The Flambda backend project for OCaml.

One-time setup for dev work or installation

Only currently tested on Linux/x86-64 and macOS/x86-64.

One-time setup:

$ opam switch 4.11.1  # or "opam switch create 4.11.1" if you haven't got that switch already
$ eval $(opam env)
$ git clone https://github.com/ocaml-flambda/dune
$ cd dune  # We'll refer to this "dune" directory below as $DUNE_DIR
$ git checkout origin/special_dune
$ make release

You probably then want to fork the ocaml-flambda/flambda-backend repo to your own Github org.

Branching and configuring

Use normal commands to make a branch from the main upstream branch (currently 4.11), e.g.:

$ git clone https://github.com/ocaml-flambda/flambda-backend
$ cd flambda-backend
$ git checkout -b myfeature origin/4.11

The Flambda backend tree has to be configured before building. The configure script is not checked in; you have to run autoconf. For example:

$ autoconf
$ ./configure --prefix=/path/to/install/dir --enable-middle-end=closure --with-dune=$DUNE_DIR/dune.exe

You can also specify --enable-middle-end=flambda or --enable-middle-end=flambda2. (The Flambda 2 compiler is not yet ready for production use.)

Building and installing

To build and install the Flambda backend, which produces a compiler installation directory whose layout is compatible with upstream, run:

$ make  # or e.g. make -j16
$ make install

Running tests

Prior to make install you can do:

• make runtest to run the Flambda backend tests (which use dune);
• make runtest-upstream to run the upstream testsuite. The upstream testsuite runs much faster if you install GNU parallel. This is likely already present on Linux machines. On macOS, install Homebrew, then brew install parallel.
• make compare to run the comparison script that finds differences between the upstream and Flambda backend install trees. This script currently only runs on Linux, although it shouldn't be hard to port to macOS, especially if using GNU binutils. It is recommended to install the Jane Street patdiff executable before running make compare.

There is also a make ci target (best run as e.g. make -j16 ci) which does a full build and test run. It does not currently run make compare as some spurious failures have been observed on the Github systems.