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1.
SIMD扩展部件是近年来集成到通用处理器中的加速部件,旨在发掘多媒体和科学计算等程序的数据级并行.控制依赖给发掘程序中的数据级并行带来了阻碍,当前不论基于loop-based还是SLP的控制流向量化方法都需要if转换,而没有考虑循环内蕴含的向量并行度,导致生成的向量代码效率较低.此外不精确的代价模型指导控制流向量化,同样导致生成的向量代码效率较低.为此提出了改进的控制流SIMD向量化方法,首先提出了含有控制依赖的循环分布算法,分离循环的可向量化部分和不可向量化部分,同时考虑分布时数据的局部性;其次提出了一种直接向量化控制流的方法,该方法考虑了基本块间的向量重用;最后利用精确的代价模型指导超字选择指令和超字条件分支指令的生成.实验结果表明,与现有的控制流向量化方法相比,本文提出的改进方法生成的向量代码性能提高24%.  相似文献   

2.
高性能微处理器中普遍采用SIMD向量扩展作为计算加速部件。在深入研究SIMD扩展部件数据依赖关系约束条件的基础上,提出一种基于依赖关系逆向图的Tarjan扩展算法,提高了SIMD并行性识别率,并结合传统向量化方法,实现了面向SIMD扩展部件的循环优化技术,消除了不可向量化语句对可向量化语句在数据重组中不必要的开销。实际程序测试结果显示,其在基于依赖关系的SIMD并行性判定方面优于ICC编译器,经过循环优化后,最终生成的SIMD代码其执行效率平均提高了12%。  相似文献   

3.
索维毅  赵荣彩  姚远  刘鹏 《计算机应用》2012,32(12):3303-3307
如今单指令多数据流(SIMD)技术在数字信号处理器(DSP)上得到了广泛的应用,现有的向量化编译器大多都实现了自动向量化的功能,但是编译器并不适合支持DSP为特征的SIMD自动向量化,主要由于DSP复杂的指令集、特有的寻址模型,以及依赖关系或者数据非对齐等原因而导致向量化效率不高。为了解决此问题,在基于Open64的超字并行(SLP)自动向量化编译系统后端,对SLP自动向量化中的指令分析和冗余优化算法进行了添加和改进,生成更加高效的向量化源程序。实验结果表明,该优化方法能有效提高DSP性能并降低功耗。  相似文献   

4.
如今,越来越多的处理器集成了SIMD(single instruction multiple data)扩展,现有的编译器大多也实现了自动向量化的功能,但是一般都只针对最内层循环进行向量化,对于多重循环缺少一种通用、易行的向量化方法.为此,提出了一种面向SLP(supcrword level parallelism)的多重循环向量化方法,从外至内依次对各个循环层次进行分析,收集各层循环对应的一些影响向量化效果的属性值,主要包括能否对该循环进行直接循环展开和压紧、有多少数组引用相对于该循环索引连续以及该循环所包含的区域等,然后根据这些属性值决定在哪些循环层次进行直接循环展开和压紧,最后通过SLP对循环中的语句进行向量化.实验结果表明,该算法相对于内层循环向量化和简单的外层循环向量化平均加速比提升了2.13和1.41,对于一些常用的核心循环可以得到高达5.3的加速比.  相似文献   

5.
面向SLP 的多重循环向量化   总被引:1,自引:0,他引:1  
魏帅  赵荣彩  姚远 《软件学报》2012,23(7):1717-1728
如今,越来越多的处理器集成了SIMD(single instruction multiple data)扩展,现有的编译器大多也实现了自动向量化的功能,但是一般都只针对最内层循环进行向量化,对于多重循环缺少一种通用、易行的向量化方法.为此,提出了一种面向SLP(superword level parallelism)的多重循环向量化方法,从外至内依次对各个循环层次进行分析,收集各层循环对应的一些影响向量化效果的属性值,主要包括能否对该循环进行直接循环展开和压紧、有多少数组引用相对于该循环索引连续以及该循环所包含的区域等,然后根据这些属性值决定在哪些循环层次进行直接循环展开和压紧,最后通过SLP对循环中的语句进行向量化.实验结果表明,该算法相对于内层循环向量化和简单的外层循环向量化平均加速比提升了2.13和1.41,对于一些常用的核心循环可以得到高达5.3的加速比.  相似文献   

6.
黄磊  姚远  侯永生  杨明 《计算机科学》2011,38(9):288-293
循环分布是开发向量化程序的一个有效的方法。但是由于程序中的数据相关性,当前的自动向量化编译器实现完全的循环分布非常困难。因此,当前的自动向量化编译器一般采用简单的循环分布方法。以数据依赖关系分析为基础,从有无依赖环的角度分析了程序中语句的向量化能力,提出了基于语句向量化识别的循环分布算法,并在自动向量化中加以实现。通过此方法,可以充分地分析语句或依赖环的向量化能力,最终采用循环分布,将可向量化的语句与不可向量化的语句分布在不同的循环中。该方法可以处理当前的自动向量化编译器无法向量化的循环,对一些语句间有依赖关系的循环可达到较好的效果。  相似文献   

7.
多媒体技术的迅速发展使得越来越多的处理器集成了SIMD扩展,当前的编译器大多数都已实现了自动向量化功能。为了发掘迭代内并行,一些编译器在自动向量化模块中引入了SLP向量化方法。多媒体数据的密集存储和规则运算使得在处理多媒体数据时需要进行频繁的数据类型转换,而目前的SLP向量化方法对数据类型转换的处理能力还不完善。为了在存在大量数据类型转换语句的程序中发掘更多的SLP向量化机会,提出了一种类型转换语句的SLP发掘方法,它能够在SLP向量化框架下利用数据重组实现具有相同向量化因子和不同向量化因子的数据类型之间的转换。实验结果表明,该方法能够有效地对类型转换语句进行SLP向量化发掘,提高了程序的向量化执行效率。  相似文献   

8.
现代编译器越来越依赖SIMD指令来提高向量化性能,但控制流的复杂性严重阻碍了SIMD向量化的发掘。现有的控制流向量化方法对于单层控制流的向量化很有效,但对嵌套等复杂控制流无法取得令人满意的效果。因此,提出了一种基于条件分类的控制流向量化方法。该方法对条件为循环不变量的控制流,以层次遍历的顺序实施IF外提;对条件为循环变量的控制流,结合语句匹配和条件合并递归地进行IF转换,生成相应的SIMD指令,从而实现嵌套控制流的向量化。实验结果表明,该方法能够有效消除循环中的嵌套控制流,提高向量化发掘的能力, 有效提升 测试程序的性能。  相似文献   

9.
SIMD扩展部件是集成到通用处理器中的加速部件,旨在发掘多媒体和科学计算等领域程序的数据级并行.当前两种基本的向量发掘方法分别是发掘迭代间并行的Loop-based方法和发掘迭代内并行的SLP方法.Loop-aware方法是对SLP方法的改进,其思想是首先通过循环展开将迭代间并行转换为迭代内并行,使循环体内的同构语句条数足够多,再利用SLP方法进行向量发掘.但当循环展开不合法或者并行度低于向量化因子时,Loop-aware方法无法实现程序向量并行性的发掘.因此提出了向量并行度指导的循环向量化方法,依据迭代间并行度、迭代内并行度和向量化因子,构建循环向量化方法选择方案,同时提出不充分向量化方法发掘并行度低于向量化因子的循环向量并行性,最后依据向量并行度对生成的向量循环进行展开.经过标准测试集测试,向量并行度指导的循环SIMD向量化方法比Loop-aware方法识别率提升107.5%,性能提升12.1%.  相似文献   

10.
分段约束的超字并行向量发掘路径优化算法   总被引:1,自引:0,他引:1  
超字并行(SLP)是一种针对基本块的向量并行发掘方法,结合循环展开可以发掘更多的并行性,但同时也会产生过多的发掘路径。针对上述问题,提出了一种分段约束的SLP发掘路径优化算法;采用分段的冗余删除方法,来保证冗余删除后段的同构性。采用段间的SLP发掘,来约束发掘路径;最后进行pack调整来处理访存重叠的情况。实验结果表明,该方法有效增强了SLP向量化功能,对于测试程序,向量化的平均加速比接近2。  相似文献   

11.
Abstract This paper describes an approach to the design of interactive multimedia materials being developed in a European Community project. The developmental process is seen as a dialogue between technologists and teachers. This dialogue is often problematic because of the differences in training, experience and culture between them. Conditions needed for fruitful dialogue are described and the generic model for learning design used in the project is explained.  相似文献   

12.
European Community policy and the market   总被引:1,自引:0,他引:1  
Abstract This paper starts with some reflections on the policy considerations and priorities which are shaping European Commission (EC) research programmes. Then it attempts to position the current projects which seek to capitalise on information and communications technologies for learning in relation to these priorities and the apparent realities of the marketplace. It concludes that while there are grounds to be optimistic about the contribution EC programmes can make to the efficiency and standard of education and training, they are still too technology driven.  相似文献   

13.
融合集成方法已经广泛应用在模式识别领域,然而一些基分类器实时性能稳定性较差,导致多分类器融合性能差,针对上述问题本文提出了一种新的基于多分类器的子融合集成分类器系统。该方法考虑在度量层融合层次之上通过对各类基多分类器进行动态选择,票数最多的类别作为融合系统中对特征向量识别的类别,构成一种新的自适应子融合集成分类器方法。实验表明,该方法比传统的分类器以及分类融合方法识别准确率明显更高,具有更好的鲁棒性。  相似文献   

14.
Development of software intensive systems (systems) in practice involves a series of self-contained phases for the lifecycle of a system. Semantic and temporal gaps, which occur among phases and among developer disciplines within and across phases, hinder the ongoing development of a system because of the interdependencies among phases and among disciplines. Such gaps are magnified among systems that are developed at different times by different development teams, which may limit reuse of artifacts of systems development and interoperability among the systems. This article discusses such gaps and a systems development process for avoiding them.  相似文献   

15.
This paper presents control charts models and the necessary simulation software for the location of economic values of the control parameters. The simulation program is written in FORTRAN, requires only 10K of main storage, and can run on most mini and micro computers. Two models are presented - one describes the process when it is operating at full capacity and the other when the process is operating under capacity. The models allow the product quality to deteriorate to a further level before an existing out-of-control state is detected, and they can also be used in situations where no prior knowledge exists of the out-of-control causes and the resulting proportion defectives.  相似文献   

16.
Going through a few examples of robot artists who are recognized worldwide, we try to analyze the deepest meaning of what is called “robot art” and the related art field definition. We also try to highlight its well-marked borders, such as kinetic sculptures, kinetic art, cyber art, and cyberpunk. A brief excursion into the importance of the context, the message, and its semiotics is also provided, case by case, together with a few hints on the history of this discipline in the light of an artistic perspective. Therefore, the aim of this article is to try to summarize the main characteristics that might classify robot art as a unique and innovative discipline, and to track down some of the principles by which a robotic artifact can or cannot be considered an art piece in terms of social, cultural, and strictly artistic interest. This work was presented in part at the 13th International Symposium on Artificial Life and Robotics, Oita, Japan, January 31–February 2, 2008  相似文献   

17.
Although there are many arguments that logic is an appropriate tool for artificial intelligence, there has been a perceived problem with the monotonicity of classical logic. This paper elaborates on the idea that reasoning should be viewed as theory formation where logic tells us the consequences of our assumptions. The two activities of predicting what is expected to be true and explaining observations are considered in a simple theory formation framework. Properties of each activity are discussed, along with a number of proposals as to what should be predicted or accepted as reasonable explanations. An architecture is proposed to combine explanation and prediction into one coherent framework. Algorithms used to implement the system as well as examples from a running implementation are given.  相似文献   

18.
为了设计一种具有低成本、低功耗、易操作、功能强且可靠性高的煤矿井下安全分站,针对煤矿安全生产实际,文章提出了采用MCS-51系列单片机为核心、具有CAN总线通信接口的煤矿井下安全监控分站的设计方案;首先给出煤矿井下安全监控分站的整体构架设计,然后着重阐述模拟量输入信号处理系统的设计过程,最后说明单片机最小系统及其键盘、显示、报警、通信等各个组成部分的设计;为验证设计方案的可行性与有效性,使用Proteus软件对设计内容进行仿真验证,设计的煤矿井下安全监控分站具有瓦斯、温度等模拟量参数超标报警功能和电机开停、风门开闭等开关量指示功能;仿真结果表明:设计的煤矿井下安全监控分站具有一定的实际应用价值.  相似文献   

19.
《计算机科学》2007,34(4):148-148
Recent years have seen rapid advances in various grid-related technologies, middleware, and applications. The GCC conference has become one of the largest scientific events worldwide in grid and cooperative computing. The 6th international conference on grid and cooperative computing (GCC2007) Sponsored by China Computer Federation (CCF),Institute of Computing Technology, Chinese Academy of Sciences (ICT) and Xinjiang University ,and in Cooperation with IEEE Computer Soceity ,is to be held from August 16 to 18, 2007 in Urumchi, Xinjiang, China.  相似文献   

20.
This paper provides the author's personal views and perspectives on software process improvement. Starting with his first work on technology assessment in IBM over 20 years ago, Watts Humphrey describes the process improvement work he has been directly involved in. This includes the development of the early process assessment methods, the original design of the CMM, and the introduction of the Personal Software Process (PSP)SM and Team Software Process (TSP){SM}. In addition to describing the original motivation for this work, the author also reviews many of the problems he and his associates encountered and why they solved them the way they did. He also comments on the outstanding issues and likely directions for future work. Finally, this work has built on the experiences and contributions of many people. Mr. Humphrey only describes work that he was personally involved in and he names many of the key contributors. However, so many people have been involved in this work that a full list of the important participants would be impractical.  相似文献   

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