Reduce tool build time!

[JohnAZoidberg]

Something has gone wrong and the build time has drastically increased. NEED to figure out why and reduce it again.

[JohnAZoidberg]

The module firmware build is still really fast. Less than 2 seconds. But the tool build is pretty slow. About 20 seconds. And this gets really bad when using rust-analyzer in vs code because it does some extra checks and blocks the build on the commandline until it's done.

[jdswensen]

I can take a look. I've got a few ideas to try. Are you trying to reduce local build times, CI build times, or both?

[JohnAZoidberg]

Cool, thanks! Both, but mainly local build. Quite annoying to have to wait 20s for a build.

[JohnAZoidberg]

Hmm so the problem is that I'm setting in the workspace global Cargo.toml the following:

[profile.release]
codegen-units = 1
debug = 2
debug-assertions = false
incremental = false
lto = 'fat'
opt-level = 3
overflow-checks = false

# do not optimize proc-macro crates = faster builds from scratch
[profile.dev.build-override]
codegen-units = 8
debug = false
debug-assertions = false
opt-level = 0
overflow-checks = false

[profile.release.build-override]
codegen-units = 8
debug = false
debug-assertions = false
opt-level = 0
overflow-checks = false

# cargo test
[profile.test]
codegen-units = 1
debug = 2
debug-assertions = true
incremental = false
opt-level = 3
overflow-checks = true

# cargo test --release
[profile.bench]
codegen-units = 1
debug = 2
debug-assertions = false
incremental = false
lto = 'fat'
opt-level = 3

which is really only meant for the firmware builds. With this, the release build of the tool takes 14s but without, just 1.4 seconds.

[sajattack]

Fat LTO is gonna be a huge contributor to build times.

[jdswensen]

Yeah. 😞 That was one of the factors in me recommending a split project in my PR. Enabling incremental builds can help the host app too. That way, you aren't rebuilding the entire project every time (only the parts that changed).

[JohnAZoidberg]

I found out how to apply the options only to the firmware, not tool.

Fat LTO is gonna be a huge contributor to build times.

Yeah, but I only applied it to release builds, that's ok.