Add fast build profile without debuginfo

[konstin]

Add a compile option -p fast-build for a 16% incremental compile speedup (linux) at the cost of having no debuginfo.

After trying various rust compiler speedup suggestions, setting mold as my default linker and removing debuginfo are the only ones showing a speedup.

hyperfine --warmup 1 --runs 3 --prepare "touch crates/uv-resolver/src/resolver/mod.rs" \
    "cargo +nightly build --bin uv" \
    "cargo +nightly build --bin uv --profile fast-build"
Benchmark 1: cargo +nightly build --bin uv
  Time (mean ± σ):      1.569 s ±  0.008 s    [User: 1.179 s, System: 0.369 s]
  Range (min … max):    1.560 s …  1.576 s    3 runs

Benchmark 2: cargo +nightly build --bin uv --profile fast-build
  Time (mean ± σ):      1.353 s ±  0.020 s    [User: 1.109 s, System: 0.301 s]
  Range (min … max):    1.338 s …  1.375 s    3 runs

Summary
  cargo +nightly build --bin uv --profile fast-build ran
    1.16 ± 0.02 times faster than cargo +nightly build --bin uv

[charliermarsh]

What's the use-case for this?

[zanieb]

Should we use this in CI?

[konstin]

What's the use-case for this?

A faster edit-run loop, ideally

[charliermarsh]

What is the practical cost of having no debug info? (My main pushback here is: who's going to remember to set this? When should they? Should this be the default? Etc.)

[konstin]

There were several reports recently about massive speedups for debug builds using advanced or experimental cargo options: Using the parallel frontend, the cranelift backend, static musl, etc. I found that none of them worked for us except using mold (which i have in my global configuration) and removing debuginfo.

This PR adds -p fast-build to cargo commands for a speedup when changing a file i commonly work on. No debuginfo means that tracebacks will be empty and you can't use an debugger on the artifact. Since i need either rarely i find this a free 16% speedup a good tradeoff. I made this a separate profile to avoid confusing people who expect the default debug build to have panic traceback and work with their debuggers.

Should we use this in CI?

We have to try! I haven't checked how much it matters for that case

[charliermarsh]

Lets give it a try.

[charliermarsh]

Can I make this my default somehow?

[konstin]

Can I make this my default somehow?

Except for aliases, i don't think so unfortunately