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4 <TITLE>2012/13 BSc Projects</TITLE> |
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30 |
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31 <H2>2012/13 BSc Projects</H2> |
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32 <H4>Supervisor: Christian Urban</H4> |
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33 <H4>Email: christian dot urban at kcl dot ac dot uk, Office: Strand Building S1.24</H4> |
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34 <H4>If you are interested in a project, please send me an email and we can discuss details. Please include |
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35 a short description about your programming skills and Computer Science background in your first email. |
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36 I will also need your King's username in order to book the project for you. Thanks.</H4> |
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37 |
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38 <H4>Note that besides being a lecturer, I am also a passionate |
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39 <A HREF="http://en.wikipedia.org/wiki/Hacker_(programmer_subculture)">hacker</A> … |
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40 defined as “a person who enjoys exploring the details of programmable systems and |
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41 stretching their capabilities, as opposed to most users, who prefer to learn only the minimum |
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42 necessary.” I am always happy to supervise like-minded students.</H4> |
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43 |
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44 <ul class="striped"> |
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45 <li> <H4>[CU1] Automata Minimisation</H4> |
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46 |
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47 <p><B>Description:</b> |
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48 <A HREF="http://en.wikipedia.org/wiki/Deterministic_finite_automaton">Deterministic finite automata</A> |
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49 have many uses in Computer Science, for example for lexing |
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50 program code. In order to improve their run-time, automata need to be minimised, that |
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51 is transformed into equivalent automata with the smallest possible number of state |
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52 nodes. |
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53 </p> |
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54 |
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55 <p> |
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56 There is a little known method for minimising deterministic finite |
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57 automata by <A HREF="http://en.wikipedia.org/wiki/Janusz_Brzozowski_(computer_scientist)"> |
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58 Janusz Brzozowski</A>. |
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59 This method first reverses the edges of an automaton, which produces |
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60 a potentially non-deterministic automaton. The non-deterministic automaton is |
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61 then determinised using the usual powerset construction. This is repeated |
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62 once more and voila you obtain a minimised version of the automaton |
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63 you started with. It is rather surprising that this method works at all: |
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64 the powerset construction might produce an automaton with an exponentially |
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65 larger number of states, completely contrary to the idea of minimising the |
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66 number of states. The task of this project is to implement this method, check that |
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67 it actually works with some examples and |
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68 compare it with more traditional methods for automata minimisation |
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69 (in terms of run-time, code complexity, etc). Examples can be |
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70 obtained by translating regular expressions into automata. |
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71 </p> |
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72 |
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73 <p> |
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74 <B>Literature:</B> |
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75 A good place to start with this project are the wikipedia articles |
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76 <A HREF="http://en.wikipedia.org/wiki/DFA_minimization">here</A> and |
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77 <A HREF="http://en.wikipedia.org/wiki/Powerset_construction">here</A>. |
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78 The authoritative <A HREF="http://infolab.stanford.edu/~ullman/ialc.html">book</A> |
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79 on automata is by John Hopcroft and Jeffrey Ullmann (available in the library). |
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80 There is also an online course about automata by Ullman at |
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81 <A HREF="https://www.coursera.org/course/automata">Coursera</A>, though IMHO not |
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82 done with love. There |
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83 is also the book <i>Automata and Computability</i> by |
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84 <A HREF="http://www.cs.cornell.edu/~kozen/">Dexter Kozen</A> including more |
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85 advanced material about automata. |
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86 Finally, there are millions of other pointers about automata |
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87 minimisation on the web. |
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88 </p> |
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89 |
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90 <p> |
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91 <B>Skills:</B> |
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92 This is a project for a student with an interest in theory and some |
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93 reasonable programming skills. The project can be easily implemented |
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94 in languages like |
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95 <A HREF="http://www.scala-lang.org/">Scala</A>, |
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96 <A HREF="http://en.wikipedia.org/wiki/Standard_ML">ML</A>, |
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97 <A HREF="http://haskell.org/haskellwiki/Haskell">Haskell</A>, |
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98 <A HREF="http://www.python.org">Python</A>, etc. |
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99 </p> |
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100 |
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101 <li> <H4>[CU2] Equivalence Checking of Regular Expressions</H4> |
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102 |
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103 <p><B>Description:</b> |
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104 Solving the problem of deciding the equivalence of regular expressions can be used |
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105 to decide a number of problems in automated reasoning. Recently, |
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106 <A HREF="http://www.cs.unibo.it/~asperti/">Andreas Asperti</A> |
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107 proposed a simple method for deciding regular expression equivalence described |
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108 <A HREF="http://www.cs.unibo.it/~asperti/PAPERS/compact.pdf">here</A>. |
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109 The task is to implement this method and test it on examples. |
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110 It would be also interesting to see whether Asperti's method also applies to |
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111 extended regular expressions, described |
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112 <A HREF="http://ww2.cs.mu.oz.au/~sulzmann/manuscript/reg-exp-partial-derivatives.pdf">here</A>. |
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113 </p> |
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114 |
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115 <p> |
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116 <B>Literature:</B> |
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117 The central literature is obviously the papers |
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118 <A HREF="http://www.cs.unibo.it/~asperti/PAPERS/compact.pdf">here</A> and |
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119 <A HREF="http://ww2.cs.mu.oz.au/~sulzmann/manuscript/reg-exp-partial-derivatives.pdf">here</A>. |
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120 Asperti has also some slides <A HREF="http://www.cs.unibo.it/~asperti/SLIDES/regular.pdf">here</a>. |
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121 More references about regular expressions can be found |
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122 <A HREF="http://en.wikipedia.org/wiki/Regular_expression">here</A>. |
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123 </p> |
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124 |
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125 <p> |
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126 <B>Skills:</B> |
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127 This is a project for a student with a passion for theory and some |
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128 reasonable programming skills. The project can be easily implemented |
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129 in languages like Scala |
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130 <A HREF="http://www.scala-lang.org/">Scala</A>, |
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131 <A HREF="http://en.wikipedia.org/wiki/Standard_ML">ML</A>, |
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132 <A HREF="http://haskell.org/haskellwiki/Haskell">Haskell</A>, |
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133 <A HREF="http://www.python.org">Python</A>, etc. |
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134 Being able to read <A HREF="http://haskell.org/haskellwiki/Haskell">Haskell</A> |
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135 code is beneficial for the part involving extended regular expressions. |
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136 </p> |
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137 |
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138 <li> <H4>[CU3] Machine Code Generation for a Simple Compiler</H4> |
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139 |
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140 <p><b>Description:</b> |
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141 Compilers translate high-level programs that humans can read and write into |
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142 efficient machine code that can be run on a CPU or virtual machine. |
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143 I recently implemented a very simple compiler for a very simple functional |
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144 programming language following this |
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145 <A HREF="http://www.cs.princeton.edu/~dpw/papers/tal-toplas.pdf">paper</A> |
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146 (also described <A HREF="http://www.cs.princeton.edu/~dpw/papers/tal-tr.pdf">here</A>). |
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147 My code, written in <A HREF="http://www.scala-lang.org/">Scala</A>, of this compiler is |
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148 <A HREF="http://www.dcs.kcl.ac.uk/staff/urbanc/compiler.scala">here</A>. |
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149 The compiler can deal with simple programs involving natural numbers, such |
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150 as Fibonacci numbers |
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151 or factorial (but it can be easily extended - that is not the point). |
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152 </p> |
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153 |
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154 <p> |
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155 While the hard work has been done (understanding the two papers above), |
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156 my compiler only produces some idealised machine code. For example I |
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157 assume there are infinitely many registers. The goal of this |
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158 project is to generate machine code which is more realistic and can |
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159 run on a CPU, like x86, or run on a virtual machine, say JVM. |
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160 This gives probably a speedup of thousand times in comparison to |
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161 my naive machine code and virtual machine. The project |
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162 requires to dig into the literature about real CPUs and generating |
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163 real machine code. |
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164 </p> |
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165 |
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166 <p> |
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167 <B>Literature:</B> |
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168 There is a lot of literature about compilers |
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169 (for example <A HREF="http://www.cs.princeton.edu/~appel/papers/cwc.html">this book</A> - |
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170 I can lend you my copy for the duration of the project). A very good overview article |
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171 about implementing compilers by |
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172 <A HREF="http://tratt.net/laurie/">Laurie Tratt</A> is |
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173 <A HREF="http://tratt.net/laurie/tech_articles/articles/how_difficult_is_it_to_write_a_compiler">here</A>. |
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174 An introduction into x86 machine code is <A HREF="http://ianseyler.github.com/easy_x86-64/">here</A>. |
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175 A simple assembler for the JVM is described <A HREF="http://jasmin.sourceforge.net">here</A>. |
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176 An interesting twist of this project is to not generate code for a CPU, but |
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177 for the intermediate language of the <A HREF="http://llvm.org">LLVM</A> compiler |
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178 (also described <A HREF="https://wiki.aalto.fi/display/t1065450/LLVM+IR">here</A> and |
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179 <A HREF="http://llvm.org/docs/LangRef.html">here</A>). |
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180 </p> |
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181 |
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182 <p><B>Skills:</B> |
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183 This is a project for a student with a deep interest in programming languages and |
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184 compilers. Since my compiler is implemented in <A HREF="http://www.scala-lang.org/">Scala</A>, |
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185 it would make sense to continue this project in this language. I can be |
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186 of help with questions and books about <A HREF="http://www.scala-lang.org/">Scala</A>. |
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187 But if Scala is a problem, my code can also be translated quickly into any other functional |
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188 language. |
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189 </p> |
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190 |
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191 <li> <H4>[CU4] Implementation of Register Spilling Algorithms</H4> |
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192 |
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193 <p><b>Description:</b> |
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194 This project is similar to [CU3]. The emphasis here, however, is on the |
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195 implementation and comparison of register spilling algorithms, also often called register allocation |
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196 algorithms. They are part of any respectable compiler. As said |
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197 in [CU3], however, my simple compiler lacks them and assumes an infinite amount of registers instead. |
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198 Real CPUs however only provide a fixed amount of registers (for example |
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199 x86-64 has 16 general purpose registers). Whenever a program needs |
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200 to hold more values than registers, the values need to be “spilled” |
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201 into the main memory. Register spilling algorithms try to minimise |
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202 this spilling, since fetching values from main memory is a costly |
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203 operation. |
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204 </p> |
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205 |
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206 <p> |
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207 The classic algorithm for register spilling uses a |
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208 <A HREF="http://en.wikipedia.org/wiki/Register_allocation">graph-colouring method</A>. |
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209 However, for some time the <A HREF="http://llvm.org">LLVM</A> compiler |
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210 used a supposedly more efficient method, called the linear scan allocation method |
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211 (described |
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212 <A HREF="http://www.cs.ucla.edu/~palsberg/course/cs132/linearscan.pdf">here</A>). |
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213 However, it was later decided to abandon this method in favour of |
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214 a <A HREF="http://blog.llvm.org/2011/09/greedy-register-allocation-in-llvm-30.html"> |
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215 greedy register allocation</A> method. It would be nice if this project can find out |
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216 what the issues are with these methods and implement at least one of them for the |
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217 simple compiler referenced in [CU3]. |
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218 </p> |
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219 |
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220 <p> |
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221 <B>Literature:</B> |
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222 The graph colouring method is described in Andrew Appel's |
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223 <A HREF="http://www.cs.princeton.edu/~appel/modern/java/">book</A> on compilers |
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224 (I can give you my copy of this book, if it is not available in the library). |
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225 There is also a survey |
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226 <A HREF="http://compilers.cs.ucla.edu/fernando/publications/drafts/survey.pdf">article</A> |
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227 about register allocation algorithms with further pointers. |
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228 </p> |
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229 |
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230 <p><B>Skills:</B> |
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231 Same skills as [CU3]. |
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232 </p> |
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233 |
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234 <li> <H4>[CU5] A Student Polling System</H4> |
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235 <p> |
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236 <B>Description:</B> |
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237 One of the more annoying aspects of giving a lecture is to ask a question |
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238 to the students and no matter how easy the questions is to not |
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239 receive an answer. Recently, the online course system |
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240 <A HREF="http://www.udacity.com">Udacity</A> made an art out of |
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241 asking questions during lectures (see for example the |
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242 <A HREF="http://www.udacity.com/overview/Course/cs253/CourseRev/apr2012">Web Application Engineering</A> |
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243 course CS253). |
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244 The lecturer there gives multiple-choice questions as part of the lecture and the students need to |
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245 click on the appropriate answer. This works very well in the online world. |
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246 For “real-world” lectures, the department has some |
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247 <A HREF="http://en.wikipedia.org/wiki/Audience_response">clickers</A> |
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248 (these are little devices part of an audience response systems). However, |
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249 they are a logistic nightmare for the lecturer: they need to be distributed |
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250 during the lecture and collected at the end. Nowadays, where students |
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251 come with their own laptop or smartphone to lectures, this can |
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252 be improved. |
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253 </p> |
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254 |
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255 <p> |
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256 The task of this project is to implement an online student |
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257 polling system. The lecturer should be able to prepare |
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258 questions beforehand (encoded as some web-form) and be able to |
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259 show them during the lecture. The students |
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260 can give their answers by clicking on the corresponding webpage. |
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261 The lecturer can then collect the responses online and evaluate them |
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262 immediately. Such a system is sometimes called |
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263 <A HREF="http://en.wikipedia.org/wiki/Audience_response#Smartphone_.2F_HTTP_voting">HTML voting</A>. |
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264 There are a number of commercial |
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265 solutions for this problem, but they are not easy to use (in addition |
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266 to being ridiculously expensive). A good student can easily improve upon |
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267 what they provide. |
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268 </p> |
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269 |
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270 <p> |
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271 The problem of student polling is not as hard as |
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272 <A HREF="http://en.wikipedia.org/wiki/Electronic_voting">electronic voting</A>, |
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273 which essentially is still an unsolved problem in Computer Science. The |
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274 students only need to be prevented from answering question more than once thus skewing |
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275 any statistics. Unlike electronic voting, no audit trail needs to be kept |
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276 for student polling. Restricting the number of questions can probably be solved |
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277 by setting appropriate cookies on the students |
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278 computers or smart phones. |
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279 </p> |
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280 |
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281 <p> |
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282 <B>Literature:</B> |
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283 The project requires fluency in a web-programming language (for example |
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284 <A HREF="http://en.wikipedia.org/wiki/JavaScript">Javascript</A>, |
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285 <A HREF="http://en.wikipedia.org/wiki/PHP">PHP</A>, |
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286 Java, <A HREF="http://www.python.org">Python</A>, <A HREF="http://en.wikipedia.org/wiki/Go_(programming_language)">Go</A>, <A HREF="http://www.scala-lang.org/">Scala</A>, |
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287 <A HREF="http://en.wikipedia.org/wiki/Ruby_(programming_language)">Ruby</A>) |
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288 and possibly a cloud application platform (for example |
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289 <A HREF="https://developers.google.com/appengine/">Google App Engine</a> or |
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290 <A HREF="http://www.heroku.com">Heroku</A>). |
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291 For web-programming the |
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292 <A HREF="http://www.udacity.com/overview/Course/cs253/CourseRev/apr2012">Web Application Engineering</A> |
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293 course at <A HREF="http://www.udacity.com">Udacity</A> is a good starting point |
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294 to be aware of the issues involved. This course uses <A HREF="http://www.python.org">Python</A>. |
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295 |
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296 </p> |
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297 |
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298 <p><B>Skills:</B> |
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299 In order to provide convenience for the lecturer, this project needs very good web-programming skills. A |
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300 <A HREF="http://en.wikipedia.org/wiki/Hacker_(programmer_subculture)">hacker mentality</A> |
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301 (see above) is probably very beneficial: web-programming is an area that only emerged recently and |
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302 many tools still lack maturity. You probably have to experiment a lot with several different |
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303 languages and tools. |
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304 </p> |
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305 |
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