1 use rustc_hir::LangItem;
2 use rustc_session::config::EntryFnType;
6 /// Create the `main` function which will initialize the rust runtime and call
7 /// users main function.
8 pub(crate) fn maybe_create_entry_wrapper(
10 module: &mut impl Module,
11 unwind_context: &mut UnwindContext<'_>,
14 let (main_def_id, use_start_lang_item) = match tcx.entry_fn(LOCAL_CRATE) {
15 Some((def_id, entry_ty)) => (
18 EntryFnType::Main => true,
19 EntryFnType::Start => false,
25 let instance = Instance::mono(tcx, main_def_id).polymorphize(tcx);
26 if module.get_name(&*tcx.symbol_name(instance).name).is_none() {
42 unwind_context: &mut UnwindContext<'_>,
43 rust_main_def_id: DefId,
44 use_start_lang_item: bool,
47 let main_ret_ty = tcx.fn_sig(rust_main_def_id).output();
48 // Given that `main()` has no arguments,
49 // then its return type cannot have
50 // late-bound regions, since late-bound
51 // regions must appear in the argument
53 let main_ret_ty = tcx.erase_regions(&main_ret_ty.no_bound_vars().unwrap());
55 let cmain_sig = Signature {
57 AbiParam::new(m.target_config().pointer_type()),
58 AbiParam::new(m.target_config().pointer_type()),
60 returns: vec![AbiParam::new(
61 m.target_config().pointer_type(), /*isize*/
63 call_conv: CallConv::triple_default(m.isa().triple()),
67 .declare_function("main", Linkage::Export, &cmain_sig)
70 let instance = Instance::mono(tcx, rust_main_def_id).polymorphize(tcx);
72 let (main_name, main_sig) =
73 get_function_name_and_sig(tcx, m.isa().triple(), instance, false);
75 .declare_function(&main_name, Linkage::Import, &main_sig)
78 let mut ctx = Context::new();
79 ctx.func = Function::with_name_signature(ExternalName::user(0, 0), cmain_sig.clone());
81 let mut func_ctx = FunctionBuilderContext::new();
82 let mut bcx = FunctionBuilder::new(&mut ctx.func, &mut func_ctx);
84 let block = bcx.create_block();
85 bcx.switch_to_block(block);
86 let arg_argc = bcx.append_block_param(block, m.target_config().pointer_type());
87 let arg_argv = bcx.append_block_param(block, m.target_config().pointer_type());
89 crate::atomic_shim::init_global_lock(m, &mut bcx, use_jit);
91 let main_func_ref = m.declare_func_in_func(main_func_id, &mut bcx.func);
93 let call_inst = if use_start_lang_item {
94 let start_def_id = tcx.require_lang_item(LangItem::Start, None);
95 let start_instance = Instance::resolve(
97 ParamEnv::reveal_all(),
99 tcx.intern_substs(&[main_ret_ty.into()]),
104 let start_func_id = import_function(tcx, m, start_instance);
108 .func_addr(m.target_config().pointer_type(), main_func_ref);
110 let func_ref = m.declare_func_in_func(start_func_id, &mut bcx.func);
111 bcx.ins().call(func_ref, &[main_val, arg_argc, arg_argv])
113 // using user-defined start fn
114 bcx.ins().call(main_func_ref, &[arg_argc, arg_argv])
117 let result = bcx.inst_results(call_inst)[0];
118 bcx.ins().return_(&[result]);
119 bcx.seal_all_blocks();
125 &mut cranelift_codegen::binemit::NullTrapSink {},
128 unwind_context.add_function(cmain_func_id, &ctx, m.isa());