1 files changed, 71 insertions, 0 deletions
diff --git a/src/bootstrap/bolt.rs b/src/bootstrap/bolt.rs
new file mode 100644
index 000000000..ea37cd470
--- /dev/null
+++ b/src/bootstrap/bolt.rs
@@ -0,0 +1,71 @@
+use std::path::Path;
+use std::process::Command;
+
+/// Uses the `llvm-bolt` binary to instrument the binary/library at the given `path` with BOLT.
+/// When the instrumented artifact is executed, it will generate BOLT profiles into
+/// `/tmp/prof.fdata.<pid>.fdata`.
+pub fn instrument_with_bolt_inplace(path: &Path) {
+    let dir = std::env::temp_dir();
+    let instrumented_path = dir.join("instrumented.so");
+
+    let status = Command::new("llvm-bolt")
+        .arg("-instrument")
+        .arg(&path)
+        // Make sure that each process will write its profiles into a separate file
+        .arg("--instrumentation-file-append-pid")
+        .arg("-o")
+        .arg(&instrumented_path)
+        .status()
+        .expect("Could not instrument artifact using BOLT");
+
+    if !status.success() {
+        panic!("Could not instrument {} with BOLT, exit code {:?}", path.display(), status.code());
+    }
+
+    std::fs::copy(&instrumented_path, path).expect("Cannot copy instrumented artifact");
+    std::fs::remove_file(instrumented_path).expect("Cannot delete instrumented artifact");
+}
+
+/// Uses the `llvm-bolt` binary to optimize the binary/library at the given `path` with BOLT,
+/// using merged profiles from `profile_path`.
+///
+/// The recorded profiles have to be merged using the `merge-fdata` tool from LLVM and the merged
+/// profile path should be then passed to this function.
+pub fn optimize_library_with_bolt_inplace(path: &Path, profile_path: &Path) {
+    let dir = std::env::temp_dir();
+    let optimized_path = dir.join("optimized.so");
+
+    let status = Command::new("llvm-bolt")
+        .arg(&path)
+        .arg("-data")
+        .arg(&profile_path)
+        .arg("-o")
+        .arg(&optimized_path)
+        // Reorder basic blocks within functions
+        .arg("-reorder-blocks=ext-tsp")
+        // Reorder functions within the binary
+        .arg("-reorder-functions=hfsort+")
+        // Split function code into hot and code regions
+        .arg("-split-functions=2")
+        // Split as many basic blocks as possible
+        .arg("-split-all-cold")
+        // Move jump tables to a separate section
+        .arg("-jump-tables=move")
+        // Use GNU_STACK program header for new segment (workaround for issues with strip/objcopy)
+        .arg("-use-gnu-stack")
+        // Fold functions with identical code
+        .arg("-icf=1")
+        // Update DWARF debug info in the final binary
+        .arg("-update-debug-sections")
+        // Print optimization statistics
+        .arg("-dyno-stats")
+        .status()
+        .expect("Could not optimize artifact using BOLT");
+
+    if !status.success() {
+        panic!("Could not optimize {} with BOLT, exit code {:?}", path.display(), status.code());
+    }
+
+    std::fs::copy(&optimized_path, path).expect("Cannot copy optimized artifact");
+    std::fs::remove_file(optimized_path).expect("Cannot delete optimized artifact");
+}