113 lines
4.1 KiB
Rust
113 lines
4.1 KiB
Rust
use crate::prelude::*;
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/// Create the `main` function which will initialize the rust runtime and call
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/// users main function.
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pub(crate) fn maybe_create_entry_wrapper(tcx: TyCtxt<'_>, module: &mut Module<impl Backend + 'static>) {
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use rustc_hir::lang_items::StartFnLangItem;
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use rustc_session::config::EntryFnType;
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let (main_def_id, use_start_lang_item) = match tcx.entry_fn(LOCAL_CRATE) {
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Some((def_id, entry_ty)) => (
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def_id,
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match entry_ty {
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EntryFnType::Main => true,
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EntryFnType::Start => false,
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},
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),
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None => return,
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};
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let instance = Instance::mono(tcx, main_def_id);
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if module.get_name(&*tcx.symbol_name(instance).name.as_str()).is_none() {
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return;
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}
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create_entry_fn(tcx, module, main_def_id, use_start_lang_item);
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fn create_entry_fn(
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tcx: TyCtxt<'_>,
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m: &mut Module<impl Backend + 'static>,
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rust_main_def_id: DefId,
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use_start_lang_item: bool,
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) {
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let main_ret_ty = tcx.fn_sig(rust_main_def_id).output();
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// Given that `main()` has no arguments,
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// then its return type cannot have
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// late-bound regions, since late-bound
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// regions must appear in the argument
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// listing.
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let main_ret_ty = tcx.erase_regions(&main_ret_ty.no_bound_vars().unwrap());
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let cmain_sig = Signature {
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params: vec![
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AbiParam::new(m.target_config().pointer_type()),
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AbiParam::new(m.target_config().pointer_type()),
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],
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returns: vec![AbiParam::new(
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m.target_config().pointer_type(), /*isize*/
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)],
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call_conv: CallConv::triple_default(m.isa().triple()),
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};
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let cmain_func_id = m
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.declare_function("main", Linkage::Export, &cmain_sig)
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.unwrap();
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let instance = Instance::mono(tcx, rust_main_def_id);
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let (main_name, main_sig) =
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get_function_name_and_sig(tcx, m.isa().triple(), instance, false);
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let main_func_id = m
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.declare_function(&main_name, Linkage::Import, &main_sig)
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.unwrap();
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let mut ctx = Context::new();
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ctx.func = Function::with_name_signature(ExternalName::user(0, 0), cmain_sig.clone());
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{
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let mut func_ctx = FunctionBuilderContext::new();
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let mut bcx = FunctionBuilder::new(&mut ctx.func, &mut func_ctx);
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let block = bcx.create_block();
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bcx.switch_to_block(block);
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let arg_argc = bcx.append_block_param(block, m.target_config().pointer_type());
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let arg_argv = bcx.append_block_param(block, m.target_config().pointer_type());
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crate::atomic_shim::init_global_lock(m, &mut bcx);
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let main_func_ref = m.declare_func_in_func(main_func_id, &mut bcx.func);
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let call_inst = if use_start_lang_item {
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let start_def_id = tcx.require_lang_item(StartFnLangItem, None);
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let start_instance = Instance::resolve(
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tcx,
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ParamEnv::reveal_all(),
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start_def_id,
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tcx.intern_substs(&[main_ret_ty.into()]),
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)
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.unwrap();
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let start_func_id = import_function(tcx, m, start_instance);
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let main_val = bcx
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.ins()
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.func_addr(m.target_config().pointer_type(), main_func_ref);
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let func_ref = m.declare_func_in_func(start_func_id, &mut bcx.func);
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bcx.ins().call(func_ref, &[main_val, arg_argc, arg_argv])
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} else {
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// using user-defined start fn
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bcx.ins().call(main_func_ref, &[arg_argc, arg_argv])
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};
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let result = bcx.inst_results(call_inst)[0];
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bcx.ins().return_(&[result]);
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bcx.seal_all_blocks();
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bcx.finalize();
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}
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m.define_function(
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cmain_func_id,
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&mut ctx,
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&mut cranelift_codegen::binemit::NullTrapSink {},
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).unwrap();
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}
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}
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