Auto merge of #125642 - khuey:zstd, r=Kobzol

Enable zstd for debug compression.

Set LLVM_ENABLE_ZSTD alongside LLVM_ENABLE_ZLIB so that --compress-debug-sections=zstd is an option.

See #120953

try-job: x86_64-gnu-tools

7 files changed, 57 insertions, 4 deletions

diff --git a/src/bootstrap/download-ci-llvm-stamp b/src/bootstrap/download-ci-llvm-stamp
index 258a0347451..11316004412 100644
--- a/src/bootstrap/download-ci-llvm-stamp
+++ b/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/126298
+Last change is for: https://github.com/rust-lang/rust/pull/125642
diff --git a/src/bootstrap/src/core/build_steps/llvm.rs b/src/bootstrap/src/core/build_steps/llvm.rs
index 81e591be699..ffae245dfb5 100644
--- a/src/bootstrap/src/core/build_steps/llvm.rs
+++ b/src/bootstrap/src/core/build_steps/llvm.rs
@@ -368,9 +368,7 @@ impl Step for Llvm {
             cfg.define("LLVM_PROFDATA_FILE", path);
         }
 
-        // Disable zstd to avoid a dependency on libzstd.so.
-        cfg.define("LLVM_ENABLE_ZSTD", "OFF");
-
+        // Libraries for ELF section compression.
         if !target.is_windows() {
             cfg.define("LLVM_ENABLE_ZLIB", "ON");
         } else {
@@ -824,6 +822,14 @@ fn configure_llvm(builder: &Builder<'_>, target: TargetSelection, cfg: &mut cmak
         }
     }
 
+    // Libraries for ELF section compression.
+    if builder.config.llvm_libzstd {
+        cfg.define("LLVM_ENABLE_ZSTD", "FORCE_ON");
+        cfg.define("LLVM_USE_STATIC_ZSTD", "TRUE");
+    } else {
+        cfg.define("LLVM_ENABLE_ZSTD", "OFF");
+    }
+
     if let Some(ref linker) = builder.config.llvm_use_linker {
         cfg.define("LLVM_USE_LINKER", linker);
     }
diff --git a/src/bootstrap/src/core/config/config.rs b/src/bootstrap/src/core/config/config.rs
index f0a55830167..915fcb449e8 100644
--- a/src/bootstrap/src/core/config/config.rs
+++ b/src/bootstrap/src/core/config/config.rs
@@ -218,6 +218,7 @@ pub struct Config {
     pub llvm_thin_lto: bool,
     pub llvm_release_debuginfo: bool,
     pub llvm_static_stdcpp: bool,
+    pub llvm_libzstd: bool,
     /// `None` if `llvm_from_ci` is true and we haven't yet downloaded llvm.
     #[cfg(not(test))]
     llvm_link_shared: Cell<Option<bool>>,
@@ -878,6 +879,7 @@ define_config! {
         plugins: Option<bool> = "plugins",
         ccache: Option<StringOrBool> = "ccache",
         static_libstdcpp: Option<bool> = "static-libstdcpp",
+        libzstd: Option<bool> = "libzstd",
         ninja: Option<bool> = "ninja",
         targets: Option<String> = "targets",
         experimental_targets: Option<String> = "experimental-targets",
@@ -1153,6 +1155,7 @@ impl Config {
             llvm_optimize: true,
             ninja_in_file: true,
             llvm_static_stdcpp: false,
+            llvm_libzstd: false,
             backtrace: true,
             rust_optimize: RustOptimize::Bool(true),
             rust_optimize_tests: true,
@@ -1791,6 +1794,7 @@ impl Config {
                 plugins,
                 ccache,
                 static_libstdcpp,
+                libzstd,
                 ninja,
                 targets,
                 experimental_targets,
@@ -1825,6 +1829,7 @@ impl Config {
             set(&mut config.llvm_thin_lto, thin_lto);
             set(&mut config.llvm_release_debuginfo, release_debuginfo);
             set(&mut config.llvm_static_stdcpp, static_libstdcpp);
+            set(&mut config.llvm_libzstd, libzstd);
             if let Some(v) = link_shared {
                 config.llvm_link_shared.set(Some(v));
             }
@@ -1875,6 +1880,7 @@ impl Config {
                 check_ci_llvm!(optimize_toml);
                 check_ci_llvm!(thin_lto);
                 check_ci_llvm!(release_debuginfo);
+                check_ci_llvm!(libzstd);
                 check_ci_llvm!(targets);
                 check_ci_llvm!(experimental_targets);
                 check_ci_llvm!(clang_cl);
diff --git a/src/bootstrap/src/utils/change_tracker.rs b/src/bootstrap/src/utils/change_tracker.rs
index b8f70fdf6a8..84dac25188e 100644
--- a/src/bootstrap/src/utils/change_tracker.rs
+++ b/src/bootstrap/src/utils/change_tracker.rs
@@ -220,4 +220,9 @@ pub const CONFIG_CHANGE_HISTORY: &[ChangeInfo] = &[
         severity: ChangeSeverity::Warning,
         summary: "For tarball sources, default value for `rust.channel` will be taken from `src/ci/channel` file.",
     },
+    ChangeInfo {
+        change_id: 125642,
+        severity: ChangeSeverity::Info,
+        summary: "New option `llvm.libzstd` to control whether llvm is built with zstd support.",
+    },
 ];
diff --git a/src/ci/docker/host-x86_64/dist-x86_64-linux/Dockerfile b/src/ci/docker/host-x86_64/dist-x86_64-linux/Dockerfile
index 4aa1a3ccc2a..61e9694f1e2 100644
--- a/src/ci/docker/host-x86_64/dist-x86_64-linux/Dockerfile
+++ b/src/ci/docker/host-x86_64/dist-x86_64-linux/Dockerfile
@@ -62,6 +62,10 @@ COPY host-x86_64/dist-x86_64-linux/build-clang.sh /tmp/
 RUN ./build-clang.sh
 ENV CC=clang CXX=clang++
 
+# rustc's LLVM needs zstd.
+COPY scripts/zstd.sh /tmp/
+RUN ./zstd.sh
+
 COPY scripts/sccache.sh /scripts/
 RUN sh /scripts/sccache.sh
 
@@ -79,6 +83,7 @@ ENV RUST_CONFIGURE_ARGS \
       --set target.x86_64-unknown-linux-gnu.ranlib=/rustroot/bin/llvm-ranlib \
       --set llvm.thin-lto=true \
       --set llvm.ninja=false \
+      --set llvm.libzstd=true \
       --set rust.jemalloc \
       --set rust.use-lld=true \
       --set rust.lto=thin \
diff --git a/src/ci/docker/host-x86_64/x86_64-gnu/Dockerfile b/src/ci/docker/host-x86_64/x86_64-gnu/Dockerfile
index 9025e9bb0a3..19683317126 100644
--- a/src/ci/docker/host-x86_64/x86_64-gnu/Dockerfile
+++ b/src/ci/docker/host-x86_64/x86_64-gnu/Dockerfile
@@ -17,6 +17,8 @@ RUN apt-get update && apt-get install -y --no-install-recommends \
   pkg-config \
   xz-utils \
   mingw-w64 \
+  zlib1g-dev \
+  libzstd-dev \
   && rm -rf /var/lib/apt/lists/*
 
 COPY scripts/sccache.sh /scripts/
diff --git a/src/ci/docker/scripts/zstd.sh b/src/ci/docker/scripts/zstd.sh
new file mode 100755
index 00000000000..a3d37ccc311
--- /dev/null
+++ b/src/ci/docker/scripts/zstd.sh
@@ -0,0 +1,29 @@
+#!/bin/bash
+set -ex
+
+hide_output() {
+  set +x
+  on_err="
+echo ERROR: An error was encountered with the build.
+cat /tmp/zstd_build.log
+exit 1
+"
+  trap "$on_err" ERR
+  bash -c "while true; do sleep 30; echo \$(date) - building ...; done" &
+  PING_LOOP_PID=$!
+  "$@" &> /tmp/zstd_build.log
+  trap - ERR
+  kill $PING_LOOP_PID
+  rm /tmp/zstd_build.log
+  set -x
+}
+
+ZSTD=1.5.6
+curl -L https://github.com/facebook/zstd/releases/download/v$ZSTD/zstd-$ZSTD.tar.gz | tar xzf -
+
+cd zstd-$ZSTD
+CFLAGS=-fPIC hide_output make -j$(nproc) VERBOSE=1
+hide_output make install
+
+cd ..
+rm -rf zstd-$ZSTD