GccEmacs

GccEmacs refers to the --with-native-compilation configuration option when building Emacs, which adds support for compiling EmacsLisp to native code using libgccjit. All of the Elisp packages shipped with Emacs are native-compiled, providing a noticeable performance improvement out-of-the-box. Third-party packages are also compiled to achieve further performance improvements.

The official development log can be found on the gccemacs page.

The feature is discussed in detail in the paper "Bringing GNU Emacs to native code" and related talk.

Installation

From source

To build the native-comp branch of Emacs, you will need libgccjit in addition to the other dependencies described in BuildingEmacs.

First, checkout the master branch of Emacs, and configure it with the --with-native-compilation flag:

    $ git clone git://git.savannah.gnu.org/emacs.git
    $ cd emacs
    $ ./autogen.sh
    $ ./configure --with-native-compilation
    $ make -j$(nproc)

You should see "Does Emacs have native lisp compiler? yes" near the end of the configure output if native compilation has been enabled.

If you wish, install conventionally with make install otherwise run it from the build tree with ./src/emacs.

fedora

    dnf copr enable deathwish/emacs-pgtk-nativecomp
    dnf update emacs

or

    dnf install emacs

ArchLinux

An emacs-native-comp-git package is available on the AUR.

Install it with your favourite AUR helper, or use the following commands to do it yourself:

    $ git clone https://aur.archlinux.org/emacs-native-comp-git.git
    $ cd emacs-native-comp-git
    $ makepkg --syncdeps --install

Debian/unstable

The emacs-snapshot packages are now built with this support: http://emacs.secretsauce.net

Daemon systemd service crashing on startup

If systemctl --user start emacs.service immediately crashes and journalctl --user -u emacs mentions a long path mentioning native-lisp and ending with .eln, add the following line to the [Service] section in /usr/lib/systemd/user/emacs.service:

    WorkingDirectory=/usr/lib/emacs/28.0.50/x86_64-pc-linux-gnu/

Guix

An emacs-native-comp package is available in this channel.

Add the channel to your ~/.config/guix/channels.scm, or use the following commands to install it as a one-off:

    $ git clone https://github.com/flatwhatson/guix-channel.git
    $ guix install --load-path=./guix-channel emacs-native-comp

Nix

An emacsGcc package is available from the Nix community’s Emacs overlay.

Detailed installation instructions are available in this Gist.

Docker

An emacs-nativecomp docker image is available. Also examine the gitlab repo for the dockerfile.

Windows

The Gccemacs prebuilt packages are available and updated semi-monthly using GitHub action. The build script is also available in the same github repo.

It’s also possible to install the package via scoop with this bucket.

    $ scoop install emacs-k

Usage

By default Emacs ships only native compiling the files included in the Emacs image.

The native compilation of the remaining Emacs distribution and external packages happen automatically and asynchronously (See Deferred compilation).

Deferred compilation

Deferred compilation refers to "just-in-time" native compilation of Elisp. When a byte-compiled Elisp module is loaded, it gets queued for native compilation. Once native compilation has finished, the native-compiled definitions automatically replace the byte-compiled versions.

This is simple to use as it does not require any user intervention. You may prefer an "ahead-of-time" solution described further below.

Deferred compilation is enabled by default and controlled by the comp-deferred-compilation customize.

Ahead-of-time compilation

Sometimes it is useful to compile ahead-of-time, for example if you are packaging Emacs for others.

Emacs distribution

It is possible to native compile ahead-of-time all the Emacs distribution using the NATIVE_FULL_AOT, for example:

    $ make NATIVE_FULL_AOT=1 -j$(nproc)

External packages

The built-in package manager package.el supports ahead-of-time native compilation when installing a package. Customize the user option ‘package-native-compile’ or add this to your init file to enable it:

    (setq package-native-compile t)

Some third-party package managers also support ahead-of-time native compilation:

You can native-compile your packages manually:

    ;; native-compile all Elisp files under a directory
    (native-compile-async "/path/to/packages" 'recursively)

This will add all Emacs Lisp files under that directory to the queue for asynchronous native compilation.

If you are running native compilation from a script, you will need to block the Emacs process until the async jobs have completed:

    ;; block until native compilation has finished
    (while (or comp-files-queue
               (> (comp-async-runnings) 0))
      (sleep-for 1))