Mehdi Jazayeri

The method of attributes for data flow analysis

SummaryThe importance of producing data flow information on demand is discussed. The method of attributes is applied to the demand analysis of live variables.Part I of this paper described the method of attributes, which is a technique for high level data flow analysis. In that paper, the method was applied to two well-known problems: analysis of dead variables and analysis of available expressions. Both of these analyses are called exhaustive because they uncover information for all program points.In this part, we apply the method of attributes to a problem in demand data flow analysis.

Space-Efficient Storage Management in an Attribute Grammar Evaluator

A space-efficient strategy for storing attributes during evaluation of an attribute grammar is presented. Attributes are classified as either one-pass or multipass. One-pass attributes are stored on a pushdown stack, and their storage is freed when no longer needed. Examination of extant grammars shows that a vast majority of attributes are indeed one-pass, and therefore the scheme presented can greatly reduce the storage requirements of an attribute grammar evaluator. Several approaches to storage management for multipass attributes are also presented. Data for several grammars are collected and used to show the effectiveness of the proposed storage management scheme.

An algorithm for hoisting

An approach to hoisting, a program optimization technique, is discussed. The safety and profitability of optimization in general and hoisting in particular is analyzed. By restricting the analysis to a spanning tree imposed on the program graph, a linear algorithm is developed that provides sufficient but not necessary conditions for hoisting. This linear algorithm is shown to provide necessary and sufficient conditions for hoisting in IF-THEN-BLSE statements.

A new approach to code motion and its application to hoisting

An approach to code motion and hoisting, a program optimization technique, is discussed. The safety and profitability of optimization in general and hoisting in particular are analyzed. By restricting the analysis to a spanning tree imposed on the program graph, a linear algorithm is developed that provides sufficient but not necessary conditions for hoisting.

Programmer productivity: program efficiency and improvement

As a solution to the problem of program maintenance, it is proposed to maintain a program in several versions. Relevant areas of current research are discussed.