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Stop building std on perf #693

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Jul 19, 2020
Merged

Stop building std on perf #693

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106 changes: 1 addition & 105 deletions collector/src/sysroot.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -34,118 +34,14 @@ impl Sysroot {
};

download.get_and_extract(ModuleVariant::Rustc)?;
// HACK(eddyb) commented out because we build our own stdlib
// (see `fn build_std` below).
// download.get_and_extract(ModuleVariant::Std)?;
download.get_and_extract(ModuleVariant::Std)?;
download.get_and_extract(ModuleVariant::Cargo)?;
download.get_and_extract(ModuleVariant::RustSrc)?;

let sysroot_dir = download.directory.join(&download.rust_sha);
let sysroot = download.into_sysroot()?;

// FIXME(eddyb) remove this once we no longer need to
// build our own stdlib (see `fn build_std` below).
sysroot.build_std(sysroot_dir)?;

Ok(sysroot)
}

/// Build `std`+`test`+`proc_macro` in a similar way to Cargo's `-Zbuild-std`
/// feature, but only once, and move the resulting libraries into the sysroot.
///
/// We only need this until https://github.com/rust-lang/cargo/pull/8073
/// reaches beta, because then `rust-lang/rust` builds will have that
/// treatment. For now, we only have access to that Cargo change here,
/// using the newly built Cargo.
///
/// For more background on why we need this, see this comment:
/// https://github.com/rust-lang/rust/issues/69060#issuecomment-604928032
/// (in short, Cargo used to include `rustc -vV` output, which contains
/// the commit hash, into `-Cmetadata`, producing different `std`s,
/// and making the perf runs incomparable, up to several % of difference).
fn build_std(&self, sysroot_dir: PathBuf) -> anyhow::Result<()> {
// Make sure everything below gets absolute directories.
let sysroot_dir = sysroot_dir.canonicalize()?;

let sysroot_rustlib_dir = sysroot_dir.join("lib/rustlib");
let rust_src_dir = sysroot_rustlib_dir.join("src/rust");

// HACK(eddyb) add a top-level `Cargo.toml` that has the necessary
// `patch.crates-io` entries for `rustc-std-workspace-{core,alloc,std}`.
// (maybe `rust-src` should include such a `Cargo.toml`?)
fs::write(
rust_src_dir.join("Cargo.toml"),
"\
[workspace]
members = ['src/libtest']

[patch.crates-io]
# See comments in `tools/rustc-std-workspace-core/README.md` for what's going on
# here
rustc-std-workspace-core = { path = 'src/tools/rustc-std-workspace-core' }
rustc-std-workspace-alloc = { path = 'src/tools/rustc-std-workspace-alloc' }
rustc-std-workspace-std = { path = 'src/tools/rustc-std-workspace-std' }
",
)?;

// HACK(eddyb) we need `std` to run the build scripts to build `std`.
let vanilla_sysroot_dir = {
let vanilla_download = SysrootDownload {
directory: sysroot_dir.join("vanilla-sysroot"),
rust_sha: self.sha.clone(),
triple: self.triple.clone(),
};
vanilla_download.get_and_extract(ModuleVariant::Std)?;
vanilla_download.directory.join(vanilla_download.rust_sha)
};

let rustflags = format!(
"--sysroot={sysroot} --remap-path-prefix={remap_from}={remap_to}",
sysroot = vanilla_sysroot_dir.display(),
remap_from = rust_src_dir.display(),
remap_to = "/rustc/REDACTED_SHA_HASH/"
);

// Run Cargo to produce `$local_build_target_dir/release/deps/lib*.rlib`.
let local_build_target_dir = sysroot_dir.join("build-std-target");
let cargo_status = std::process::Command::new(&self.cargo)
.env("RUSTC", &self.rustc)
.env("RUSTFLAGS", rustflags)
.env("__CARGO_DEFAULT_LIB_METADATA", "rustc-perf-std")
.args(&["build", "--release"])
.arg("--target-dir")
.arg(&local_build_target_dir)
.args(&["--features", "panic-unwind", "--features", "backtrace"])
.arg("--manifest-path")
.arg(rust_src_dir.join("src/libtest/Cargo.toml"))
.status()?;
if !cargo_status.success() {
return Err(anyhow!(
"unable to build stdlib for {} triple {}",
self.sha,
self.triple
));
}

// Move all of the `rlib` files into the main sysroot.
let sysroot_target_lib_dir = sysroot_rustlib_dir.join(&self.triple).join("lib");
fs::create_dir_all(&sysroot_target_lib_dir)?;
for entry in fs::read_dir(local_build_target_dir.join("release/deps"))? {
let entry = entry?;
let path = entry.path();
if let (Some(name), Some(ext)) = (path.file_name(), path.extension()) {
if ext == "rlib" {
fs::rename(&path, sysroot_target_lib_dir.join(name))?;
}
}
}

// Clean up, to avoid accidental usage of these directories.
fs::remove_dir_all(vanilla_sysroot_dir)?;
fs::remove_dir_all(local_build_target_dir)?;

Ok(())
}
}

impl Drop for Sysroot {
Expand Down