Revert "Use multiple codegen units"

This reverts commit 03acf67.

Author: bjorn3

src/driver.rs

@@ -72,9 +72,7 @@ fn run_jit(tcx: TyCtxt<'_>) -> ! {
         .iter()
         .map(|cgu| cgu.items_in_deterministic_order(tcx).into_iter())
         .flatten()
-        .collect::<FxHashMap<_, (_, _)>>()
-        .into_iter()
-        .collect::<Vec<(_, (_, _))>>();
+        .collect::<FxHashMap<_, (_, _)>>();
 
     time(tcx.sess, "codegen mono items", || {
         codegen_mono_items(tcx, &mut jit_module, None, mono_items);
@@ -210,35 +208,36 @@ fn run_aot(
         };
 
     let (_, cgus) = tcx.collect_and_partition_mono_items(LOCAL_CRATE);
+    let mono_items = cgus
+        .iter()
+        .map(|cgu| cgu.items_in_deterministic_order(tcx).into_iter())
+        .flatten()
+        .collect::<FxHashMap<_, (_, _)>>();
 
-    let modules = time(tcx.sess, "codegen mono items", move || {
-        cgus.iter().map(|cgu| {
-            let mono_items = cgu.items_in_deterministic_order(tcx);
-
-            let mut module = new_module(cgu.name().as_str().to_string());
-
-            let mut debug = if tcx.sess.opts.debuginfo != DebugInfo::None {
-                let debug = DebugContext::new(
-                    tcx,
-                    module.target_config().pointer_type().bytes() as u8,
-                );
-                Some(debug)
-            } else {
-                None
-            };
+    let mut module = new_module("some_file".to_string());
 
-            codegen_mono_items(tcx, &mut module, debug.as_mut(), mono_items);
-            crate::main_shim::maybe_create_entry_wrapper(tcx, &mut module);
+    let mut debug = if tcx.sess.opts.debuginfo != DebugInfo::None {
+        let debug = DebugContext::new(
+            tcx,
+            module.target_config().pointer_type().bytes() as u8,
+        );
+        Some(debug)
+    } else {
+        None
+    };
 
-            emit_module(
-                tcx,
-                cgu.name().as_str().to_string(),
-                ModuleKind::Regular,
-                module,
-                debug,
-            )
-        }).collect::<Vec<_>>()
+    time(tcx.sess, "codegen mono items", || {
+        codegen_mono_items(tcx, &mut module, debug.as_mut(), mono_items);
     });
+    crate::main_shim::maybe_create_entry_wrapper(tcx, &mut module);
+
+    let modules = vec![emit_module(
+        tcx,
+        "some_file".to_string(),
+        ModuleKind::Regular,
+        module,
+        debug,
+    )];
 
     tcx.sess.abort_if_errors();
 
@@ -311,12 +310,12 @@ fn codegen_mono_items<'tcx>(
     tcx: TyCtxt<'tcx>,
     module: &mut Module<impl Backend + 'static>,
     debug_context: Option<&mut DebugContext<'tcx>>,
-    mono_items: Vec<(MonoItem<'tcx>, (RLinkage, Visibility))>,
+    mono_items: FxHashMap<MonoItem<'tcx>, (RLinkage, Visibility)>,
 ) {
     let mut cx = CodegenCx::new(tcx, module, debug_context);
 
     tcx.sess.time("predefine functions", || {
-        for &(mono_item, (linkage, visibility)) in &mono_items {
+        for (&mono_item, &(linkage, visibility)) in &mono_items {
             match mono_item {
                 MonoItem::Fn(instance) => {
                     let (name, sig) =