The design of a language processor generator

Language processor generators are systems that produce various language processors (including compilers) on the basis of a high-level specification. The design of language processor generators is discussed on the basis of experiments with a traditional compiler writing system (HLP78) employing pore LALR parsing and general attribute grammars. It is argued that these methods are too primitive from the practical point of view. The design of a new language processor generator, HLP84, is based on this view. This system is an attempt to provide high-level tools for a restricted class of applications (one-pass analysis). The syntactic facilities include regular expressions on the right-hand sides of productions, a disambiguating mechanism that is integrated with regular expressions, and a mechanism for using semantic information to aid parsing. The semantic facilities include automatic support for semantic error handling and for symbol tables. Early experiences with the new system show that in spite of the general overhead caused by the higher automation level, the system allows the generation of reasonably efficient processors.     

A pattern matching macro processor

A general-purpose pattern matching macro processor is described. Macro patterns can be defined using regular expressions. Macro calls are treated by balancing pattern matching at the token unit level, allowing options, alternatives and repetition. Thus, text in a language with a nested structure can be dealt with. In a macro body, Algol-style macro-time operations are allowed, which improves writing and reading. Our macro processor can also be used as a tool for language conversion since it incorporates a feature to declare language-dependent constructs such as comments, string notations and parentheses pairs. Although our macro processor is not biased towards any particular language, it has successfully converted an Algol 68-style text into a Fortran text. Problems of language conversion using macros are briefly discussed based upon the experience obtained through this macro processor.     

New Functionalities of the System for Processing Natural Language Specifications and its Operating Environment

This paper describes the operating environment of the language processor intended for processing behavioral models of systems represented in natural language. This environment provides the tuning of the language processor; the main stage of this tuning is the construction of a syntactic table. An approach is proposed for automating the construction of grammar rules intended for replenishment of the syntactic table used by the language processor.     

An embedded implementation of the Common Language Infrastructure

The Common Language Infrastructure provides a unified instruction set which may be targeted by a variety of high level language compilers. This unified instruction set simplifies the construction of compilers and gives application designers the ability to choose the high level programming language that best suits the problem being solved. While the Common Language Infrastructure solves many problems related to design of applications and compilers, it is not without its own problems. The Common Language Infrastructure is based upon a virtual machine, much like the Java Virtual Machine. This requires that all instructions being executed on the Common Language Infrastructure be translated to native machine instructions before they can be executed on the host processor. This leads to degradation in performance. In order to overcome this problem it is proposed that an embedded processor capable of natively executing the CLI instruction set be developed. The objective of this work is the design and implementation, using VHDL and simulation, of an embedded processor capable of natively executing the CLI instruction set. This processor provides a platform easily targeted by software developers.     

基于IDA处理器模块扩充的描述语言建立

目前的IDA不能支持所有处理器模型的反汇编。为此,给出一种适用于IDA处理器模块自动生成的反汇编描述语言,为IDA处理器模块插件的扩充提供支持。该描述语言采用基于上下文无关文法的属性文法表现形式,包括对处理器存储系统的声明以及对处理器指令集的语法和语义描述。应用结果表明,该方法适用于IDA处理器模块插件的扩充。     

Semantic equivalence of covering attribute grammars

This paper investigates some methods for proving the equivalence of different language specifications that are given in terms of attribute grammars. Different specifications of the same language may be used for different purposes, such as language definition, program verification, or language implementation. The concept of syntactic coverings is extended to the semantic part of attribute grammars. Given two attribute grammars, the paper discusses several propositions that give sufficient conditions for one attribute grammar to be semantically covered by the other one. These tools are used for a comparison of two attribute grammars that specify syntax and semantics of mixed-type expressions. This example shows a trade-off between the complexity of syntactic and semantic specifications. Another example discussed is the equivalence of different attribute grammars for the translation of the while-statement, as used in compilers for top-down and bottom-up syntax analysis.This work was in part supported by the National Research Council of Canada.     

Modelling of space-efficient one-pass translation using attribute grammars

Automatic production of one-pass compilers from attribute grammars is considered. An examination of a one-pass grammar for the programming language Euclid shows that the present definition of one-pass grammars is too general: the space behaviour of the produced compilers differs from that found in conventional hand-written compilers. A new class of attribute grammars is defined. The class models naturally the use of space in a hand-written compiler. This implies that the compiler produced automatically on the basis of the grammar uses space in the same way as a practical hand-written recursive descent compiler. Furthermore, a graphical notation is introduced as a design tool for obtaining grammars in the proposed class.     

基于多核处理器的并行编程模型

为解决传统编程模型与并行架构间存在的矛盾,针对多媒体和网络应用程序的特点,提出一种基于多核处理器的并行编程模型,该模型采用节点化的并行程序描述方式,将并行编译器划分到多个核上运行。实验结果表明,这种新的并行编程模型能有效提高程序的执行效率。     

Relational Interpretations of Recursive Types in an Operational Setting

Relational interpretations of type systems are useful for establishing properties of programming languages. For languages with recursive types it is difficult to establish the existence of a relational interpretation. The usual approach is to pass to a domain-theoretic model of the language and, exploiting the structure of the model, to derive relational properties of it. We investigate the construction of relational interpretations of recursive types in a purely operational setting, drawing on recent ideas from domain theory and operational semantics as a guide. We prove syntactic minimal invariance for an extension of PCF with a recursive type, a syntactic analogue of the minimal invariance property used by Freyd and Pitts to characterize the domain interpretation of a recursive type. As Pitts has shown in the setting of domains, syntactic minimal invariance suffices to establish the existence of relational interpretations. We give two applications of this construction. First, we derive a notion of logical equivalence for expressions of the language that we show coincides with experimental equivalence and which, by virtue of its construction, validates useful induction and coinduction principles for reasoning about the recursive type. Second, we give a relational proof of correctness of the continuation-passing transformation, which is used in some compilers for functional languages.     

Deriving a compiler from an operational semantics written in VDL

This paper addresses the issue of compiler correctness. The approach taken is to systematically construct a correct compiler for a language from a formal semantic definition of the language. For this purpose, an operational semantics of a language is chosen as the basis for the approach. That is, the compiler for a language is derived from an interpreter of the language. The derivation process uses the notion of mixed computation proposed by Ershov. Briefly stated, one begins interpreting and when a primitive state changing instruction is about to be executed, the instruction is emitted as code instead. The correctness of all compilers produced by the method is guaranteed by proving the derivation rules correct. This proof is a one-time task for each specification language. The specification language studied in this paper is the Vienna Definition Language (VDL). The object code generated by the compiler is in an intermediate language close to an assembly language. Therefore, the translation from the intermediate language into the assembly language should be straightforward.     

Portability—some experiences with FORTRAN

During the development of a portable problem-oriented language processor a number of unexpected difficulties and incompatibilities in various FORTRAN compilers were encountered. These are related, and an approach which minimizes the problems suggested.     

PIT: A macro-implemented implementation language

An implementation technique called PIT, for pseudo instructional technique, is described which utilizes the macro capabilities of most macro assemblers. A low level machine architecture is described via a set of macros that include some ‘high level’ features. Since the macros manipulate computer words, and refer to actual registers, their implementation in a system is relatively efficient, but since they do not reflect any one particular hardware design, they can be implemented by almost any macro assembler. Tests are built into the macros so that a PIT program will run without change on any machine that has defined these macros This technique should provide an alternative to using higher level languages as implementation languages if the object code produced by those compilers is deemed too slow (or too large) for the application that is being programmed.