1 use cranelift_codegen::binemit::{NullStackMapSink, NullTrapSink};
2 use rustc_hir::LangItem;
3 use rustc_middle::ty::subst::GenericArg;
4 use rustc_middle::ty::AssocKind;
5 use rustc_session::config::EntryFnType;
6 use rustc_span::symbol::Ident;
10 /// Create the `main` function which will initialize the rust runtime and call
11 /// users main function.
12 pub(crate) fn maybe_create_entry_wrapper(
14 module: &mut impl Module,
15 unwind_context: &mut UnwindContext,
18 let (main_def_id, is_main_fn) = match tcx.entry_fn(LOCAL_CRATE) {
19 Some((def_id, entry_ty)) => (
22 EntryFnType::Main => true,
23 EntryFnType::Start => false,
29 let instance = Instance::mono(tcx, main_def_id).polymorphize(tcx);
30 if !is_jit && module.get_name(&*tcx.symbol_name(instance).name).is_none() {
34 create_entry_fn(tcx, module, unwind_context, main_def_id, is_jit, is_main_fn);
39 unwind_context: &mut UnwindContext,
40 rust_main_def_id: DefId,
41 ignore_lang_start_wrapper: bool,
44 let main_ret_ty = tcx.fn_sig(rust_main_def_id).output();
45 // Given that `main()` has no arguments,
46 // then its return type cannot have
47 // late-bound regions, since late-bound
48 // regions must appear in the argument
50 let main_ret_ty = tcx.erase_regions(main_ret_ty.no_bound_vars().unwrap());
52 let cmain_sig = Signature {
54 AbiParam::new(m.target_config().pointer_type()),
55 AbiParam::new(m.target_config().pointer_type()),
57 returns: vec![AbiParam::new(m.target_config().pointer_type() /*isize*/)],
58 call_conv: CallConv::triple_default(m.isa().triple()),
61 let cmain_func_id = m.declare_function("main", Linkage::Export, &cmain_sig).unwrap();
63 let instance = Instance::mono(tcx, rust_main_def_id).polymorphize(tcx);
65 let main_name = tcx.symbol_name(instance).name.to_string();
66 let main_sig = get_function_sig(tcx, m.isa().triple(), instance);
67 let main_func_id = m.declare_function(&main_name, Linkage::Import, &main_sig).unwrap();
69 let mut ctx = Context::new();
70 ctx.func = Function::with_name_signature(ExternalName::user(0, 0), cmain_sig);
72 let mut func_ctx = FunctionBuilderContext::new();
73 let mut bcx = FunctionBuilder::new(&mut ctx.func, &mut func_ctx);
75 let block = bcx.create_block();
76 bcx.switch_to_block(block);
77 let arg_argc = bcx.append_block_param(block, m.target_config().pointer_type());
78 let arg_argv = bcx.append_block_param(block, m.target_config().pointer_type());
80 let main_func_ref = m.declare_func_in_func(main_func_id, &mut bcx.func);
82 let result = if is_main_fn && ignore_lang_start_wrapper {
83 // regular main fn, but ignoring #[lang = "start"] as we are running in the jit
84 // FIXME set program arguments somehow
85 let call_inst = bcx.ins().call(main_func_ref, &[]);
86 let call_results = bcx.func.dfg.inst_results(call_inst).to_owned();
88 let termination_trait = tcx.require_lang_item(LangItem::Termination, None);
90 .associated_items(termination_trait)
91 .find_by_name_and_kind(
93 Ident::from_str("report"),
98 let report = Instance::resolve(
100 ParamEnv::reveal_all(),
102 tcx.mk_substs([GenericArg::from(main_ret_ty)].iter()),
107 let report_name = tcx.symbol_name(report).name;
108 let report_sig = get_function_sig(tcx, m.isa().triple(), report);
110 m.declare_function(report_name, Linkage::Import, &report_sig).unwrap();
111 let report_func_ref = m.declare_func_in_func(report_func_id, &mut bcx.func);
113 // FIXME do proper abi handling instead of expecting the pass mode to be identical
114 // for returns and arguments.
115 let report_call_inst = bcx.ins().call(report_func_ref, &call_results);
116 bcx.func.dfg.inst_results(report_call_inst)[0]
117 } else if is_main_fn {
118 let start_def_id = tcx.require_lang_item(LangItem::Start, None);
119 let start_instance = Instance::resolve(
121 ParamEnv::reveal_all(),
123 tcx.intern_substs(&[main_ret_ty.into()]),
128 let start_func_id = import_function(tcx, m, start_instance);
130 let main_val = bcx.ins().func_addr(m.target_config().pointer_type(), main_func_ref);
132 let func_ref = m.declare_func_in_func(start_func_id, &mut bcx.func);
133 let call_inst = bcx.ins().call(func_ref, &[main_val, arg_argc, arg_argv]);
134 bcx.inst_results(call_inst)[0]
136 // using user-defined start fn
137 let call_inst = bcx.ins().call(main_func_ref, &[arg_argc, arg_argv]);
138 bcx.inst_results(call_inst)[0]
141 bcx.ins().return_(&[result]);
142 bcx.seal_all_blocks();
145 m.define_function(cmain_func_id, &mut ctx, &mut NullTrapSink {}, &mut NullStackMapSink {})
147 unwind_context.add_function(cmain_func_id, &ctx, m.isa());