incr: cache dwarf objects in work products

Cache DWARF objects alongside object files in work products when those
exist so that DWARF object files are available for thorin in packed mode
in incremental scenarios.

Signed-off-by: David Wood <david.wood@huawei.com>

Author: davidtwco

src/driver/aot.rs

@@ -66,7 +66,11 @@ fn emit_module(
     let work_product = if backend_config.disable_incr_cache {
         None
     } else {
-        rustc_incremental::copy_cgu_workproduct_to_incr_comp_cache_dir(tcx.sess, &name, &tmp_file)
+        rustc_incremental::copy_cgu_workproduct_to_incr_comp_cache_dir(
+            tcx.sess,
+            &name,
+            &[("o", &tmp_file)],
+        )
     };
 
     ModuleCodegenResult(
@@ -82,7 +86,10 @@ fn reuse_workproduct_for_cgu(
 ) -> CompiledModule {
     let work_product = cgu.previous_work_product(tcx);
     let obj_out = tcx.output_filenames(()).temp_path(OutputType::Object, Some(cgu.name().as_str()));
-    let source_file = rustc_incremental::in_incr_comp_dir_sess(&tcx.sess, &work_product.saved_file);
+    let source_file = rustc_incremental::in_incr_comp_dir_sess(
+        &tcx.sess,
+        &work_product.saved_files.get("o").expect("no saved object file in work product"),
+    );
     if let Err(err) = rustc_fs_util::link_or_copy(&source_file, &obj_out) {
         tcx.sess.err(&format!(
             "unable to copy {} to {}: {}",