Semantics Directed Compiler Generation Research Articles

Natural Semantics-Directed Generation of Compilers and Abstract Machines

Abstract. In this paper we present the motivation, theory and transformations of our semantics-directed compiler generator. The main novelty of our generator is that it generates compilers and abstract machines. The execution times of the abstract machine programs produced by our generated compiler compare well to those of target programs produced by compilers generated by other semantics-directed generators. The generated specifications of compilers and abstract machines are suitable as a starting point for handwriting compilers and abstract machines. Our generator is fully automated and its core transformations are proved correct.

Realistic compilation by partial evaluation

Two key steps in the compilation of strict functional languages are the conversion of higher-order functions to data structures ( closures ) and the transformation to tail-recursive style. We show how to perform both steps at once by applying first-order offline partial evaluation to a suitable interpreter. The resulting code is easy to transliterate to low-level C or native code. We have implemented the compilation to C; it yields a performance comparable to that of other modern Scheme-to-C compilers. In addition, we have integrated various optimizations such as constant propagation, higher-order removal, and arity raising simply by modifying the underlying interpreter. Purely first-order methods suffice to achieve the transformations. Our approach is an instance of semantics-directed compiler generation.

Transformations of denotational semantics in semantics directed compiler generation

In semantics-directed compiler generation one is faced with the problem of how to translate a source semantic definition of a programming language into on equivalent target semantics closer to an implementation. Most of the existing works solve this problem in a non constructive way : a target semantics is exhibited first and then only proved correct against the source. We try to show that target semantics can be derived from source semantics in a constructive way and so that some correctness ideas are automatically preserved. The framework is denotational semantics.

Pebble games for studying storage sharing

Pebble games are played on a directed acyclic graph (dag). Placing a pebble on a vertex may be thought of as entering the value of the subexpression represented by the vertex into accessible storage. In some applications, there are types associated with vertices e.g. some vertices may represent functions, others may represent function values. We are interested in determining if vertices of the same type can share storage. The problem considered is as follows. We are given a labelled dag to be pebbled. A pebble may be placed on a vertex if all sons of the vertex have pebbles—in fact it is legal to move a pebble from a son to a father. Pebbles may be picked up at any time. The objective is to pebble each vertex exactly once. We will be interested in ‘one pebblings of l vertices’ in which there is at most one pebble on vertices with label l, at all times; and ‘stack pebblings of l vertices’ in which the pebbled vertices with label l are along a path, at all times. Results about the existence of such pebblings are presented. The results have applications to testing serializability of database updates, and potential applications to semantics directed compiler generation.

Mathematical Foundation of A Semantic Directed Compiler Generator

<p>This paper describes technical details which were not included in the paper ''Control Flow Treatment in a Simple Semantics-Directed Compiler Generator'', presented at the IFIP working conference on Formal Description of Programming Concepts, Germany, 1982, due to lack of space. The present paper cannot be read separately.</p><p>We describe our method in full detail, including the <em>iterate</em>-operator in the S-algebra. Furthermore we give complete formal descriptions of the semantic algebra S and its models (Section 1), the compiler generation function d^c and the compile time interpretation J (Section 2), the target language semantics (Section 3), and in Section 4 the correctness proof.</p>

Circular expressions: elimination of static environments

Consider the connection between denotational semantics for a language with goto statements and flow diagrams for programs in such a language. The main point of interest is that the denotational semantics uses a recursively defined environment to give the meaning of labels, while a flow diagram merely has a jump to the appropriate program point. A simple reduction called “indirection elimination” strips away the environment from the denotational semantics and extracts an expression with cycles that is very close to the flow diagram of a program. The same idea applies to associating bodies with recursive procedures, or to any construct whose semantics is not wedded to the syntax. In addition to being a useful data structure and conceptual device, expressions with cycles are well defined mathematical objects—their semantics can be given by unfolding them into infinite structures that have been well studied. The practicality of the elimination of environments has been tested by constructing a trial implementation, which serves as the front end of a semantics directed compiler generator. The implementation takes a denotational semantics of a language and constructs a “black box” that maps programs in the language into an intermediate representation. The intermediate representation is a circular expression.