Victor Ivannikov

The use of contract specifications for representing requirements and for functional testing of hardware models

Contract specifications in the form of pre-and postconditions are widely used in software engineering for formal description of interfaces of software components. On the one hand, such specifications are convenient for the developers since they can easily be attached to the system architecture. On the other hand, test oracles verifying conformance of the behavior of the target system to the specifications can automatically be generated from them. In the paper, it is suggested to use contract specifications for representing requirements and for functional testing of hardware models developed in languages such as VHDL, Verilog, SystemC, System Verilog, etc. An approach to specification of such systems is proposed and compared with the existing methods of hardware specification. An experience of its practical use is described. The approach is based on the UniTESK testing technology developed at the Institute for System Programming.

Improving Properties of a Parallel Program in ParJava Environment

ParJava integrated environment supporting development and maintenance of data parallel Java-programs is discussed. When a parallel program is developed it is necessary to assure not only its correctness, but also its efficiency and scalability. For this purpose it is useful to know some dynamic properties of the program. This information may help to modify the program in order to improve its parallel features. ParJava provides a collection of such tools. Symbolic execution allows to estimate expected execution time and limits of scalability of Java SPMD-program.

Static analyzer Svace for finding defects in a source program code

This paper describes Svace, a tool for static program analysis developed at the Institute for Systems Programming, Russian Academy of Sciences. This tool allows one to find defects and potential vulnerabilities in the source program code written in C/C++ languages. The main features of the tool are simplicity of use, wide variety of supported types of warnings, scalability up to programs of millions of code lines, and acceptable quality of analysis (30–80% of true positive warnings).

Software for improving the energy efficiency of a computer cluster

Methods for reducing the energy consumption of a uniform computer cluster due to flexible control strategies of the node states (waking them up or shutting down) and of the execution order of the awaiting tasks are considered. A software system developed in the Institute for System Programming of the Russian Academy of Sciences (ISP RAN) for the dynamic control of the nodes in order to reduce the energy consumption is described. Several strategies for controlling the stats of the nodes are proposed and investigated. Simulation showed that when the average density of tasks1 is 0.5, the energy saving is about 10%. When the density of the flow of tasks decreases, the effect of using the proposed system drastically increases: when the average density is 0.3, the saving is 30%; when the average density is 0.2, the saving is 50%; and when the average density is 0.1, the saving is 70%.

Estimation of dynamical characteristics of a parallel program on a model

This paper considers a model of a parallel program that can efficiently be interpreted on an instrumental computer, providing a means for a sufficiently accurate prediction of the actual time needed for execution of the parallel program on a given parallel computational system. The model is designed for parallel programs with explicit message passing written in Java with calls to the MPI library and is a part of the ParJava environment. The model is obtained by transforming the program control tree, which, for Java programs, can be constructed by modifying the abstract syntax tree. The communication functions are simulated on the basis of the LogGP model, which makes it possible to take into account specific features of the distributed computational system.

Modular parallel programming in mpC for distributed memory machines

The mpC language is an ANSI C superset supporting modular parallel programming for distributed memory machines. It allows the user to specify dynamically an application topology, and the mpC programming environment uses this information in run time to provide the most efficient execution of the program on any particular distributed memory machine. The paper describes the features of mpC and its programming environment which allow to use them for developing libraries of parallel programs.

Productivity prediction of MPI programs based on models

A model of parallel program that can be effectively interpreted on the development computer guaranteeing the possibility of a sufficiently precise prediction of real run time for a simulated parallel program at the prescribed computer system is studied. The model is worked out for parallel programs with explicit message passing written in the Java language with MPI library access and is included into the composition of ParJava environment. The model is obtained by transforming the program control tree that can be constructed for Java programs by modifying the abstract syntax tree. To model communication functions, the model LogGP is used which allows taking into consideration the specific character of the communication network of the distributed computer system.

Реализация запутывающих преобразований в компиляторной инфраструктуре LLVM

The paper describes the methods for obfuscating C/C++ programs to prevent applying static analyzers to them. The methods are implemented within the well-known LLVM compiler infrastructure. Experimental results presenting resulting program slowdown and used memory growth are given.

Construction of speculative optimization algorithms

In modern processors, instructions to perform operations are often produced before it becomes known that this is required. Such an expedient, which is called speculative execution, helps to reveal parallelism at the instruction level. In the EPIC architectures, the speculative execution is completely controlled by the compiler, which makes it possible to avoid using complex hardware mechanisms for supporting speculative instruction production. Moreover, the idea of the speculative execution can be used by the compiler in machine-independent optimizations. The paper describes a scheme of construction of the speculative optimization that is based on the selection of properties of the control flow and data flow that are important from the optimization standpoint and on the estimation of the probabilities of their fulfillment. The probabilities found are used for searching and constructing advantageous speculative and bookkeeping transformations. For optimizations that include only speculative movements of instructions upwards along the control flow graph, on the basis of the suggested scheme, a method has been developed that includes algorithms for finding probabilities of data and control dependences, for estimating benefit of speculative movements, and for constructing a recovery code. On the basis of this method, an algorithm for the speculative scheduling of instructions for the Intel Itanium architecture has been developed and implemented. Specific features of its implementation and experimental results are described.

Efficient Metaobject Control Using Mediators

In this paper we propose an approach to optimization of reflection which combines flexibility and efficiency while implementing metaobject-based systems. The main idea is to flatten nested metainterpreter layers using a particular kind of mediator objects, which provide object/metaobject connection. One of the most significant features of the approach is that it allows to carry out what we called metaupgrading of existing software systems in a systematic way, efficient and transparent for the application. The meta-upgrading approach based on Interface Object technology can be efficiently used for system integration and re-use of legacy software components.