Introduction

llvm-lua now has support for native cross-compiling support.

Required software

• Get LLVM 2.6 from here
• Get Clang 2.6 from here
• CMake, used to build llvm-lua

See this page for how to compile LLVM & Clang.

Compiling llvm-luac as a cross-compiler

1. Setup build folder for cmake:

• download http://llvm-lua.googlecode.com/files/llvm_lua-1.1.0_pre2.tar.gz
• tar zxvf llvm_lua-1.1.0_pre2.tar.gz
• cd llvm-lua-1.1.0
• mkdir build-cross
• cd build-cross
• cmake ..

2. Set the following cmake variables using the "ccmake" GUI:

• CROSS_COMPILE=ON
• CROSS_CPU=arm1136j-s
• CROSS_ISYSTEM=/path/to/arm-target/system/includes
• CROSS_TRIPLE=arm-linux
• LLVM_CC=/opt/llvm-2.6/libexec/clang-cc

For good performance it is important to select the correct CROSS_CPU that matches the target cpu you will be compiling for. You can change this later in the "lua-cross-compiler" script, in case you need to compile for different arm cpus.

3. Compile llvm-luac

• make
• make install

You should now have the following files for llvm-luac: /usr/local/bin/arm-linux-llvm-luac /usr/local/bin/lua-cross-compiler

Cross compiling a Lua script.

To native compile a single Lua script into a standalone execute for the target architecture:

• lua-cross-compiler script.lua

To native compile sub-modules into the same standalone execute:

• lua-cross-compiler -L sub1.lua -L sub2 -L modules/sub3.lua script.lua