refactor: add rustc-perf submodule to src/tools #125166

Currently, it's very challenging to perform a sandboxed `opt-dist` bootstrap because the tool requires `rustc-perf` to be present, but there is no proper management/tracking of it. Instead, a specific commit is hardcoded where it is needed, and a non-checksummed zip is fetched ad-hoc. This happens in two places: `src/ci/docker/host-x86_64/dist-x86_64-linux/Dockerfile`: ```dockerfile ENV PERF_COMMIT 4f313ad RUN curl -LS -o perf.zip https://ci-mirrors.rust-lang.org/rustc/rustc-perf-$PERF_COMMIT.zip && \ unzip perf.zip && \ mv rustc-perf-$PERF_COMMIT rustc-perf && \ rm perf.zip ``` `src/tools/opt-dist/src/main.rs` ```rust // FIXME: add some mechanism for synchronization of this commit SHA with // Linux (which builds rustc-perf in a Dockerfile) // rustc-perf version from 2023-10-22 const PERF_COMMIT: &str = "4f313add609f43e928e98132358e8426ed3969ae"; let url = format!("https://ci-mirrors.rust-lang.org/rustc/rustc-perf-{PERF_COMMIT}.zip"); let client = reqwest::blocking::Client::builder() .timeout(Duration::from_secs(60 * 2)) .connect_timeout(Duration::from_secs(60 * 2)) .build()?; let response = retry_action( || Ok(client.get(&url).send()?.error_for_status()?.bytes()?.to_vec()), "Download rustc-perf archive", 5, )?; ``` This causes a few issues: 1. Maintainers need to be careful to bump PERF_COMMIT in both places every time 2. In order to run `opt-dist` in a sandbox, you need to provide your own `rustc-perf` (rust-lang#125125), but to figure out which commit to provide you need to grep the Dockerfile 3. Even if you manage to provide the correct `rustc-perf`, its dependencies are not included in the `vendor/` dir created during `dist`, so it will fail to build from the published source tarballs 4. It is hard to provide any level of automation around updating the `rustc-perf` in use, leading to staleness Fundamentally, this means `rustc-src` tarballs no longer contain everything you need to bootstrap Rust, and packagers hoping to leverage `opt-dist` need to go out of their way to keep track of this "hidden" dependency on `rustc-perf`. This change adds rustc-perf as a git submodule, pinned to the current `PERF_COMMIT` 4f313ad. Subsequent commits ensure the submodule is initialized when necessary, and make use of it in `opt-dist`.

This avoids having normal builds pay the cost of initializing that submodule, while still ensuring it's available whenever `opt-dist` is built. Note that, at this point, `opt-dist` will not yet use the submodule, that will be handled in a subsequent commit.

This replaces the hardcoded rustc-perf commit and ad-hoc downloading and unpacking of its zipped source with defaulting to use the new rustc-perf submodule. While it would be nice to make `opt-dist` able to initialize the submodule automatically when pointing to a Rust checkout _other_ than the one opt-dist was built in, that would require a bigger refactor that moved `update_submodule`, from bootstrap, into build_helper. Regardless, I imagine it must be quite rare to use `opt-dist` with a checkout that is neither from a rust-src tarball (which will contain the submodule), nor the checkout opt-dist itself was built (bootstrap will update the submodule when opt-dist is built).

It is now available as a submodule in src/tools/rustc-perf, and is initialized when building opt-dist

…or logic

… for opt-dist

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refactor: add rustc-perf submodule to src/tools #125166

refactor: add rustc-perf submodule to src/tools #125166

Commits on May 20, 2024