Build configuration

Size optimizations

To reduce binary size, add this to your Cargo.toml:

[profile.release]
strip = true
opt-level = "z"

You might also consider using feature dynamic if wishing to ship multiple binaries with shared libraries (Rust's libstd and libkas_dylib); note however that these are not ABI-stable.

Faster builds

People variously complain that Rust / KAS is slow to compile, and they have a point: just recompiling the gallery example takes over six seconds on a 5800X!

There are two strategies we can use to speed this up:

1. Dynamic linking. I wouldn't recommend shipping code with dynamic linking due to dependency complications (although it is possible and potentially useful, especially within Linux distributions), but during development it can make a lot of sense.

   Enabling dynamic linking is very easy: use --features dynamic.

2. A faster linker: LLD or better yet mold.

   Using LLD: (1) install (e.g. via Linux distribution packages), (2) create $HOME/.cargo/config, (3) add this:

   [build]
   rustflags = ["-C", "link-arg=-fuse-ld=lld"]

   Using Mold: (1) install (see project page), (2) prefix build commands with mold -run.

Here are some crude benchmarks. Method: build the gallery example, touch (or re-save) gallery.rs, and rebuild. Use the Unix time command, run three times, and report the best real time of the three. Machine: 5800X, Fedora 34, SSD.

configuration	time	version
standard	0m6.124s	rustc 1.54.0 (a178d0322 2021-07-26)
dynamic	0m2.275s
lld	0m1.537s	LLD 12.0.1 (lld-12.0.1-1.fc34.src.rpm)
lld + dynamic	0m1.061s
mold	0m1.147s	mold 0.9.3 (ec3319b37f653dccfa4d1a859a5c687565ab722d)
mold + dynamic	0m0.971s