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  35 <a href="http://luajit.org"><span>Lua<span id="logo">JIT</span></span></a>
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  38 <h1>Running LuaJIT</h1>
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  82 <p>
  83 LuaJIT has only a single stand-alone executable, called <tt>luajit</tt> on
  84 POSIX systems or <tt>luajit.exe</tt> on Windows. It can be used to run simple
  85 Lua statements or whole Lua applications from the command line. It has an
  86 interactive mode, too.
  87 </p>
  88
  89 <h2 id="options">Command Line Options</h2>
  90 <p>
  91 The <tt>luajit</tt> stand-alone executable is just a slightly modified
  92 version of the regular <tt>lua</tt> stand-alone executable.
  93 It supports the same basic options, too. <tt>luajit&nbsp;-h</tt>
  94 prints a short list of the available options. Please have a look at the
  95 <a href="http://www.lua.org/manual/5.1/manual.html#6"><span class="ext">&raquo;</span>&nbsp;Lua manual</a>
  96 for details.
  97 </p>
  98 <p>
  99 LuaJIT has some additional options:
 100 </p>
 101
 102 <h3 id="opt_b"><tt>-b[options] input output</tt></h3>
 103 <p>
 104 This option saves or lists bytecode. The following additional options
 105 are accepted:
 106 </p>
 107 <ul>
 108 <li><tt>-l</tt> &mdash; Only list bytecode.</li>
 109 <li><tt>-s</tt> &mdash; Strip debug info (this is the default).</li>
 110 <li><tt>-g</tt> &mdash; Keep debug info.</li>
 111 <li><tt>-n name</tt> &mdash; Set module name (default: auto-detect from input name)</li>
 112 <li><tt>-t type</tt> &mdash; Set output file type (default: auto-detect from output name).</li>
 113 <li><tt>-a arch</tt> &mdash; Override architecture for object files (default: native).</li>
 114 <li><tt>-o os</tt> &mdash; Override OS for object files (default: native).</li>
 115 <li><tt>-e chunk</tt> &mdash; Use chunk string as input.</li>
 116 <li><tt>-</tt> (a single minus sign) &mdash; Use stdin as input and/or stdout as output.</li>
 117 </ul>
 118 <p>
 119 The output file type is auto-detected from the extension of the output
 120 file name:
 121 </p>
 122 <ul>
 123 <li><tt>c</tt> &mdash; C source file, exported bytecode data.</li>
 124 <li><tt>h</tt> &mdash; C header file, static bytecode data.</li>
 125 <li><tt>obj</tt> or <tt>o</tt> &mdash; Object file, exported bytecode data
 126 (OS- and architecture-specific).</li>
 127 <li><tt>raw</tt> or any other extension &mdash; Raw bytecode file (portable).
 128 </ul>
 129 <p>
 130 Notes:
 131 </p>
 132 <ul>
 133 <li>See also <a href="extensions.html#string_dump">string.dump()</a>
 134 for information on bytecode portability and compatibility.</li>
 135 <li>A file in raw bytecode format is auto-detected and can be loaded like
 136 any Lua source file. E.g. directly from the command line or with
 137 <tt>loadfile()</tt>, <tt>dofile()</tt> etc.</li>
 138 <li>To statically embed the bytecode of a module in your application,
 139 generate an object file and just link it with your application.</li>
 140 <li>On most ELF-based systems (e.g. Linux) you need to explicitly export the
 141 global symbols when linking your application, e.g. with: <tt>-Wl,-E</tt></li>
 142 <li><tt>require()</tt> tries to load embedded bytecode data from exported
 143 symbols (in <tt>*.exe</tt> or <tt>lua51.dll</tt> on Windows) and from
 144 shared libraries in <tt>package.cpath</tt>.</li>
 145 </ul>
 146 <p>
 147 Typical usage examples:
 148 </p>
 149 <pre class="code">
 150 luajit -b test.lua test.out                 # Save bytecode to test.out
 151 luajit -bg test.lua test.out                # Keep debug info
 152 luajit -be "print('hello world')" test.out  # Save cmdline script
 153
 154 luajit -bl test.lua                         # List to stdout
 155 luajit -bl test.lua test.txt                # List to test.txt
 156 luajit -ble "print('hello world')"          # List cmdline script
 157
 158 luajit -b test.lua test.obj                 # Generate object file
 159 # Link test.obj with your application and load it with require("test")
 160 </pre>
 161
 162 <h3 id="opt_j"><tt>-j cmd[=arg[,arg...]]</tt></h3>
 163 <p>
 164 This option performs a LuaJIT control command or activates one of the
 165 loadable extension modules. The command is first looked up in the
 166 <tt>jit.*</tt> library. If no matching function is found, a module
 167 named <tt>jit.&lt;cmd&gt;</tt> is loaded and the <tt>start()</tt>
 168 function of the module is called with the specified arguments (if
 169 any). The space between <tt>-j</tt> and <tt>cmd</tt> is optional.
 170 </p>
 171 <p>
 172 Here are the available LuaJIT control commands:
 173 </p>
 174 <ul>
 175 <li id="j_on"><tt>-jon</tt> &mdash; Turns the JIT compiler on (default).</li>
 176 <li id="j_off"><tt>-joff</tt> &mdash; Turns the JIT compiler off (only use the interpreter).</li>
 177 <li id="j_flush"><tt>-jflush</tt> &mdash; Flushes the whole cache of compiled code.</li>
 178 <li id="j_v"><tt>-jv</tt> &mdash; Shows verbose information about the progress of the JIT compiler.</li>
 179 <li id="j_dump"><tt>-jdump</tt> &mdash; Dumps the code and structures used in various compiler stages.</li>
 180 </ul>
 181 <p>
 182 The <tt>-jv</tt> and <tt>-jdump</tt> commands are extension modules
 183 written in Lua. They are mainly used for debugging the JIT compiler
 184 itself. For a description of their options and output format, please
 185 read the comment block at the start of their source.
 186 They can be found in the <tt>lib</tt> directory of the source
 187 distribution or installed under the <tt>jit</tt> directory. By default
 188 this is <tt>/usr/local/share/luajit-2.0.5/jit</tt> on POSIX
 189 systems.
 190 </p>
 191
 192 <h3 id="opt_O"><tt>-O[level]</tt><br>
 193 <tt>-O[+]flag</tt>&nbsp;&nbsp;&nbsp;<tt>-O-flag</tt><br>
 194 <tt>-Oparam=value</tt></h3>
 195 <p>
 196 This options allows fine-tuned control of the optimizations used by
 197 the JIT compiler. This is mainly intended for debugging LuaJIT itself.
 198 Please note that the JIT compiler is extremely fast (we are talking
 199 about the microsecond to millisecond range). Disabling optimizations
 200 doesn't have any visible impact on its overhead, but usually generates
 201 code that runs slower.
 202 </p>
 203 <p>
 204 The first form sets an optimization level &mdash; this enables a
 205 specific mix of optimization flags. <tt>-O0</tt> turns off all
 206 optimizations and higher numbers enable more optimizations. Omitting
 207 the level (i.e. just <tt>-O</tt>) sets the default optimization level,
 208 which is <tt>-O3</tt> in the current version.
 209 </p>
 210 <p>
 211 The second form adds or removes individual optimization flags.
 212 The third form sets a parameter for the VM or the JIT compiler
 213 to a specific value.
 214 </p>
 215 <p>
 216 You can either use this option multiple times (like <tt>-Ocse
 217 -O-dce -Ohotloop=10</tt>) or separate several settings with a comma
 218 (like <tt>-O+cse,-dce,hotloop=10</tt>). The settings are applied from
 219 left to right and later settings override earlier ones. You can freely
 220 mix the three forms, but note that setting an optimization level
 221 overrides all earlier flags.
 222 </p>
 223 <p>
 224 Here are the available flags and at what optimization levels they
 225 are enabled:
 226 </p>
 227 <table class="opt">
 228 <tr class="opthead">
 229 <td class="flag_name">Flag</td>
 230 <td class="flag_level">-O1</td>
 231 <td class="flag_level">-O2</td>
 232 <td class="flag_level">-O3</td>
 233 <td class="flag_desc">&nbsp;</td>
 234 </tr>
 235 <tr class="odd separate">
 236 <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>
 237 <tr class="even">
 238 <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>
 239 <tr class="odd">
 240 <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>
 241 <tr class="even">
 242 <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>
 243 <tr class="odd">
 244 <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>
 245 <tr class="even">
 246 <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>
 247 <tr class="odd">
 248 <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>
 249 <tr class="even">
 250 <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>
 251 <tr class="odd">
 252 <td class="flag_name">sink</td><td class="flag_level">&nbsp;</td><td class="flag_level">&nbsp;</td><td class="flag_level">&bull;</td><td class="flag_desc">Allocation/Store Sinking</td></tr>
 253 <tr class="even">
 254 <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>
 255 </table>
 256 <p>
 257 Here are the parameters and their default settings:
 258 </p>
 259 <table class="opt">
 260 <tr class="opthead">
 261 <td class="param_name">Parameter</td>
 262 <td class="param_default">Default</td>
 263 <td class="param_desc">&nbsp;</td>
 264 </tr>
 265 <tr class="odd separate">
 266 <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>
 267 <tr class="even">
 268 <td class="param_name">maxrecord</td><td class="param_default">4000</td><td class="param_desc">Max. number of recorded IR instructions</td></tr>
 269 <tr class="odd">
 270 <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>
 271 <tr class="even">
 272 <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>
 273 <tr class="odd">
 274 <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>
 275 <tr class="even separate">
 276 <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>
 277 <tr class="odd">
 278 <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>
 279 <tr class="even">
 280 <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>
 281 <tr class="odd separate">
 282 <td class="param_name">instunroll</td><td class="param_default">4</td><td class="param_desc">Max. unroll factor for instable loops</td></tr>
 283 <tr class="even">
 284 <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>
 285 <tr class="odd">
 286 <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>
 287 <tr class="even">
 288 <td class="param_name">recunroll</td><td class="param_default">2</td><td class="param_desc">Min. unroll factor for true recursion</td></tr>
 289 <tr class="odd separate">
 290 <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>
 291 <tr class="even">
 292 <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>
 293 </table>
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