# Building TinyGo

TinyGo depends on LLVM and libclang, which are both big C++ libraries. It can
also optionally use a built-in lld to ease cross compiling. There are two ways
these can be linked: dynamically and statically. An install with `go install` is
dynamic linking because it is fast and works almost out of the box on
Debian-based systems with the right packages installed.

This guide describes how to statically link TinyGo against LLVM, libclang and
lld so that the binary can be easily moved between systems. It also shows how to
build a release tarball that includes this binary and all necessary extra files.

## Dependencies

LLVM, Clang and LLD are quite light on dependencies, requiring only standard
build tools to be built. Go is of course necessary to build TinyGo itself.

  * Go (1.11+)
  * Standard build tools (gcc/clang)
  * git
  * CMake
  * [Ninja](https://ninja-build.org/)

The rest of this guide assumes you're running Linux, but it should be equivalent
on a different system like Mac.

## Download the source

The first step is to download the TinyGo sources (use `--recursive` if you clone
the git repository). Then, inside the directory, download the LLVM source:

    make llvm-source

You can also store LLVM outside of the TinyGo root directory by setting the
`LLVM_BUILDDIR`, `CLANG_SRC` and `LLD_SRC` make variables, but that is not
covered by this guide.

TinyGo uses Go modules, so if you clone TinyGo inside your GOPATH (and are using
Go below 1.13), make sure that Go modules are enabled:

    export GO111MODULE=on

## Build LLVM, Clang, LLD

Before starting the build, you may want to set the following environment
variables to speed up the build. Most Linux distributions ship with GCC as the
default compiler, but Clang is significantly faster and uses much less memory
while producing binaries that are about as fast.

    export CC=clang
    export CXX=clang++

The Makefile includes a default configuration that is good for most users. It
builds a release version of LLVM (optimized, no asserts) and includes all
targets supported by TinyGo:

    make llvm-build

This can take over an hour depending on the speed of your system.

## Build TinyGo

The last step of course is to build TinyGo itself. This can again be done with
make:

    make

## Verify TinyGo

Try running TinyGo:

    ./build/tinygo help

Also, make sure the `tinygo` binary really is statically linked. Check this
using `ldd` (not to be confused with `lld`):

    ldd ./build/tinygo

The result should not contain libclang or libLLVM.

## Make a release tarball

Now that we have a working static build, it's time to make a release tarball:

    make release

The release tarball is stored in build/release.tar.gz, and can be extracted with
the following command (for example in ~/lib):

    tar -xvf path/to/release.tar.gz

TinyGo will get extracted to a `tinygo` directory. You can then call it with:

    ./tinygo/bin/tinygo