to make context switches cheap. Code that would be executed redundantly by logical processes is converted to abstract code and executed only once. Aims of this effort are maximizing the amount of parallelism, keeping communication cheap and managing parallelism efficiently.

The Reformation coincided with a boom in the publication of astrological almanacs and astrology became a potent means of propagandising for differing political positions. One of the most notable Reformation astrologers was Philipp Melanchthon (1497-1560), professor of Greek at Wittenberg from 1518, where he became one of Martin Luther's closest friends and collaborators. In 1521 he briefly found himself leader of the Reformation when Luther was confined in the Wartburg. His interest in astrology and his position at the centre of the Reformation raises important questions concerning the possible use of astrological forecasts of the Reformation's future course. Martin Luther's birth chart was to become a focus of debate amongst astrologers who wished to establish whether he was a new messiah or the Anti-Christ. The astrological debates concerning Luther's destiny took place in the context of an earlier prophecy which dated back to 1415, when Jan Hus, the Bohemian religious reformer, was burned at the stake. According to this prophecy a new reformer, perhaps even the Messiah, would be born a hundred years later, and when it was included in Johannes Lichtenberger's predictions, published in Heidelberg in 1488, it became part of the currency of late fifteenth century prognostication. Luther himself took this prophecy personally when he wrote that 'St. Johann Hus has prophesied about me, when in prison in Bohemia he wrote: they are roasting a goose [Hus = goose in Bohemian] now; but in a hundred years they are going to hear a swan sing for which they shall suffer. That it shall be, as God wants'. Naturally his enemies placed a different interpretation on the prophecy, for in their view the leader of the Reformation was in league with the Devil. The extent to which astrological forecasts may have influenced the general apocalyptic mood of the Reformation is still to be satisfactorily dealt with. When, for example, Luther nailed his 95 theses to the door of

The Reformation coincided with a boom in the publication of astrological almanacs and astrology became a potent means of propagandising for differing political positions. One of the most notable Reformation astrologers was Philipp Melanchthon (1497-1560), professor of Greek at Wittenberg from 1518, where he became one of Martin Luther&#39;s closest friends and collaborators. In 1521 he briefly found himself leader of the Reformation when Luther was confined in the Wartburg. His interest in astrology and his position at the centre of the Reformation raises important questions concerning the possible use of astrological forecasts of the Reformation&#39;s future course. Martin Luther&#39;s birth chart was to become a focus of debate amongst astrologers who wished to establish whether he was a new messiah or the Anti-Christ.

Within late medieval alchemical texts, Latin authors adopted both classical and Arabic concepts of physical matter. They assumed that metals were composed of two polarized substances -hot, dry and masculine Philosophic Sulphur, and cool, wet and feminine Philosophic Mercury -whose 'Chemical Wedding' within the laboratory produced the Philosophers' Stone. As visual illustrations developed in alchemical manuscripts and early printed books from the late fourteenth century onward, artists represented these substances with a variety of male and female characters, with Philosophic Mercury almost always depicted as a woman. At the same time, the planet Mercury, which oversaw the ripening of the metal Quicksilver within the earth, also played an important role within alchemical illustrations. This paper will examine how artists navigated this confusion by examining gendered images of the philosophical concept Mercury, the metal Mercury, and the planet Mercury, in light of shifting attitudes towards women in early modern science.

CompCert is a formally verified compiler for C that is specified, programmed and proved correct with the Coq proof assistant. CompCert was used in industry to compile critical embedded software. Its correctness proof states that the compiler does not introduce bugs. This semantic preservation property involves the formal semantics of the source and target languages of the compiler. Reasoning on C semantics to prove compiler correctness is challenging, as C is a real language that was not designed with semantics in mind. This paper presents the operational style that was designed for the C semantics of CompCert in order to facilitate the mechanized reasoning on terminating and diverging programs, and details the semantics of the Clight source language of CompCert.

Petra, the ancient Nabataean capital, has been one of our main research objectives since the first field campaign on site in 1996. 1 In December 2015 a new visit to the city was made to coincide with the winter solstice. Historical, ethnographic, epigraphic and archaeological records are compared in order to gain an insight on the Nabataean calendar. From this multi-source analysis two main points arise: the importance of both equinoxes and winter solstice within the lunisolar calendar and the relevance of some processions and pilgrimages. These combined with illumination effects observed and broadcasted at the principal monuments of Petra, and new important hierophanies, predicted in previous campaigns,2 indicate the relevance of these dates at the time of the Nabataeans. Winter solstice was an important event in the Nabataean cultic calendar when a festival of the main deities of the city, the God Dushara and his partner the goddess Al-Uzza, was commemorated. This probably took th...

This paper describes VTIstate, VLSI Technology&#x27;s state machine compiler. The compiler derives combinational logic and registers to make a state machine, and synthesizes the combinational logic with three optimization steps. The 1986 Design Automation conference synthesis benchmark set is used to compare the results with previously reported logic synthesis programs.

The general translator formalism and computing specific implementations are proposed. The implementation of specific elements necessary to process the source and destination information within the translators are presented. Some common directives or instructions, such as classes and procedures, were unified and generalized in order to allow general translations implementations. In order to cover general cases, two levels of processing are required, related to the source and destination information appropriate transformations, with the related control and processing instructions. The proposed general translator elements are useful for processing natural or artificial information described through any types of languages or systems.