1 //! The JIT driver uses [`cranelift_simplejit`] to JIT execute programs without writing any object
5 use std::os::raw::{c_char, c_int};
7 use rustc_codegen_ssa::CrateInfo;
11 pub(super) fn run_jit(tcx: TyCtxt<'_>) -> ! {
12 use cranelift_simplejit::{SimpleJITBackend, SimpleJITBuilder};
16 // When not using our custom driver rustc will open us without the RTLD_GLOBAL flag, so
17 // __cg_clif_global_atomic_mutex will not be exported. We fix this by opening ourself again
19 // FIXME remove once atomic_shim is gone
21 let mut dl_info: libc::Dl_info = std::mem::zeroed();
23 libc::dladdr(run_jit as *const libc::c_void, &mut dl_info),
27 libc::dlopen(dl_info.dli_fname, libc::RTLD_NOW | libc::RTLD_GLOBAL),
32 let imported_symbols = load_imported_symbols_for_jit(tcx);
34 let mut jit_builder = SimpleJITBuilder::with_isa(
35 crate::build_isa(tcx.sess, false),
36 cranelift_module::default_libcall_names(),
38 jit_builder.symbols(imported_symbols);
39 let mut jit_module: Module<SimpleJITBackend> = Module::new(jit_builder);
40 assert_eq!(pointer_ty(tcx), jit_module.target_config().pointer_type());
44 AbiParam::new(jit_module.target_config().pointer_type()),
45 AbiParam::new(jit_module.target_config().pointer_type()),
47 returns: vec![AbiParam::new(
48 jit_module.target_config().pointer_type(), /*isize*/
50 call_conv: CallConv::triple_default(&crate::target_triple(tcx.sess)),
52 let main_func_id = jit_module
53 .declare_function("main", Linkage::Import, &sig)
56 if !tcx.sess.opts.output_types.should_codegen() {
57 tcx.sess.fatal("JIT mode doesn't work with `cargo check`.");
60 let (_, cgus) = tcx.collect_and_partition_mono_items(LOCAL_CRATE);
63 .map(|cgu| cgu.items_in_deterministic_order(tcx).into_iter())
65 .collect::<FxHashMap<_, (_, _)>>()
67 .collect::<Vec<(_, (_, _))>>();
69 let mut cx = crate::CodegenCx::new(tcx, jit_module, false);
71 let (mut jit_module, global_asm, _debug, mut unwind_context) =
72 super::time(tcx, "codegen mono items", || {
73 super::codegen_mono_items(&mut cx, mono_items);
74 tcx.sess.time("finalize CodegenCx", || cx.finalize())
76 if !global_asm.is_empty() {
77 tcx.sess.fatal("Global asm is not supported in JIT mode");
79 crate::main_shim::maybe_create_entry_wrapper(tcx, &mut jit_module, &mut unwind_context, true);
80 crate::allocator::codegen(tcx, &mut jit_module, &mut unwind_context);
82 jit_module.finalize_definitions();
84 let _unwind_register_guard = unsafe { unwind_context.register_jit(&mut jit_module) };
86 tcx.sess.abort_if_errors();
88 let finalized_main: *const u8 = jit_module.get_finalized_function(main_func_id);
90 println!("Rustc codegen cranelift will JIT run the executable, because the CG_CLIF_JIT env var is set");
92 let f: extern "C" fn(c_int, *const *const c_char) -> c_int =
93 unsafe { ::std::mem::transmute(finalized_main) };
95 let args = ::std::env::var("CG_CLIF_JIT_ARGS").unwrap_or_else(|_| String::new());
96 let args = std::iter::once(&*tcx.crate_name(LOCAL_CRATE).as_str().to_string())
97 .chain(args.split(" "))
98 .map(|arg| CString::new(arg).unwrap())
100 let mut argv = args.iter().map(|arg| arg.as_ptr()).collect::<Vec<_>>();
102 // Push a null pointer as a terminating argument. This is required by POSIX and
103 // useful as some dynamic linkers use it as a marker to jump over.
104 argv.push(std::ptr::null());
106 let ret = f(args.len() as c_int, argv.as_ptr());
109 std::process::exit(ret);
112 fn load_imported_symbols_for_jit(tcx: TyCtxt<'_>) -> Vec<(String, *const u8)> {
113 use rustc_middle::middle::dependency_format::Linkage;
115 let mut dylib_paths = Vec::new();
117 let crate_info = CrateInfo::new(tcx);
118 let formats = tcx.dependency_formats(LOCAL_CRATE);
121 .find(|(crate_type, _data)| *crate_type == rustc_session::config::CrateType::Executable)
124 for &(cnum, _) in &crate_info.used_crates_dynamic {
125 let src = &crate_info.used_crate_source[&cnum];
126 match data[cnum.as_usize() - 1] {
127 Linkage::NotLinked | Linkage::IncludedFromDylib => {}
129 let name = tcx.crate_name(cnum);
132 .struct_err(&format!("Can't load static lib {}", name.as_str()));
133 err.note("rustc_codegen_cranelift can only load dylibs in JIT mode.");
136 Linkage::Dynamic => {
137 dylib_paths.push(src.dylib.as_ref().unwrap().0.clone());
142 let mut imported_symbols = Vec::new();
143 for path in dylib_paths {
145 let lib = libloading::Library::new(&path).unwrap();
146 let obj = std::fs::read(path).unwrap();
147 let obj = object::File::parse(&obj).unwrap();
148 imported_symbols.extend(obj.dynamic_symbols().filter_map(|(_idx, symbol)| {
149 let name = symbol.name().unwrap().to_string();
150 if name.is_empty() || !symbol.is_global() || symbol.is_undefined() {
153 let dlsym_name = if cfg!(target_os = "macos") {
154 // On macOS `dlsym` expects the name without leading `_`.
155 assert!(name.starts_with("_"), "{:?}", name);
160 let symbol: libloading::Symbol<'_, *const u8> =
161 unsafe { lib.get(dlsym_name.as_bytes()) }.unwrap();
162 Some((name, *symbol))
164 std::mem::forget(lib)
167 tcx.sess.abort_if_errors();