scholarly journals Instruction Scheduling Across Control Flow

1993 ◽  
Vol 2 (3) ◽  
pp. 1-5
Author(s):  
Martin Charles Golumbic ◽  
Vladimir Rainish
Keyword(s):  
Time Delays ◽  
Instruction Scheduling ◽  
Control Flow ◽  
Basic Block ◽  
High Quality ◽  
Assembly Code ◽  
Considerable Research ◽  
Straight Line ◽  
Compiled Code ◽  
Basic Blocks

Instruction scheduling algorithms are used in compilers to reduce run-time delays for the compiled code by the reordering or transformation of program statements, usually at the intermediate language or assembly code level. Considerable research has been carried out on scheduling code within the scope of basic blocks, i.e., straight line sections of code, and very effective basic block schedulers are now included in most modern compilers and especially for pipeline processors. In previous work Golumbic and Rainis: IBM J. Res. Dev., Vol. 34, pp.93–97, 1990, we presented code replication techniques for scheduling beyond the scope of basic blocks that provide reasonable improvements of running time of the compiled code, but which still leaves room for further improvement. In this article we present a new method for scheduling beyond basic blocks called SHACOOF. This new technique takes advantage of a conventional, high quality basic block scheduler by first suppressing selected subsequences of instructions and then scheduling the modified sequence of instructions using the basic block scheduler. A candidate subsequence for suppression can be found by identifying a region of a program control flow graph, called an S-region, which has a unique entry and a unique exit and meets predetermined criteria. This enables scheduling of a sequence of instructions beyond basic block boundaries, with only minimal changes to an existing compiler, by identifying beneficial opportunities to cover delays that would otherwise have been beyond its scope.

Improving Similarity Measure for Java Programs Based on Optimal Matching of Control Flow Graphs

2015 ◽  
Vol 25 (07) ◽  
pp. 1171-1197 ◽  
Author(s):  
Dehong Qiu ◽  
Jialin Sun ◽  
Hao Li
Keyword(s):  
Graph Matching ◽  
Control Flow ◽  
Basic Block ◽  
New Approach ◽  
Java Program ◽  
Java Programs ◽  
Instruction Sequences ◽  
High Level ◽  
Flow Graphs ◽  
Basic Blocks

Measuring program similarity plays an important role in solving many problems in software engineering. However, because programs are instruction sequences with complex structures and semantic functions and furthermore, programs may be obfuscated deliberately through semantics-preserving transformations, measuring program similarity is a difficult task that has not been adequately addressed. In this paper, we propose a new approach to measuring Java program similarity. The approach first measures the low-level similarity between basic blocks according to the bytecode instruction sequences and the structural property of the basic blocks. Then, an error-tolerant graph matching algorithm that can combat structure transformations is used to match the Control Flow Graphs (CFG) based on the basic block similarity. The high-level similarity between Java programs is subsequently calculated on the matched pairs of the independent paths extracted from the optimal CFG matching. The proposed CFG-Match approach is compared with a string-based approach, a tree-based approach and a graph-based approach. Experimental results show that the CFG-Match approach is more accurate and robust against semantics-preserving transformations. The CFG-Match approach is used to detect Java program plagiarism. Experiments on the collection of benchmark program pairs collected from the students’ submission of project assignments demonstrate that the CFG-Match approach outperforms the comparative approaches in the detection of Java program plagiarism.

scholarly journals StFuzzer: Contribution-Aware Coverage-Guided Fuzzing for Smart Devices

2021 ◽  
Vol 2021 ◽  
pp. 1-15
Author(s):  
Jiageng Yang ◽  
Xinguo Zhang ◽  
Hui Lu ◽  
Muhammad Shafiq ◽  
Zhihong Tian
Keyword(s):  
Real World ◽  
Control Flow ◽  
Smart Devices ◽  
Smart Device ◽  
Basic Block ◽  
Optimization Approach ◽  
Seed Selection ◽  
Code Coverage ◽  
Real World Applications ◽  
Basic Blocks

The root cause of the insecurity for smart devices is the potential vulnerabilities in smart devices. There are many approaches to find the potential bugs in smart devices. Fuzzing is the most effective vulnerability finding technique, especially the coverage-guided fuzzing. The coverage-guided fuzzing identifies the high-quality seeds according to the corresponding code coverage triggered by these seeds. Existing coverage-guided fuzzers consider that the higher the code coverage of seeds, the greater the probability of triggering potential bugs. However, in real-world applications running on smart devices or the operation system of the smart device, the logic of these programs is very complex. Basic blocks of these programs play a different role in the process of application exploration. This observation is ignored by existing seed selection strategies, which reduces the efficiency of bug discovery on smart devices. In this paper, we propose a contribution-aware coverage-guided fuzzing, which estimates the contributions of basic blocks for the process of smart device exploration. According to the control flow of the target on any smart device and the runtime information during the fuzzing process, we propose the static contribution of a basic block and the dynamic contribution built on the execution frequency of each block. The contribution-aware optimization approach does not require any prior knowledge of the target device, which ensures our optimization adapting gray-box fuzzing and white-box fuzzing. We designed and implemented a contribution-aware coverage-guided fuzzer for smart devices, called StFuzzer. We evaluated StFuzzer on four real-world applications that are often applied on smart devices to demonstrate the efficiency of our contribution-aware optimization. The result of our trials shows that the contribution-aware approach significantly improves the capability of bug discovery and obtains better execution speed than state-of-the-art fuzzers.

scholarly journals Implementing a high-efficiency similarity analysis approach for firmware code

PLoS ONE ◽  
2021 ◽  
Vol 16 (1) ◽  
pp. e0245098
Author(s):  
Yisen Wang ◽  
Ruimin Wang ◽  
Jing Jing ◽  
Huanwei Wang
Keyword(s):  
Machine Learning ◽  
High Efficiency ◽  
Control Flow ◽  
Rapid Expansion ◽  
Analysis Approach ◽  
Similarity Analysis ◽  
Basic Block ◽  
Comparison Results ◽  
Flow Features ◽  
Basic Blocks

The rapid expansion of the open-source community has shortened the software development cycle, but the spread of vulnerabilities has been accelerated, especially in the field of the Internet of Things. In recent years, the frequency of attacks against connected devices is increasing exponentially; thus, the vulnerabilities are more serious in nature. The state-of-the-art firmware security inspection technologies, such as methods based on machine learning and graph theory, find similar applications depending on the known vulnerabilities but cannot do anything without detailed information about the vulnerabilities. Moreover, model training, which is necessary for the machine learning technologies, requires a significant amount of time and data, resulting in low efficiency and poor extensibility. Aiming at the above shortcomings, a high-efficiency similarity analysis approach for firmware code is proposed in this study. First, the function control flow features and data flow features are extracted from the functions of the firmware and of the vulnerabilities, and the features are used to calculate the SimHash of the functions. The mass storage and fast query capabilities of the SimHash are implemented by the pigeonhole principle. Second, the similarity function pairs are analyzed in detail within and among the basic blocks. Within the basic blocks, the symbolic execution is used to generate the basic block semantic information, and the constraint solver is used to determine the semantic equivalence. Among the basic blocks, the local control flow graphs are analyzed to obtain their similarity. Then, we implemented a prototype and present the evaluation. The evaluation results demonstrate that the proposed approach can implement large-scale firmware function similarity analysis. It can also get the location of the real-world firmware patch without vulnerability function information. Finally, we compare our method with existing methods. The comparison results demonstrate that our method is more efficient and accurate than the Gemini and StagedMethod. More than 90% of the firmware functions can be indexed within 0.1 s, while the search time of 100,000 firmware functions is less than 2 s.

OPTIMAL BASIC BLOCK INSTRUCTION SCHEDULING FOR MULTIPLE-ISSUE PROCESSORS USING CONSTRAINT PROGRAMMING

2008 ◽  
Vol 17 (01) ◽  
pp. 37-54 ◽  
Author(s):  
ABID M. MALIK ◽  
JIM McINNES ◽  
PETER VAN BEEK
Keyword(s):  
Constraint Programming ◽  
Fundamental Problem ◽  
Instruction Scheduling ◽  
Minimum Length ◽  
Basic Block ◽  
Exit Point ◽  
Benchmark Suite ◽  
Constraint Model ◽  
Basic Blocks ◽  
Optimal Scheduler

Instruction scheduling is one of the most important steps for improving the performance of object code produced by a compiler. A fundamental problem that arises in instruction scheduling is to find a minimum length schedule for a basic block — a straight-line sequence of code with a single entry point and a single exit point — subject to precedence, latency, and resource constraints. Solving the problem exactly is NP-complete, and heuristic approaches are currently used in most compilers. In contrast, we present a scheduler that finds provably optimal schedules for basic blocks using techniques from constraint programming. In developing our optimal scheduler, the key to scaling up to large, real problems was in the development of preprocessing techniques for improving the constraint model. We experimentally evaluated our optimal scheduler on the SPEC 2000 integer and floating point benchmarks. On this benchmark suite, the optimal scheduler was very robust — all but a handful of the hundreds of thousands of basic blocks in our benchmark suite were solved optimally within a reasonable time limit — and scaled to the largest basic blocks, including basic blocks with up to 2600 instructions. This compares favorably to the best previous exact approaches.

scholarly journals Negating the Gender Citation Advantage in Political Science

2017 ◽  
Vol 50 (02) ◽  
pp. 448-455 ◽  
Author(s):  
Amy L. Atchison
Keyword(s):  
Open Access ◽  
Gender Bias ◽  
Academic Publishing ◽  
High Quality ◽  
High Quality Research ◽  
Quality Research ◽  
Male And Female ◽  
Research Areas ◽  
Considerable Research ◽  
Citation Advantage

ABSTRACTOpen-access (OA) advocates have long promoted OA as an egalitarian alternative to traditional subscription-based academic publishing. The argument is simple: OA gives everyone access to high-quality research at no cost. In turn, this should benefit individual researchers by increasing the number of people reading and citing academic articles. As the OA movement gains traction in the academy, scholars are investing considerable research energy to determine whether there is an OA citation advantage—that is, does OA increase an article’s citation counts? Research indicates that it does. Scholars also explored patterns of gender bias in academic publishing and found that women are cited at lower rates in many disciplines. Indeed, in many disciplines, men enjoy a significant and positive gender citation effect (GCE) compared to their female colleagues. This article combines these research areas to determine whether the OA citation advantage varies by gender. Using Wilcoxon-Mann-Whitney (WMW) tests, the nonparametric analog to the independent samples T-test, I conclude that OA benefits male and female political scientists at similar rates. Thus, OA negates the gender citation advantage that typically accrues to male political scientists.

scholarly journals Lower First Permanent Molar with an Additional Root Diagnosis and Management

2019 ◽  
Vol 2019 ◽  
pp. 1-4
Author(s):  
Abdullah Mahmoud Riyahi
Keyword(s):  
Early Diagnosis ◽  
Sodium Hypochlorite ◽  
Root Canal ◽  
Three Dimensional ◽  
Operating Microscope ◽  
High Quality ◽  
New Techniques ◽  
Permanent Molar ◽  
Straight Line ◽  
Warm Vertical Compaction

Three rooted lower first permanent molar represents one of the main anatomical variants which is a treatment challenge of clinicians. This study is aimed at presenting a case of a lower first molar with an additional root that was diagnosed and managed successfully using new techniques in endodontics. Tooth #46 was diagnosed as a necrotic pulp with symptomatic apical periodontitis. Different angle radiographs were obtained, and they clearly showed three roots. The procedure was completed under magnification and illumination using an operating microscope. The access cavity was modified to achieve straight line access for all the canals. Careful step-by-step instrumentation was performed using flexible NiTi rotary files. The canals were irrigated using 6% sodium hypochlorite. Afterwards, three-dimensional obturation was completed using warm vertical compaction. Knowledge of the anatomy and an early diagnosis are required to achieve high-quality root canal treatment.

scholarly journals Novel Basic Block of Multilevel Inverter Using Reduced Number of On-State Switches and Cascaded Circuit Topology

2017 ◽  
Vol 2017 ◽  
pp. 1-16 ◽  
Author(s):  
Aparna Prayag ◽  
Sanjay Bodkhe
Keyword(s):  
Computer Simulation ◽  
Output Voltage ◽  
Multilevel Inverter ◽  
Basic Block ◽  
Matlab Simulink ◽  
Dc Voltage ◽  
Operating Modes ◽  
Power Switches ◽  
In Series ◽  
Basic Blocks

In this paper a basic block of novel topology of multilevel inverter is proposed. The proposed approach significantly requires reduced number of dc voltage sources and power switches to attain maximum number of output voltage levels. By connecting basic blocks in series a cascaded multilevel topology is developed. Each block itself is also a multilevel inverter. Analysis of proposed topology is carried out in symmetric as well as asymmetric operating modes. The topology is investigated through computer simulation using MATLAB/Simulink and validated experimentally on prototype in the laboratory.

Innovating Across Cultural Boundaries: Applying Conflict Theory to Develop a Common Approach

2004 ◽  
Vol 9 (2) ◽  
pp. 291-313 ◽  
Author(s):  
Alfred Wong ◽  
Dean Tjosvold
Keyword(s):  
Conflict Theory ◽  
Mutual Benefit ◽  
Cultural Groups ◽  
The West ◽  
High Quality ◽  
Team Members ◽  
Cooperative Approach ◽  
Considerable Research ◽  
Cultural Boundaries ◽  
Do So

AbstractDiversity of people and perspectives can contribute to the ability of teams to develop and implement innovation in organizations. However, to do so they must manage their conflicts. Considerable research in the West and recent studies in China have documented the value of a cooperative approach to conflict for teamwork and innovation in collectivist as well as individualist cultures. When team members attempt to resolve their disputes for mutual benefit, they have been found to make high quality decisions to which they are committed. This article proposes that diverse people can use this theory to develop common values, norms, and procedures that are accessible and effective for all cultural groups.

Learning heuristics for basic block instruction scheduling

2007 ◽  
Vol 14 (6) ◽  
pp. 549-569 ◽  
Author(s):  
Abid M. Malik ◽  
Tyrel Russell ◽  
Michael Chase ◽  
Peter van Beek
Keyword(s):  
Instruction Scheduling ◽  
Basic Block ◽  
Learning Heuristics
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