Re: Enabling native compilation by default when libgccjit is present

[Jim Myhrberg <jimehgeek@gmail.com>]

Hi, first time I'm participating on the devel list here, but I wanted to chime in with my experience using native compilation on macOS.

> I'd be curious to know where people are seeing speedups.

On macOS, native compilation is the single biggest improvement/feature I've seen since I started using Emacs in 2011.

Before native-comp, Emacs' performance was for the most part acceptable, sluggish in some areas, and sometimes just plain horrible. Especially in larger Ruby RSpec test files (over 400-500 lines), where each keystroke could take somewhere around 100-1000ms to register. Native-comp solved all of that for me, with everything being fast and responsive, even those worst case scenario RSpec files.

Basically, I simply cannot live without native compilation anymore, to the point I've gone through the hassle to setup nightly builds via GitHub Actions, so new builds are waiting for me when I wake up.

As for if native compilation should be enabled by default, I'd say it might be simpler/safer if it needs to be explicitly enabled. One reason for it, is that on macOS "make install" with native-comp enabled does not produce a Emacs.app bundle which can be distributed to other machines without them first needing to install gcc, libgccgit, and potentially other homebrew formulas. Bundling all external dependencies including libgccjit/gcc into Emacs.app is a rather complicated process, made even more complicated if you want to sign and notarize the app too. I've got a quite a bit of code in my build script to handle it for my own builds.

--jimeh