Run link_binary_remove_temps in the background

Author: Zoxc

src/librustc_codegen_llvm/lib.rs

@@ -44,6 +44,7 @@ use rustc::ty::{self, TyCtxt};
 use rustc::util::common::ErrorReported;
 use rustc_codegen_ssa::ModuleCodegen;
 use rustc_codegen_utils::codegen_backend::CodegenBackend;
+use rustc_data_structures::sync::Lrc;
 
 mod back {
     pub mod archive;
@@ -271,7 +272,7 @@ impl CodegenBackend for LlvmCodegenBackend {
     fn join_codegen_and_link(
         &self,
         ongoing_codegen: Box<dyn Any>,
-        sess: &Session,
+        sess: &Lrc<Session>,
         dep_graph: &DepGraph,
         outputs: &OutputFilenames,
     ) -> Result<(), ErrorReported> {
@@ -298,9 +299,11 @@ impl CodegenBackend for LlvmCodegenBackend {
             return Ok(());
         }
 
+        let codegen_results = Lrc::new(codegen_results);
+
         // Run the linker on any artifacts that resulted from the LLVM run.
         // This should produce either a finished executable or library.
-        sess.time("link_crate", || {
+        let cleanup_future = sess.time("link_crate", || {
             use crate::back::archive::LlvmArchiveBuilder;
             use rustc_codegen_ssa::back::link::link_binary;
 
@@ -311,13 +314,16 @@ impl CodegenBackend for LlvmCodegenBackend {
                 outputs,
                 &codegen_results.crate_name.as_str(),
                 target_cpu,
-            );
+            )
         });
 
         // Now that we won't touch anything in the incremental compilation directory
         // any more, we can finalize it (which involves renaming it)
         rustc_incremental::finalize_session_directory(sess, codegen_results.crate_hash);
 
+        // Join the cleanup future so it drops the `Lrc<Session>` it holds.
+        cleanup_future.join();
+
         Ok(())
     }
 }

src/librustc_codegen_ssa/back/link.rs

@@ -8,6 +8,8 @@ use rustc::session::search_paths::PathKind;
 /// need out of the shared crate context before we get rid of it.
 use rustc::session::{filesearch, Session};
 use rustc_data_structures::fx::FxHashSet;
+use rustc_data_structures::sync::future::Future;
+use rustc_data_structures::sync::Lrc;
 use rustc_fs_util::fix_windows_verbatim_for_gcc;
 use rustc_hir::def_id::CrateNum;
 use rustc_span::symbol::Symbol;
@@ -47,12 +49,12 @@ pub fn remove(sess: &Session, path: &Path) {
 /// Performs the linkage portion of the compilation phase. This will generate all
 /// of the requested outputs for this compilation session.
 pub fn link_binary<'a, B: ArchiveBuilder<'a>>(
-    sess: &'a Session,
-    codegen_results: &CodegenResults,
+    sess: &'a Lrc<Session>,
+    codegen_results: &Lrc<CodegenResults>,
     outputs: &OutputFilenames,
     crate_name: &str,
     target_cpu: &str,
-) {
+) -> Future<'static, ()> {
     let _timer = sess.timer("link_binary");
     let output_metadata = sess.opts.output_types.contains_key(&OutputType::Metadata);
     for &crate_type in sess.crate_types.borrow().iter() {
@@ -122,34 +124,40 @@ pub fn link_binary<'a, B: ArchiveBuilder<'a>>(
     }
 
     // Remove the temporary object file and metadata if we aren't saving temps
-    sess.time("link_binary_remove_temps", || {
-        if !sess.opts.cg.save_temps {
-            if sess.opts.output_types.should_codegen()
-                && !preserve_objects_for_their_debuginfo(sess)
-            {
-                for obj in codegen_results.modules.iter().filter_map(|m| m.object.as_ref()) {
-                    remove(sess, obj);
+    let sess = sess.clone();
+    let codegen_results = codegen_results.clone();
+    Future::spawn(move || {
+        let sess = &*sess;
+        sess.time("link_binary_remove_temps", || {
+            if !sess.opts.cg.save_temps {
+                if sess.opts.output_types.should_codegen()
+                    && !preserve_objects_for_their_debuginfo(sess)
+                {
+                    for obj in codegen_results.modules.iter().filter_map(|m| m.object.as_ref()) {
+                        remove(sess, obj);
+                    }
                 }
-            }
-            for obj in codegen_results.modules.iter().filter_map(|m| m.bytecode_compressed.as_ref())
-            {
-                remove(sess, obj);
-            }
-            if let Some(ref metadata_module) = codegen_results.metadata_module {
-                if let Some(ref obj) = metadata_module.object {
+                for obj in
+                    codegen_results.modules.iter().filter_map(|m| m.bytecode_compressed.as_ref())
+                {
                     remove(sess, obj);
                 }
-            }
-            if let Some(ref allocator_module) = codegen_results.allocator_module {
-                if let Some(ref obj) = allocator_module.object {
-                    remove(sess, obj);
+                if let Some(ref metadata_module) = codegen_results.metadata_module {
+                    if let Some(ref obj) = metadata_module.object {
+                        remove(sess, obj);
+                    }
                 }
-                if let Some(ref bc) = allocator_module.bytecode_compressed {
-                    remove(sess, bc);
+                if let Some(ref allocator_module) = codegen_results.allocator_module {
+                    if let Some(ref obj) = allocator_module.object {
+                        remove(sess, obj);
+                    }
+                    if let Some(ref bc) = allocator_module.bytecode_compressed {
+                        remove(sess, bc);
+                    }
                 }
             }
-        }
-    });
+        });
+    })
 }
 
 // The third parameter is for env vars, used on windows to set up the

src/librustc_codegen_utils/codegen_backend.rs

@@ -15,6 +15,7 @@ use rustc::session::Session;
 use rustc::ty::query::Providers;
 use rustc::ty::TyCtxt;
 use rustc::util::common::ErrorReported;
+use rustc_data_structures::sync::Lrc;
 use rustc_span::symbol::Symbol;
 
 pub use rustc_data_structures::sync::MetadataRef;
@@ -46,7 +47,7 @@ pub trait CodegenBackend {
     fn join_codegen_and_link(
         &self,
         ongoing_codegen: Box<dyn Any>,
-        sess: &Session,
+        sess: &Lrc<Session>,
         dep_graph: &DepGraph,
         outputs: &OutputFilenames,
     ) -> Result<(), ErrorReported>;

src/test/run-make-fulldeps/hotplug_codegen_backend/the_backend.rs

@@ -4,32 +4,33 @@ extern crate rustc;
 extern crate rustc_codegen_utils;
 #[macro_use]
 extern crate rustc_data_structures;
-extern crate rustc_hir;
-extern crate rustc_target;
 extern crate rustc_driver;
+extern crate rustc_hir;
 extern crate rustc_span;
+extern crate rustc_target;
 
-use std::any::Any;
-use std::sync::Arc;
-use std::path::Path;
-use rustc_span::symbol::Symbol;
-use rustc::session::Session;
+use rustc::dep_graph::DepGraph;
+use rustc::middle::cstore::{EncodedMetadata, MetadataLoader, MetadataLoaderDyn};
 use rustc::session::config::OutputFilenames;
-use rustc::ty::TyCtxt;
+use rustc::session::Session;
 use rustc::ty::query::Providers;
-use rustc::middle::cstore::{EncodedMetadata, MetadataLoader, MetadataLoaderDyn};
-use rustc::dep_graph::DepGraph;
+use rustc::ty::TyCtxt;
 use rustc::util::common::ErrorReported;
 use rustc_codegen_utils::codegen_backend::CodegenBackend;
-use rustc_data_structures::sync::MetadataRef;
 use rustc_data_structures::owning_ref::OwningRef;
+use rustc_data_structures::sync::{Lrc, MetadataRef};
+use rustc_span::symbol::Symbol;
 use rustc_target::spec::Target;
+use std::any::Any;
+use std::path::Path;
+use std::sync::Arc;
 
 pub struct NoLlvmMetadataLoader;
 
 impl MetadataLoader for NoLlvmMetadataLoader {
     fn get_rlib_metadata(&self, _: &Target, filename: &Path) -> Result<MetadataRef, String> {
-        let buf = std::fs::read(filename).map_err(|e| format!("metadata file open err: {:?}", e))?;
+        let buf =
+            std::fs::read(filename).map_err(|e| format!("metadata file open err: {:?}", e))?;
         let buf: OwningRef<Vec<u8>, [u8]> = OwningRef::new(buf);
         Ok(rustc_erase_owner!(buf.map_owner_box()))
     }
@@ -74,21 +75,21 @@ impl CodegenBackend for TheBackend {
     fn join_codegen_and_link(
         &self,
         ongoing_codegen: Box<dyn Any>,
-        sess: &Session,
+        sess: &Lrc<Session>,
         _dep_graph: &DepGraph,
         outputs: &OutputFilenames,
     ) -> Result<(), ErrorReported> {
-        use std::io::Write;
         use rustc::session::config::CrateType;
         use rustc_codegen_utils::link::out_filename;
-        let crate_name = ongoing_codegen.downcast::<Symbol>()
+        use std::io::Write;
+        let crate_name = ongoing_codegen
+            .downcast::<Symbol>()
             .expect("in join_codegen_and_link: ongoing_codegen is not a Symbol");
         for &crate_type in sess.opts.crate_types.iter() {
             if crate_type != CrateType::Rlib {
                 sess.fatal(&format!("Crate type is {:?}", crate_type));
             }
-            let output_name =
-                out_filename(sess, crate_type, &outputs, &*crate_name.as_str());
+            let output_name = out_filename(sess, crate_type, &outputs, &*crate_name.as_str());
             let mut out_file = ::std::fs::File::create(output_name).unwrap();
             write!(out_file, "This has been \"compiled\" successfully.").unwrap();
         }