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  4. <title>Running LuaJIT</title>
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  34. <body>
  35. <div id="site">
  36. <a href="http://luajit.org"><span>Lua<span id="logo">JIT</span></span></a>
  37. </div>
  38. <div id="head">
  39. <h1>Running LuaJIT</h1>
  40. </div>
  41. <div id="nav">
  42. <ul><li>
  43. <a href="luajit.html">LuaJIT</a>
  44. <ul><li>
  45. <a href="install.html">Installation</a>
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  52. <a href="ext_ffi.html">FFI Library</a>
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  73. <a href="http://luajit.org/performance.html">Performance <span class="ext">&raquo;</span></a>
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  75. <a href="http://luajit.org/download.html">Download <span class="ext">&raquo;</span></a>
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  79. </div>
  80. <div id="main">
  81. <p>
  82. LuaJIT has only a single stand-alone executable, called <tt>luajit</tt> on
  83. POSIX systems or <tt>luajit.exe</tt> on Windows. It can be used to run simple
  84. Lua statements or whole Lua applications from the command line. It has an
  85. interactive mode, too.
  86. </p>
  87. <p class="indent" style="color: #c00000;">
  88. Note: the beta test releases only install under the versioned name on
  89. POSIX systems (to avoid overwriting a previous version). You either need
  90. to type <tt>luajit-2.0.0-beta10</tt> to start it or create a symlink
  91. with a command like this:
  92. </p>
  93. <pre class="code" style="color: #c00000;">
  94. sudo ln -sf luajit-2.0.0-beta10&nbsp;/usr/local/bin/luajit
  95. </pre>
  96. <p>
  97. Unlike previous versions <b>optimization is turned on by default</b> in
  98. LuaJIT 2.0!<br>It's no longer necessary to use <tt>luajit&nbsp;-O</tt>.
  99. </p>
  100. <h2 id="options">Command Line Options</h2>
  101. <p>
  102. The <tt>luajit</tt> stand-alone executable is just a slightly modified
  103. version of the regular <tt>lua</tt> stand-alone executable.
  104. It supports the same basic options, too. <tt>luajit&nbsp;-h</tt>
  105. prints a short list of the available options. Please have a look at the
  106. <a href="http://www.lua.org/manual/5.1/manual.html#6"><span class="ext">&raquo;</span>&nbsp;Lua manual</a>
  107. for details.
  108. </p>
  109. <p>
  110. LuaJIT has some additional options:
  111. </p>
  112. <h3 id="opt_b"><tt>-b[options] input output</tt></h3>
  113. <p>
  114. This option saves or lists bytecode. The following additional options
  115. are accepted:
  116. </p>
  117. <ul>
  118. <li><tt>-l</tt> &mdash; Only list bytecode.</li>
  119. <li><tt>-s</tt> &mdash; Strip debug info (this is the default).</li>
  120. <li><tt>-g</tt> &mdash; Keep debug info.</li>
  121. <li><tt>-n name</tt> &mdash; Set module name (default: auto-detect from input name)</li>
  122. <li><tt>-t type</tt> &mdash; Set output file type (default: auto-detect from output name).</li>
  123. <li><tt>-a arch</tt> &mdash; Override architecture for object files (default: native).</li>
  124. <li><tt>-o os</tt> &mdash; Override OS for object files (default: native).</li>
  125. <li><tt>-e chunk</tt> &mdash; Use chunk string as input.</li>
  126. <li><tt>-</tt> (a single minus sign) &mdash; Use stdin as input and/or stdout as output.</li>
  127. </ul>
  128. <p>
  129. The output file type is auto-detected from the extension of the output
  130. file name:
  131. </p>
  132. <ul>
  133. <li><tt>c</tt> &mdash; C source file, exported bytecode data.</li>
  134. <li><tt>h</tt> &mdash; C header file, static bytecode data.</li>
  135. <li><tt>obj</tt> or <tt>o</tt> &mdash; Object file, exported bytecode data
  136. (OS- and architecture-specific).</li>
  137. <li><tt>raw</tt> or any other extension &mdash; Raw bytecode file (portable).
  138. </ul>
  139. <p>
  140. Notes:
  141. </p>
  142. <ul>
  143. <li>See also <a href="extensions.html#string_dump">string.dump()</a>
  144. for information on bytecode portability and compatibility.</li>
  145. <li>A file in raw bytecode format is auto-detected and can be loaded like
  146. any Lua source file. E.g. directly from the command line or with
  147. <tt>loadfile()</tt>, <tt>dofile()</tt> etc.</li>
  148. <li>To statically embed the bytecode of a module in your application,
  149. generate an object file and just link it with your application.</li>
  150. <li>On most ELF-based systems (e.g. Linux) you need to explicitly export the
  151. global symbols when linking your application, e.g. with: <tt>-Wl,-E</tt></li>
  152. <li><tt>require()</tt> tries to load embedded bytecode data from exported
  153. symbols (in <tt>*.exe</tt> or <tt>lua51.dll</tt> on Windows) and from
  154. shared libraries in <tt>package.cpath</tt>.</li>
  155. </ul>
  156. <p>
  157. Typical usage examples:
  158. </p>
  159. <pre class="code">
  160. luajit -b test.lua test.out # Save bytecode to test.out
  161. luajit -bg test.lua test.out # Keep debug info
  162. luajit -be "print('hello world')" test.out # Save cmdline script
  163. luajit -bl test.lua # List to stdout
  164. luajit -bl test.lua test.txt # List to test.txt
  165. luajit -ble "print('hello world')" # List cmdline script
  166. luajit -b test.lua test.obj # Generate object file
  167. # Link test.obj with your application and load it with require("test")
  168. </pre>
  169. <h3 id="opt_j"><tt>-j cmd[=arg[,arg...]]</tt></h3>
  170. <p>
  171. This option performs a LuaJIT control command or activates one of the
  172. loadable extension modules. The command is first looked up in the
  173. <tt>jit.*</tt> library. If no matching function is found, a module
  174. named <tt>jit.&lt;cmd&gt;</tt> is loaded and the <tt>start()</tt>
  175. function of the module is called with the specified arguments (if
  176. any). The space between <tt>-j</tt> and <tt>cmd</tt> is optional.
  177. </p>
  178. <p>
  179. Here are the available LuaJIT control commands:
  180. </p>
  181. <ul>
  182. <li id="j_on"><tt>-jon</tt> &mdash; Turns the JIT compiler on (default).</li>
  183. <li id="j_off"><tt>-joff</tt> &mdash; Turns the JIT compiler off (only use the interpreter).</li>
  184. <li id="j_flush"><tt>-jflush</tt> &mdash; Flushes the whole cache of compiled code.</li>
  185. <li id="j_v"><tt>-jv</tt> &mdash; Shows verbose information about the progress of the JIT compiler.</li>
  186. <li id="j_dump"><tt>-jdump</tt> &mdash; Dumps the code and structures used in various compiler stages.</li>
  187. </ul>
  188. <p>
  189. The <tt>-jv</tt> and <tt>-jdump</tt> commands are extension modules
  190. written in Lua. They are mainly used for debugging the JIT compiler
  191. itself. For a description of their options and output format, please
  192. read the comment block at the start of their source.
  193. They can be found in the <tt>lib</tt> directory of the source
  194. distribution or installed under the <tt>jit</tt> directory. By default
  195. this is <tt>/usr/local/share/luajit-2.0.0-beta10/jit</tt> on POSIX
  196. systems.
  197. </p>
  198. <h3 id="opt_O"><tt>-O[level]</tt><br>
  199. <tt>-O[+]flag</tt>&nbsp;&nbsp;&nbsp;<tt>-O-flag</tt><br>
  200. <tt>-Oparam=value</tt></h3>
  201. <p>
  202. This options allows fine-tuned control of the optimizations used by
  203. the JIT compiler. This is mainly intended for debugging LuaJIT itself.
  204. Please note that the JIT compiler is extremely fast (we are talking
  205. about the microsecond to millisecond range). Disabling optimizations
  206. doesn't have any visible impact on its overhead, but usually generates
  207. code that runs slower.
  208. </p>
  209. <p>
  210. The first form sets an optimization level &mdash; this enables a
  211. specific mix of optimization flags. <tt>-O0</tt> turns off all
  212. optimizations and higher numbers enable more optimizations. Omitting
  213. the level (i.e. just <tt>-O</tt>) sets the default optimization level,
  214. which is <tt>-O3</tt> in the current version.
  215. </p>
  216. <p>
  217. The second form adds or removes individual optimization flags.
  218. The third form sets a parameter for the VM or the JIT compiler
  219. to a specific value.
  220. </p>
  221. <p>
  222. You can either use this option multiple times (like <tt>-Ocse
  223. -O-dce -Ohotloop=10</tt>) or separate several settings with a comma
  224. (like <tt>-O+cse,-dce,hotloop=10</tt>). The settings are applied from
  225. left to right and later settings override earlier ones. You can freely
  226. mix the three forms, but note that setting an optimization level
  227. overrides all earlier flags.
  228. </p>
  229. <p>
  230. Here are the available flags and at what optimization levels they
  231. are enabled:
  232. </p>
  233. <table class="opt">
  234. <tr class="opthead">
  235. <td class="flag_name">Flag</td>
  236. <td class="flag_level">-O1</td>
  237. <td class="flag_level">-O2</td>
  238. <td class="flag_level">-O3</td>
  239. <td class="flag_desc">&nbsp;</td>
  240. </tr>
  241. <tr class="odd separate">
  242. <td class="flag_name">fold</td><td class="flag_level">&bull;</td><td class="flag_level">&bull;</td><td class="flag_level">&bull;</td><td class="flag_desc">Constant Folding, Simplifications and Reassociation</td></tr>
  243. <tr class="even">
  244. <td class="flag_name">cse</td><td class="flag_level">&bull;</td><td class="flag_level">&bull;</td><td class="flag_level">&bull;</td><td class="flag_desc">Common-Subexpression Elimination</td></tr>
  245. <tr class="odd">
  246. <td class="flag_name">dce</td><td class="flag_level">&bull;</td><td class="flag_level">&bull;</td><td class="flag_level">&bull;</td><td class="flag_desc">Dead-Code Elimination</td></tr>
  247. <tr class="even">
  248. <td class="flag_name">narrow</td><td class="flag_level">&nbsp;</td><td class="flag_level">&bull;</td><td class="flag_level">&bull;</td><td class="flag_desc">Narrowing of numbers to integers</td></tr>
  249. <tr class="odd">
  250. <td class="flag_name">loop</td><td class="flag_level">&nbsp;</td><td class="flag_level">&bull;</td><td class="flag_level">&bull;</td><td class="flag_desc">Loop Optimizations (code hoisting)</td></tr>
  251. <tr class="even">
  252. <td class="flag_name">fwd</td><td class="flag_level">&nbsp;</td><td class="flag_level">&nbsp;</td><td class="flag_level">&bull;</td><td class="flag_desc">Load Forwarding (L2L) and Store Forwarding (S2L)</td></tr>
  253. <tr class="odd">
  254. <td class="flag_name">dse</td><td class="flag_level">&nbsp;</td><td class="flag_level">&nbsp;</td><td class="flag_level">&bull;</td><td class="flag_desc">Dead-Store Elimination</td></tr>
  255. <tr class="even">
  256. <td class="flag_name">abc</td><td class="flag_level">&nbsp;</td><td class="flag_level">&nbsp;</td><td class="flag_level">&bull;</td><td class="flag_desc">Array Bounds Check Elimination</td></tr>
  257. <tr class="odd">
  258. <td class="flag_name">fuse</td><td class="flag_level">&nbsp;</td><td class="flag_level">&nbsp;</td><td class="flag_level">&bull;</td><td class="flag_desc">Fusion of operands into instructions</td></tr>
  259. </table>
  260. <p>
  261. Here are the parameters and their default settings:
  262. </p>
  263. <table class="opt">
  264. <tr class="opthead">
  265. <td class="param_name">Parameter</td>
  266. <td class="param_default">Default</td>
  267. <td class="param_desc">&nbsp;</td>
  268. </tr>
  269. <tr class="odd separate">
  270. <td class="param_name">maxtrace</td><td class="param_default">1000</td><td class="param_desc">Max. number of traces in the cache</td></tr>
  271. <tr class="even">
  272. <td class="param_name">maxrecord</td><td class="param_default">4000</td><td class="param_desc">Max. number of recorded IR instructions</td></tr>
  273. <tr class="odd">
  274. <td class="param_name">maxirconst</td><td class="param_default">500</td><td class="param_desc">Max. number of IR constants of a trace</td></tr>
  275. <tr class="even">
  276. <td class="param_name">maxside</td><td class="param_default">100</td><td class="param_desc">Max. number of side traces of a root trace</td></tr>
  277. <tr class="odd">
  278. <td class="param_name">maxsnap</td><td class="param_default">500</td><td class="param_desc">Max. number of snapshots for a trace</td></tr>
  279. <tr class="even separate">
  280. <td class="param_name">hotloop</td><td class="param_default">56</td><td class="param_desc">Number of iterations to detect a hot loop or hot call</td></tr>
  281. <tr class="odd">
  282. <td class="param_name">hotexit</td><td class="param_default">10</td><td class="param_desc">Number of taken exits to start a side trace</td></tr>
  283. <tr class="even">
  284. <td class="param_name">tryside</td><td class="param_default">4</td><td class="param_desc">Number of attempts to compile a side trace</td></tr>
  285. <tr class="odd separate">
  286. <td class="param_name">instunroll</td><td class="param_default">4</td><td class="param_desc">Max. unroll factor for instable loops</td></tr>
  287. <tr class="even">
  288. <td class="param_name">loopunroll</td><td class="param_default">15</td><td class="param_desc">Max. unroll factor for loop ops in side traces</td></tr>
  289. <tr class="odd">
  290. <td class="param_name">callunroll</td><td class="param_default">3</td><td class="param_desc">Max. unroll factor for pseudo-recursive calls</td></tr>
  291. <tr class="even">
  292. <td class="param_name">recunroll</td><td class="param_default">2</td><td class="param_desc">Min. unroll factor for true recursion</td></tr>
  293. <tr class="odd separate">
  294. <td class="param_name">sizemcode</td><td class="param_default">32</td><td class="param_desc">Size of each machine code area in KBytes (Windows: 64K)</td></tr>
  295. <tr class="even">
  296. <td class="param_name">maxmcode</td><td class="param_default">512</td><td class="param_desc">Max. total size of all machine code areas in KBytes</td></tr>
  297. </table>
  298. <br class="flush">
  299. </div>
  300. <div id="foot">
  301. <hr class="hide">
  302. Copyright &copy; 2005-2012 Mike Pall
  303. <span class="noprint">
  304. &middot;
  305. <a href="contact.html">Contact</a>
  306. </span>
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