In this paper we present a modular interprocedural pointer analysis algorithm based on access-paths for C programs. We argue that access paths can reduce the overhead of representing context-sensitive transfer functions and effectively distinguish non-recursive heap objects. And when the modular analysis paradigm is used together with other techniques to handle type casts and function pointers, we are able to handle significant programs like those in the SPECcint92 and SPECcint95 suites. We have implemented the algorithm and tested it on a Pentium II 450 PC running Linux. The observed resource consumption and performance improvement are very encouraging.

The Marmot system is a research platform for studying the implementation of high level programming languages. It currently comprises an optimizing native-code compiler, runtime system, and libraries for a large subset of Java. Marmot integrates well-known representation, optimization, code generation, and runtime techniques with a few Java-specific features to achieve competitive performance. This paper contains a description of the Marmot system design, along with highlights of our experience applying and adapting traditional implementation techniques to Java. A detailed performance evaluation assesses both Marmot's overall performance relative to other Java and C++ implementations and the relative costs of various Java language features in Marmot-compiled code. Our experience with Marmot has demonstrated that well-known compilation techniques can produce very good performance for static Java applications---comparable or superior to other Java systems, and approaching that o...

Speculative multithreading (SpMT) promises to be an effective mechanism for parallelizing non-numeric programs, which tend to use irregular data structures with pointers and have complex flows of control. Proper thread selection is crucial to obtaining good speedup in an SpMT system. This paper presents a compiler framework for partitioning a sequential program into multiple threads for parallel execution in an SpMT system. This framework is very general, and support a wide variety of threads, such as speculative threads, non-speculative threads, loop-centric threads, and out-of-order thread spawning. To do efficient partitioning, the compiler uses profiling, intra-procedural pointer analysis, data dependence information and control dependence information. Our compiler framework is implemented on the SUIF-MachSUIF platform, and is able to partition large programs, such as the SPEC benchmarks. A simulation-based evaluation of the generated threads shows that an average speedup of 3 can be obtained with 6 processing elements for non-numeric programs. This speedup reduces to 2 if we use only loop-based threads.

Programmers confront a minefield when they design interactive Web programs. Web interactions take place via Web browsers. With browsers, consumers can whimsically navigate among the various stages of a dialog and can thus confuse the most sophisticated corporate Web sites. In turn, Web services can fault in frustrating and inexplicable ways. The quickening transition from Web scripts to Web services lends these problems immediacy.

. We describe a system which decompiles (reverse engineers) C programs from target machine code by type-inference techniques. This extends recent trends in the converse process of compiling high-level languages whereby type information is preserved during compilation. The algorithms remain independent of the particular architecture by virtue of treating target instructions as register-transfer specications. Target code expressed in such RTL form is then transformed into SSA form (undoing register colouring etc.); this then generates a set of type constraints. Iteration and recursion over data-structures causes synthesis of appropriate recursive C structs; this is triggered by and resolves occurscheck constraint violation. Other constraint violations are resolved by C's casts and unions. In the limit we use heuristics to select between equally suitable C code|a good GUI would clearly facilitate its professional use. 1 Introduction Over the last forty years there has been much work on ...

We present # CIL , a typed #-calculus which serves as the foundation for a typed intermediate language for optimizing compilers for higher-order polymorphic programming languages. The key innovation of # CIL is a novel formulation of intersection and union types and flow labels on both terms and types. These flow types can encode polyvariant control and data flow information within a polymorphically typed program representation. Flow types can guide a compiler in generating customized data representations in a strongly typed setting. Since # CIL enjoys confluence, standardization, and subject reduction properties, it is a valuable tool for reasoning about programs and program transformations.

A linear time algorithm is presented for finding dominators in control flow graphs.

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We present an interprocedural and compositional algorithm for nding pairs of compatible allocation sites, which have the property that no object allocated at one site is live at the same time as any object allocated at the other site. If an allocation site is compatible with itself, it is said to be unitary : at most one object allocated at that site is live at any given point in the execution of the program. We use the results of the analysis to statically preallocate memory space for the objects allocated at unitary sites, thus simplifying the computation of an upper bound on the amount of memory required to execute the program. We also use the analysis to enable objects allocated at several compatible allocation sites to share the same preallocated memory. Our experimental results show that, for our set of Java benchmark programs, 60% of the allocation sites are unitary and can be statically preallocated. Moreover, allowing compatible unitary allocation sites to share the same preallocated memory leads to a 95% reduction in the amount of memory preallocated for these sites.

This paper explores the concept of loops and loop nesting forests of control-flow graphs, using the problem of constructing the dominator tree of a graph and the problem of computing the iterated dominance frontier of a set of vertices in a graph as guiding applications. The contributions of this paper include: (1) An axiomatic characterization, as well as a constructive characterization, of a family of loop nesting forests that includes various specific loop nesting forests that have been previously defined. (2) The definition of a new loop nesting forest, as well as an e#cient, almost linear time, algorithm for constructing this forest. (3) An illustration of how loop nesting forests can be used to transform arbitrary (potentially irreducible) problem instances into equivalent acylic graph problem instances in the case of the two problems of (a) constructing the dominator tree of a graph, and (b) computing the iterated dominance frontier of a set of vertices in a graph, leading to new, almost linear time, algorithms for these problems