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59
An open graph visualization system and its applications to software engineering
 SOFTWARE  PRACTICE AND EXPERIENCE
, 2000
"... We describe a package of practical tools and libraries for manipulating graphs and their drawings. Our design, which aimed at facilitating the combination of the package components with other tools, includes stream and event interfaces for graph operations, highquality static and dynamic layout alg ..."
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Cited by 309 (9 self)
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We describe a package of practical tools and libraries for manipulating graphs and their drawings. Our design, which aimed at facilitating the combination of the package components with other tools, includes stream and event interfaces for graph operations, highquality static and dynamic layout algorithms, and the ability to handle sizable graphs. We conclude with a description of the applications of this package to a variety of software engineering tools.
Lazy Code Motion
, 1992
"... We present a bitvector algorithm for the optimal and economical placement of computations within flow graphs, which is as efficient as standard unidirectional analyses. The point of our algorithm is the decomposition of the bidirectional structure of the known placement algorithms into a sequenc ..."
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Cited by 157 (20 self)
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We present a bitvector algorithm for the optimal and economical placement of computations within flow graphs, which is as efficient as standard unidirectional analyses. The point of our algorithm is the decomposition of the bidirectional structure of the known placement algorithms into a sequence of a backward and a forward analysis, which directly implies the efficiency result. Moreover, the new compositional structure opens the algorithm for modification: two further unidirectional analysis components exclude any unnecessary code motion. This laziness of our algorithm minimizes the register pressure, which has drastic effects on the runtime behaviour of the optimized programs in practice, where an economical use of registers is essential.
Contrastive estimation: Training loglinear models on unlabeled data
 In Proc. of ACL
, 2005
"... Conditional random fields (Lafferty et al., 2001) are quite effective at sequence labeling tasks like shallow parsing (Sha and Pereira, 2003) and namedentity extraction (McCallum and Li, 2003). CRFs are loglinear, allowing the incorporation of arbitrary features into the model. To train on unlabele ..."
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Cited by 115 (14 self)
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Conditional random fields (Lafferty et al., 2001) are quite effective at sequence labeling tasks like shallow parsing (Sha and Pereira, 2003) and namedentity extraction (McCallum and Li, 2003). CRFs are loglinear, allowing the incorporation of arbitrary features into the model. To train on unlabeled data, we require unsupervised estimation methods for loglinear models; few exist. We describe a novel approach, contrastive estimation. We show that the new technique can be intuitively understood as exploiting implicit negative evidence and is computationally efficient. Applied to a sequence labeling problem—POS tagging given a tagging dictionary and unlabeled text—contrastive estimation outperforms EM (with the same feature set), is more robust to degradations of the dictionary, and can largely recover by modeling additional features. 1
Optimal Code Motion: Theory and Practice
, 1993
"... An implementation oriented algorithm for lazy code motion is presented that minimizes the number of computations in programs while suppressing any unnecessary code motion in order to avoid superfluous register pressure. In particular, this variant of the original algorithm for lazy code motion works ..."
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Cited by 112 (18 self)
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An implementation oriented algorithm for lazy code motion is presented that minimizes the number of computations in programs while suppressing any unnecessary code motion in order to avoid superfluous register pressure. In particular, this variant of the original algorithm for lazy code motion works on flowgraphs whose nodes are basic blocks rather than single statements, as this format is standard in optimizing compilers. The theoretical foundations of the modified algorithm are given in the first part, where trefined flowgraphs are introduced for simplifying the treatment of flowgraphs whose nodes are basic blocks. The second part presents the `basic block' algorithm in standard notation, and gives directions for its implementation in standard compiler environments. Keywords Elimination of partial redundancies, code motion, data flow analysis (bitvector, unidirectional, bidirectional), nondeterministic flowgraphs, trefined flow graphs, critical edges, lifetimes of registers, com...
Combining Analyses, Combining Optimizations
, 1995
"... This thesis presents a framework for describing optimizations. It shows how to combine two such frameworks and how to reason about the properties of the resulting framework. The structure of the framework provides insight into when a combination yields better results. Also presented is a simple iter ..."
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Cited by 74 (4 self)
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This thesis presents a framework for describing optimizations. It shows how to combine two such frameworks and how to reason about the properties of the resulting framework. The structure of the framework provides insight into when a combination yields better results. Also presented is a simple iterative algorithm for solving these frameworks. A framework is shown that combines Constant Propagation, Unreachable Code Elimination, Global Congruence Finding and Global Value Numbering. For these optimizations, the iterative algorithm runs in O(n^2) time.
This thesis then presents an O(n log n) algorithm for combining the same optimizations. This technique also finds many of the common subexpressions found by Partial Redundancy Elimination. However, it requires a global code motion pass to make the optimized code correct, also presented. The global code motion algorithm removes some Partially Dead Code as a sideeffect. An implementation demonstrates that the algorithm has shorter compile times than repeated passes of the separate optimizations while producing runtime speedups of 4%–7%.
While global analyses are stronger, peephole analyses can be unexpectedly powerful. This thesis demonstrates parsetime peephole optimizations that find more than 95% of the constants and common subexpressions found by the best combined analysis. Finding constants and common subexpressions while parsing reduces peak intermediate representation size. This speeds up the later global analyses, reducing total compilation time by 10%. In conjunction with global code motion, these peephole optimizations generate excellent code very quickly, a useful feature for compilers that stress compilation speed over code quality.
SEMIRING FRAMEWORKS AND ALGORITHMS FOR SHORTESTDISTANCE PROBLEMS
, 2002
"... We define general algebraic frameworks for shortestdistance problems based on the structure of semirings. We give a generic algorithm for finding singlesource shortest distances in a weighted directed graph when the weights satisfy the conditions of our general semiring framework. The same algorit ..."
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Cited by 72 (20 self)
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We define general algebraic frameworks for shortestdistance problems based on the structure of semirings. We give a generic algorithm for finding singlesource shortest distances in a weighted directed graph when the weights satisfy the conditions of our general semiring framework. The same algorithm can be used to solve efficiently classical shortest paths problems or to find the kshortest distances in a directed graph. It can be used to solve singlesource shortestdistance problems in weighted directed acyclic graphs over any semiring. We examine several semirings and describe some specific instances of our generic algorithms to illustrate their use and compare them with existing methods and algorithms. The proof of the soundness of all algorithms is given in detail, including their pseudocode and a full analysis of their running time complexity.
Elimination algorithms for data flow analysis
 ACM Computing Surveys
, 1986
"... A unified model of a family of data flow algorithms, called elimination methods, is presented. The algorithms, which gather information about the definition and use of data in a program or a set of programs, are characterized by the manner in which they solve the systems of equations that describe d ..."
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Cited by 53 (8 self)
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A unified model of a family of data flow algorithms, called elimination methods, is presented. The algorithms, which gather information about the definition and use of data in a program or a set of programs, are characterized by the manner in which they solve the systems of equations that describe data flow problems of interest. The unified model
The Integration Project for the JACK Environement
 BULLETIN OF THE EATCS
, 1994
"... JACK, standing for Just Another Concurrency Kit, is a new environment integrating a set of verification tools, supported by a graphical interface offering facilities to use these tools separately or in combination. The environment proposes several functionalities for the design, analysis and verif ..."
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Cited by 35 (12 self)
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JACK, standing for Just Another Concurrency Kit, is a new environment integrating a set of verification tools, supported by a graphical interface offering facilities to use these tools separately or in combination. The environment proposes several functionalities for the design, analysis and verification of concurrent systems specified using process algebra. Tools exchange information through a text format called Fc2. Users are able to graphically layout their specifications, that will be automatically converted into the Fc2 format and then minimised with respect to various kinds of equivalences. A branching time and action based logic, ACTL, is used to describe the properties that the specification must satisfy, and model checking of ACTL formulae on the specification is performed in linear time. A translator from Natural Language to ACTL formulae is provided, in order to simplify the job to describe the specification properties by ACTL formulae. A description of the graphical interface is given together with its functionalities and the exchange format used by the tools. As an example of use of JACK, we present a small case study within JACK, that covers both verification of a software system and verification of its properties.
Interprocedural optimization: eliminating unnecessary recompilation
 ACM Transactions on Programming Languages and Systems
, 1993
"... While efficient new algorithms for interprocedural dataflow analysis have made these techniques practical for use in production compilation systems,a new problem has arisen: collecting and using interprocedural information in a compiler introduces subtle dependence among the proceduresof a program. ..."
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Cited by 35 (4 self)
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While efficient new algorithms for interprocedural dataflow analysis have made these techniques practical for use in production compilation systems,a new problem has arisen: collecting and using interprocedural information in a compiler introduces subtle dependence among the proceduresof a program. If the compiler dependson interprocedural information to optimize a given module, a subsequentediting changeto another module in the program may changethe interprocedural information and necessitaterecompilation. To avoid having to recompile every module in a program in responseto a single editing changeto one module, we have developed techniquesto more precisely determine which compilations have actually beeninvalidated by a changeto the program’s source.This paper presents a general recoinpzlatton test to determine which proceduresmust be compiled in responseto a series of editing changes.Three different implementation strategies, which demonstrate the fundamental tradeoff between the cost of analysis and the precision of the resulting test, are also discussed.