1 use rustc_hir::LangItem;
2 use rustc_middle::ty::subst::GenericArg;
3 use rustc_middle::ty::AssocKind;
4 use rustc_session::config::{sigpipe, 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, sigpipe)) = match tcx.entry_fn(()) {
19 Some((def_id, entry_ty)) => (
22 EntryFnType::Main { sigpipe } => (true, sigpipe),
23 EntryFnType::Start => (false, sigpipe::DEFAULT),
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, sigpipe);
43 unwind_context: &mut UnwindContext,
44 rust_main_def_id: DefId,
45 ignore_lang_start_wrapper: bool,
49 let main_ret_ty = tcx.fn_sig(rust_main_def_id).output();
50 // Given that `main()` has no arguments,
51 // then its return type cannot have
52 // late-bound regions, since late-bound
53 // regions must appear in the argument
55 let main_ret_ty = tcx.normalize_erasing_regions(
56 ty::ParamEnv::reveal_all(),
57 main_ret_ty.no_bound_vars().unwrap(),
60 let cmain_sig = Signature {
62 AbiParam::new(m.target_config().pointer_type()),
63 AbiParam::new(m.target_config().pointer_type()),
65 returns: vec![AbiParam::new(m.target_config().pointer_type() /*isize*/)],
66 call_conv: crate::conv_to_call_conv(
68 tcx.sess.target.options.entry_abi,
69 m.target_config().default_call_conv,
73 let entry_name = tcx.sess.target.options.entry_name.as_ref();
74 let cmain_func_id = match m.declare_function(entry_name, Linkage::Export, &cmain_sig) {
75 Ok(func_id) => func_id,
78 .fatal(&format!("entry symbol `{entry_name}` declared multiple times: {err}"));
82 let instance = Instance::mono(tcx, rust_main_def_id).polymorphize(tcx);
84 let main_name = tcx.symbol_name(instance).name;
85 let main_sig = get_function_sig(tcx, m.target_config().default_call_conv, instance);
86 let main_func_id = m.declare_function(main_name, Linkage::Import, &main_sig).unwrap();
88 let mut ctx = Context::new();
89 ctx.func.signature = cmain_sig;
91 let mut func_ctx = FunctionBuilderContext::new();
92 let mut bcx = FunctionBuilder::new(&mut ctx.func, &mut func_ctx);
94 let block = bcx.create_block();
95 bcx.switch_to_block(block);
96 let arg_argc = bcx.append_block_param(block, m.target_config().pointer_type());
97 let arg_argv = bcx.append_block_param(block, m.target_config().pointer_type());
98 let arg_sigpipe = bcx.ins().iconst(types::I8, sigpipe as i64);
100 let main_func_ref = m.declare_func_in_func(main_func_id, &mut bcx.func);
102 let result = if is_main_fn && ignore_lang_start_wrapper {
103 // regular main fn, but ignoring #[lang = "start"] as we are running in the jit
104 // FIXME set program arguments somehow
105 let call_inst = bcx.ins().call(main_func_ref, &[]);
106 let call_results = bcx.func.dfg.inst_results(call_inst).to_owned();
108 let termination_trait = tcx.require_lang_item(LangItem::Termination, None);
110 .associated_items(termination_trait)
111 .find_by_name_and_kind(
113 Ident::from_str("report"),
118 let report = Instance::resolve(
120 ParamEnv::reveal_all(),
122 tcx.mk_substs([GenericArg::from(main_ret_ty)].iter()),
128 let report_name = tcx.symbol_name(report).name;
129 let report_sig = get_function_sig(tcx, m.target_config().default_call_conv, report);
131 m.declare_function(report_name, Linkage::Import, &report_sig).unwrap();
132 let report_func_ref = m.declare_func_in_func(report_func_id, &mut bcx.func);
134 // FIXME do proper abi handling instead of expecting the pass mode to be identical
135 // for returns and arguments.
136 let report_call_inst = bcx.ins().call(report_func_ref, &call_results);
137 let res = bcx.func.dfg.inst_results(report_call_inst)[0];
138 match m.target_config().pointer_type() {
140 types::I64 => bcx.ins().sextend(types::I64, res),
141 _ => unimplemented!("16bit systems are not yet supported"),
143 } else if is_main_fn {
144 let start_def_id = tcx.require_lang_item(LangItem::Start, None);
145 let start_instance = Instance::resolve(
147 ParamEnv::reveal_all(),
149 tcx.intern_substs(&[main_ret_ty.into()]),
154 let start_func_id = import_function(tcx, m, start_instance);
156 let main_val = bcx.ins().func_addr(m.target_config().pointer_type(), main_func_ref);
158 let func_ref = m.declare_func_in_func(start_func_id, &mut bcx.func);
160 bcx.ins().call(func_ref, &[main_val, arg_argc, arg_argv, arg_sigpipe]);
161 bcx.inst_results(call_inst)[0]
163 // using user-defined start fn
164 let call_inst = bcx.ins().call(main_func_ref, &[arg_argc, arg_argv]);
165 bcx.inst_results(call_inst)[0]
168 bcx.ins().return_(&[result]);
169 bcx.seal_all_blocks();
173 if let Err(err) = m.define_function(cmain_func_id, &mut ctx) {
174 tcx.sess.fatal(&format!("entry symbol `{entry_name}` defined multiple times: {err}"));
177 unwind_context.add_function(cmain_func_id, &ctx, m.isa());