rustc_codegen_ssa: write .dwp in a streaming fashion

Author: weihanglo

compiler/rustc_codegen_ssa/src/back/link.rs

@@ -676,17 +676,18 @@ fn link_dwarf_object<'a>(
             thorin::MissingReferencedObjectBehaviour::Skip,
         )?;
 
-        let output = package.finish()?.write()?;
-        let mut output_stream = BufWriter::new(
+        let output_stream = BufWriter::new(
             OpenOptions::new()
                 .read(true)
                 .write(true)
                 .create(true)
                 .truncate(true)
                 .open(dwp_out_filename)?,
         );
-        output_stream.write_all(&output)?;
-        output_stream.flush()?;
+        let mut output_stream = object::write::StreamingBuffer::new(output_stream);
+        package.finish()?.emit(&mut output_stream)?;
+        output_stream.result()?;
+        output_stream.into_inner().flush()?;
 
         Ok(())
     }) {