A framework for optimizing Java using attributes

Pominville, Patrice; Qian, Feng; Vallée-Rai, Raja; Hendren, Laurie; Verbrugge, Clark

doi:10.1145/1925805.1925819

Cited by 8 publications

(5 citation statements)

References 21 publications

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“…Pominville et al achieved 2% to 10% performance gain in Java bytecode when they annotated Java class files with assumptions about the "nullness" and array bounds [2]. With respect to null, their framework, SOOT [10], performs intra-procedural null analysis to make assumptions about variables being null or not to be able to remove unnecessary null checks in the bytecode level.…”

Section: Motivationmentioning

confidence: 99%

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Tracking Null Checks in Open-Source Java Systems

Osman

Leuenberger

Lungu

et al. 2016

2016 IEEE 23rd International Conference on Software Analysis, Evolution, and Reengineering (SANER)

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It is widely acknowledged that null values should be avoided if possible or carefully used when necessary in Java code. The careless use of null has negative effects on maintainability, code readability, and software performance. However, a study on understanding null usage is still missing.In this paper we analyze null checks in 810 open-source Java systems and manually inspect 100 code samples to understand when and why developers use null. We find that 35% of all conditional statements contain null checks. A deeper investigation reveals many questionable practices with respect to using null. Uninitialized member variables, returning null in methods, and passing null as a method parameter are among the most recurrent reasons for introducing null checks. Developers often return null in methods to signal errors instead of throwing a proper exception. As a result, 71% of the values checked for null are returned from method calls.Our study provides a novel evidence of an overuse of null checks and of the null value itself in Java, and at the same time, reveals actionable recommendations to reduce this null usage.

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Section: Motivationmentioning

confidence: 99%

“…Besides the bugs it introduces in running systems, null usage hinders performance [2], increases maintenance costs [3], and decreases code readability.…”

Section: Introductionmentioning

confidence: 99%

Tracking Null Checks in Open-Source Java Systems

Osman

Leuenberger

Lungu

et al. 2016

2016 IEEE 23rd International Conference on Software Analysis, Evolution, and Reengineering (SANER)

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“…al. [6] annotate Java programs with assumptions for nullness and bounds information. The optimizations that use this information achieve better results (2% -10%) on some benchmarks.…”

Section: Related Workmentioning

confidence: 99%

“…Programmers can communicate their intended semantics by placing assumptions into the program ( [5,6]). For example, when an assumption-aware optimizer encounters a statement that has an assumption @neverThrows (NullPointerException) the optimizer can ignore the case when the statement throws the NullPointerException.…”

Section: Introductionmentioning

confidence: 99%

Optimizing programs with intended semantics

Dincklage¹,

Diwan²

2009

Proceedings of the 24th ACM SIGPLAN Conference on Object Oriented Programming Systems Languages and Applications

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Modern object-oriented languages have complex features that cause programmers to overspecify their programs. This overspecification hinders automatic optimizers, since they must preserve the overspecified semantics. If an optimizer knew which semantics the programmer intended, it could do a better job.Making a programmer clarify his intentions by placing assumptions into the program is rarely practical. This is because the programmer does not know which parts of the programs' overspecified semantics hinder the optimizer. Therefore, the programmer has to guess which assumption to add. Since the programmer can add many different assumptions to a large program, he will need to place many such assumptions before he guesses right and helps the optimizer.We present IOpt, a practical optimizer that uses a specification of the programmers' intended semantics to enable additional optimizations. That way, our optimizer can significantly improve the performance of a program. We present case studies in which we use IOpt to speed up two programs by a factor of 2.To make specifying the intended semantics practical, IOpt communicates with the programmer. IOpt identifies which assumptions the programmer should place, and where he should place them. IOpt ranks each assumption by (i) the likelyhood that the assumption conforms to the programmers' intended semantics and (ii) how much the assumption will help IOpt improve the programs' performance. IOpt proposes ranked assumptions to the programmer, who just picks those that conform to his intended semantics. With this approach, IOpt keeps the programmers' specification burden low. In our case studies, programmers had to add just a few assumptions to realize significant performance speedups.

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“…These attributes give virtual machine more information about program. Significant speed-ups have been demonstrated in [15]. The major shortcoming of this approach is that most of virtual machines do not support these additional attributes.…”

Section: Related Workmentioning

confidence: 99%

Bytecode optimization

Babic¹,

Rakamaric²

ITI 2002. Proceedings of the 24th International Conference on Information Technology Interfaces (IEEE Cat. No.02EX534)

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Today, when Java is entering the embedded market it needs performance enhancements more than ever. Large-scale enterprise applications would also beneJit from better code optimization techniques.In this paper we present the results of optimization with an optimizing framework we have developed. We measure the impact of dijfevent optimizations on run times in different execution environments and propose further enhancements.

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A framework for optimizing Java using attributes

Cited by 8 publications

References 21 publications

Tracking Null Checks in Open-Source Java Systems

Tracking Null Checks in Open-Source Java Systems

Optimizing programs with intended semantics

Bytecode optimization

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