Add 'compiler/rustc_codegen_cranelift/' from commit '793d26047f'

git-subtree-dir: compiler/rustc_codegen_cranelift
git-subtree-mainline: cf798c1ec6
git-subtree-split: 793d26047f

compiler/rustc_codegen_cranelift/src/driver/jit.rs

@@ -0,0 +1,169 @@
+//! The JIT driver uses [`cranelift_simplejit`] to JIT execute programs without writing any object
+//! files.
+
+use std::ffi::CString;
+use std::os::raw::{c_char, c_int};
+
+use rustc_codegen_ssa::CrateInfo;
+
+use cranelift_simplejit::{SimpleJITBuilder, SimpleJITModule};
+
+use crate::prelude::*;
+
+pub(super) fn run_jit(tcx: TyCtxt<'_>) -> ! {
+    if !tcx.sess.opts.output_types.should_codegen() {
+        tcx.sess.fatal("JIT mode doesn't work with `cargo check`.");
+    }
+
+    #[cfg(unix)]
+    unsafe {
+        // When not using our custom driver rustc will open us without the RTLD_GLOBAL flag, so
+        // __cg_clif_global_atomic_mutex will not be exported. We fix this by opening ourself again
+        // as global.
+        // FIXME remove once atomic_shim is gone
+
+        let mut dl_info: libc::Dl_info = std::mem::zeroed();
+        assert_ne!(
+            libc::dladdr(run_jit as *const libc::c_void, &mut dl_info),
+            0
+        );
+        assert_ne!(
+            libc::dlopen(dl_info.dli_fname, libc::RTLD_NOW | libc::RTLD_GLOBAL),
+            std::ptr::null_mut(),
+        );
+    }
+
+    let imported_symbols = load_imported_symbols_for_jit(tcx);
+
+    let mut jit_builder = SimpleJITBuilder::with_isa(
+        crate::build_isa(tcx.sess, false),
+        cranelift_module::default_libcall_names(),
+    );
+    jit_builder.symbols(imported_symbols);
+    let mut jit_module = SimpleJITModule::new(jit_builder);
+    assert_eq!(pointer_ty(tcx), jit_module.target_config().pointer_type());
+
+    let 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: CallConv::triple_default(&crate::target_triple(tcx.sess)),
+    };
+    let main_func_id = jit_module
+        .declare_function("main", Linkage::Import, &sig)
+        .unwrap();
+
+    let (_, cgus) = tcx.collect_and_partition_mono_items(LOCAL_CRATE);
+    let mono_items = cgus
+        .iter()
+        .map(|cgu| cgu.items_in_deterministic_order(tcx).into_iter())
+        .flatten()
+        .collect::<FxHashMap<_, (_, _)>>()
+        .into_iter()
+        .collect::<Vec<(_, (_, _))>>();
+
+    let mut cx = crate::CodegenCx::new(tcx, jit_module, false);
+
+    let (mut jit_module, global_asm, _debug, mut unwind_context) =
+        super::time(tcx, "codegen mono items", || {
+            super::codegen_mono_items(&mut cx, mono_items);
+            tcx.sess.time("finalize CodegenCx", || cx.finalize())
+        });
+    if !global_asm.is_empty() {
+        tcx.sess.fatal("Global asm is not supported in JIT mode");
+    }
+    crate::main_shim::maybe_create_entry_wrapper(tcx, &mut jit_module, &mut unwind_context, true);
+    crate::allocator::codegen(tcx, &mut jit_module, &mut unwind_context);
+
+    tcx.sess.abort_if_errors();
+
+    let jit_product = jit_module.finish();
+
+    let _unwind_register_guard = unsafe { unwind_context.register_jit(&jit_product) };
+
+    let finalized_main: *const u8 = jit_product.lookup_func(main_func_id);
+
+    println!("Rustc codegen cranelift will JIT run the executable, because --jit was passed");
+
+    let f: extern "C" fn(c_int, *const *const c_char) -> c_int =
+        unsafe { ::std::mem::transmute(finalized_main) };
+
+    let args = ::std::env::var("CG_CLIF_JIT_ARGS").unwrap_or_else(|_| String::new());
+    let args = std::iter::once(&*tcx.crate_name(LOCAL_CRATE).as_str().to_string())
+        .chain(args.split(" "))
+        .map(|arg| CString::new(arg).unwrap())
+        .collect::<Vec<_>>();
+    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);
+}
+
+fn load_imported_symbols_for_jit(tcx: TyCtxt<'_>) -> Vec<(String, *const u8)> {
+    use rustc_middle::middle::dependency_format::Linkage;
+
+    let mut dylib_paths = Vec::new();
+
+    let crate_info = CrateInfo::new(tcx);
+    let formats = tcx.dependency_formats(LOCAL_CRATE);
+    let data = &formats
+        .iter()
+        .find(|(crate_type, _data)| *crate_type == rustc_session::config::CrateType::Executable)
+        .unwrap()
+        .1;
+    for &(cnum, _) in &crate_info.used_crates_dynamic {
+        let src = &crate_info.used_crate_source[&cnum];
+        match data[cnum.as_usize() - 1] {
+            Linkage::NotLinked | Linkage::IncludedFromDylib => {}
+            Linkage::Static => {
+                let name = tcx.crate_name(cnum);
+                let mut err = tcx
+                    .sess
+                    .struct_err(&format!("Can't load static lib {}", name.as_str()));
+                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;
+        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(|(_idx, symbol)| {
+            let name = symbol.name().unwrap().to_string();
+            if name.is_empty() || !symbol.is_global() || symbol.is_undefined() {
+                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)
+    }
+
+    tcx.sess.abort_if_errors();
+
+    imported_symbols
+}