-LuaJIT has only a single stand-alone executable, called luajit on -POSIX systems or luajit.exe on Windows. It can be used to run simple -Lua statements or whole Lua applications from the command line. It has an -interactive mode, too. -
--Note: the beta test releases only install under the versioned name on -POSIX systems (to avoid overwriting a previous version). You either need -to type luajit-2.0.0-beta9 to start it or create a symlink -with a command like this: -
--sudo ln -sf luajit-2.0.0-beta9 /usr/local/bin/luajit --
-Unlike previous versions optimization is turned on by default in
-LuaJIT 2.0!
It's no longer necessary to use luajit -O.
-
Command Line Options
--The luajit stand-alone executable is just a slightly modified -version of the regular lua stand-alone executable. -It supports the same basic options, too. luajit -h -prints a short list of the available options. Please have a look at the -» Lua manual -for details. -
--LuaJIT has some additional options: -
- --b[options] input output
--This option saves or lists bytecode. The following additional options -are accepted: -
--
-
- -l — Only list bytecode. -
- -s — Strip debug info (this is the default). -
- -g — Keep debug info. -
- -n name — Set module name (default: auto-detect from input name) -
- -t type — Set output file type (default: auto-detect from output name). -
- -a arch — Override architecture for object files (default: native). -
- -o os — Override OS for object files (default: native). -
- -e chunk — Use chunk string as input. -
- - (a single minus sign) — Use stdin as input and/or stdout as output. -
-The output file type is auto-detected from the extension of the output -file name: -
--
-
- c — C source file, exported bytecode data. -
- h — C header file, static bytecode data. -
- obj or o — Object file, exported bytecode data -(OS- and architecture-specific). -
- raw or any other extension — Raw bytecode file (portable). -
-Notes: -
--
-
- See also string.dump() -for information on bytecode portability and compatibility. -
- A file in raw bytecode format is auto-detected and can be loaded like -any Lua source file. E.g. directly from the command line or with -loadfile(), dofile() etc. -
- To statically embed the bytecode of a module in your application, -generate an object file and just link it with your application. -
- On most ELF-based systems (e.g. Linux) you need to explicitly export the -global symbols when linking your application, e.g. with: -Wl,-E -
- require() tries to load embedded bytecode data from exported -symbols (in *.exe or lua51.dll on Windows) and from -shared libraries in package.cpath. -
-Typical usage examples: -
-
-luajit -b test.lua test.out # Save bytecode to test.out
-luajit -bg test.lua test.out # Keep debug info
-luajit -be "print('hello world')" test.out # Save cmdline script
-
-luajit -bl test.lua # List to stdout
-luajit -bl test.lua test.txt # List to test.txt
-luajit -ble "print('hello world')" # List cmdline script
-
-luajit -b test.lua test.obj # Generate object file
-# Link test.obj with your application and load it with require("test")
-
-
--j cmd[=arg[,arg...]]
--This option performs a LuaJIT control command or activates one of the -loadable extension modules. The command is first looked up in the -jit.* library. If no matching function is found, a module -named jit.<cmd> is loaded and the start() -function of the module is called with the specified arguments (if -any). The space between -j and cmd is optional. -
--Here are the available LuaJIT control commands: -
--
-
- -jon — Turns the JIT compiler on (default). -
- -joff — Turns the JIT compiler off (only use the interpreter). -
- -jflush — Flushes the whole cache of compiled code. -
- -jv — Shows verbose information about the progress of the JIT compiler. -
- -jdump — Dumps the code and structures used in various compiler stages. -
-The -jv and -jdump commands are extension modules -written in Lua. They are mainly used for debugging the JIT compiler -itself. For a description of their options and output format, please -read the comment block at the start of their source. -They can be found in the lib directory of the source -distribution or installed under the jit directory. By default -this is /usr/local/share/luajit-2.0.0-beta9/jit on POSIX -systems. -
- --O[level]
--O[+]flag -O-flag
--Oparam=value
--This options allows fine-tuned control of the optimizations used by -the JIT compiler. This is mainly intended for debugging LuaJIT itself. -Please note that the JIT compiler is extremely fast (we are talking -about the microsecond to millisecond range). Disabling optimizations -doesn't have any visible impact on its overhead, but usually generates -code that runs slower. -
--The first form sets an optimization level — this enables a -specific mix of optimization flags. -O0 turns off all -optimizations and higher numbers enable more optimizations. Omitting -the level (i.e. just -O) sets the default optimization level, -which is -O3 in the current version. -
--The second form adds or removes individual optimization flags. -The third form sets a parameter for the VM or the JIT compiler -to a specific value. -
--You can either use this option multiple times (like -Ocse --O-dce -Ohotloop=10) or separate several settings with a comma -(like -O+cse,-dce,hotloop=10). The settings are applied from -left to right and later settings override earlier ones. You can freely -mix the three forms, but note that setting an optimization level -overrides all earlier flags. -
--Here are the available flags and at what optimization levels they -are enabled: -
-| Flag | --O1 | --O2 | --O3 | -- |
| fold | • | • | • | Constant Folding, Simplifications and Reassociation |
| cse | • | • | • | Common-Subexpression Elimination |
| dce | • | • | • | Dead-Code Elimination |
| narrow | • | • | Narrowing of numbers to integers | |
| loop | • | • | Loop Optimizations (code hoisting) | |
| fwd | • | Load Forwarding (L2L) and Store Forwarding (S2L) | ||
| dse | • | Dead-Store Elimination | ||
| abc | • | Array Bounds Check Elimination | ||
| fuse | • | Fusion of operands into instructions |
-Here are the parameters and their default settings: -
-| Parameter | -Default | -- |
| maxtrace | 1000 | Max. number of traces in the cache |
| maxrecord | 4000 | Max. number of recorded IR instructions |
| maxirconst | 500 | Max. number of IR constants of a trace |
| maxside | 100 | Max. number of side traces of a root trace |
| maxsnap | 500 | Max. number of snapshots for a trace |
| hotloop | 56 | Number of iterations to detect a hot loop or hot call |
| hotexit | 10 | Number of taken exits to start a side trace |
| tryside | 4 | Number of attempts to compile a side trace |
| instunroll | 4 | Max. unroll factor for instable loops |
| loopunroll | 15 | Max. unroll factor for loop ops in side traces |
| callunroll | 3 | Max. unroll factor for pseudo-recursive calls |
| recunroll | 2 | Min. unroll factor for true recursion |
| sizemcode | 32 | Size of each machine code area in KBytes (Windows: 64K) |
| maxmcode | 512 | Max. total size of all machine code areas in KBytes |
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