Add .comment section with producer name

Fixes rust-lang#1211

Author: bjorn3

src/debuginfo/mod.rs

@@ -20,6 +20,14 @@ use indexmap::IndexSet;
 pub(crate) use emit::{DebugReloc, DebugRelocName};
 pub(crate) use unwind::UnwindContext;
 
+pub(crate) fn producer() -> String {
+    format!(
+        "cg_clif (rustc {}, cranelift {})",
+        rustc_interface::util::rustc_version_str().unwrap_or("unknown version"),
+        cranelift_codegen::VERSION,
+    )
+}
+
 pub(crate) struct DebugContext {
     endian: RunTimeEndian,
 
@@ -57,11 +65,7 @@ impl DebugContext {
 
         let mut dwarf = DwarfUnit::new(encoding);
 
-        let producer = format!(
-            "cg_clif (rustc {}, cranelift {})",
-            rustc_interface::util::rustc_version_str().unwrap_or("unknown version"),
-            cranelift_codegen::VERSION,
-        );
+        let producer = producer();
         let comp_dir = tcx
             .sess
             .opts

src/driver/aot.rs

@@ -169,10 +169,22 @@ fn emit_cgu(
 fn emit_module(
     output_filenames: &OutputFilenames,
     prof: &SelfProfilerRef,
-    object: cranelift_object::object::write::Object<'_>,
+    mut object: cranelift_object::object::write::Object<'_>,
     kind: ModuleKind,
     name: String,
 ) -> Result<CompiledModule, String> {
+    if object.format() == cranelift_object::object::BinaryFormat::Elf {
+        let comment_section = object.add_section(
+            Vec::new(),
+            b".comment".to_vec(),
+            cranelift_object::object::SectionKind::OtherString,
+        );
+        let mut producer = vec![0];
+        producer.extend(crate::debuginfo::producer().as_bytes());
+        producer.push(0);
+        object.set_section_data(comment_section, producer, 1);
+    }
+
     let tmp_file = output_filenames.temp_path(OutputType::Object, Some(&name));
     let mut file = match File::create(&tmp_file) {
         Ok(file) => file,