compiler/rustc_codegen_cranelift/src/driver/aot.rs - toolchain/rustc - Git at Google

 //! The AOT driver uses [`cranelift_object`] to write object files suitable for linking into a
 //! standalone executable.

 use std::path::PathBuf;

 use rustc_ast::{InlineAsmOptions, InlineAsmTemplatePiece};
 use rustc_codegen_ssa::back::metadata::create_compressed_metadata_file;
 use rustc_codegen_ssa::{CodegenResults, CompiledModule, CrateInfo, ModuleKind};
 use rustc_data_structures::stable_hasher::{HashStable, StableHasher};
 use rustc_metadata::EncodedMetadata;
 use rustc_middle::dep_graph::{WorkProduct, WorkProductId};
 use rustc_middle::mir::mono::{CodegenUnit, MonoItem};
 use rustc_session::cgu_reuse_tracker::CguReuse;
 use rustc_session::config::{DebugInfo, OutputType};
 use rustc_session::Session;

 use cranelift_codegen::isa::TargetIsa;
 use cranelift_object::{ObjectBuilder, ObjectModule};

 use crate::{prelude::*, BackendConfig};

 struct ModuleCodegenResult(CompiledModule, Option<(WorkProductId, WorkProduct)>);

 impl<HCX> HashStable<HCX> for ModuleCodegenResult {
     fn hash_stable(&self, _: &mut HCX, _: &mut StableHasher) {
         // do nothing
     }
 }

 fn make_module(sess: &Session, isa: Box<dyn TargetIsa>, name: String) -> ObjectModule {
     let mut builder =
         ObjectBuilder::new(isa, name + ".o", cranelift_module::default_libcall_names()).unwrap();
     // Unlike cg_llvm, cg_clif defaults to disabling -Zfunction-sections. For cg_llvm binary size
     // is important, while cg_clif cares more about compilation times. Enabling -Zfunction-sections
     // can easily double the amount of time necessary to perform linking.
     builder.per_function_section(sess.opts.unstable_opts.function_sections.unwrap_or(false));
     ObjectModule::new(builder)
 }

 fn emit_module(
     tcx: TyCtxt<'_>,
     backend_config: &BackendConfig,
     name: String,
     kind: ModuleKind,
     module: ObjectModule,
     debug: Option<DebugContext<'_>>,
     unwind_context: UnwindContext,
 ) -> ModuleCodegenResult {
     let mut product = module.finish();

     if let Some(mut debug) = debug {
         debug.emit(&mut product);
     }

     unwind_context.emit(&mut product);

     let tmp_file = tcx.output_filenames(()).temp_path(OutputType::Object, Some(&name));
     let obj = product.object.write().unwrap();

     tcx.sess.prof.artifact_size("object_file", name.clone(), obj.len().try_into().unwrap());

     if let Err(err) = std::fs::write(&tmp_file, obj) {
         tcx.sess.fatal(&format!("error writing object file: {}", err));
     }

     let work_product = if backend_config.disable_incr_cache {
         None
     } else {
         rustc_incremental::copy_cgu_workproduct_to_incr_comp_cache_dir(
             tcx.sess,
             &name,
             &[("o", &tmp_file)],
         )
     };

     ModuleCodegenResult(
         CompiledModule { name, kind, object: Some(tmp_file), dwarf_object: None, bytecode: None },
         work_product,
     )
 }

 fn reuse_workproduct_for_cgu(
     tcx: TyCtxt<'_>,
     cgu: &CodegenUnit<'_>,
     work_products: &mut FxHashMap<WorkProductId, WorkProduct>,
 ) -> CompiledModule {
     let work_product = cgu.previous_work_product(tcx);
     let obj_out = tcx.output_filenames(()).temp_path(OutputType::Object, Some(cgu.name().as_str()));
     let source_file = rustc_incremental::in_incr_comp_dir_sess(
         &tcx.sess,
         &work_product.saved_files.get("o").expect("no saved object file in work product"),
     );
     if let Err(err) = rustc_fs_util::link_or_copy(&source_file, &obj_out) {
         tcx.sess.err(&format!(
             "unable to copy {} to {}: {}",
             source_file.display(),
             obj_out.display(),
             err
         ));
     }

     work_products.insert(cgu.work_product_id(), work_product);

     CompiledModule {
         name: cgu.name().to_string(),
         kind: ModuleKind::Regular,
         object: Some(obj_out),
         dwarf_object: None,
         bytecode: None,
     }
 }

 fn module_codegen(
     tcx: TyCtxt<'_>,
     (backend_config, cgu_name): (BackendConfig, rustc_span::Symbol),
 ) -> ModuleCodegenResult {
     let cgu = tcx.codegen_unit(cgu_name);
     let mono_items = cgu.items_in_deterministic_order(tcx);

     let isa = crate::build_isa(tcx.sess, &backend_config);
     let mut module = make_module(tcx.sess, isa, cgu_name.as_str().to_string());

     let mut cx = crate::CodegenCx::new(
         tcx,
         backend_config.clone(),
         module.isa(),
         tcx.sess.opts.debuginfo != DebugInfo::None,
         cgu_name,
     );
     super::predefine_mono_items(tcx, &mut module, &mono_items);
     for (mono_item, _) in mono_items {
         match mono_item {
             MonoItem::Fn(inst) => {
                 cx.tcx
                     .sess
                     .time("codegen fn", || crate::base::codegen_fn(&mut cx, &mut module, inst));
             }
             MonoItem::Static(def_id) => crate::constant::codegen_static(tcx, &mut module, def_id),
             MonoItem::GlobalAsm(item_id) => {
                 let item = cx.tcx.hir().item(item_id);
                 if let rustc_hir::ItemKind::GlobalAsm(asm) = item.kind {
                     if !asm.options.contains(InlineAsmOptions::ATT_SYNTAX) {
                         cx.global_asm.push_str("\n.intel_syntax noprefix\n");
                     } else {
                         cx.global_asm.push_str("\n.att_syntax\n");
                     }
                     for piece in asm.template {
                         match *piece {
                             InlineAsmTemplatePiece::String(ref s) => cx.global_asm.push_str(s),
                             InlineAsmTemplatePiece::Placeholder { .. } => todo!(),
                         }
                     }
                     cx.global_asm.push_str("\n.att_syntax\n\n");
                 } else {
                     bug!("Expected GlobalAsm found {:?}", item);
                 }
             }
         }
     }
     crate::main_shim::maybe_create_entry_wrapper(
         tcx,
         &mut module,
         &mut cx.unwind_context,
         false,
         cgu.is_primary(),
     );

     let debug_context = cx.debug_context;
     let unwind_context = cx.unwind_context;
     let codegen_result = tcx.sess.time("write object file", || {
         emit_module(
             tcx,
             &backend_config,
             cgu.name().as_str().to_string(),
             ModuleKind::Regular,
             module,
             debug_context,
             unwind_context,
         )
     });

     codegen_global_asm(tcx, cgu.name().as_str(), &cx.global_asm);

     codegen_result
 }

 pub(crate) fn run_aot(
     tcx: TyCtxt<'_>,
     backend_config: BackendConfig,
     metadata: EncodedMetadata,
     need_metadata_module: bool,
 ) -> Box<(CodegenResults, FxHashMap<WorkProductId, WorkProduct>)> {
     let mut work_products = FxHashMap::default();

     let cgus = if tcx.sess.opts.output_types.should_codegen() {
         tcx.collect_and_partition_mono_items(()).1
     } else {
         // If only `--emit metadata` is used, we shouldn't perform any codegen.
         // Also `tcx.collect_and_partition_mono_items` may panic in that case.
         &[]
     };

     if tcx.dep_graph.is_fully_enabled() {
         for cgu in &*cgus {
             tcx.ensure().codegen_unit(cgu.name());
         }
     }

     let modules = super::time(tcx, backend_config.display_cg_time, "codegen mono items", || {
         cgus.iter()
             .map(|cgu| {
                 let cgu_reuse = determine_cgu_reuse(tcx, cgu);
                 tcx.sess.cgu_reuse_tracker.set_actual_reuse(cgu.name().as_str(), cgu_reuse);

                 match cgu_reuse {
                     _ if backend_config.disable_incr_cache => {}
                     CguReuse::No => {}
                     CguReuse::PreLto => {
                         return reuse_workproduct_for_cgu(tcx, &*cgu, &mut work_products);
                     }
                     CguReuse::PostLto => unreachable!(),
                 }

                 let dep_node = cgu.codegen_dep_node(tcx);
                 let (ModuleCodegenResult(module, work_product), _) = tcx.dep_graph.with_task(
                     dep_node,
                     tcx,
                     (backend_config.clone(), cgu.name()),
                     module_codegen,
                     Some(rustc_middle::dep_graph::hash_result),
                 );

                 if let Some((id, product)) = work_product {
                     work_products.insert(id, product);
                 }

                 module
             })
             .collect::<Vec<_>>()
     });

     tcx.sess.abort_if_errors();

     let isa = crate::build_isa(tcx.sess, &backend_config);
     let mut allocator_module = make_module(tcx.sess, isa, "allocator_shim".to_string());
     assert_eq!(pointer_ty(tcx), allocator_module.target_config().pointer_type());
     let mut allocator_unwind_context = UnwindContext::new(allocator_module.isa(), true);
     let created_alloc_shim =
         crate::allocator::codegen(tcx, &mut allocator_module, &mut allocator_unwind_context);

     let allocator_module = if created_alloc_shim {
         let ModuleCodegenResult(module, work_product) = emit_module(
             tcx,
             &backend_config,
             "allocator_shim".to_string(),
             ModuleKind::Allocator,
             allocator_module,
             None,
             allocator_unwind_context,
         );
         if let Some((id, product)) = work_product {
             work_products.insert(id, product);
         }
         Some(module)
     } else {
         None
     };

     let metadata_module = if need_metadata_module {
         let _timer = tcx.prof.generic_activity("codegen crate metadata");
         let (metadata_cgu_name, tmp_file) = tcx.sess.time("write compressed metadata", || {
             use rustc_middle::mir::mono::CodegenUnitNameBuilder;

             let cgu_name_builder = &mut CodegenUnitNameBuilder::new(tcx);
             let metadata_cgu_name = cgu_name_builder
                 .build_cgu_name(LOCAL_CRATE, &["crate"], Some("metadata"))
                 .as_str()
                 .to_string();

             let tmp_file =
                 tcx.output_filenames(()).temp_path(OutputType::Metadata, Some(&metadata_cgu_name));

             let symbol_name = rustc_middle::middle::exported_symbols::metadata_symbol_name(tcx);
             let obj = create_compressed_metadata_file(tcx.sess, &metadata, &symbol_name);

             if let Err(err) = std::fs::write(&tmp_file, obj) {
                 tcx.sess.fatal(&format!("error writing metadata object file: {}", err));
             }

             (metadata_cgu_name, tmp_file)
         });

         Some(CompiledModule {
             name: metadata_cgu_name,
             kind: ModuleKind::Metadata,
             object: Some(tmp_file),
             dwarf_object: None,
             bytecode: None,
         })
     } else {
         None
     };

     // FIXME handle `-Ctarget-cpu=native`
     let target_cpu = match tcx.sess.opts.cg.target_cpu {
         Some(ref name) => name,
         None => tcx.sess.target.cpu.as_ref(),
     }
     .to_owned();

     Box::new((
         CodegenResults {
             modules,
             allocator_module,
             metadata_module,
             metadata,
             crate_info: CrateInfo::new(tcx, target_cpu),
         },
         work_products,
     ))
 }

 fn codegen_global_asm(tcx: TyCtxt<'_>, cgu_name: &str, global_asm: &str) {
     use std::io::Write;
     use std::process::{Command, Stdio};

     if global_asm.is_empty() {
         return;
     }

     if cfg!(not(feature = "inline_asm"))
         || tcx.sess.target.is_like_osx
         || tcx.sess.target.is_like_windows
     {
         if global_asm.contains("__rust_probestack") {
             return;
         }

         // FIXME fix linker error on macOS
         if cfg!(not(feature = "inline_asm")) {
             tcx.sess.fatal(
                 "asm! and global_asm! support is disabled while compiling rustc_codegen_cranelift",
             );
         } else {
             tcx.sess.fatal("asm! and global_asm! are not yet supported on macOS and Windows");
         }
     }

     let assembler = crate::toolchain::get_toolchain_binary(tcx.sess, "as");
     let linker = crate::toolchain::get_toolchain_binary(tcx.sess, "ld");

     // Remove all LLVM style comments
     let global_asm = global_asm
         .lines()
         .map(|line| if let Some(index) = line.find("//") { &line[0..index] } else { line })
         .collect::<Vec<_>>()
         .join("\n");

     let output_object_file = tcx.output_filenames(()).temp_path(OutputType::Object, Some(cgu_name));

     // Assemble `global_asm`
     let global_asm_object_file = add_file_stem_postfix(output_object_file.clone(), ".asm");
     let mut child = Command::new(assembler)
         .arg("-o")
         .arg(&global_asm_object_file)
         .stdin(Stdio::piped())
         .spawn()
         .expect("Failed to spawn `as`.");
     child.stdin.take().unwrap().write_all(global_asm.as_bytes()).unwrap();
     let status = child.wait().expect("Failed to wait for `as`.");
     if !status.success() {
         tcx.sess.fatal(&format!("Failed to assemble `{}`", global_asm));
     }

     // Link the global asm and main object file together
     let main_object_file = add_file_stem_postfix(output_object_file.clone(), ".main");
     std::fs::rename(&output_object_file, &main_object_file).unwrap();
     let status = Command::new(linker)
         .arg("-r") // Create a new object file
         .arg("-o")
         .arg(output_object_file)
         .arg(&main_object_file)
         .arg(&global_asm_object_file)
         .status()
         .unwrap();
     if !status.success() {
         tcx.sess.fatal(&format!(
             "Failed to link `{}` and `{}` together",
             main_object_file.display(),
             global_asm_object_file.display(),
         ));
     }

     std::fs::remove_file(global_asm_object_file).unwrap();
     std::fs::remove_file(main_object_file).unwrap();
 }

 fn add_file_stem_postfix(mut path: PathBuf, postfix: &str) -> PathBuf {
     let mut new_filename = path.file_stem().unwrap().to_owned();
     new_filename.push(postfix);
     if let Some(extension) = path.extension() {
         new_filename.push(".");
         new_filename.push(extension);
     }
     path.set_file_name(new_filename);
     path
 }

 // Adapted from https://github.com/rust-lang/rust/blob/303d8aff6092709edd4dbd35b1c88e9aa40bf6d8/src/librustc_codegen_ssa/base.rs#L922-L953
 fn determine_cgu_reuse<'tcx>(tcx: TyCtxt<'tcx>, cgu: &CodegenUnit<'tcx>) -> CguReuse {
     if !tcx.dep_graph.is_fully_enabled() {
         return CguReuse::No;
     }

     let work_product_id = &cgu.work_product_id();
     if tcx.dep_graph.previous_work_product(work_product_id).is_none() {
         // We don't have anything cached for this CGU. This can happen
         // if the CGU did not exist in the previous session.
         return CguReuse::No;
     }

     // Try to mark the CGU as green. If it we can do so, it means that nothing
     // affecting the LLVM module has changed and we can re-use a cached version.
     // If we compile with any kind of LTO, this means we can re-use the bitcode
     // of the Pre-LTO stage (possibly also the Post-LTO version but we'll only
     // know that later). If we are not doing LTO, there is only one optimized
     // version of each module, so we re-use that.
     let dep_node = cgu.codegen_dep_node(tcx);
     assert!(
         !tcx.dep_graph.dep_node_exists(&dep_node),
         "CompileCodegenUnit dep-node for CGU `{}` already exists before marking.",
         cgu.name()
     );

     if tcx.try_mark_green(&dep_node) { CguReuse::PreLto } else { CguReuse::No }
 }
	//! The AOT driver uses [`cranelift_object`] to write object files suitable for linking into a
	//! standalone executable.

	use std::path::PathBuf;

	use rustc_ast::{InlineAsmOptions, InlineAsmTemplatePiece};
	use rustc_codegen_ssa::back::metadata::create_compressed_metadata_file;
	use rustc_codegen_ssa::{CodegenResults, CompiledModule, CrateInfo, ModuleKind};
	use rustc_data_structures::stable_hasher::{HashStable, StableHasher};
	use rustc_metadata::EncodedMetadata;
	use rustc_middle::dep_graph::{WorkProduct, WorkProductId};
	use rustc_middle::mir::mono::{CodegenUnit, MonoItem};
	use rustc_session::cgu_reuse_tracker::CguReuse;
	use rustc_session::config::{DebugInfo, OutputType};
	use rustc_session::Session;

	use cranelift_codegen::isa::TargetIsa;
	use cranelift_object::{ObjectBuilder, ObjectModule};

	use crate::{prelude::*, BackendConfig};

	struct ModuleCodegenResult(CompiledModule, Option<(WorkProductId, WorkProduct)>);

	impl<HCX> HashStable<HCX> for ModuleCodegenResult {
	fn hash_stable(&self, _: &mut HCX, _: &mut StableHasher) {
	// do nothing
	}
	}

	fn make_module(sess: &Session, isa: Box<dyn TargetIsa>, name: String) -> ObjectModule {
	let mut builder =
	ObjectBuilder::new(isa, name + ".o", cranelift_module::default_libcall_names()).unwrap();
	// Unlike cg_llvm, cg_clif defaults to disabling -Zfunction-sections. For cg_llvm binary size
	// is important, while cg_clif cares more about compilation times. Enabling -Zfunction-sections
	// can easily double the amount of time necessary to perform linking.
	builder.per_function_section(sess.opts.unstable_opts.function_sections.unwrap_or(false));
	ObjectModule::new(builder)
	}

	fn emit_module(
	tcx: TyCtxt<'_>,
	backend_config: &BackendConfig,
	name: String,
	kind: ModuleKind,
	module: ObjectModule,
	debug: Option<DebugContext<'_>>,
	unwind_context: UnwindContext,
	) -> ModuleCodegenResult {
	let mut product = module.finish();

	if let Some(mut debug) = debug {
	debug.emit(&mut product);
	}

	unwind_context.emit(&mut product);

	let tmp_file = tcx.output_filenames(()).temp_path(OutputType::Object, Some(&name));
	let obj = product.object.write().unwrap();

	tcx.sess.prof.artifact_size("object_file", name.clone(), obj.len().try_into().unwrap());

	if let Err(err) = std::fs::write(&tmp_file, obj) {
	tcx.sess.fatal(&format!("error writing object file: {}", err));
	}

	let work_product = if backend_config.disable_incr_cache {
	None
	} else {
	rustc_incremental::copy_cgu_workproduct_to_incr_comp_cache_dir(
	tcx.sess,
	&name,
	&[("o", &tmp_file)],
	)
	};

	ModuleCodegenResult(
	CompiledModule { name, kind, object: Some(tmp_file), dwarf_object: None, bytecode: None },
	work_product,
	)
	}

	fn reuse_workproduct_for_cgu(
	tcx: TyCtxt<'_>,
	cgu: &CodegenUnit<'_>,
	work_products: &mut FxHashMap<WorkProductId, WorkProduct>,
	) -> CompiledModule {
	let work_product = cgu.previous_work_product(tcx);
	let obj_out = tcx.output_filenames(()).temp_path(OutputType::Object, Some(cgu.name().as_str()));
	let source_file = rustc_incremental::in_incr_comp_dir_sess(
	&tcx.sess,
	&work_product.saved_files.get("o").expect("no saved object file in work product"),
	);
	if let Err(err) = rustc_fs_util::link_or_copy(&source_file, &obj_out) {
	tcx.sess.err(&format!(
	"unable to copy {} to {}: {}",
	source_file.display(),
	obj_out.display(),
	err
	));
	}

	work_products.insert(cgu.work_product_id(), work_product);

	CompiledModule {
	name: cgu.name().to_string(),
	kind: ModuleKind::Regular,
	object: Some(obj_out),
	dwarf_object: None,
	bytecode: None,
	}
	}

	fn module_codegen(
	tcx: TyCtxt<'_>,
	(backend_config, cgu_name): (BackendConfig, rustc_span::Symbol),
	) -> ModuleCodegenResult {
	let cgu = tcx.codegen_unit(cgu_name);
	let mono_items = cgu.items_in_deterministic_order(tcx);

	let isa = crate::build_isa(tcx.sess, &backend_config);
	let mut module = make_module(tcx.sess, isa, cgu_name.as_str().to_string());

	let mut cx = crate::CodegenCx::new(
	tcx,
	backend_config.clone(),
	module.isa(),
	tcx.sess.opts.debuginfo != DebugInfo::None,
	cgu_name,
	);
	super::predefine_mono_items(tcx, &mut module, &mono_items);
	for (mono_item, _) in mono_items {
	match mono_item {
	MonoItem::Fn(inst) => {
	cx.tcx
	.sess
	.time("codegen fn", \|\| crate::base::codegen_fn(&mut cx, &mut module, inst));
	}
	MonoItem::Static(def_id) => crate::constant::codegen_static(tcx, &mut module, def_id),
	MonoItem::GlobalAsm(item_id) => {
	let item = cx.tcx.hir().item(item_id);
	if let rustc_hir::ItemKind::GlobalAsm(asm) = item.kind {
	if !asm.options.contains(InlineAsmOptions::ATT_SYNTAX) {
	cx.global_asm.push_str("\n.intel_syntax noprefix\n");
	} else {
	cx.global_asm.push_str("\n.att_syntax\n");
	}
	for piece in asm.template {
	match *piece {
	InlineAsmTemplatePiece::String(ref s) => cx.global_asm.push_str(s),
	InlineAsmTemplatePiece::Placeholder { .. } => todo!(),
	}
	}
	cx.global_asm.push_str("\n.att_syntax\n\n");
	} else {
	bug!("Expected GlobalAsm found {:?}", item);
	}
	}
	}
	}
	crate::main_shim::maybe_create_entry_wrapper(
	tcx,
	&mut module,
	&mut cx.unwind_context,
	false,
	cgu.is_primary(),
	);

	let debug_context = cx.debug_context;
	let unwind_context = cx.unwind_context;
	let codegen_result = tcx.sess.time("write object file", \|\| {
	emit_module(
	tcx,
	&backend_config,
	cgu.name().as_str().to_string(),
	ModuleKind::Regular,
	module,
	debug_context,
	unwind_context,
	)
	});

	codegen_global_asm(tcx, cgu.name().as_str(), &cx.global_asm);

	codegen_result
	}

	pub(crate) fn run_aot(
	tcx: TyCtxt<'_>,
	backend_config: BackendConfig,
	metadata: EncodedMetadata,
	need_metadata_module: bool,
	) -> Box<(CodegenResults, FxHashMap<WorkProductId, WorkProduct>)> {
	let mut work_products = FxHashMap::default();

	let cgus = if tcx.sess.opts.output_types.should_codegen() {
	tcx.collect_and_partition_mono_items(()).1
	} else {
	// If only `--emit metadata` is used, we shouldn't perform any codegen.
	// Also `tcx.collect_and_partition_mono_items` may panic in that case.
	&[]
	};

	if tcx.dep_graph.is_fully_enabled() {
	for cgu in &*cgus {
	tcx.ensure().codegen_unit(cgu.name());
	}
	}

	let modules = super::time(tcx, backend_config.display_cg_time, "codegen mono items", \|\| {
	cgus.iter()
	.map(\|cgu\| {
	let cgu_reuse = determine_cgu_reuse(tcx, cgu);
	tcx.sess.cgu_reuse_tracker.set_actual_reuse(cgu.name().as_str(), cgu_reuse);

	match cgu_reuse {
	_ if backend_config.disable_incr_cache => {}
	CguReuse::No => {}
	CguReuse::PreLto => {
	return reuse_workproduct_for_cgu(tcx, &*cgu, &mut work_products);
	}
	CguReuse::PostLto => unreachable!(),
	}

	let dep_node = cgu.codegen_dep_node(tcx);
	let (ModuleCodegenResult(module, work_product), _) = tcx.dep_graph.with_task(
	dep_node,
	tcx,
	(backend_config.clone(), cgu.name()),
	module_codegen,
	Some(rustc_middle::dep_graph::hash_result),
	);

	if let Some((id, product)) = work_product {
	work_products.insert(id, product);
	}

	module
	})
	.collect::<Vec<_>>()
	});

	tcx.sess.abort_if_errors();

	let isa = crate::build_isa(tcx.sess, &backend_config);
	let mut allocator_module = make_module(tcx.sess, isa, "allocator_shim".to_string());
	assert_eq!(pointer_ty(tcx), allocator_module.target_config().pointer_type());
	let mut allocator_unwind_context = UnwindContext::new(allocator_module.isa(), true);
	let created_alloc_shim =
	crate::allocator::codegen(tcx, &mut allocator_module, &mut allocator_unwind_context);

	let allocator_module = if created_alloc_shim {
	let ModuleCodegenResult(module, work_product) = emit_module(
	tcx,
	&backend_config,
	"allocator_shim".to_string(),
	ModuleKind::Allocator,
	allocator_module,
	None,
	allocator_unwind_context,
	);
	if let Some((id, product)) = work_product {
	work_products.insert(id, product);
	}
	Some(module)
	} else {
	None
	};

	let metadata_module = if need_metadata_module {
	let _timer = tcx.prof.generic_activity("codegen crate metadata");
	let (metadata_cgu_name, tmp_file) = tcx.sess.time("write compressed metadata", \|\| {
	use rustc_middle::mir::mono::CodegenUnitNameBuilder;

	let cgu_name_builder = &mut CodegenUnitNameBuilder::new(tcx);
	let metadata_cgu_name = cgu_name_builder
	.build_cgu_name(LOCAL_CRATE, &["crate"], Some("metadata"))
	.as_str()
	.to_string();

	let tmp_file =
	tcx.output_filenames(()).temp_path(OutputType::Metadata, Some(&metadata_cgu_name));

	let symbol_name = rustc_middle::middle::exported_symbols::metadata_symbol_name(tcx);
	let obj = create_compressed_metadata_file(tcx.sess, &metadata, &symbol_name);

	if let Err(err) = std::fs::write(&tmp_file, obj) {
	tcx.sess.fatal(&format!("error writing metadata object file: {}", err));
	}

	(metadata_cgu_name, tmp_file)
	});

	Some(CompiledModule {
	name: metadata_cgu_name,
	kind: ModuleKind::Metadata,
	object: Some(tmp_file),
	dwarf_object: None,
	bytecode: None,
	})
	} else {
	None
	};

	// FIXME handle `-Ctarget-cpu=native`
	let target_cpu = match tcx.sess.opts.cg.target_cpu {
	Some(ref name) => name,
	None => tcx.sess.target.cpu.as_ref(),
	}
	.to_owned();

	Box::new((
	CodegenResults {
	modules,
	allocator_module,
	metadata_module,
	metadata,
	crate_info: CrateInfo::new(tcx, target_cpu),
	},
	work_products,
	))
	}

	fn codegen_global_asm(tcx: TyCtxt<'_>, cgu_name: &str, global_asm: &str) {
	use std::io::Write;
	use std::process::{Command, Stdio};

	if global_asm.is_empty() {
	return;
	}

	if cfg!(not(feature = "inline_asm"))
	\|\| tcx.sess.target.is_like_osx
	\|\| tcx.sess.target.is_like_windows
	{
	if global_asm.contains("__rust_probestack") {
	return;
	}

	// FIXME fix linker error on macOS
	if cfg!(not(feature = "inline_asm")) {
	tcx.sess.fatal(
	"asm! and global_asm! support is disabled while compiling rustc_codegen_cranelift",
	);
	} else {
	tcx.sess.fatal("asm! and global_asm! are not yet supported on macOS and Windows");
	}
	}

	let assembler = crate::toolchain::get_toolchain_binary(tcx.sess, "as");
	let linker = crate::toolchain::get_toolchain_binary(tcx.sess, "ld");

	// Remove all LLVM style comments
	let global_asm = global_asm
	.lines()
	.map(\|line\| if let Some(index) = line.find("//") { &line[0..index] } else { line })
	.collect::<Vec<_>>()
	.join("\n");

	let output_object_file = tcx.output_filenames(()).temp_path(OutputType::Object, Some(cgu_name));

	// Assemble `global_asm`
	let global_asm_object_file = add_file_stem_postfix(output_object_file.clone(), ".asm");
	let mut child = Command::new(assembler)
	.arg("-o")
	.arg(&global_asm_object_file)
	.stdin(Stdio::piped())
	.spawn()
	.expect("Failed to spawn `as`.");
	child.stdin.take().unwrap().write_all(global_asm.as_bytes()).unwrap();
	let status = child.wait().expect("Failed to wait for `as`.");
	if !status.success() {
	tcx.sess.fatal(&format!("Failed to assemble `{}`", global_asm));
	}

	// Link the global asm and main object file together
	let main_object_file = add_file_stem_postfix(output_object_file.clone(), ".main");
	std::fs::rename(&output_object_file, &main_object_file).unwrap();
	let status = Command::new(linker)
	.arg("-r") // Create a new object file
	.arg("-o")
	.arg(output_object_file)
	.arg(&main_object_file)
	.arg(&global_asm_object_file)
	.status()
	.unwrap();
	if !status.success() {
	tcx.sess.fatal(&format!(
	"Failed to link `{}` and `{}` together",
	main_object_file.display(),
	global_asm_object_file.display(),
	));
	}

	std::fs::remove_file(global_asm_object_file).unwrap();
	std::fs::remove_file(main_object_file).unwrap();
	}

	fn add_file_stem_postfix(mut path: PathBuf, postfix: &str) -> PathBuf {
	let mut new_filename = path.file_stem().unwrap().to_owned();
	new_filename.push(postfix);
	if let Some(extension) = path.extension() {
	new_filename.push(".");
	new_filename.push(extension);
	}
	path.set_file_name(new_filename);
	path
	}

	// Adapted from https://github.com/rust-lang/rust/blob/303d8aff6092709edd4dbd35b1c88e9aa40bf6d8/src/librustc_codegen_ssa/base.rs#L922-L953
	fn determine_cgu_reuse<'tcx>(tcx: TyCtxt<'tcx>, cgu: &CodegenUnit<'tcx>) -> CguReuse {
	if !tcx.dep_graph.is_fully_enabled() {
	return CguReuse::No;
	}

	let work_product_id = &cgu.work_product_id();
	if tcx.dep_graph.previous_work_product(work_product_id).is_none() {
	// We don't have anything cached for this CGU. This can happen
	// if the CGU did not exist in the previous session.
	return CguReuse::No;
	}

	// Try to mark the CGU as green. If it we can do so, it means that nothing
	// affecting the LLVM module has changed and we can re-use a cached version.
	// If we compile with any kind of LTO, this means we can re-use the bitcode
	// of the Pre-LTO stage (possibly also the Post-LTO version but we'll only
	// know that later). If we are not doing LTO, there is only one optimized
	// version of each module, so we re-use that.
	let dep_node = cgu.codegen_dep_node(tcx);
	assert!(
	!tcx.dep_graph.dep_node_exists(&dep_node),
	"CompileCodegenUnit dep-node for CGU `{}` already exists before marking.",
	cgu.name()
	);

	if tcx.try_mark_green(&dep_node) { CguReuse::PreLto } else { CguReuse::No }
	}