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