ThinLTO: Don't keep files open after mmaping them (because it's not needed).

Author: michaelwoerister

src/librustc_codegen_llvm/back/lto.rs

@@ -29,7 +29,7 @@ use {ModuleCodegen, ModuleLlvm, ModuleKind};
 use libc;
 
 use std::ffi::{CStr, CString};
-use std::fs::{self, File};
+use std::fs;
 use std::ptr;
 use std::slice;
 use std::sync::Arc;
@@ -619,15 +619,15 @@ fn run_pass_manager(cgcx: &CodegenContext,
 pub enum SerializedModule {
     Local(ModuleBuffer),
     FromRlib(Vec<u8>),
-    FromUncompressedFile(memmap::Mmap, File),
+    FromUncompressedFile(memmap::Mmap),
 }
 
 impl SerializedModule {
     fn data(&self) -> &[u8] {
         match *self {
             SerializedModule::Local(ref m) => m.data(),
             SerializedModule::FromRlib(ref m) => m,
-            SerializedModule::FromUncompressedFile(ref m, _) => m,
+            SerializedModule::FromUncompressedFile(ref m) => m,
         }
     }
 }

src/librustc_codegen_llvm/back/write.rs

@@ -2485,7 +2485,7 @@ pub(crate) fn submit_pre_lto_module_to_llvm(tcx: TyCtxt,
 
     // Schedule the module to be loaded
     drop(tcx.tx_to_llvm_workers.lock().send(Box::new(Message::AddImportOnlyModule {
-        module_data: SerializedModule::FromUncompressedFile(mmap, file),
+        module_data: SerializedModule::FromUncompressedFile(mmap),
         work_product: module.source,
     })));
 }