ci: Enable opt-dist for dist-aarch64-linux builds

Enable optimised AArch64 dist builds with the opt-dist pipeline.

For the time being, disable bolt on aarch64 due to upstream bolt bugs.

Author: mrkajetanp

src/ci/docker/host-aarch64/dist-aarch64-linux/Dockerfile

@@ -91,9 +91,12 @@ ENV RUST_CONFIGURE_ARGS \
       --set rust.debug-assertions=false \
       --set rust.jemalloc \
       --set rust.use-lld=true \
+      --set rust.lto=thin \
       --set rust.codegen-units=1
 
-ENV SCRIPT python3 ../x.py dist --host $HOSTS --target $HOSTS
+ENV SCRIPT python3 ../x.py build --set rust.debug=true opt-dist && \
+      ./build/$HOSTS/stage0-tools-bin/opt-dist linux-ci --  python3 ../x.py dist \
+      --host $HOSTS --target $HOSTS --include-default-paths build-manifest bootstrap
 
 ENV CARGO_TARGET_AARCH64_UNKNOWN_LINUX_GNU_LINKER=clang
 ENV LIBCURL_NO_PKG_CONFIG 1

src/tools/opt-dist/src/bolt.rs

@@ -1,6 +1,7 @@
 use anyhow::Context;
 use camino::{Utf8Path, Utf8PathBuf};
 
+use crate::environment::Environment;
 use crate::exec::cmd;
 use crate::training::BoltProfile;
 use crate::utils::io::copy_file;
@@ -45,13 +46,21 @@ pub fn with_bolt_instrumented<F: FnOnce(&Utf8Path) -> anyhow::Result<R>, R>(
 }
 
 /// Optimizes the file at `path` with BOLT in-place using the given `profile`.
-pub fn bolt_optimize(path: &Utf8Path, profile: &BoltProfile) -> anyhow::Result<()> {
+pub fn bolt_optimize(
+    path: &Utf8Path,
+    profile: &BoltProfile,
+    env: &Environment,
+) -> anyhow::Result<()> {
     // Copy the artifact to a new location, so that we do not use the same input and output file.
     // BOLT cannot handle optimizing when the input and output is the same file, because it performs
     // in-place patching.
     let temp_path = tempfile::NamedTempFile::new()?.into_temp_path();
     copy_file(path, &temp_path)?;
 
+    // FIXME: cdsplit in llvm-bolt is currently broken on AArch64, drop this once it's fixed upstream
+    let split_strategy =
+        if env.host_tuple().starts_with("aarch64") { "profile2" } else { "cdsplit" };
+
     cmd(&["llvm-bolt"])
         .arg(temp_path.display())
         .arg("-data")
@@ -65,7 +74,7 @@ pub fn bolt_optimize(path: &Utf8Path, profile: &BoltProfile) -> anyhow::Result<(
         // Split function code into hot and code regions
         .arg("-split-functions")
         // Split using best available strategy (three-way splitting, Cache-Directed Sort)
-        .arg("-split-strategy=cdsplit")
+        .arg(format!("-split-strategy={split_strategy}"))
         // Split as many basic blocks as possible
         .arg("-split-all-cold")
         // Move jump tables to a separate section

src/tools/opt-dist/src/main.rs

@@ -146,6 +146,21 @@ fn create_environment(args: Args) -> anyhow::Result<(Environment, Vec<String>)>
             let target_triple =
                 std::env::var("PGO_HOST").expect("PGO_HOST environment variable missing");
 
+            let is_aarch64 = target_triple.starts_with("aarch64");
+
+            let mut skip_tests = vec![
+                // Fails because of linker errors, as of June 2023.
+                "tests/ui/process/nofile-limit.rs".to_string(),
+            ];
+
+            if is_aarch64 {
+                skip_tests.extend([
+                    // Those tests fail only inside of Docker on aarch64, as of December 2024
+                    "tests/ui/consts/promoted_running_out_of_memory_issue-130687.rs".to_string(),
+                    "tests/ui/consts/large_const_alloc.rs".to_string(),
+                ]);
+            }
+
             let checkout_dir = Utf8PathBuf::from("/checkout");
             let env = EnvironmentBuilder::default()
                 .host_tuple(target_triple)
@@ -155,11 +170,9 @@ fn create_environment(args: Args) -> anyhow::Result<(Environment, Vec<String>)>
                 .artifact_dir(Utf8PathBuf::from("/tmp/tmp-multistage/opt-artifacts"))
                 .build_dir(checkout_dir.join("obj"))
                 .shared_llvm(true)
-                .use_bolt(true)
-                .skipped_tests(vec![
-                    // Fails because of linker errors, as of June 2023.
-                    "tests/ui/process/nofile-limit.rs".to_string(),
-                ])
+                // FIXME: Enable bolt for aarch64 once it's fixed upstream. Broken as of December 2024.
+                .use_bolt(!is_aarch64)
+                .skipped_tests(skip_tests)
                 .build()?;
 
             (env, shared.build_args)
@@ -304,7 +317,8 @@ fn execute_pipeline(
             // the final dist build. However, when BOLT optimizes an artifact, it does so *in-place*,
             // therefore it will actually optimize all the hard links, which means that the final
             // packaged `libLLVM.so` file *will* be BOLT optimized.
-            bolt_optimize(&llvm_lib, &llvm_profile).context("Could not optimize LLVM with BOLT")?;
+            bolt_optimize(&llvm_lib, &llvm_profile, env)
+                .context("Could not optimize LLVM with BOLT")?;
 
             let rustc_lib = io::find_file_in_dir(&libdir, "librustc_driver", ".so")?;
 
@@ -319,7 +333,7 @@ fn execute_pipeline(
             print_free_disk_space()?;
 
             // Now optimize the library with BOLT.
-            bolt_optimize(&rustc_lib, &rustc_profile)
+            bolt_optimize(&rustc_lib, &rustc_profile, env)
                 .context("Could not optimize rustc with BOLT")?;
 
             // LLVM is not being cleared here, we want to use the BOLT-optimized LLVM