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author | Daniel Baumann <daniel.baumann@progress-linux.org> | 2024-04-17 12:02:58 +0000 |
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committer | Daniel Baumann <daniel.baumann@progress-linux.org> | 2024-04-17 12:02:58 +0000 |
commit | 698f8c2f01ea549d77d7dc3338a12e04c11057b9 (patch) | |
tree | 173a775858bd501c378080a10dca74132f05bc50 /compiler/rustc_codegen_cranelift/src/driver/jit.rs | |
parent | Initial commit. (diff) | |
download | rustc-698f8c2f01ea549d77d7dc3338a12e04c11057b9.tar.xz rustc-698f8c2f01ea549d77d7dc3338a12e04c11057b9.zip |
Adding upstream version 1.64.0+dfsg1.upstream/1.64.0+dfsg1
Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>
Diffstat (limited to 'compiler/rustc_codegen_cranelift/src/driver/jit.rs')
-rw-r--r-- | compiler/rustc_codegen_cranelift/src/driver/jit.rs | 385 |
1 files changed, 385 insertions, 0 deletions
diff --git a/compiler/rustc_codegen_cranelift/src/driver/jit.rs b/compiler/rustc_codegen_cranelift/src/driver/jit.rs new file mode 100644 index 000000000..a56a91000 --- /dev/null +++ b/compiler/rustc_codegen_cranelift/src/driver/jit.rs @@ -0,0 +1,385 @@ +//! The JIT driver uses [`cranelift_jit`] to JIT execute programs without writing any object +//! files. + +use std::cell::RefCell; +use std::ffi::CString; +use std::os::raw::{c_char, c_int}; +use std::sync::{mpsc, Mutex}; + +use rustc_codegen_ssa::CrateInfo; +use rustc_middle::mir::mono::MonoItem; +use rustc_session::Session; +use rustc_span::Symbol; + +use cranelift_jit::{JITBuilder, JITModule}; + +// FIXME use std::sync::OnceLock once it stabilizes +use once_cell::sync::OnceCell; + +use crate::{prelude::*, BackendConfig}; +use crate::{CodegenCx, CodegenMode}; + +struct JitState { + backend_config: BackendConfig, + jit_module: JITModule, +} + +thread_local! { + static LAZY_JIT_STATE: RefCell<Option<JitState>> = const { RefCell::new(None) }; +} + +/// The Sender owned by the rustc thread +static GLOBAL_MESSAGE_SENDER: OnceCell<Mutex<mpsc::Sender<UnsafeMessage>>> = OnceCell::new(); + +/// A message that is sent from the jitted runtime to the rustc thread. +/// Senders are responsible for upholding `Send` semantics. +enum UnsafeMessage { + /// Request that the specified `Instance` be lazily jitted. + /// + /// Nothing accessible through `instance_ptr` may be moved or mutated by the sender after + /// this message is sent. + JitFn { + instance_ptr: *const Instance<'static>, + trampoline_ptr: *const u8, + tx: mpsc::Sender<*const u8>, + }, +} +unsafe impl Send for UnsafeMessage {} + +impl UnsafeMessage { + /// Send the message. + fn send(self) -> Result<(), mpsc::SendError<UnsafeMessage>> { + thread_local! { + /// The Sender owned by the local thread + static LOCAL_MESSAGE_SENDER: mpsc::Sender<UnsafeMessage> = + GLOBAL_MESSAGE_SENDER + .get().unwrap() + .lock().unwrap() + .clone(); + } + LOCAL_MESSAGE_SENDER.with(|sender| sender.send(self)) + } +} + +fn create_jit_module<'tcx>( + tcx: TyCtxt<'tcx>, + backend_config: &BackendConfig, + hotswap: bool, +) -> (JITModule, CodegenCx<'tcx>) { + let crate_info = CrateInfo::new(tcx, "dummy_target_cpu".to_string()); + let imported_symbols = load_imported_symbols_for_jit(tcx.sess, crate_info); + + let isa = crate::build_isa(tcx.sess, backend_config); + let mut jit_builder = JITBuilder::with_isa(isa, cranelift_module::default_libcall_names()); + jit_builder.hotswap(hotswap); + crate::compiler_builtins::register_functions_for_jit(&mut jit_builder); + jit_builder.symbols(imported_symbols); + jit_builder.symbol("__clif_jit_fn", clif_jit_fn as *const u8); + let mut jit_module = JITModule::new(jit_builder); + + let mut cx = crate::CodegenCx::new( + tcx, + backend_config.clone(), + jit_module.isa(), + false, + Symbol::intern("dummy_cgu_name"), + ); + + crate::allocator::codegen(tcx, &mut jit_module, &mut cx.unwind_context); + crate::main_shim::maybe_create_entry_wrapper( + tcx, + &mut jit_module, + &mut cx.unwind_context, + true, + true, + ); + + (jit_module, cx) +} + +pub(crate) fn run_jit(tcx: TyCtxt<'_>, backend_config: BackendConfig) -> ! { + if !tcx.sess.opts.output_types.should_codegen() { + tcx.sess.fatal("JIT mode doesn't work with `cargo check`"); + } + + if !tcx.sess.crate_types().contains(&rustc_session::config::CrateType::Executable) { + tcx.sess.fatal("can't jit non-executable crate"); + } + + let (mut jit_module, mut cx) = create_jit_module( + tcx, + &backend_config, + matches!(backend_config.codegen_mode, CodegenMode::JitLazy), + ); + + let (_, cgus) = tcx.collect_and_partition_mono_items(()); + let mono_items = cgus + .iter() + .map(|cgu| cgu.items_in_deterministic_order(tcx).into_iter()) + .flatten() + .collect::<FxHashMap<_, (_, _)>>() + .into_iter() + .collect::<Vec<(_, (_, _))>>(); + + super::time(tcx, backend_config.display_cg_time, "codegen mono items", || { + super::predefine_mono_items(tcx, &mut jit_module, &mono_items); + for (mono_item, _) in mono_items { + match mono_item { + MonoItem::Fn(inst) => match backend_config.codegen_mode { + CodegenMode::Aot => unreachable!(), + CodegenMode::Jit => { + cx.tcx.sess.time("codegen fn", || { + crate::base::codegen_fn(&mut cx, &mut jit_module, inst) + }); + } + CodegenMode::JitLazy => codegen_shim(&mut cx, &mut jit_module, inst), + }, + MonoItem::Static(def_id) => { + crate::constant::codegen_static(tcx, &mut jit_module, def_id); + } + MonoItem::GlobalAsm(item_id) => { + let item = tcx.hir().item(item_id); + tcx.sess.span_fatal(item.span, "Global asm is not supported in JIT mode"); + } + } + } + }); + + if !cx.global_asm.is_empty() { + tcx.sess.fatal("Inline asm is not supported in JIT mode"); + } + + tcx.sess.abort_if_errors(); + + jit_module.finalize_definitions(); + unsafe { cx.unwind_context.register_jit(&jit_module) }; + + println!( + "Rustc codegen cranelift will JIT run the executable, because -Cllvm-args=mode=jit was passed" + ); + + let args = std::iter::once(&*tcx.crate_name(LOCAL_CRATE).as_str().to_string()) + .chain(backend_config.jit_args.iter().map(|arg| &**arg)) + .map(|arg| CString::new(arg).unwrap()) + .collect::<Vec<_>>(); + + let start_sig = Signature { + params: vec![ + AbiParam::new(jit_module.target_config().pointer_type()), + AbiParam::new(jit_module.target_config().pointer_type()), + ], + returns: vec![AbiParam::new(jit_module.target_config().pointer_type() /*isize*/)], + call_conv: jit_module.target_config().default_call_conv, + }; + let start_func_id = jit_module.declare_function("main", Linkage::Import, &start_sig).unwrap(); + let finalized_start: *const u8 = jit_module.get_finalized_function(start_func_id); + + LAZY_JIT_STATE.with(|lazy_jit_state| { + let mut lazy_jit_state = lazy_jit_state.borrow_mut(); + assert!(lazy_jit_state.is_none()); + *lazy_jit_state = Some(JitState { backend_config, jit_module }); + }); + + let f: extern "C" fn(c_int, *const *const c_char) -> c_int = + unsafe { ::std::mem::transmute(finalized_start) }; + + let (tx, rx) = mpsc::channel(); + GLOBAL_MESSAGE_SENDER.set(Mutex::new(tx)).unwrap(); + + // Spawn the jitted runtime in a new thread so that this rustc thread can handle messages + // (eg to lazily JIT further functions as required) + std::thread::spawn(move || { + let mut argv = args.iter().map(|arg| arg.as_ptr()).collect::<Vec<_>>(); + + // Push a null pointer as a terminating argument. This is required by POSIX and + // useful as some dynamic linkers use it as a marker to jump over. + argv.push(std::ptr::null()); + + let ret = f(args.len() as c_int, argv.as_ptr()); + std::process::exit(ret); + }); + + // Handle messages + loop { + match rx.recv().unwrap() { + // lazy JIT compilation request - compile requested instance and return pointer to result + UnsafeMessage::JitFn { instance_ptr, trampoline_ptr, tx } => { + tx.send(jit_fn(instance_ptr, trampoline_ptr)) + .expect("jitted runtime hung up before response to lazy JIT request was sent"); + } + } + } +} + +extern "C" fn clif_jit_fn( + instance_ptr: *const Instance<'static>, + trampoline_ptr: *const u8, +) -> *const u8 { + // send the JIT request to the rustc thread, with a channel for the response + let (tx, rx) = mpsc::channel(); + UnsafeMessage::JitFn { instance_ptr, trampoline_ptr, tx } + .send() + .expect("rustc thread hung up before lazy JIT request was sent"); + + // block on JIT compilation result + rx.recv().expect("rustc thread hung up before responding to sent lazy JIT request") +} + +fn jit_fn(instance_ptr: *const Instance<'static>, trampoline_ptr: *const u8) -> *const u8 { + rustc_middle::ty::tls::with(|tcx| { + // lift is used to ensure the correct lifetime for instance. + let instance = tcx.lift(unsafe { *instance_ptr }).unwrap(); + + LAZY_JIT_STATE.with(|lazy_jit_state| { + let mut lazy_jit_state = lazy_jit_state.borrow_mut(); + let lazy_jit_state = lazy_jit_state.as_mut().unwrap(); + let jit_module = &mut lazy_jit_state.jit_module; + let backend_config = lazy_jit_state.backend_config.clone(); + + let name = tcx.symbol_name(instance).name; + let sig = crate::abi::get_function_sig(tcx, jit_module.isa().triple(), instance); + let func_id = jit_module.declare_function(name, Linkage::Export, &sig).unwrap(); + + let current_ptr = jit_module.read_got_entry(func_id); + + // If the function's GOT entry has already been updated to point at something other + // than the shim trampoline, don't re-jit but just return the new pointer instead. + // This does not need synchronization as this code is executed only by a sole rustc + // thread. + if current_ptr != trampoline_ptr { + return current_ptr; + } + + jit_module.prepare_for_function_redefine(func_id).unwrap(); + + let mut cx = crate::CodegenCx::new( + tcx, + backend_config, + jit_module.isa(), + false, + Symbol::intern("dummy_cgu_name"), + ); + tcx.sess.time("codegen fn", || crate::base::codegen_fn(&mut cx, jit_module, instance)); + + assert!(cx.global_asm.is_empty()); + jit_module.finalize_definitions(); + unsafe { cx.unwind_context.register_jit(&jit_module) }; + jit_module.get_finalized_function(func_id) + }) + }) +} + +fn load_imported_symbols_for_jit( + sess: &Session, + crate_info: CrateInfo, +) -> Vec<(String, *const u8)> { + use rustc_middle::middle::dependency_format::Linkage; + + let mut dylib_paths = Vec::new(); + + let data = &crate_info + .dependency_formats + .iter() + .find(|(crate_type, _data)| *crate_type == rustc_session::config::CrateType::Executable) + .unwrap() + .1; + for &cnum in &crate_info.used_crates { + let src = &crate_info.used_crate_source[&cnum]; + match data[cnum.as_usize() - 1] { + Linkage::NotLinked | Linkage::IncludedFromDylib => {} + Linkage::Static => { + let name = crate_info.crate_name[&cnum]; + let mut err = sess.struct_err(&format!("Can't load static lib {}", name)); + err.note("rustc_codegen_cranelift can only load dylibs in JIT mode."); + err.emit(); + } + Linkage::Dynamic => { + dylib_paths.push(src.dylib.as_ref().unwrap().0.clone()); + } + } + } + + let mut imported_symbols = Vec::new(); + for path in dylib_paths { + use object::{Object, ObjectSymbol}; + let lib = libloading::Library::new(&path).unwrap(); + let obj = std::fs::read(path).unwrap(); + let obj = object::File::parse(&*obj).unwrap(); + imported_symbols.extend(obj.dynamic_symbols().filter_map(|symbol| { + let name = symbol.name().unwrap().to_string(); + if name.is_empty() || !symbol.is_global() || symbol.is_undefined() { + return None; + } + if name.starts_with("rust_metadata_") { + // The metadata is part of a section that is not loaded by the dynamic linker in + // case of cg_llvm. + return None; + } + let dlsym_name = if cfg!(target_os = "macos") { + // On macOS `dlsym` expects the name without leading `_`. + assert!(name.starts_with('_'), "{:?}", name); + &name[1..] + } else { + &name + }; + let symbol: libloading::Symbol<'_, *const u8> = + unsafe { lib.get(dlsym_name.as_bytes()) }.unwrap(); + Some((name, *symbol)) + })); + std::mem::forget(lib) + } + + sess.abort_if_errors(); + + imported_symbols +} + +fn codegen_shim<'tcx>(cx: &mut CodegenCx<'tcx>, module: &mut JITModule, inst: Instance<'tcx>) { + let tcx = cx.tcx; + + let pointer_type = module.target_config().pointer_type(); + + let name = tcx.symbol_name(inst).name; + let sig = crate::abi::get_function_sig(tcx, module.isa().triple(), inst); + let func_id = module.declare_function(name, Linkage::Export, &sig).unwrap(); + + let instance_ptr = Box::into_raw(Box::new(inst)); + + let jit_fn = module + .declare_function( + "__clif_jit_fn", + Linkage::Import, + &Signature { + call_conv: module.target_config().default_call_conv, + params: vec![AbiParam::new(pointer_type), AbiParam::new(pointer_type)], + returns: vec![AbiParam::new(pointer_type)], + }, + ) + .unwrap(); + + cx.cached_context.clear(); + let trampoline = &mut cx.cached_context.func; + trampoline.signature = sig.clone(); + + let mut builder_ctx = FunctionBuilderContext::new(); + let mut trampoline_builder = FunctionBuilder::new(trampoline, &mut builder_ctx); + + let trampoline_fn = module.declare_func_in_func(func_id, trampoline_builder.func); + let jit_fn = module.declare_func_in_func(jit_fn, trampoline_builder.func); + let sig_ref = trampoline_builder.func.import_signature(sig); + + let entry_block = trampoline_builder.create_block(); + trampoline_builder.append_block_params_for_function_params(entry_block); + let fn_args = trampoline_builder.func.dfg.block_params(entry_block).to_vec(); + + trampoline_builder.switch_to_block(entry_block); + let instance_ptr = trampoline_builder.ins().iconst(pointer_type, instance_ptr as u64 as i64); + let trampoline_ptr = trampoline_builder.ins().func_addr(pointer_type, trampoline_fn); + let jitted_fn = trampoline_builder.ins().call(jit_fn, &[instance_ptr, trampoline_ptr]); + let jitted_fn = trampoline_builder.func.dfg.inst_results(jitted_fn)[0]; + let call_inst = trampoline_builder.ins().call_indirect(sig_ref, jitted_fn, &fn_args); + let ret_vals = trampoline_builder.func.dfg.inst_results(call_inst).to_vec(); + trampoline_builder.ins().return_(&ret_vals); + + module.define_function(func_id, &mut cx.cached_context).unwrap(); +} |