PGO for LLVM builds on x86_64-unknown-linux-gnu in CI

src/bootstrap/config.rs

@@ -143,6 +143,8 @@ pub struct Config {
     pub rust_new_symbol_mangling: bool,
     pub rust_profile_use: Option<String>,
     pub rust_profile_generate: Option<String>,
+    pub llvm_profile_use: Option<String>,
+    pub llvm_profile_generate: bool,
 
     pub build: TargetSelection,
     pub hosts: Vec<TargetSelection>,
@@ -605,6 +607,8 @@ impl Config {
         if let Some(value) = flags.deny_warnings {
             config.deny_warnings = value;
         }
+        config.llvm_profile_use = flags.llvm_profile_use;
+        config.llvm_profile_generate = flags.llvm_profile_generate;
 
         if config.dry_run {
             let dir = config.out.join("tmp-dry-run");

src/bootstrap/dist.rs

@@ -2157,10 +2157,16 @@ impl Step for ReproducibleArtifacts {
     }
 
     fn run(self, builder: &Builder<'_>) -> Self::Output {
-        let path = builder.config.rust_profile_use.as_ref()?;
-
+        let mut added_anything = false;
         let tarball = Tarball::new(builder, "reproducible-artifacts", &self.target.triple);
-        tarball.add_file(path, ".", 0o644);
-        Some(tarball.generate())
+        if let Some(path) = builder.config.rust_profile_use.as_ref() {
+            tarball.add_file(path, ".", 0o644);
+            added_anything = true;
+        }
+        if let Some(path) = builder.config.llvm_profile_use.as_ref() {
+            tarball.add_file(path, ".", 0o644);
+            added_anything = true;
+        }
+        if added_anything { Some(tarball.generate()) } else { None }
     }
 }

src/bootstrap/download-ci-llvm-stamp

@@ -1,4 +1,4 @@
 Change this file to make users of the `download-ci-llvm` configuration download
 a new version of LLVM from CI, even if the LLVM submodule hasn’t changed.
 
-Last change is for: https://github.com/rust-lang/rust/pull/80932
+Last change is for: https://github.com/rust-lang/rust/pull/88069

src/bootstrap/flags.rs

@@ -71,6 +71,13 @@ pub struct Flags {
 
     pub rust_profile_use: Option<String>,
     pub rust_profile_generate: Option<String>,
+
+    pub llvm_profile_use: Option<String>,
+    // LLVM doesn't support a custom location for generating profile
+    // information.
+    //
+    // llvm_out/build/profiles/ is the location this writes to.
+    pub llvm_profile_generate: bool,
 }
 
 pub enum Subcommand {
@@ -222,8 +229,15 @@ 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", "generate PGO profile with rustc build", "FORMAT");
-        opts.optopt("", "rust-profile-use", "use PGO profile for rustc build", "FORMAT");
+        opts.optopt(
+            "",
+            "rust-profile-generate",
+            "generate PGO profile with rustc build",
+            "PROFILE",
+        );
+        opts.optopt("", "rust-profile-use", "use PGO profile for rustc build", "PROFILE");
+        opts.optflag("", "llvm-profile-generate", "generate PGO profile with llvm built for rustc");
+        opts.optopt("", "llvm-profile-use", "use PGO profile for llvm build", "PROFILE");
 
         // 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
@@ -687,6 +701,8 @@ Arguments:
                 .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"),
+            llvm_profile_use: matches.opt_str("llvm-profile-use"),
+            llvm_profile_generate: matches.opt_present("llvm-profile-generate"),
         }
     }
 }

src/bootstrap/native.rs

@@ -189,6 +189,14 @@ impl Step for Llvm {
             .define("LLVM_TARGET_ARCH", target_native.split('-').next().unwrap())
             .define("LLVM_DEFAULT_TARGET_TRIPLE", target_native);
 
+        if builder.config.llvm_profile_generate {
+            cfg.define("LLVM_BUILD_INSTRUMENTED", "IR");
+            cfg.define("LLVM_BUILD_RUNTIME", "No");
+        }
+        if let Some(path) = builder.config.llvm_profile_use.as_ref() {
+            cfg.define("LLVM_PROFDATA_FILE", &path);
+        }
+
         if target != "aarch64-apple-darwin" && !target.contains("windows") {
             cfg.define("LLVM_ENABLE_ZLIB", "ON");
         } else {

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

@@ -82,6 +82,12 @@ COPY host-x86_64/dist-x86_64-linux/build-clang.sh /tmp/
 RUN ./build-clang.sh
 ENV CC=clang CXX=clang++
 
+ENV PERF_COMMIT 1e19fc4c6168d2f7596e512f42f358f245d8f09d
+RUN curl -LS -o perf.zip https://github.com/rust-lang/rustc-perf/archive/$PERF_COMMIT.zip && \
+    unzip perf.zip && \
+    mv rustc-perf-$PERF_COMMIT rustc-perf && \
+    rm perf.zip
+
 COPY scripts/sccache.sh /scripts/
 RUN sh /scripts/sccache.sh
 

src/ci/docker/host-x86_64/dist-x86_64-linux/build-clang.sh

@@ -20,14 +20,18 @@ cd clang-build
 # include path, /rustroot/include, to clang's default include path.
 INC="/rustroot/include:/usr/include"
 
+# We need compiler-rt for the profile runtime (used later to PGO the LLVM build)
+# but sanitizers aren't currently building. Since we don't need those, just
+# disable them.
 hide_output \
     cmake ../llvm \
       -DCMAKE_C_COMPILER=/rustroot/bin/gcc \
       -DCMAKE_CXX_COMPILER=/rustroot/bin/g++ \
       -DCMAKE_BUILD_TYPE=Release \
       -DCMAKE_INSTALL_PREFIX=/rustroot \
+      -DCOMPILER_RT_BUILD_SANITIZERS=OFF \
       -DLLVM_TARGETS_TO_BUILD=X86 \
-      -DLLVM_ENABLE_PROJECTS="clang;lld" \
+      -DLLVM_ENABLE_PROJECTS="clang;lld;compiler-rt" \
       -DC_INCLUDE_DIRS="$INC"
 
 hide_output make -j$(nproc)

src/ci/docker/scripts/sccache.sh

@@ -1,12 +1,15 @@
 #!/bin/sh
+
+# ignore-tidy-linelength
+
 set -ex
 
 case "$(uname -m)" in
     x86_64)
-        url="https://ci-mirrors.rust-lang.org/rustc/2018-04-02-sccache-x86_64-unknown-linux-musl"
+        url="https://ci-mirrors.rust-lang.org/rustc/2021-08-24-sccache-v0.2.15-x86_64-unknown-linux-musl"
         ;;
     aarch64)
-        url="https://ci-mirrors.rust-lang.org/rustc/2019-12-17-sccache-aarch64-unknown-linux-gnu"
+        url="https://ci-mirrors.rust-lang.org/rustc/2021-08-25-sccache-v0.2.15-aarch64-unknown-linux-musl"
         ;;
     *)
         echo "unsupported architecture: $(uname -m)"

src/ci/pgo.sh

@@ -5,61 +5,59 @@ set -euxo pipefail
 rm -rf /tmp/rustc-pgo
 
 python3 ../x.py build --target=$PGO_HOST --host=$PGO_HOST \
-    --stage 2 library/std --rust-profile-generate=/tmp/rustc-pgo
+    --stage 2 library/std \
+    --rust-profile-generate=/tmp/rustc-pgo \
+    --llvm-profile-generate
 
+# Profile libcore compilation in opt-level=0 and opt-level=3
 RUSTC_BOOTSTRAP=1 ./build/$PGO_HOST/stage2/bin/rustc --edition=2018 \
     --crate-type=lib ../library/core/src/lib.rs
-
-# Download and build a single-file stress test benchmark on perf.rust-lang.org.
-function pgo_perf_benchmark {
-    local PERF=1e19fc4c6168d2f7596e512f42f358f245d8f09d
-    local github_prefix=https://raw.githubusercontent.com/rust-lang/rustc-perf/$PERF
-    local name=$1
-    local edition=$2
-    curl -o /tmp/$name.rs $github_prefix/collector/benchmarks/$name/src/lib.rs
-
-    RUSTC_BOOTSTRAP=1 ./build/$PGO_HOST/stage2/bin/rustc --edition=$edition \
-        --crate-type=lib /tmp/$name.rs
-}
-
-pgo_perf_benchmark externs 2018
-pgo_perf_benchmark ctfe-stress-4 2018
-pgo_perf_benchmark inflate 2015
-
-cp -pri ../src/tools/cargo /tmp/cargo
-
-# The Cargo repository does not have a Cargo.lock in it, as it relies on the
-# lockfile already present in the rust-lang/rust monorepo. This decision breaks
-# down when Cargo is built outside the monorepo though (like in this case),
-# resulting in a build without any dependency locking.
-#
-# To ensure Cargo is built with locked dependencies even during PGO profiling
-# the following command copies the monorepo's lockfile into the Cargo temporary
-# directory. Cargo will *not* keep that lockfile intact, as it will remove all
-# the dependencies Cargo itself doesn't rely on. Still, it will prevent
-# building Cargo with arbitrary dependency versions.
-#
-# See #81378 for the bug that prompted adding this.
-cp -p ../Cargo.lock /tmp/cargo
-
-# Build cargo (with some flags)
-function pgo_cargo {
-    RUSTC=./build/$PGO_HOST/stage2/bin/rustc \
-        ./build/$PGO_HOST/stage0/bin/cargo $@ \
-        --manifest-path /tmp/cargo/Cargo.toml
-}
-
-# Build a couple different variants of Cargo
-CARGO_INCREMENTAL=1 pgo_cargo check
-echo 'pub fn barbarbar() {}' >> /tmp/cargo/src/cargo/lib.rs
-CARGO_INCREMENTAL=1 pgo_cargo check
-touch /tmp/cargo/src/cargo/lib.rs
-CARGO_INCREMENTAL=1 pgo_cargo check
-pgo_cargo build --release
+RUSTC_BOOTSTRAP=1 ./build/$PGO_HOST/stage2/bin/rustc --edition=2018 \
+    --crate-type=lib -Copt-level=3 ../library/core/src/lib.rs
+
+cp -r /tmp/rustc-perf ./
+chown -R $(whoami): ./rustc-perf
+cd rustc-perf
+
+# Build the collector ahead of time, which is needed to make sure the rustc-fake
+# binary used by the collector is present.
+RUSTC=/checkout/obj/build/$PGO_HOST/stage0/bin/rustc \
+RUSTC_BOOTSTRAP=1 \
+/checkout/obj/build/$PGO_HOST/stage0/bin/cargo build -p collector
+
+# benchmark using profile_local with eprintln, which essentially just means
+# don't actually benchmark -- just make sure we run rustc a bunch of times.
+RUST_LOG=collector=debug \
+RUSTC=/checkout/obj/build/$PGO_HOST/stage0/bin/rustc \
+RUSTC_BOOTSTRAP=1 \
+/checkout/obj/build/$PGO_HOST/stage0/bin/cargo run -p collector --bin collector -- \
+        profile_local \
+        eprintln \
+        /checkout/obj/build/$PGO_HOST/stage2/bin/rustc \
+        Test \
+        --builds Check,Debug,Opt \
+        --cargo /checkout/obj/build/$PGO_HOST/stage0/bin/cargo \
+        --runs All \
+        --include externs,ctfe-stress-4,inflate,cargo,token-stream-stress,match-stress-enum
+
+cd /checkout/obj
 
 # Merge the profile data we gathered
 ./build/$PGO_HOST/llvm/bin/llvm-profdata \
     merge -o /tmp/rustc-pgo.profdata /tmp/rustc-pgo
 
+# Merge the profile data we gathered for LLVM
+# Note that this uses the profdata from the clang we used to build LLVM,
+# which likely has a different version than our in-tree clang.
+/rustroot/bin/llvm-profdata \
+    merge -o /tmp/llvm-pgo.profdata ./build/$PGO_HOST/llvm/build/profiles
+
+# Rustbuild currently doesn't support rebuilding LLVM when PGO options
+# change (or any other llvm-related options); so just clear out the relevant
+# directories ourselves.
+rm -r ./build/$PGO_HOST/llvm ./build/$PGO_HOST/lld
+
 # This produces the actual final set of artifacts.
-$@ --rust-profile-use=/tmp/rustc-pgo.profdata
+$@ \
+    --rust-profile-use=/tmp/rustc-pgo.profdata \
+    --llvm-profile-use=/tmp/llvm-pgo.profdata

src/ci/scripts/install-sccache.sh

@@ -8,7 +8,7 @@ IFS=$'\n\t'
 source "$(cd "$(dirname "$0")" && pwd)/../shared.sh"
 
 if isMacOS; then
-    curl -fo /usr/local/bin/sccache "${MIRRORS_BASE}/2018-04-02-sccache-x86_64-apple-darwin"
+    curl -fo /usr/local/bin/sccache "${MIRRORS_BASE}/2021-08-25-sccache-v0.2.15-x86_64-apple-darwin"
     chmod +x /usr/local/bin/sccache
 elif isWindows; then
     mkdir -p sccache