The design and specification of an extensible class library presents a difficult challenge: because extensibility comes from allowing the user to override parts of the implementation, more of the internal structure mu...
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ISBN:
(纸本)0897915399
The design and specification of an extensible class library presents a difficult challenge: because extensibility comes from allowing the user to override parts of the implementation, more of the internal structure must be exposed to the user than in a typical procedure library. This raises issues in both how the library is designed and how its specification is written. Specification of the CLOS Metaobject Protocol required a combination of new and existing techniques to address these issues. We present those techniques, and discuss their relation to the underlying issues.
This paper examines a problem that arises during global register allocation - rematerialization. If a value cannot be kept in a register, the allocator should recognize when it is cheaper to recompute the value (remat...
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ISBN:
(纸本)0897914759
This paper examines a problem that arises during global register allocation - rematerialization. If a value cannot be kept in a register, the allocator should recognize when it is cheaper to recompute the value (rematerialize it) than to store and reload it. Chaitin's original graph-coloring allocator handled simple instances of this problem correctly. This paper details a general solution to the problem and presents experimental evidence that shows its importance. Our approach is to tag individual values in the procedure's SSA graph with information specifying how it should be spilled. We use a variant of Wegman and Zadeck's sparse simple constant algorithm to propagate tags throughout the graph. The allocator then splits live ranges into values with different tags. This isolates those values that can be easily rematerialized from values that require general spilling. We modify the base allocator to use this information when estimating spill costs and introducing spill code. Our presentation focuses on rematerialization in the context of Chaitin's allocator;however, the problem arises in any global allocator. We believe that our approach will work in other allocators - while the details of implementation will vary, the key insights should carry over directly.
The practical value of research involving the abstract interpretation of Prolog programs was examined experimentally. The design and implementation of the generic abstract interpretation algorithm originally proposed ...
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ISBN:
(纸本)0818625856
The practical value of research involving the abstract interpretation of Prolog programs was examined experimentally. The design and implementation of the generic abstract interpretation algorithm originally proposed by B. Le Charlier (1991), its instantiation in a sophisticated abstract domain containing modes, types, sharing, and aliasing, and its evaluation in terms of performance and accuracy are described. The overall implementation (over 5000 lines of Pascal) was systematically analyzed on a variety of programs. The experimental results, given the abstract domain and the programs analyzed, indicate that (1) the number of iterations of the algorithm is bounded by 7.5 × N and is in most cases smaller than 3 × N, where N is the size of the analyzed program (e.g., the number of program points);(2) the CPU time in seconds is bounded by N and is in most cases smaller than 0.6 × N;(3) the algorithm explores few elements (less than 11% and often none) outside the subset of the fixpoint required to answer the query and hence is close to optimality;and (4) the results are quite accurate and could be used in a Prolog compiler.
These are the highlights of a successfully completed application of object-oriented software development for a new product. The project was of medium size, the duration was less than 24 months (from the end of the req...
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ISBN:
(纸本)0201533723
These are the highlights of a successfully completed application of object-oriented software development for a new product. The project was of medium size, the duration was less than 24 months (from the end of the requirements specification to product shipment), and the average team size was 8-10 software engineers. We discuss how the team dealt with major new aspects: a different paradigm, a different programminglanguage, a different user interface environment, and a different development environment. In spite of all these novelties and in spite of the fact that almost twice as much code was produced as was predicted, the project schedule slipped only by 20%. We touch upon all phases of the development life cycle: requirement capture, OO analysis, OO design, OO implementation and the verification phase. Some management perspectives are addressed as well.
Even though impressive progress has been made in the area of optimizing and parallelizing programs with arrays, the application of similar techniques to programs with pointer data structures has remained difficult. In...
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ISBN:
(纸本)0897914759
Even though impressive progress has been made in the area of optimizing and parallelizing programs with arrays, the application of similar techniques to programs with pointer data structures has remained difficult. In this paper we introduce a new approach that leads to improved analysis and transformation of programs with recursively-defined pointer data structures. Our approach is based on a mechanism for the Abstract Description of Data Structures (ADDS), which makes explicit the important properties, such as dimensionality, of pointer data structures. Numerous examples demonstrate that ADDS definitions are both natural to specify and flexible enough to describe complex, cyclic pointer data structures. We discuss how an abstract data structure description can improve program analysis by presenting an analysis approach that combines an alias analysis technique, path matrix analysis, with information available from an ADDS declaration. Given this improved alias analysis technique, we provide a concrete example of applying a software pipelining transformation to loops involving pointer data structures.
Some of the inherently difficult issues that will be faced by a designer of any imperative debugging language are surveyed. A powerful debugging language called GDL (General-purpose Debugging language) is outlined, th...
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ISBN:
(纸本)0818625856
Some of the inherently difficult issues that will be faced by a designer of any imperative debugging language are surveyed. A powerful debugging language called GDL (General-purpose Debugging language) is outlined, the particular set of mechanisms included in GDL is justified, and the issue of minimality of this set is addressed. The focus is especially on the semantic issues that arise when the language's mechanisms are combined, in short, the issue of being well-integrated. It is noted that GDL's mechanisms are well-integrated, but some mechanisms are rather inefficient for many debugging applications. However, in expanding GDL's mechanisms for such applications, new semantic problems arise. It is shown how these semantic problems can be avoided by following certain coding conventions.
A wide variety of object-oriented (OO) methodologies and tools are currently available for software development Each methodology emphasizes various phases and activities of the software life cycle using different term...
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