Hierarchical VLSI design systems based on attribute grammars

Abstract

The attribute grammar technique used for design of structure editors is suggested as a foundation for building hierarchical incremental design editors for VLSI circuits.The usual definition of attribute grammars is extended: the cycles that occur in VLSI design make us come to terms with circuiar attributes (under conditions that guarantee their least fixpoint solution, namely that the functions be monotone and yield values over a lattice of bounded height). Many interesting VLSI design problems can be cast in attributes meeting this condition, for example, timing verification, logic simulation, power dissipation, and adherence to clocking disciplines, to name a few. .As an illustration of the formalism, attributes are presented which solve the All Bidirectional Edges problem that labels the direction of information flow in a circuit. The incremental evaluation algorithm of [Rep821 is extended to handle fixpoint computations of circular attributes by noting that when the dependency graph is broken into its strongly connected components, a directed acyclic graph results, The wors~:ease running time of the resulting incremental evaluation algorithm is bounded by O (kk tAFFECTEDSCCD, where h is the height of the largest attribute lattice, k the largest number of attributes in any one strongly connected component, and ]A.FFEC-TEDSCC 1 the number of strongly connected components affected by a single modification to the design tree.to IntroductionIt has been suggested that the programming process carl be improved by the use of str.uet~Lre editors, as a means to remove the possibility of syntactic and semantic errors and to allow the programmer to concentrate on the design of correct and efficient algorithms. A number of structure editors [TeR81] [JoF82] have been implemented using attribute grammara [Knu68a] which bind semantics to the syntax of the target programming language, and have been shown to be an efficient, natural method for the operations required by an interactive editor [Rep82]. Structure editors based on attribute grammars can exploit the strict hierarchy given by the grammatical structure of the programs.Hierarchies also arise in VLSI design: it is well known that hierarchical design techniques facilitate the design of complicated VLSI projects. Several systems have been developed that take advantage of this to provide the user the ability to abstract and hide details of circuit, design as wall as simptify the verification process. Some systems have even attempted to provide the user with feedback about the correctness of design [OHM84} [MEW781 The purpose of this paper is to suggest that the problem of designing correct VLSt circuits can be simplified through the use of a hierarchical incremental design editor based on attribute grammars. Such a system could interactively compute estimates for the speed and power dissipation of a circuit, check adherence to clocking disciplines [SeiS01 [Kar84], and recompute these at reasonable cost as the designer changes the circuit, uses new modules, subsystems or ...

Management of Constraints in Vlsi Data Bases

“…This paper has not discussed issues of circularity (Jones and Simon, 1986;Farrow, 1986)t and nonmonotonic semantic functions. The experiment detThe application of AGs to VLSI circuit analysis presented by Jones and Simon (1986) was not known to the author at the time of this research.…”

“…The experiment detThe application of AGs to VLSI circuit analysis presented by Jones and Simon (1986) was not known to the author at the time of this research. This paper describes experimental results of applying AGs to VLSI.…”

Combine and Conquer

“…Attribute grammars [23] are much studied and have applications in areas such as language-based editor [32], [3] and VLSI design [20]. Incremental algorithms for attribute grammars have been presented [31], [19] which give an O(a · t) running time per operation where a is the number of attributes affected by a change and t is the time to make a single change.…”

On the optimality of change propagation for incremental evaluation of hierarchical attribute grammars

“…The meaning of a syntax tree defined by an attribute grammar is the value that results from explicitly constructing the computation graph for the syntax tree according to the attribute grammar specification and then evaluating the computation graph. The majority of the research into incremental evaluation of attribute grammars has concentrated on tree-walking evaluation algorithms [Hoover 1987;Jia and Qian 1985;Jones 1990;Jones and Simon 1986;Reps 1984;Reps et al 1983;Walz and Johnson 1988;Yeh 1983;Yeh and Kastens 1988]. A tree-walking evaluator traverses a syntax tree computing attribute values that are then stored in cells associated with each of the syntax tree nodes.…”