LuaJIT

# Installation

LuaJIT is only distributed as a source package. This page explains how to build and install LuaJIT with different operating systems and C compilers.

For the impatient (on POSIX systems):

    make && sudo make install

LuaJIT currently builds out-of-the box on most systems. Here's the compatibility matrix for the supported combinations of operating systems, CPUs and compilers:

CPU / OS | Linux or Android | *BSD, Other | macOS 10.4+ or iOS 3.0+ | Windows 7 or later
x86 (32 bit) | GCC 4.2+ | GCC 4.2+ | XCode 5.0+ Clang | MSVC MinGW, Cygwin
x64 (64 bit) | GCC 4.2+ | GCC 4.2+ ORBIS (PS4) | XCode 5.0+ Clang | MSVC Durango (Xbox One)
ARMv5+ ARM9E+ | GCC 4.2+ | GCC 4.2+ PSP2 (PS VITA) | XCode 5.0+ Clang |
ARM64 ARM64be | GCC 4.8+ |  | XCode 6.0+ Clang 3.5+ |
PPC | GCC 4.3+ | GCC 4.3+ GCC 4.1 (PS3) |  | XEDK (Xbox 360)
MIPS32 MIPS64 MIPS64r6 | GCC 4.3+ | GCC 4.3+ |  |

## Configuring LuaJIT

The standard configuration should work fine for most installations. Usually there is no need to tweak the settings. The following files hold all user-configurable settings:

- `src/luaconf.h` sets some configuration variables.
- `Makefile` has settings for installing LuaJIT (POSIX only).
- `src/Makefile` has settings for compiling LuaJIT under POSIX, MinGW or Cygwin.
- `src/msvcbuild.bat` has settings for compiling LuaJIT with MSVC (Visual Studio).

Please read the instructions given in these files, before changing any settings.

All LuaJIT 64 bit ports use 64 bit GC objects by default (`LJ_GC64`). For x64, you can select the old 32-on-64 bit mode by adding `XCFLAGS=-DLUAJIT_DISABLE_GC64` to the make command. Please check the note about the bytecode format differences, too.

## POSIX Systems (Linux, macOS, *BSD etc.)

### Prerequisites

Depending on your distribution, you may need to install a package for GCC, the development headers and/or a complete SDK. E.g. on a current Debian/Ubuntu, install `libc6-dev` with the package manager.

The recommended way to fetch the latest version is to do a pull from the git repository.

Alternatively download the latest source package of LuaJIT (pick the .tar.gz). Move it to a directory of your choice, open a terminal window and change to this directory. Now unpack the archive and change to the newly created directory (replace XX.YY.ZZ with the version you downloaded):

    tar zxf LuaJIT-XX.YY.ZZ.tar.gz
    cd LuaJIT-XX.YY.ZZ

### Building LuaJIT

The supplied Makefiles try to auto-detect the settings needed for your operating system and your compiler. They need to be run with GNU Make, which is probably the default on your system, anyway. Simply run:

    make

This always builds a native binary, depending on the host OS you're running this command on. Check the section on cross-compilation for more options.

By default, modules are only searched under the prefix `/usr/local`. You can add an extra prefix to the search paths by appending the `PREFIX` option, e.g.:

    make PREFIX=/home/myself/lj2

Note for macOS: you must set the `MACOSX_DEPLOYMENT_TARGET` environment variable to a value supported by your toolchain:

    MACOSX_DEPLOYMENT_TARGET=XX.YY make

### Installing LuaJIT

The top-level Makefile installs LuaJIT by default under `/usr/local`, i.e. the executable ends up in `/usr/local/bin` and so on. You need root privileges to write to this path. So, assuming sudo is installed on your system, run the following command and enter your sudo password:

    sudo make install

Otherwise specify the directory prefix as an absolute path, e.g.:

    make install PREFIX=/home/myself/lj2

Obviously the prefixes given during build and installation need to be the same.

## Windows Systems

### Prerequisites

Either install one of the open source SDKs (» MinGW or » Cygwin), which come with a modified GCC plus the required development headers. Or install Microsoft's Visual Studio (MSVC).

Next, pull from the git repository or download the source package and unpack it using an archive manager (e.g. the Windows Explorer) to a directory of your choice.

### Building with MSVC

Open a "Visual Studio Command Prompt" (either x86 or x64), `cd` to the directory where you've unpacked the sources and run these commands:

    cd src
    msvcbuild

Check the `msvcbuild.bat` file for more options. Then follow the installation instructions below.

### Building with MinGW or Cygwin

Open a command prompt window and make sure the MinGW or Cygwin programs are in your path. Then `cd` to the directory of the git repository or where you've unpacked the sources. Then run this command for MinGW:

    mingw32-make

Or this command for Cygwin:

    make

Then follow the installation instructions below.

### Installing LuaJIT

Copy `luajit.exe` and `lua51.dll` (built in the `src` directory) to a newly created directory (any location is ok). Add `lua` and `lua\jit` directories below it and copy all Lua files from the `src\jit` directory of the distribution to the latter directory.

There are no hardcoded absolute path names — all modules are loaded relative to the directory where `luajit.exe` is installed (see `src/luaconf.h`).

## Cross-compiling LuaJIT

First, let's clear up some terminology:

- Host: This is your development system, usually based on a x64 or x86 CPU.
- Target: This is the target system you want LuaJIT to run on, e.g. Android/ARM.
- Toolchain: This comprises a C compiler, linker, assembler and a matching C library.
- Host (or system) toolchain: This is the toolchain used to build native binaries for your host system.
- Cross-compile toolchain: This is the toolchain used to build binaries for the target system. They can only be run on the target system.

The GNU Makefile-based build system allows cross-compiling on any host for any supported target:

- Yes, you need a toolchain for both your host and your target!
- Both host and target architectures must have the same pointer size.
- E.g. if you want to cross-compile to a 32 bit target on a 64 bit host, you need to install the multilib development package (e.g. `libc6-dev-i386` on Debian/Ubuntu) and build a 32 bit host part (`HOST_CC="gcc -m32"`).
- 64 bit targets always require compilation on a 64 bit host.

You need to specify `TARGET_SYS` whenever the host OS and the target OS differ, or you'll get assembler or linker errors:

- E.g. if you're compiling on a Windows or macOS host for embedded Linux or Android, you need to add `TARGET_SYS=Linux` to the examples below.
- For a minimal target OS, you may need to disable the built-in allocator in `src/Makefile` and use `TARGET_SYS=Other`.
- Don't forget to specify the same `TARGET_SYS` for the install step, too.

Here are some examples where host and target have the same CPU:

    # Cross-compile to a 32 bit binary on a multilib x64 OS
    make CC="gcc -m32"

    # Cross-compile on Debian/Ubuntu for Windows (mingw32 package)
    make HOST_CC="gcc -m32" CROSS=i586-mingw32msvc- TARGET_SYS=Windows

The `CROSS` prefix allows specifying a standard GNU cross-compile toolchain (Binutils, GCC and a matching libc). The prefix may vary depending on the `--target` the toolchain was built for (note the `CROSS` prefix has a trailing `"-"`). The examples below use the canonical toolchain triplets for Linux.

Since there's often no easy way to detect CPU features at runtime, it's important to compile with the proper CPU or architecture settings:

- The best way to get consistent results is to specify the correct settings when building the toolchain yourself.
- For a pre-built, generic toolchain add `-mcpu=...` or `-march=...` and other necessary flags to `TARGET_CFLAGS`.
- For ARM it's important to have the correct `-mfloat-abi=...` setting, too. Otherwise LuaJIT may not run at the full performance of your target CPU.
- For MIPS it's important to select a supported ABI (o32 on MIPS32, n64 on MIPS64) and consistently compile your project either with hard-float or soft-float compiler settings.

Here are some examples for targets with a different CPU than the host:

    # ARM soft-float
    make HOST_CC="gcc -m32" CROSS=arm-linux-gnueabi- \
         TARGET_CFLAGS="-mfloat-abi=soft"

    # ARM soft-float ABI with VFP (example for Cortex-A9)
    make HOST_CC="gcc -m32" CROSS=arm-linux-gnueabi- \
         TARGET_CFLAGS="-mcpu=cortex-a9 -mfloat-abi=softfp"

    # ARM hard-float ABI with VFP (armhf, most modern toolchains)
    make HOST_CC="gcc -m32" CROSS=arm-linux-gnueabihf-

    # ARM64
    make CROSS=aarch64-linux-

    # PPC
    make HOST_CC="gcc -m32" CROSS=powerpc-linux-gnu-

    # MIPS32 big-endian
    make HOST_CC="gcc -m32" CROSS=mips-linux-
    # MIPS32 little-endian
    make HOST_CC="gcc -m32" CROSS=mipsel-linux-

    # MIPS64 big-endian
    make CROSS=mips-linux- TARGET_CFLAGS="-mips64r2 -mabi=64"
    # MIPS64 little-endian
    make CROSS=mipsel-linux- TARGET_CFLAGS="-mips64r2 -mabi=64"

You can cross-compile for Android using the » Android NDK. Please adapt the environment variables to match the install locations and the desired target platform. E.g. Android 4.1 corresponds to ABI level 16.

    # Android/ARM64, aarch64, Android 5.0+ (L)
    NDKDIR=/opt/android/ndk
    NDKBIN=$NDKDIR/toolchains/llvm/prebuilt/linux-x86_64/bin
    NDKCROSS=$NDKBIN/aarch64-linux-android-
    NDKCC=$NDKBIN/aarch64-linux-android21-clang
    make CROSS=$NDKCROSS \
         STATIC_CC=$NDKCC DYNAMIC_CC="$NDKCC -fPIC" \
         TARGET_LD=$NDKCC TARGET_AR="$NDKBIN/llvm-ar rcus" \
         TARGET_STRIP=$NDKBIN/llvm-strip

    # Android/ARM, armeabi-v7a (ARMv7 VFP), Android 4.1+ (JB)
    NDKDIR=/opt/android/ndk
    NDKBIN=$NDKDIR/toolchains/llvm/prebuilt/linux-x86_64/bin
    NDKCROSS=$NDKBIN/arm-linux-androideabi-
    NDKCC=$NDKBIN/armv7a-linux-androideabi16-clang
    make HOST_CC="gcc -m32" CROSS=$NDKCROSS \
         STATIC_CC=$NDKCC DYNAMIC_CC="$NDKCC -fPIC" \
         TARGET_LD=$NDKCC TARGET_AR="$NDKBIN/llvm-ar rcus" \
         TARGET_STRIP=$NDKBIN/llvm-strip

You can cross-compile for iOS 3.0+ (iPhone/iPad) using the » iOS SDK:

Note: the JIT compiler is disabled for iOS, because regular iOS Apps are not allowed to generate code at runtime. You'll only get the performance of the LuaJIT interpreter on iOS. This is still faster than plain Lua, but much slower than the JIT compiler. Please complain to Apple, not me. Or use Android. :-p

    # iOS/ARM64
    ISDKP=$(xcrun --sdk iphoneos --show-sdk-path)
    ICC=$(xcrun --sdk iphoneos --find clang)
    ISDKF="-arch arm64 -isysroot $ISDKP"
    make DEFAULT_CC=clang CROSS="$(dirname $ICC)/" \
         TARGET_FLAGS="$ISDKF" TARGET_SYS=iOS

### Cross-compiling for consoles

Building LuaJIT for consoles requires both a supported host compiler (x86 or x64) and a cross-compiler (to PPC or ARM) from the official console SDK.

Due to restrictions on consoles, the JIT compiler is disabled and only the fast interpreter is built. This is still faster than plain Lua, but much slower than the JIT compiler. The FFI is disabled, too, since it's not very useful in such an environment.

The following commands build a static library `libluajit.a`, which can be linked against your game, just like the Lua library.

To cross-compile for PS3 from a Linux host (requires 32 bit GCC, i.e. multilib Linux/x64) or a Windows host (requires 32 bit MinGW), run this command:

    make HOST_CC="gcc -m32" CROSS=ppu-lv2-

To cross-compile for PS4 from a Windows host, open a "Visual Studio .NET Command Prompt" (64 bit host compiler), `cd` to the directory where you've unpacked the sources and run the following commands:

    cd src
    ps4build

To cross-compile for PS Vita from a Windows host, open a "Visual Studio .NET Command Prompt" (32 bit host compiler), `cd` to the directory where you've unpacked the sources and run the following commands:

    cd src
    psvitabuild

To cross-compile for Xbox 360 from a Windows host, open a "Visual Studio .NET Command Prompt" (32 bit host compiler), `cd` to the directory where you've unpacked the sources and run the following commands:

    cd src
    xedkbuild

To cross-compile for Xbox One from a Windows host, open a "Visual Studio .NET Command Prompt" (64 bit host compiler), `cd` to the directory where you've unpacked the sources and run the following commands:

    cd src
    xb1build

## Embedding LuaJIT

LuaJIT is API-compatible with Lua 5.1. If you've already embedded Lua into your application, you probably don't need to do anything to switch to LuaJIT, except link with a different library:

- It's strongly suggested to build LuaJIT separately using the supplied build system. Please do not attempt to integrate the individual source files into your build tree. You'll most likely get the internal build dependencies wrong or mess up the compiler flags. Treat LuaJIT like any other external library and link your application with either the dynamic or static library, depending on your needs.
- If you want to load C modules compiled for plain Lua with `require()`, you need to make sure the public symbols (e.g. `lua_pushnumber`) are exported, too:
  - On POSIX systems you can either link to the shared library or link the static library into your application. In the latter case you'll need to export all public symbols from your main executable (e.g. `-Wl,-E` on Linux) and add the external dependencies (e.g. `-lm -ldl` on Linux).
  - Since Windows symbols are bound to a specific DLL name, you need to link to the `lua51.dll` created by the LuaJIT build (do not rename the DLL). You may link LuaJIT statically on Windows only if you don't intend to load Lua/C modules at runtime.

Additional hints for initializing LuaJIT using the C API functions:

- Here's a » simple example for embedding Lua or LuaJIT into your application.
- Make sure you use `luaL_newstate`. Avoid using `lua_newstate`, since this uses the (slower) default memory allocator from your system (no support for this on 64 bit architectures).
- Make sure you use `luaL_openlibs` and not the old Lua 5.0 style of calling `luaopen_base` etc. directly.
- To change or extend the list of standard libraries to load, copy `src/lib_init.c` to your project and modify it accordingly. Make sure the `jit` library is loaded or the JIT compiler will not be activated.
- The `bit.*` module for bitwise operations is already built-in. There's no need to statically link » Lua BitOp to your application.

## Hints for Distribution Maintainers

The LuaJIT build system has extra provisions for the needs of most POSIX-based distributions. If you're a package maintainer for a distribution, please make use of these features and avoid patching, subverting, autotoolizing or messing up the build system in unspeakable ways.

There should be absolutely no need to patch `luaconf.h` or any of the Makefiles. And please do not hand-pick files for your packages — simply use whatever `make install` creates. There's a reason for all of the files and directories it creates.

The build system uses GNU make and auto-detects most settings based on the host you're building it on. This should work fine for native builds, even when sandboxed. You may need to pass some of the following flags to both the `make` and the `make install` command lines for a regular distribution build:

- `PREFIX` overrides the installation path and should usually be set to `/usr`. Setting this also changes the module paths and the paths needed to locate the shared library.
- `DESTDIR` is an absolute path which allows you to install to a shadow tree instead of the root tree of the build system.
- `MULTILIB` sets the architecture-specific library path component for multilib systems. The default is `lib`.
- Have a look at the top-level `Makefile` and `src/Makefile` for additional variables to tweak. The following variables may be overridden, but it's not recommended, except for special needs like cross-builds: `BUILDMODE, CC, HOST_CC, STATIC_CC, DYNAMIC_CC, CFLAGS, HOST_CFLAGS, TARGET_CFLAGS, LDFLAGS, HOST_LDFLAGS, TARGET_LDFLAGS, TARGET_SHLDFLAGS, TARGET_FLAGS, LIBS, HOST_LIBS, TARGET_LIBS, CROSS, HOST_SYS, TARGET_SYS`

The build system has a special target for an amalgamated build, i.e. `make amalg`. This compiles the LuaJIT core as one huge C file and allows GCC to generate faster and shorter code. Alas, this requires lots of memory during the build. This may be a problem for some users, that's why it's not enabled by default. But it shouldn't be a problem for most build farms. It's recommended that binary distributions use this target for their LuaJIT builds.

The tl;dr version of the above:

    make amalg PREFIX=/usr && \
    make install PREFIX=/usr DESTDIR=/tmp/buildroot

Finally, if you encounter any difficulties, please contact me first, instead of releasing a broken package onto unsuspecting users. Because they'll usually gonna complain to me (the upstream) and not you (the package maintainer), anyway.

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