Also profile finishing the encoding.

compiler/rustc_incremental/src/persist/save.rs

@@ -49,7 +49,7 @@ pub fn save_dep_graph(tcx: TyCtxt<'_>) {
             },
             move || {
                 sess.time("incr_comp_persist_dep_graph", || {
-                    if let Err(err) = tcx.dep_graph.encode() {
+                    if let Err(err) = tcx.dep_graph.encode(&tcx.sess.prof) {
                         sess.err(&format!(
                             "failed to write dependency graph to `{}`: {}",
                             staging_dep_graph_path.display(),

compiler/rustc_query_system/src/dep_graph/graph.rs

@@ -789,8 +789,12 @@ pub fn print_incremental_info(&self) {
         }
     }
 
-    pub fn encode(&self) -> FileEncodeResult {
-        if let Some(data) = &self.data { data.current.encoder.steal().finish() } else { Ok(()) }
+    pub fn encode(&self, profiler: &SelfProfilerRef) -> FileEncodeResult {
+        if let Some(data) = &self.data {
+            data.current.encoder.steal().finish(profiler)
+        } else {
+            Ok(())
+        }
     }
 
     fn next_virtual_depnode_index(&self) -> DepNodeIndex {

compiler/rustc_query_system/src/dep_graph/serialized.rs

@@ -304,7 +304,8 @@ pub(crate) fn send(
         self.status.lock().encode_node(&node, &self.record_graph)
     }
 
-    pub fn finish(self) -> FileEncodeResult {
+    pub fn finish(self, profiler: &SelfProfilerRef) -> FileEncodeResult {
+        let _prof_timer = profiler.generic_activity("incr_comp_encode_dep_graph");
         self.status.into_inner().finish()
     }
 }