1 use rustc_hir::LangItem;
2 use rustc_middle::ty::subst::GenericArg;
3 use rustc_middle::ty::AssocKind;
4 use rustc_session::config::EntryFnType;
5 use rustc_span::symbol::Ident;
9 /// Create the `main` function which will initialize the rust runtime and call
10 /// users main function.
11 pub(crate) fn maybe_create_entry_wrapper(
13 module: &mut impl Module,
14 unwind_context: &mut UnwindContext,
18 let (main_def_id, is_main_fn) = match tcx.entry_fn(()) {
19 Some((def_id, entry_ty)) => (
22 EntryFnType::Main => true,
23 EntryFnType::Start => false,
29 if main_def_id.is_local() {
30 let instance = Instance::mono(tcx, main_def_id).polymorphize(tcx);
31 if !is_jit && module.get_name(&*tcx.symbol_name(instance).name).is_none() {
34 } else if !is_primary_cgu {
38 create_entry_fn(tcx, module, unwind_context, main_def_id, is_jit, is_main_fn);
43 unwind_context: &mut UnwindContext,
44 rust_main_def_id: DefId,
45 ignore_lang_start_wrapper: bool,
48 let main_ret_ty = tcx.fn_sig(rust_main_def_id).output();
49 // Given that `main()` has no arguments,
50 // then its return type cannot have
51 // late-bound regions, since late-bound
52 // regions must appear in the argument
54 let main_ret_ty = tcx.normalize_erasing_regions(
55 ty::ParamEnv::reveal_all(),
56 main_ret_ty.no_bound_vars().unwrap(),
59 let cmain_sig = Signature {
61 AbiParam::new(m.target_config().pointer_type()),
62 AbiParam::new(m.target_config().pointer_type()),
64 returns: vec![AbiParam::new(m.target_config().pointer_type() /*isize*/)],
65 call_conv: CallConv::triple_default(m.isa().triple()),
68 let cmain_func_id = m.declare_function("main", Linkage::Export, &cmain_sig).unwrap();
70 let instance = Instance::mono(tcx, rust_main_def_id).polymorphize(tcx);
72 let main_name = tcx.symbol_name(instance).name;
73 let main_sig = get_function_sig(tcx, m.isa().triple(), instance);
74 let main_func_id = m.declare_function(main_name, Linkage::Import, &main_sig).unwrap();
76 let mut ctx = Context::new();
77 ctx.func = Function::with_name_signature(ExternalName::user(0, 0), cmain_sig);
79 let mut func_ctx = FunctionBuilderContext::new();
80 let mut bcx = FunctionBuilder::new(&mut ctx.func, &mut func_ctx);
82 let block = bcx.create_block();
83 bcx.switch_to_block(block);
84 let arg_argc = bcx.append_block_param(block, m.target_config().pointer_type());
85 let arg_argv = bcx.append_block_param(block, m.target_config().pointer_type());
87 let main_func_ref = m.declare_func_in_func(main_func_id, &mut bcx.func);
89 let result = if is_main_fn && ignore_lang_start_wrapper {
90 // regular main fn, but ignoring #[lang = "start"] as we are running in the jit
91 // FIXME set program arguments somehow
92 let call_inst = bcx.ins().call(main_func_ref, &[]);
93 let call_results = bcx.func.dfg.inst_results(call_inst).to_owned();
95 let termination_trait = tcx.require_lang_item(LangItem::Termination, None);
97 .associated_items(termination_trait)
98 .find_by_name_and_kind(
100 Ident::from_str("report"),
105 let report = Instance::resolve(
107 ParamEnv::reveal_all(),
109 tcx.mk_substs([GenericArg::from(main_ret_ty)].iter()),
115 let report_name = tcx.symbol_name(report).name;
116 let report_sig = get_function_sig(tcx, m.isa().triple(), report);
118 m.declare_function(report_name, Linkage::Import, &report_sig).unwrap();
119 let report_func_ref = m.declare_func_in_func(report_func_id, &mut bcx.func);
121 // FIXME do proper abi handling instead of expecting the pass mode to be identical
122 // for returns and arguments.
123 let report_call_inst = bcx.ins().call(report_func_ref, &call_results);
124 let res = bcx.func.dfg.inst_results(report_call_inst)[0];
125 match m.target_config().pointer_type() {
127 types::I64 => bcx.ins().sextend(types::I64, res),
128 _ => unimplemented!("16bit systems are not yet supported"),
130 } else if is_main_fn {
131 let start_def_id = tcx.require_lang_item(LangItem::Start, None);
132 let start_instance = Instance::resolve(
134 ParamEnv::reveal_all(),
136 tcx.intern_substs(&[main_ret_ty.into()]),
141 let start_func_id = import_function(tcx, m, start_instance);
143 let main_val = bcx.ins().func_addr(m.target_config().pointer_type(), main_func_ref);
145 let func_ref = m.declare_func_in_func(start_func_id, &mut bcx.func);
146 let call_inst = bcx.ins().call(func_ref, &[main_val, arg_argc, arg_argv]);
147 bcx.inst_results(call_inst)[0]
149 // using user-defined start fn
150 let call_inst = bcx.ins().call(main_func_ref, &[arg_argc, arg_argv]);
151 bcx.inst_results(call_inst)[0]
154 bcx.ins().return_(&[result]);
155 bcx.seal_all_blocks();
158 m.define_function(cmain_func_id, &mut ctx).unwrap();
159 unwind_context.add_function(cmain_func_id, &ctx, m.isa());