Utilize PGO for rustc linux dist builds

src/bootstrap/builder.rs

@@ -471,6 +471,7 @@ impl<'a> Builder<'a> {
                 dist::RustDev,
                 dist::Extended,
                 dist::BuildManifest,
+                dist::ReproducibleArtifacts,
             ),
             Kind::Install => describe!(
                 install::Docs,

src/bootstrap/compile.rs

@@ -501,6 +501,41 @@ impl Step for Rustc {
         let mut cargo = builder.cargo(compiler, Mode::Rustc, SourceType::InTree, target, "build");
         rustc_cargo(builder, &mut cargo, target);
 
+        if builder.config.rust_profile_use.is_some()
+            && builder.config.rust_profile_generate.is_some()
+        {
+            panic!("Cannot use and generate PGO profiles at the same time");
+        }
+
+        let is_collecting = if let Some(path) = &builder.config.rust_profile_generate {
+            if compiler.stage == 1 {
+                cargo.rustflag(&format!("-Cprofile-generate={}", path));
+                // Apparently necessary to avoid overflowing the counters during
+                // a Cargo build profile
+                cargo.rustflag("-Cllvm-args=-vp-counters-per-site=4");
+                true
+            } else {
+                false
+            }
+        } else if let Some(path) = &builder.config.rust_profile_use {
+            if compiler.stage == 1 {
+                cargo.rustflag(&format!("-Cprofile-use={}", path));
+                cargo.rustflag("-Cllvm-args=-pgo-warn-missing-function");
+                true
+            } else {
+                false
+            }
+        } else {
+            false
+        };
+        if is_collecting {
+            // Ensure paths to Rust sources are relative, not absolute.
+            cargo.rustflag(&format!(
+                "-Cllvm-args=-static-func-strip-dirname-prefix={}",
+                builder.config.src.components().count()
+            ));
+        }
+
         builder.info(&format!(
             "Building stage{} compiler artifacts ({} -> {})",
             compiler.stage, &compiler.host, target
@@ -752,7 +787,7 @@ fn copy_codegen_backends_to_sysroot(
     // Here we're looking for the output dylib of the `CodegenBackend` step and
     // we're copying that into the `codegen-backends` folder.
     let dst = builder.sysroot_codegen_backends(target_compiler);
-    t!(fs::create_dir_all(&dst));
+    t!(fs::create_dir_all(&dst), dst);
 
     if builder.config.dry_run {
         return;

src/bootstrap/config.rs

@@ -133,6 +133,8 @@ pub struct Config {
     pub rust_thin_lto_import_instr_limit: Option<u32>,
     pub rust_remap_debuginfo: bool,
     pub rust_new_symbol_mangling: bool,
+    pub rust_profile_use: Option<String>,
+    pub rust_profile_generate: Option<String>,
 
     pub build: TargetSelection,
     pub hosts: Vec<TargetSelection>,
@@ -494,6 +496,8 @@ struct Rust {
     llvm_libunwind: Option<String>,
     control_flow_guard: Option<bool>,
     new_symbol_mangling: Option<bool>,
+    profile_generate: Option<String>,
+    profile_use: Option<String>,
 }
 
 /// TOML representation of how each build target is configured.
@@ -871,6 +875,11 @@ impl Config {
 
             config.rust_codegen_units = rust.codegen_units.map(threads_from_config);
             config.rust_codegen_units_std = rust.codegen_units_std.map(threads_from_config);
+            config.rust_profile_use = flags.rust_profile_use.or(rust.profile_use);
+            config.rust_profile_generate = flags.rust_profile_generate.or(rust.profile_generate);
+        } else {
+            config.rust_profile_use = flags.rust_profile_use;
+            config.rust_profile_generate = flags.rust_profile_generate;
         }
 
         if let Some(t) = toml.target {

src/bootstrap/dist.rs

@@ -2664,3 +2664,72 @@ impl Step for BuildManifest {
         distdir(builder).join(format!("{}-{}.tar.gz", name, self.target.triple))
     }
 }
+
+/// Tarball containing artifacts necessary to reproduce the build of rustc.
+///
+/// Currently this is the PGO profile data.
+///
+/// Should not be considered stable by end users.
+#[derive(Clone, Debug, Eq, Hash, PartialEq)]
+pub struct ReproducibleArtifacts {
+    pub target: TargetSelection,
+}
+
+impl Step for ReproducibleArtifacts {
+    type Output = Option<PathBuf>;
+    const DEFAULT: bool = true;
+    const ONLY_HOSTS: bool = true;
+
+    fn should_run(run: ShouldRun<'_>) -> ShouldRun<'_> {
+        run.path("reproducible")
+    }
+
+    fn make_run(run: RunConfig<'_>) {
+        run.builder.ensure(ReproducibleArtifacts { target: run.target });
+    }
+
+    fn run(self, builder: &Builder<'_>) -> Self::Output {
+        let name = pkgname(builder, "reproducible-artifacts");
+        let tmp = tmpdir(builder);
+
+        // Prepare the image.
+        let image = tmp.join("reproducible-artifacts-image");
+        let _ = fs::remove_dir_all(&image);
+
+        if let Some(path) = &builder.config.rust_profile_use {
+            builder.install(std::path::Path::new(path), &image, 0o644);
+        } else {
+            return None;
+        }
+
+        // Prepare the overlay.
+        let overlay = tmp.join("reproducible-artifacts-overlay");
+        let _ = fs::remove_dir_all(&overlay);
+        builder.create_dir(&overlay);
+        builder.create(&overlay.join("version"), &builder.rust_version());
+        for file in &["COPYRIGHT", "LICENSE-APACHE", "LICENSE-MIT", "README.md"] {
+            builder.install(&builder.src.join(file), &overlay, 0o644);
+        }
+
+        // Create the final tarball.
+        let mut cmd = rust_installer(builder);
+        cmd.arg("generate")
+            .arg("--product-name=Rust")
+            .arg("--rel-manifest-dir=rustlib")
+            .arg("--success-message=reproducible-artifacts installed.")
+            .arg("--image-dir")
+            .arg(&image)
+            .arg("--work-dir")
+            .arg(&tmpdir(builder))
+            .arg("--output-dir")
+            .arg(&distdir(builder))
+            .arg("--non-installed-overlay")
+            .arg(&overlay)
+            .arg(format!("--package-name={}-{}", name, self.target.triple))
+            .arg("--legacy-manifest-dirs=rustlib,cargo")
+            .arg("--component-name=reproducible-artifacts");
+
+        builder.run(&mut cmd);
+        Some(distdir(builder).join(format!("{}-{}.tar.gz", name, self.target.triple)))
+    }
+}

src/bootstrap/flags.rs

@@ -68,6 +68,9 @@ pub struct Flags {
     pub deny_warnings: Option<bool>,
 
     pub llvm_skip_rebuild: Option<bool>,
+
+    pub rust_profile_use: Option<String>,
+    pub rust_profile_generate: Option<String>,
 }
 
 pub enum Subcommand {
@@ -219,6 +222,8 @@ To learn more about a subcommand, run `./x.py <subcommand> -h`",
              VALUE overrides the skip-rebuild option in config.toml.",
             "VALUE",
         );
+        opts.optopt("", "rust-profile-generate", "rustc error format", "FORMAT");
+        opts.optopt("", "rust-profile-use", "rustc error format", "FORMAT");
 
         // We can't use getopt to parse the options until we have completed specifying which
         // options are valid, but under the current implementation, some options are conditional on
@@ -674,6 +679,8 @@ Arguments:
             color: matches
                 .opt_get_default("color", Color::Auto)
                 .expect("`color` should be `always`, `never`, or `auto`"),
+            rust_profile_use: matches.opt_str("rust-profile-use"),
+            rust_profile_generate: matches.opt_str("rust-profile-generate"),
         }
     }
 }

src/ci/docker/host-x86_64/dist-x86_64-linux/Dockerfile

@@ -85,6 +85,8 @@ ENV CC=clang CXX=clang++
 COPY scripts/sccache.sh /scripts/
 RUN sh /scripts/sccache.sh
 
+ENV PGO_HOST=x86_64-unknown-linux-gnu
+
 ENV HOSTS=x86_64-unknown-linux-gnu
 
 ENV RUST_CONFIGURE_ARGS \
@@ -98,9 +100,10 @@ ENV RUST_CONFIGURE_ARGS \
       --set llvm.thin-lto=true \
       --set llvm.ninja=false \
       --set rust.jemalloc
-ENV SCRIPT python2.7 ../x.py dist --host $HOSTS --target $HOSTS \
-        --include-default-paths \
-        src/tools/build-manifest
+ENV SCRIPT ../src/ci/pgo.sh python2.7 ../x.py dist \
+    --host $HOSTS --target $HOSTS \
+    --include-default-paths \
+    src/tools/build-manifest
 ENV CARGO_TARGET_X86_64_UNKNOWN_LINUX_GNU_LINKER=clang
 
 # This is the only builder which will create source tarballs

src/ci/pgo.sh

@@ -0,0 +1,47 @@
+#!/bin/bash
+
+set -euxo pipefail
+
+rm -rf /tmp/rustc-pgo
+
+python2.7 ../x.py build --target=$PGO_HOST --host=$PGO_HOST \
+    --stage 2 library/std --rust-profile-generate=/tmp/rustc-pgo
+
+./build/$PGO_HOST/stage2/bin/rustc --edition=2018 \
+    --crate-type=lib ../library/core/src/lib.rs
+
+# Download and build a single-file stress test benchmark on perf.rust-lang.org.
+function pgo_perf_benchmark {
+    local PERF=e095f5021bf01cf3800f50b3a9f14a9683eb3e4e
+    local github_prefix=https://raw.githubusercontent.com/rust-lang/rustc-perf/$PERF
+    local name=$1
+    curl -o /tmp/$name.rs $github_prefix/collector/benchmarks/$name/src/lib.rs
+    ./build/$PGO_HOST/stage2/bin/rustc --edition=2018 --crate-type=lib /tmp/$name.rs
+}
+
+pgo_perf_benchmark externs
+pgo_perf_benchmark ctfe-stress-4
+
+cp -pri ../src/tools/cargo /tmp/cargo
+
+# Build cargo (with some flags)
+function pgo_cargo {
+    RUSTC=./build/$PGO_HOST/stage2/bin/rustc \
+        ./build/$PGO_HOST/stage0/bin/cargo $@ \
+        --manifest-path /tmp/cargo/Cargo.toml
+}
+
+# Build a couple different variants of Cargo
+CARGO_INCREMENTAL=1 pgo_cargo check
+echo 'pub fn barbarbar() {}' >> /tmp/cargo/src/cargo/lib.rs
+CARGO_INCREMENTAL=1 pgo_cargo check
+touch /tmp/cargo/src/cargo/lib.rs
+CARGO_INCREMENTAL=1 pgo_cargo check
+pgo_cargo build --release
+
+# Merge the profile data we gathered
+./build/$PGO_HOST/llvm/bin/llvm-profdata \
+    merge -o /tmp/rustc-pgo.profdata /tmp/rustc-pgo
+
+# This produces the actual final set of artifacts.
+$@ --rust-profile-use=/tmp/rustc-pgo.profdata

src/tools/build-manifest/src/main.rs

@@ -299,6 +299,7 @@ impl Builder {
         let mut package = |name, targets| self.package(name, &mut manifest.pkg, targets);
         package("rustc", HOSTS);
         package("rustc-dev", HOSTS);
+        package("reproducible-artifacts", HOSTS);
         package("rustc-docs", HOSTS);
         package("cargo", HOSTS);
         package("rust-mingw", MINGW);