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Mailing list archives
Rohár, Pavol ; Mareš, Martin (advisor) ; Hubička, Jan (referee)
This thesis deals with the concept of automated archiving of e-mails from mailing list archives. It is supposed to provide suitable tool for archiving e-mails for administrators and enable users to read archived e-mails via web browser. The main objective of the thesis is to produce an effective program which will support e-mails in MIME format and will be able to work with attachments. The program will be able to correctly display e-mails in various national character encodings and safely process potential untrustworthy data. It will also be able to reasonably group e-mails into individual threads. Lastly, the program will be able to process e-mails which don't meet required and customary Internet Standards in the best possible way.
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Optimizing large applications
Liška, Martin ; Hubička, Jan (advisor) ; Mareš, Martin (referee)
Both uppermost open source compilers, GCC and LLVM, are mature enough to link-time optimize large applications. In case of large applications, we must take into account, except standard speed efficiency and memory consumption, different aspects. We focus on size of the code, cold start-up time, etc. Developers of applications often come up with ad-hoc solutions such as Elfhack utility, start-up of an application via a pre-loading utility and dlopen; prelinking and variety of different tools that reorder functions to fit the order of execution. The goal of the thesis is to analyse all existing techniques of optimization, evaluate their efficiency and design new solutions based on the link-time optimization platform. Powered by TCPDF (www.tcpdf.org)
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Pattern matching in compilers
Bílka, Ondřej ; Hubička, Jan (advisor) ; Mareš, Martin (referee)
Title: Pattern matching in compilers Author: Ondřej Bílka Department: Department of Applied Mathematics Supervisor: Jan Hubička, Department of Applied Mathematics Abstract: In this thesis we develop tools for effective and flexible pattern matching. We introduce a new pattern matching system called amethyst. Amethyst is not only a generator of parsers of programming languages, but can also serve as an alternative to tools for matching regular expressions. Our framework also produces dynamic parsers. Its intended use is in the context of IDE (accurate syntax highlighting and error detection on the fly). Amethyst offers pattern matching of general data structures. This makes it a useful tool for implement- ing compiler optimizations such as constant folding, instruction scheduling, and dataflow analysis in general. The parsers produced are essentially top-down parsers. Linear time complexity is obtained by introducing the novel notion of structured grammars and reg- ularized regular expressions. Amethyst uses techniques known from compiler optimizations to produce effective parsers. Keywords: Packrat parsing, dynamic parsing, structured grammars, functional programming 1
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Implementation of operations in double-ended heaps
Bardiovský, Vojtech ; Koubek, Václav (advisor) ; Hubička, Jan (referee)
There are several approaches for creating double-ended heaps from the single-ended heaps. We build on one of them, the leaf correspondence heap, to create a generic double ended heap scheme called L-correspondence heap. This will broaden the class of eligible base single-ended heaps (e.g. by Fibonacci heap, Rank-pairing heap) and make the operations Decrease and Increase possible. We show this approach on specific examples for three different single-ended base heaps and give time complexity bounds for all operations. Another result is that for these three examples, the expected amortized time for Decrease and Increase operations in the L-correspondence heap is bounded by a constant.
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Displaying images in JPEG format
Falt, Zbyněk ; Hubička, Jan (referee) ; Mareš, Martin (advisor)
The content of this work is the description of techniques and algorithms, which accelerate loading of sequential JPEG images. To reach this, special methods, such as the elimination of arithmetic computation, the reduction of conditional jumps in the most critical sections, the use of the vector instruction and the multithreaded preloading of images, are used. These techniques are platform independent, except the usa of SSE2 vector instructions, which are supported only on the IA-32 platform. The attached computer program demonstrates their real implementation and their efficiency.
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Pre-press adjustment of documents
Šnupárek, Aleš ; Mareš, Martin (advisor) ; Hubička, Jan (referee)
In the present work I study printing formats (PDF, PostScript) and abilities of modifying already finished documents before printing. In the other part of my work I focus on commonly used tools for pre-print preparations of documents. Last part of my work is design and implementation of tool for pre-print preparations of documents.
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Combinatorial Properties of Finite Models
Hubička, Jan ; Nešetřil, Jaroslav (advisor) ; Pultr, Aleš (referee) ; Cameron, P. (referee)
We study countable embedding-universal and homomorphism-universal structures and unify results related to both of these notions. We show that many universal and ultrahomogeneous structures allow a concise description (called here a finite presentation). Extending classical work of Rado (for the random graph), we find a finite presentation for each of the following classes: homogeneous undirected graphs, homogeneous tournaments and homogeneous partially ordered sets. We also give a finite presentation of the rational Urysohn metric space and some homogeneous directed graphs. We survey well known structures that are finitely presented. We focus on structures endowed with natural partial orders and prove their universality. These partial orders include partial orders on sets of words, partial orders formed by geometric objects, grammars, polynomials and homomorphism orders for various combinatorial objects. We give a new combinatorial proof of the existence of embedding-universal objects for homomorphism-defined classes of structures. This relates countable embedding-universal structures to homomorphism dualities (finite homomorphism-universal structures) and Urysohn metric spaces. Our explicit construction also allows us to show several properties of these structures.
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Optimizations in the GNU Compiler Collection targeted at scientific computing
Jambor, Martin ; Jelínek, Jakub (referee) ; Hubička, Jan (advisor)
Many members of the scientific community look for alternatives to Fortran to increase maintainability, reusability and interoperability of their projects and component and to achieve rapid development and deployment. C++ appears to be an ever more appealing alternative because evolving compilers and coding techniques continually boost the efficiency of the resultant code. This work describes what C++ scientific code typically looks like, and discuses a number of contemporary optimizing techniques compilers use to remove overhead caused by levels of abstraction. Moreover, it proposes a new Intraprocedural Analysis of Aggregates to expose even more information stored within objects and track object behaviour. It also describes implementation of intraprocedural propagation of constants within aggregates built on top of this analysis. Finally, it discusses its efficiency and potential for future work.
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Scalable link-time optimization
Láska, Ladislav ; Hubička, Jan (advisor) ; Mareš, Martin (referee)
Both major open-source compilers, GCC and LLVM, have a mature link-time optimization framework usable on most current programs. They are however not free from many performance issues, which prevent them to perform certain analyses and optimizations. We analyze bottlenecks and identify multiple places for improvement, focusing on improving interprocedural points-to analysis. For this purpose, we design a new data structure derived from Bloom filters and use it to significantly improve performance and memory consumption of link-time optimization. Powered by TCPDF (www.tcpdf.org)
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