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;
6
7 use crate::prelude::*;
8
9 /// Create the `main` function which will initialize the rust runtime and call
10 /// users main function.
maybe_create_entry_wrapper( tcx: TyCtxt<'_>, module: &mut impl Module, unwind_context: &mut UnwindContext, is_jit: bool, is_primary_cgu: bool, )11 pub(crate) fn maybe_create_entry_wrapper(
12 tcx: TyCtxt<'_>,
13 module: &mut impl Module,
14 unwind_context: &mut UnwindContext,
15 is_jit: bool,
16 is_primary_cgu: bool,
17 ) {
18 let (main_def_id, (is_main_fn, sigpipe)) = match tcx.entry_fn(()) {
19 Some((def_id, entry_ty)) => (
20 def_id,
21 match entry_ty {
22 EntryFnType::Main { sigpipe } => (true, sigpipe),
23 EntryFnType::Start => (false, sigpipe::DEFAULT),
24 },
25 ),
26 None => return,
27 };
28
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() {
32 return;
33 }
34 } else if !is_primary_cgu {
35 return;
36 }
37
38 create_entry_fn(tcx, module, unwind_context, main_def_id, is_jit, is_main_fn, sigpipe);
39
40 fn create_entry_fn(
41 tcx: TyCtxt<'_>,
42 m: &mut impl Module,
43 unwind_context: &mut UnwindContext,
44 rust_main_def_id: DefId,
45 ignore_lang_start_wrapper: bool,
46 is_main_fn: bool,
47 sigpipe: u8,
48 ) {
49 let main_ret_ty = tcx.fn_sig(rust_main_def_id).no_bound_vars().unwrap().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
54 // listing.
55 let main_ret_ty = tcx.normalize_erasing_regions(
56 ty::ParamEnv::reveal_all(),
57 main_ret_ty.no_bound_vars().unwrap(),
58 );
59
60 let cmain_sig = Signature {
61 params: vec![
62 AbiParam::new(m.target_config().pointer_type()),
63 AbiParam::new(m.target_config().pointer_type()),
64 ],
65 returns: vec![AbiParam::new(m.target_config().pointer_type() /*isize*/)],
66 call_conv: crate::conv_to_call_conv(
67 tcx.sess,
68 tcx.sess.target.options.entry_abi,
69 m.target_config().default_call_conv,
70 ),
71 };
72
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,
76 Err(err) => {
77 tcx.sess
78 .fatal(format!("entry symbol `{entry_name}` declared multiple times: {err}"));
79 }
80 };
81
82 let instance = Instance::mono(tcx, rust_main_def_id).polymorphize(tcx);
83
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();
87
88 let mut ctx = Context::new();
89 ctx.func.signature = cmain_sig;
90 {
91 let mut func_ctx = FunctionBuilderContext::new();
92 let mut bcx = FunctionBuilder::new(&mut ctx.func, &mut func_ctx);
93
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);
99
100 let main_func_ref = m.declare_func_in_func(main_func_id, &mut bcx.func);
101
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();
107
108 let termination_trait = tcx.require_lang_item(LangItem::Termination, None);
109 let report = tcx
110 .associated_items(termination_trait)
111 .find_by_name_and_kind(
112 tcx,
113 Ident::from_str("report"),
114 AssocKind::Fn,
115 termination_trait,
116 )
117 .unwrap();
118 let report = Instance::resolve(
119 tcx,
120 ParamEnv::reveal_all(),
121 report.def_id,
122 tcx.mk_substs(&[GenericArg::from(main_ret_ty)]),
123 )
124 .unwrap()
125 .unwrap()
126 .polymorphize(tcx);
127
128 let report_name = tcx.symbol_name(report).name;
129 let report_sig = get_function_sig(tcx, m.target_config().default_call_conv, report);
130 let report_func_id =
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);
133
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() {
139 types::I32 => res,
140 types::I64 => bcx.ins().sextend(types::I64, res),
141 _ => unimplemented!("16bit systems are not yet supported"),
142 }
143 } else if is_main_fn {
144 let start_def_id = tcx.require_lang_item(LangItem::Start, None);
145 let start_instance = Instance::resolve(
146 tcx,
147 ParamEnv::reveal_all(),
148 start_def_id,
149 tcx.mk_substs(&[main_ret_ty.into()]),
150 )
151 .unwrap()
152 .unwrap()
153 .polymorphize(tcx);
154 let start_func_id = import_function(tcx, m, start_instance);
155
156 let main_val = bcx.ins().func_addr(m.target_config().pointer_type(), main_func_ref);
157
158 let func_ref = m.declare_func_in_func(start_func_id, &mut bcx.func);
159 let call_inst =
160 bcx.ins().call(func_ref, &[main_val, arg_argc, arg_argv, arg_sigpipe]);
161 bcx.inst_results(call_inst)[0]
162 } else {
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]
166 };
167
168 bcx.ins().return_(&[result]);
169 bcx.seal_all_blocks();
170 bcx.finalize();
171 }
172
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}"));
175 }
176
177 unwind_context.add_function(cmain_func_id, &ctx, m.isa());
178 }
179 }
180