The aliasing question (can two reference expressions point, during an execution, to the same object?) is both one of the most critical in practice, for applications ranging from compiler optimization to programmer verification, and one of the most heavily researched, with many hundreds of publications over several decades. One might then expect that good off-the-shelf solutions are widely available, ready to be plugged into a compiler or verifier. This is not the case. In practice, efficient and precise alias analysis remains an open problem. We present a practical tool, AutoAlias, which can be used to perform automatic alias analysis for object-oriented programs. Based on the theory of “duality semantics”, an application of Abstract Interpretation ideas, it is directed at object-oriented languages and has been implemented for Eiffel as an addition to the EiffelStudio environment. It offers variable-precision analysis, controllable through the choice of a constant that governs the number of fixpoint iterations: a higher number means better precision and higher computation time. All the source code of AutoAlias, as well as detailed results of analyses reported in this article, are publicly available. Practical applications so far have covered a library of data structures and algorithms and a library for GUI creation. For the former, AutoAlias achieves a precision appropriate for practical purposes and execution times in the order of 25 s for about 8000 lines of intricate code. For the GUI library, AutoAlias produces the alias analysis in around 232 s for about 150,000 lines of intricate code.
Software engineers are faced with a dilemma. They want to write general and wellstructured programs that are flexible and easy to maintain. On the other hand, generality has a price: efficiency. A specialized program solving a particular problem is often significantly faster than a general program. However, the development of specialized software is time-consuming, and is likely to exceed the production of today’s programmers. New techniques are required to solve this so-called software crisis. Partial evaluation is a program specialization technique that reconciles the benefits of generality with efficiency. This thesis presents an automatic partial evaluator for the Ansi C programming language. The content of this thesis is analysis and transformation of C programs. We develop several analyses that support the transformation of a program into its generating extension. A generating extension is a program that produces specialized programs when executed on parts of the input. The thesis contains the following main results. • We develop a generating-extension transformation, and describe specialization of the various parts of C, including pointers and structures. • We develop constraint-based inter-procedural pointer and binding-time analysis. Both analyses are specified via non-standard type inference systems, and implemented by constraint solving. • We develop a side-effect and an in-use analysis. These analyses are developed in the classical monotone data-flow analysis framework. Some intriguing similarities with constraint-based analysis are observed. • We investigate separate and incremental program analysis and transformation. Realistic programs are structured into modules, which break down inter-procedural analyses that need global information about functions. • We prove that partial evaluation at most can accomplish linear speedup, and develop an automatic speedup analysis. • We study the stronger transformation technique driving, and initiate the development of generating super-extensions. The developments in this thesis are supported by an implementation. Throughout the chapters we present empirical results.