A new global register allocation technique, probabilistic register allocation, is described. Probabilistic register allocation quantifies the costs and benefits of allocating variables to registers over live ranges so...
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ISBN:
(纸本)0897914759
A new global register allocation technique, probabilistic register allocation, is described. Probabilistic register allocation quantifies the costs and benefits of allocating variables to registers over live ranges so that excellent allocation choices can be made. Local allocation is done first, and then global allocation is done iteratively beginning in the the most deeply nested loops. Because local allocation precedes global allocation, probabilistic allocation does not interfere with the use of well-known, high-quality local register allocation and instruction scheduling techniques.
In this paper, we first characterize distributed real-time systems by the following two properties that have to be supported: best effort and least suffering. Then, we propose a distributed real-time object model DRO ...
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ISBN:
(纸本)0897915399
In this paper, we first characterize distributed real-time systems by the following two properties that have to be supported: best effort and least suffering. Then, we propose a distributed real-time object model DRO which complies these properties. Based on the DRO model, we design an object oriented programminglanguage DROL: an extension of C++ with the capability of describing distributed real-time systems. The most eminent feature of DROL is that users can describe on meta level the semantics of message communications as a communication protocol with sending and receiving primitives. With this feature, we can construct a flexible distributed real-time system satisfying specifications which include timing constraints. We implement a run-time system of DROL on the ARTS kernel, and evaluate the efficiency of the prototype implementation as well as confirm the high expressive power of the language.
HoME is a version of Smalltalk which can be efficiently executed on a multiprocessor and can be executed in parallel by combining a Smalltalk process with a Mach thread and executing the process on the thread. HoME is...
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ISBN:
(纸本)0897914759
HoME is a version of Smalltalk which can be efficiently executed on a multiprocessor and can be executed in parallel by combining a Smalltalk process with a Mach thread and executing the process on the thread. HoME is nearly the same as ordinary Smalltalk except that multiple processes may execute in parallel. Thus, almost all applications running on ordinary Smalltalk can be executed on HoME without changes in their code. HoME was designed and implemented based on the following fundamental policies: (1) theoretically, an infinite number of processes can become active;(2) the moment a process is scheduled, it becomes active;(3) no process switching occurs;(4) HoME is equivalent to ordinary Smalltalk except for the previous three policies. The performance of the current implementation of HoME running on OMRON LUNA-88K, which had four processors, was measured by benchmarks which execute in parallel with multiple processes. In all benchmarks, the results showed that HoME's performance is much better than HPS on the same workstation.
We present a bit-vector algorithm for the optimal and economical placement of computations within flow graphs, which is as efficient as standard uni-directional analyses. The point of our algorithm is the decompositio...
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ISBN:
(纸本)0897914759
We present a bit-vector algorithm for the optimal and economical placement of computations within flow graphs, which is as efficient as standard uni-directional analyses. The point of our algorithm is the decomposition of the bi-directional 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 uni-directional analysis components exclude any unnecessary code motion. This laziness of our algorithm minimizes the register pressure, which has drastic effects on the run-time behaviour of the optimized programs in practice, where an economical use of registers is essential.
This paper introduces Composable Attribute Grammars (CAGs), a formalism that extends classical attribute grammars to allow for the modular composition of translation specifications and of translators. CAGs bring to co...
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ISBN:
(纸本)0897914538
This paper introduces Composable Attribute Grammars (CAGs), a formalism that extends classical attribute grammars to allow for the modular composition of translation specifications and of translators. CAGs bring to complex translator writing systems the same benefits of modularity found in modern programminglanguages, including comprehensibility, reusability, and incremental metal-compilation. A CAG is built from several smaller component AGs, each of which solves a particular subproblem, such as name analysis or register allocation. A component AG is based upon a simplified phrase-structure that reflects the properties of its subproblem rather than the phrase-structure of the source language. Different component phrase-structures for various subproblems are combined by mapping them into a phrase-structure for the source language. Both input and output attributes can be associated with the terminal symbols of a component AG. Output attributes enable the results of solving a subproblem to be distributed back to anywhere that originally contributed part of the subproblem, e.g. transparently distributing the results of global name analysis back to every symbolic reference in the source program. After introducing CAGs by way of an example, we provide a formal definition of CAGs and their semantics. We describe a subclass of CAGs, called separable CAGs, that have favorable implementation properties. We discuss the novel aspects of CAGs, compare them to other proposals for inserting modularity into attribute grammars, and relate our experience using CAGs in the Linguist translator-writing system.
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.
We describe an approach to implementing a wide-range of concurrency paradigms in high-level (symbolic) programminglanguages. The focus of our discussion is STING, a dialect of Scheme, that supports lightweight thread...
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ISBN:
(纸本)0897914759
We describe an approach to implementing a wide-range of concurrency paradigms in high-level (symbolic) programminglanguages. The focus of our discussion is STING, a dialect of Scheme, that supports lightweight threads of control and virtual processors as first-class objects. Given the significant degree to which the behavior of these objects may be customized, we can easily express a variety of concurrency paradigms and linguistic structures within a common framework without loss of efficiency. Unlike parallel systems that rely on operating system services for managing concurrency, STING implements concurrency management entirely in terms of Scheme objects and procedures. It, therefore, permits users to optimize the runtime behavior of their applications without requiring knowledge of the underlying runtime system. This paper concentrates on (a) the implications of the design for building asynchronous concurrency structures, (b) organizing large-scale concurrent computations, and (c) implementing robust programming environments for symbolic computing.
Functional-style programming and languages have an important role to play in the software life cycle, but for a variety of technical and organisational reasons are of limited utility until they are integrated with exi...
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This study evaluates a global optimization technique that avoids unconditional jumps by replicating code. When implemented in the back-end of an optimizing compiler, this technique can be generalized to work on almost...
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ISBN:
(纸本)0897914759
This study evaluates a global optimization technique that avoids unconditional jumps by replicating code. When implemented in the back-end of an optimizing compiler, this technique can be generalized to work on almost all instances of unconditional jumps, including those generated from conditional statements and unstructured loops. The replication method is based on the idea of finding a replacement for each unconditional jump which minimizes the growth in code size. This is achieved by choosing the shortest sequence of instructions as a replacement. Measurements taken from a variety of programs showed that not only the number of executed instructions decreased, but also that the total cache work was reduced (except for small caches) despite increases in code size. Pipelined and superscalar machines may also benefit from an increase in the average basic block size.
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