diff --git a/Cargo.lock b/Cargo.lock index 37761f29708..72a05753d09 100644 --- a/Cargo.lock +++ b/Cargo.lock @@ -2634,6 +2634,7 @@ dependencies = [ "serialize 0.0.0", "syntax 0.0.0", "syntax_pos 0.0.0", + "tempfile 3.0.5 (registry+https://github.com/rust-lang/crates.io-index)", ] [[package]] diff --git a/src/librustc_codegen_llvm/back/link.rs b/src/librustc_codegen_llvm/back/link.rs index 021d185da79..1350676ea0a 100644 --- a/src/librustc_codegen_llvm/back/link.rs +++ b/src/librustc_codegen_llvm/back/link.rs @@ -1,1112 +1,25 @@ -use super::archive::LlvmArchiveBuilder; -use super::rpath::RPathConfig; -use super::rpath; -use crate::back::wasm; -use rustc_codegen_ssa::{METADATA_FILENAME, RLIB_BYTECODE_EXTENSION}; -use rustc_codegen_ssa::back::archive::ArchiveBuilder; -use rustc_codegen_ssa::back::linker::Linker; -use rustc_codegen_ssa::back::link::*; -use rustc_codegen_ssa::back::command::Command; -use rustc::session::config::{self, DebugInfo, OutputFilenames, OutputType, PrintRequest}; -use rustc::session::config::{RUST_CGU_EXT, Sanitizer}; -use rustc::session::filesearch; -use rustc::session::search_paths::PathKind; +use rustc::session::config::OutputFilenames; use rustc::session::Session; -use rustc::middle::cstore::NativeLibraryKind; -use rustc::middle::dependency_format::Linkage; use rustc_codegen_ssa::CodegenResults; -use rustc::util::common::{time, time_ext}; -use rustc_fs_util::fix_windows_verbatim_for_gcc; -use rustc::hir::def_id::CrateNum; -use tempfile::{Builder as TempFileBuilder, TempDir}; -use rustc_target::spec::{PanicStrategy, RelroLevel, LinkerFlavor}; -use rustc_data_structures::fx::FxHashSet; - -use std::ascii; -use std::char; -use std::env; -use std::fs; -use std::io; -use std::path::{Path, PathBuf}; -use std::str; +use super::archive::LlvmArchiveBuilder; +use std::path::PathBuf; pub use rustc_codegen_utils::link::*; /// Performs the linkage portion of the compilation phase. This will generate all /// of the requested outputs for this compilation session. -pub(crate) fn link_binary<'a>(sess: &'a Session, - codegen_results: &CodegenResults, - outputs: &OutputFilenames, - crate_name: &str) -> Vec { - let target_cpu = crate::llvm_util::target_cpu(sess); - let mut out_filenames = Vec::new(); - for &crate_type in sess.crate_types.borrow().iter() { - // Ignore executable crates if we have -Z no-codegen, as they will error. - let output_metadata = sess.opts.output_types.contains_key(&OutputType::Metadata); - if (sess.opts.debugging_opts.no_codegen || !sess.opts.output_types.should_codegen()) && - !output_metadata && - crate_type == config::CrateType::Executable { - continue; - } - - if invalid_output_for_target(sess, crate_type) { - bug!("invalid output type `{:?}` for target os `{}`", - crate_type, sess.opts.target_triple); - } - let out_files = link_binary_output::>(sess, - codegen_results, - crate_type, - outputs, - crate_name, - target_cpu); - out_filenames.extend(out_files); - } - - // Remove the temporary object file and metadata if we aren't saving temps - if !sess.opts.cg.save_temps { - if sess.opts.output_types.should_codegen() && !preserve_objects_for_their_debuginfo(sess) { - for obj in codegen_results.modules.iter().filter_map(|m| m.object.as_ref()) { - remove(sess, obj); - } - } - for obj in codegen_results.modules.iter().filter_map(|m| m.bytecode_compressed.as_ref()) { - remove(sess, obj); - } - if let Some(ref obj) = codegen_results.metadata_module.object { - remove(sess, obj); - } - if let Some(ref allocator) = codegen_results.allocator_module { - if let Some(ref obj) = allocator.object { - remove(sess, obj); - } - if let Some(ref bc) = allocator.bytecode_compressed { - remove(sess, bc); - } - } - } - - out_filenames -} - -fn link_binary_output<'a, B: ArchiveBuilder<'a>>(sess: &'a Session, - codegen_results: &CodegenResults, - crate_type: config::CrateType, - outputs: &OutputFilenames, - crate_name: &str, - target_cpu: &str) -> Vec { - for obj in codegen_results.modules.iter().filter_map(|m| m.object.as_ref()) { - check_file_is_writeable(obj, sess); - } - - let mut out_filenames = vec![]; - - if outputs.outputs.contains_key(&OutputType::Metadata) { - let out_filename = filename_for_metadata(sess, crate_name, outputs); - // To avoid races with another rustc process scanning the output directory, - // we need to write the file somewhere else and atomically move it to its - // final destination, with a `fs::rename` call. In order for the rename to - // always succeed, the temporary file needs to be on the same filesystem, - // which is why we create it inside the output directory specifically. - let metadata_tmpdir = TempFileBuilder::new() - .prefix("rmeta") - .tempdir_in(out_filename.parent().unwrap()) - .unwrap_or_else(|err| sess.fatal(&format!("couldn't create a temp dir: {}", err))); - let metadata = emit_metadata(sess, codegen_results, &metadata_tmpdir); - if let Err(e) = fs::rename(metadata, &out_filename) { - sess.fatal(&format!("failed to write {}: {}", out_filename.display(), e)); - } - out_filenames.push(out_filename); - } - - let tmpdir = TempFileBuilder::new().prefix("rustc").tempdir().unwrap_or_else(|err| - sess.fatal(&format!("couldn't create a temp dir: {}", err))); - - if outputs.outputs.should_codegen() { - let out_filename = out_filename(sess, crate_type, outputs, crate_name); - match crate_type { - config::CrateType::Rlib => { - link_rlib::(sess, - codegen_results, - RlibFlavor::Normal, - &out_filename, - &tmpdir).build(); - } - config::CrateType::Staticlib => { - link_staticlib::(sess, codegen_results, &out_filename, &tmpdir); - } - _ => { - link_natively::(sess, crate_type, &out_filename, codegen_results, tmpdir.path(), target_cpu); - } - } - out_filenames.push(out_filename); - } - - if sess.opts.cg.save_temps { - let _ = tmpdir.into_path(); - } - - out_filenames -} - -/// We use a temp directory here to avoid races between concurrent rustc processes, -/// such as builds in the same directory using the same filename for metadata while -/// building an `.rlib` (stomping over one another), or writing an `.rmeta` into a -/// directory being searched for `extern crate` (observing an incomplete file). -/// The returned path is the temporary file containing the complete metadata. -fn emit_metadata<'a>( +pub(crate) fn link_binary<'a>( sess: &'a Session, codegen_results: &CodegenResults, - tmpdir: &TempDir -) -> PathBuf { - let out_filename = tmpdir.path().join(METADATA_FILENAME); - let result = fs::write(&out_filename, &codegen_results.metadata.raw_data); - - if let Err(e) = result { - sess.fatal(&format!("failed to write {}: {}", out_filename.display(), e)); - } - - out_filename -} - -// Create an 'rlib' -// -// An rlib in its current incarnation is essentially a renamed .a file. The -// rlib primarily contains the object file of the crate, but it also contains -// all of the object files from native libraries. This is done by unzipping -// native libraries and inserting all of the contents into this archive. -fn link_rlib<'a, B: ArchiveBuilder<'a>>(sess: &'a Session, - codegen_results: &CodegenResults, - flavor: RlibFlavor, - out_filename: &Path, - tmpdir: &TempDir) -> B { - info!("preparing rlib to {:?}", out_filename); - let mut ab = ::new(sess, out_filename, None); - - for obj in codegen_results.modules.iter().filter_map(|m| m.object.as_ref()) { - ab.add_file(obj); - } - - // Note that in this loop we are ignoring the value of `lib.cfg`. That is, - // we may not be configured to actually include a static library if we're - // adding it here. That's because later when we consume this rlib we'll - // decide whether we actually needed the static library or not. - // - // To do this "correctly" we'd need to keep track of which libraries added - // which object files to the archive. We don't do that here, however. The - // #[link(cfg(..))] feature is unstable, though, and only intended to get - // liblibc working. In that sense the check below just indicates that if - // there are any libraries we want to omit object files for at link time we - // just exclude all custom object files. - // - // Eventually if we want to stabilize or flesh out the #[link(cfg(..))] - // feature then we'll need to figure out how to record what objects were - // loaded from the libraries found here and then encode that into the - // metadata of the rlib we're generating somehow. - for lib in codegen_results.crate_info.used_libraries.iter() { - match lib.kind { - NativeLibraryKind::NativeStatic => {} - NativeLibraryKind::NativeStaticNobundle | - NativeLibraryKind::NativeFramework | - NativeLibraryKind::NativeUnknown => continue, - } - if let Some(name) = lib.name { - ab.add_native_library(&name.as_str()); - } - } - - // After adding all files to the archive, we need to update the - // symbol table of the archive. - ab.update_symbols(); - - // Note that it is important that we add all of our non-object "magical - // files" *after* all of the object files in the archive. The reason for - // this is as follows: - // - // * When performing LTO, this archive will be modified to remove - // objects from above. The reason for this is described below. - // - // * When the system linker looks at an archive, it will attempt to - // determine the architecture of the archive in order to see whether its - // linkable. - // - // The algorithm for this detection is: iterate over the files in the - // archive. Skip magical SYMDEF names. Interpret the first file as an - // object file. Read architecture from the object file. - // - // * As one can probably see, if "metadata" and "foo.bc" were placed - // before all of the objects, then the architecture of this archive would - // not be correctly inferred once 'foo.o' is removed. - // - // Basically, all this means is that this code should not move above the - // code above. - match flavor { - RlibFlavor::Normal => { - // Instead of putting the metadata in an object file section, rlibs - // contain the metadata in a separate file. - ab.add_file(&emit_metadata(sess, codegen_results, tmpdir)); - - // For LTO purposes, the bytecode of this library is also inserted - // into the archive. - for bytecode in codegen_results - .modules - .iter() - .filter_map(|m| m.bytecode_compressed.as_ref()) - { - ab.add_file(bytecode); - } - - // After adding all files to the archive, we need to update the - // symbol table of the archive. This currently dies on macOS (see - // #11162), and isn't necessary there anyway - if !sess.target.target.options.is_like_osx { - ab.update_symbols(); - } - } - - RlibFlavor::StaticlibBase => { - let obj = codegen_results.allocator_module - .as_ref() - .and_then(|m| m.object.as_ref()); - if let Some(obj) = obj { - ab.add_file(obj); - } - } - } - - ab -} - -// Create a static archive -// -// This is essentially the same thing as an rlib, but it also involves adding -// all of the upstream crates' objects into the archive. This will slurp in -// all of the native libraries of upstream dependencies as well. -// -// Additionally, there's no way for us to link dynamic libraries, so we warn -// about all dynamic library dependencies that they're not linked in. -// -// There's no need to include metadata in a static archive, so ensure to not -// link in the metadata object file (and also don't prepare the archive with a -// metadata file). -fn link_staticlib<'a, B: ArchiveBuilder<'a>>(sess: &'a Session, - codegen_results: &CodegenResults, - out_filename: &Path, - tempdir: &TempDir) { - let mut ab = link_rlib::(sess, - codegen_results, - RlibFlavor::StaticlibBase, - out_filename, - tempdir); - let mut all_native_libs = vec![]; - - let res = each_linked_rlib(sess, &codegen_results.crate_info, &mut |cnum, path| { - let name = &codegen_results.crate_info.crate_name[&cnum]; - let native_libs = &codegen_results.crate_info.native_libraries[&cnum]; - - // Here when we include the rlib into our staticlib we need to make a - // decision whether to include the extra object files along the way. - // These extra object files come from statically included native - // libraries, but they may be cfg'd away with #[link(cfg(..))]. - // - // This unstable feature, though, only needs liblibc to work. The only - // use case there is where musl is statically included in liblibc.rlib, - // so if we don't want the included version we just need to skip it. As - // a result the logic here is that if *any* linked library is cfg'd away - // we just skip all object files. - // - // Clearly this is not sufficient for a general purpose feature, and - // we'd want to read from the library's metadata to determine which - // object files come from where and selectively skip them. - let skip_object_files = native_libs.iter().any(|lib| { - lib.kind == NativeLibraryKind::NativeStatic && !relevant_lib(sess, lib) - }); - ab.add_rlib(path, - &name.as_str(), - are_upstream_rust_objects_already_included(sess) && - !ignored_for_lto(sess, &codegen_results.crate_info, cnum), - skip_object_files).unwrap(); - - all_native_libs.extend(codegen_results.crate_info.native_libraries[&cnum].iter().cloned()); - }); - if let Err(e) = res { - sess.fatal(&e); - } - - ab.update_symbols(); - ab.build(); - - if !all_native_libs.is_empty() { - if sess.opts.prints.contains(&PrintRequest::NativeStaticLibs) { - print_native_static_libs(sess, &all_native_libs); - } - } -} - -// Create a dynamic library or executable -// -// This will invoke the system linker/cc to create the resulting file. This -// links to all upstream files as well. -fn link_natively<'a, B: ArchiveBuilder<'a>>(sess: &'a Session, - crate_type: config::CrateType, - out_filename: &Path, - codegen_results: &CodegenResults, - tmpdir: &Path, - target_cpu: &str) { - info!("preparing {:?} to {:?}", crate_type, out_filename); - let (linker, flavor) = linker_and_flavor(sess); - - // The invocations of cc share some flags across platforms - let (pname, mut cmd) = get_linker(sess, &linker, flavor); - - if let Some(args) = sess.target.target.options.pre_link_args.get(&flavor) { - cmd.args(args); - } - if let Some(args) = sess.target.target.options.pre_link_args_crt.get(&flavor) { - if sess.crt_static() { - cmd.args(args); - } - } - if let Some(ref args) = sess.opts.debugging_opts.pre_link_args { - cmd.args(args); - } - cmd.args(&sess.opts.debugging_opts.pre_link_arg); - - if sess.target.target.options.is_like_fuchsia { - let prefix = match sess.opts.debugging_opts.sanitizer { - Some(Sanitizer::Address) => "asan/", - _ => "", - }; - cmd.arg(format!("--dynamic-linker={}ld.so.1", prefix)); - } - - let pre_link_objects = if crate_type == config::CrateType::Executable { - &sess.target.target.options.pre_link_objects_exe - } else { - &sess.target.target.options.pre_link_objects_dll - }; - for obj in pre_link_objects { - cmd.arg(get_file_path(sess, obj)); - } - - if crate_type == config::CrateType::Executable && sess.crt_static() { - for obj in &sess.target.target.options.pre_link_objects_exe_crt { - cmd.arg(get_file_path(sess, obj)); - } - } - - if sess.target.target.options.is_like_emscripten { - cmd.arg("-s"); - cmd.arg(if sess.panic_strategy() == PanicStrategy::Abort { - "DISABLE_EXCEPTION_CATCHING=1" - } else { - "DISABLE_EXCEPTION_CATCHING=0" - }); - } - - { - let mut linker = codegen_results.linker_info.to_linker(cmd, &sess, flavor, target_cpu); - link_args::(&mut *linker, flavor, sess, crate_type, tmpdir, - out_filename, codegen_results); - cmd = linker.finalize(); - } - if let Some(args) = sess.target.target.options.late_link_args.get(&flavor) { - cmd.args(args); - } - for obj in &sess.target.target.options.post_link_objects { - cmd.arg(get_file_path(sess, obj)); - } - if sess.crt_static() { - for obj in &sess.target.target.options.post_link_objects_crt { - cmd.arg(get_file_path(sess, obj)); - } - } - if let Some(args) = sess.target.target.options.post_link_args.get(&flavor) { - cmd.args(args); - } - for &(ref k, ref v) in &sess.target.target.options.link_env { - cmd.env(k, v); - } - - if sess.opts.debugging_opts.print_link_args { - println!("{:?}", &cmd); - } - - // May have not found libraries in the right formats. - sess.abort_if_errors(); - - // Invoke the system linker - // - // Note that there's a terribly awful hack that really shouldn't be present - // in any compiler. Here an environment variable is supported to - // automatically retry the linker invocation if the linker looks like it - // segfaulted. - // - // Gee that seems odd, normally segfaults are things we want to know about! - // Unfortunately though in rust-lang/rust#38878 we're experiencing the - // linker segfaulting on Travis quite a bit which is causing quite a bit of - // pain to land PRs when they spuriously fail due to a segfault. - // - // The issue #38878 has some more debugging information on it as well, but - // this unfortunately looks like it's just a race condition in macOS's linker - // with some thread pool working in the background. It seems that no one - // currently knows a fix for this so in the meantime we're left with this... - info!("{:?}", &cmd); - let retry_on_segfault = env::var("RUSTC_RETRY_LINKER_ON_SEGFAULT").is_ok(); - let mut prog; - let mut i = 0; - loop { - i += 1; - prog = time(sess, "running linker", || { - exec_linker(sess, &mut cmd, out_filename, tmpdir) - }); - let output = match prog { - Ok(ref output) => output, - Err(_) => break, - }; - if output.status.success() { - break - } - let mut out = output.stderr.clone(); - out.extend(&output.stdout); - let out = String::from_utf8_lossy(&out); - - // Check to see if the link failed with "unrecognized command line option: - // '-no-pie'" for gcc or "unknown argument: '-no-pie'" for clang. If so, - // reperform the link step without the -no-pie option. This is safe because - // if the linker doesn't support -no-pie then it should not default to - // linking executables as pie. Different versions of gcc seem to use - // different quotes in the error message so don't check for them. - if sess.target.target.options.linker_is_gnu && - flavor != LinkerFlavor::Ld && - (out.contains("unrecognized command line option") || - out.contains("unknown argument")) && - out.contains("-no-pie") && - cmd.get_args().iter().any(|e| e.to_string_lossy() == "-no-pie") { - info!("linker output: {:?}", out); - warn!("Linker does not support -no-pie command line option. Retrying without."); - for arg in cmd.take_args() { - if arg.to_string_lossy() != "-no-pie" { - cmd.arg(arg); - } - } - info!("{:?}", &cmd); - continue; - } - if !retry_on_segfault || i > 3 { - break - } - let msg_segv = "clang: error: unable to execute command: Segmentation fault: 11"; - let msg_bus = "clang: error: unable to execute command: Bus error: 10"; - if !(out.contains(msg_segv) || out.contains(msg_bus)) { - break - } - - warn!( - "looks like the linker segfaulted when we tried to call it, \ - automatically retrying again. cmd = {:?}, out = {}.", - cmd, - out, - ); - } - - match prog { - Ok(prog) => { - fn escape_string(s: &[u8]) -> String { - str::from_utf8(s).map(|s| s.to_owned()) - .unwrap_or_else(|_| { - let mut x = "Non-UTF-8 output: ".to_string(); - x.extend(s.iter() - .flat_map(|&b| ascii::escape_default(b)) - .map(char::from)); - x - }) - } - if !prog.status.success() { - let mut output = prog.stderr.clone(); - output.extend_from_slice(&prog.stdout); - sess.struct_err(&format!("linking with `{}` failed: {}", - pname.display(), - prog.status)) - .note(&format!("{:?}", &cmd)) - .note(&escape_string(&output)) - .emit(); - sess.abort_if_errors(); - } - info!("linker stderr:\n{}", escape_string(&prog.stderr)); - info!("linker stdout:\n{}", escape_string(&prog.stdout)); - }, - Err(e) => { - let linker_not_found = e.kind() == io::ErrorKind::NotFound; - - let mut linker_error = { - if linker_not_found { - sess.struct_err(&format!("linker `{}` not found", pname.display())) - } else { - sess.struct_err(&format!("could not exec the linker `{}`", pname.display())) - } - }; - - linker_error.note(&e.to_string()); - - if !linker_not_found { - linker_error.note(&format!("{:?}", &cmd)); - } - - linker_error.emit(); - - if sess.target.target.options.is_like_msvc && linker_not_found { - sess.note_without_error("the msvc targets depend on the msvc linker \ - but `link.exe` was not found"); - sess.note_without_error("please ensure that VS 2013, VS 2015 or VS 2017 \ - was installed with the Visual C++ option"); - } - sess.abort_if_errors(); - } - } - - - // On macOS, debuggers need this utility to get run to do some munging of - // the symbols. Note, though, that if the object files are being preserved - // for their debug information there's no need for us to run dsymutil. - if sess.target.target.options.is_like_osx && - sess.opts.debuginfo != DebugInfo::None && - !preserve_objects_for_their_debuginfo(sess) - { - if let Err(e) = Command::new("dsymutil").arg(out_filename).output() { - sess.fatal(&format!("failed to run dsymutil: {}", e)) - } - } - - if sess.opts.target_triple.triple() == "wasm32-unknown-unknown" { - wasm::add_producer_section( - &out_filename, - &sess.edition().to_string(), - option_env!("CFG_VERSION").unwrap_or("unknown"), - ); - } -} - -fn link_args<'a, B: ArchiveBuilder<'a>>(cmd: &mut dyn Linker, - flavor: LinkerFlavor, - sess: &'a Session, - crate_type: config::CrateType, - tmpdir: &Path, - out_filename: &Path, - codegen_results: &CodegenResults) { - - // Linker plugins should be specified early in the list of arguments - cmd.linker_plugin_lto(); - - // The default library location, we need this to find the runtime. - // The location of crates will be determined as needed. - let lib_path = sess.target_filesearch(PathKind::All).get_lib_path(); - - // target descriptor - let t = &sess.target.target; - - cmd.include_path(&fix_windows_verbatim_for_gcc(&lib_path)); - for obj in codegen_results.modules.iter().filter_map(|m| m.object.as_ref()) { - cmd.add_object(obj); - } - cmd.output_filename(out_filename); - - if crate_type == config::CrateType::Executable && - sess.target.target.options.is_like_windows { - if let Some(ref s) = codegen_results.windows_subsystem { - cmd.subsystem(s); - } - } - - // If we're building a dynamic library then some platforms need to make sure - // that all symbols are exported correctly from the dynamic library. - if crate_type != config::CrateType::Executable || - sess.target.target.options.is_like_emscripten { - cmd.export_symbols(tmpdir, crate_type); - } - - // When linking a dynamic library, we put the metadata into a section of the - // executable. This metadata is in a separate object file from the main - // object file, so we link that in here. - if crate_type == config::CrateType::Dylib || - crate_type == config::CrateType::ProcMacro { - if let Some(obj) = codegen_results.metadata_module.object.as_ref() { - cmd.add_object(obj); - } - } - - let obj = codegen_results.allocator_module - .as_ref() - .and_then(|m| m.object.as_ref()); - if let Some(obj) = obj { - cmd.add_object(obj); - } - - // Try to strip as much out of the generated object by removing unused - // sections if possible. See more comments in linker.rs - if !sess.opts.cg.link_dead_code { - let keep_metadata = crate_type == config::CrateType::Dylib; - cmd.gc_sections(keep_metadata); - } - - let used_link_args = &codegen_results.crate_info.link_args; - - if crate_type == config::CrateType::Executable { - let mut position_independent_executable = false; - - if t.options.position_independent_executables { - let empty_vec = Vec::new(); - let args = sess.opts.cg.link_args.as_ref().unwrap_or(&empty_vec); - let more_args = &sess.opts.cg.link_arg; - let mut args = args.iter().chain(more_args.iter()).chain(used_link_args.iter()); - - if is_pic(sess) && !sess.crt_static() && !args.any(|x| *x == "-static") { - position_independent_executable = true; - } - } - - if position_independent_executable { - cmd.position_independent_executable(); - } else { - // recent versions of gcc can be configured to generate position - // independent executables by default. We have to pass -no-pie to - // explicitly turn that off. Not applicable to ld. - if sess.target.target.options.linker_is_gnu - && flavor != LinkerFlavor::Ld { - cmd.no_position_independent_executable(); - } - } - } - - let relro_level = match sess.opts.debugging_opts.relro_level { - Some(level) => level, - None => t.options.relro_level, - }; - match relro_level { - RelroLevel::Full => { - cmd.full_relro(); - }, - RelroLevel::Partial => { - cmd.partial_relro(); - }, - RelroLevel::Off => { - cmd.no_relro(); - }, - RelroLevel::None => { - }, - } - - // Pass optimization flags down to the linker. - cmd.optimize(); - - // Pass debuginfo flags down to the linker. - cmd.debuginfo(); - - // We want to, by default, prevent the compiler from accidentally leaking in - // any system libraries, so we may explicitly ask linkers to not link to any - // libraries by default. Note that this does not happen for windows because - // windows pulls in some large number of libraries and I couldn't quite - // figure out which subset we wanted. - // - // This is all naturally configurable via the standard methods as well. - if !sess.opts.cg.default_linker_libraries.unwrap_or(false) && - t.options.no_default_libraries - { - cmd.no_default_libraries(); - } - - // Take careful note of the ordering of the arguments we pass to the linker - // here. Linkers will assume that things on the left depend on things to the - // right. Things on the right cannot depend on things on the left. This is - // all formally implemented in terms of resolving symbols (libs on the right - // resolve unknown symbols of libs on the left, but not vice versa). - // - // For this reason, we have organized the arguments we pass to the linker as - // such: - // - // 1. The local object that LLVM just generated - // 2. Local native libraries - // 3. Upstream rust libraries - // 4. Upstream native libraries - // - // The rationale behind this ordering is that those items lower down in the - // list can't depend on items higher up in the list. For example nothing can - // depend on what we just generated (e.g., that'd be a circular dependency). - // Upstream rust libraries are not allowed to depend on our local native - // libraries as that would violate the structure of the DAG, in that - // scenario they are required to link to them as well in a shared fashion. - // - // Note that upstream rust libraries may contain native dependencies as - // well, but they also can't depend on what we just started to add to the - // link line. And finally upstream native libraries can't depend on anything - // in this DAG so far because they're only dylibs and dylibs can only depend - // on other dylibs (e.g., other native deps). - add_local_native_libraries(cmd, sess, codegen_results); - add_upstream_rust_crates::(cmd, sess, codegen_results, crate_type, tmpdir); - add_upstream_native_libraries(cmd, sess, codegen_results, crate_type); - - // Tell the linker what we're doing. - if crate_type != config::CrateType::Executable { - cmd.build_dylib(out_filename); - } - if crate_type == config::CrateType::Executable && sess.crt_static() { - cmd.build_static_executable(); - } - - if sess.opts.debugging_opts.pgo_gen.enabled() { - cmd.pgo_gen(); - } - - // FIXME (#2397): At some point we want to rpath our guesses as to - // where extern libraries might live, based on the - // addl_lib_search_paths - if sess.opts.cg.rpath { - let target_triple = sess.opts.target_triple.triple(); - let mut get_install_prefix_lib_path = || { - let install_prefix = option_env!("CFG_PREFIX").expect("CFG_PREFIX"); - let tlib = filesearch::relative_target_lib_path(&sess.sysroot, target_triple); - let mut path = PathBuf::from(install_prefix); - path.push(&tlib); - - path - }; - let mut rpath_config = RPathConfig { - used_crates: &codegen_results.crate_info.used_crates_dynamic, - out_filename: out_filename.to_path_buf(), - has_rpath: sess.target.target.options.has_rpath, - is_like_osx: sess.target.target.options.is_like_osx, - linker_is_gnu: sess.target.target.options.linker_is_gnu, - get_install_prefix_lib_path: &mut get_install_prefix_lib_path, - }; - cmd.args(&rpath::get_rpath_flags(&mut rpath_config)); - } - - // Finally add all the linker arguments provided on the command line along - // with any #[link_args] attributes found inside the crate - if let Some(ref args) = sess.opts.cg.link_args { - cmd.args(args); - } - cmd.args(&sess.opts.cg.link_arg); - cmd.args(&used_link_args); -} - -// # Rust Crate linking -// -// Rust crates are not considered at all when creating an rlib output. All -// dependencies will be linked when producing the final output (instead of -// the intermediate rlib version) -fn add_upstream_rust_crates<'a, B: ArchiveBuilder<'a>>(cmd: &mut dyn Linker, - sess: &'a Session, - codegen_results: &CodegenResults, - crate_type: config::CrateType, - tmpdir: &Path) { - // All of the heavy lifting has previously been accomplished by the - // dependency_format module of the compiler. This is just crawling the - // output of that module, adding crates as necessary. - // - // Linking to a rlib involves just passing it to the linker (the linker - // will slurp up the object files inside), and linking to a dynamic library - // involves just passing the right -l flag. - - let formats = sess.dependency_formats.borrow(); - let data = formats.get(&crate_type).unwrap(); - - // Invoke get_used_crates to ensure that we get a topological sorting of - // crates. - let deps = &codegen_results.crate_info.used_crates_dynamic; - - // There's a few internal crates in the standard library (aka libcore and - // libstd) which actually have a circular dependence upon one another. This - // currently arises through "weak lang items" where libcore requires things - // like `rust_begin_unwind` but libstd ends up defining it. To get this - // circular dependence to work correctly in all situations we'll need to be - // sure to correctly apply the `--start-group` and `--end-group` options to - // GNU linkers, otherwise if we don't use any other symbol from the standard - // library it'll get discarded and the whole application won't link. - // - // In this loop we're calculating the `group_end`, after which crate to - // pass `--end-group` and `group_start`, before which crate to pass - // `--start-group`. We currently do this by passing `--end-group` after - // the first crate (when iterating backwards) that requires a lang item - // defined somewhere else. Once that's set then when we've defined all the - // necessary lang items we'll pass `--start-group`. - // - // Note that this isn't amazing logic for now but it should do the trick - // for the current implementation of the standard library. - let mut group_end = None; - let mut group_start = None; - let mut end_with = FxHashSet::default(); - let info = &codegen_results.crate_info; - for &(cnum, _) in deps.iter().rev() { - if let Some(missing) = info.missing_lang_items.get(&cnum) { - end_with.extend(missing.iter().cloned()); - if end_with.len() > 0 && group_end.is_none() { - group_end = Some(cnum); - } - } - end_with.retain(|item| info.lang_item_to_crate.get(item) != Some(&cnum)); - if end_with.len() == 0 && group_end.is_some() { - group_start = Some(cnum); - break - } - } - - // If we didn't end up filling in all lang items from upstream crates then - // we'll be filling it in with our crate. This probably means we're the - // standard library itself, so skip this for now. - if group_end.is_some() && group_start.is_none() { - group_end = None; - } - - let mut compiler_builtins = None; - - for &(cnum, _) in deps.iter() { - if group_start == Some(cnum) { - cmd.group_start(); - } - - // We may not pass all crates through to the linker. Some crates may - // appear statically in an existing dylib, meaning we'll pick up all the - // symbols from the dylib. - let src = &codegen_results.crate_info.used_crate_source[&cnum]; - match data[cnum.as_usize() - 1] { - _ if codegen_results.crate_info.profiler_runtime == Some(cnum) => { - add_static_crate::(cmd, sess, codegen_results, tmpdir, crate_type, cnum); - } - _ if codegen_results.crate_info.sanitizer_runtime == Some(cnum) => { - link_sanitizer_runtime::(cmd, sess, codegen_results, tmpdir, cnum); - } - // compiler-builtins are always placed last to ensure that they're - // linked correctly. - _ if codegen_results.crate_info.compiler_builtins == Some(cnum) => { - assert!(compiler_builtins.is_none()); - compiler_builtins = Some(cnum); - } - Linkage::NotLinked | - Linkage::IncludedFromDylib => {} - Linkage::Static => { - add_static_crate::(cmd, sess, codegen_results, tmpdir, crate_type, cnum); - } - Linkage::Dynamic => { - add_dynamic_crate(cmd, sess, &src.dylib.as_ref().unwrap().0) - } - } - - if group_end == Some(cnum) { - cmd.group_end(); - } - } - - // compiler-builtins are always placed last to ensure that they're - // linked correctly. - // We must always link the `compiler_builtins` crate statically. Even if it - // was already "included" in a dylib (e.g., `libstd` when `-C prefer-dynamic` - // is used) - if let Some(cnum) = compiler_builtins { - add_static_crate::(cmd, sess, codegen_results, tmpdir, crate_type, cnum); - } - - // Converts a library file-stem into a cc -l argument - fn unlib<'a>(config: &config::Config, stem: &'a str) -> &'a str { - if stem.starts_with("lib") && !config.target.options.is_like_windows { - &stem[3..] - } else { - stem - } - } - - // We must link the sanitizer runtime using -Wl,--whole-archive but since - // it's packed in a .rlib, it contains stuff that are not objects that will - // make the linker error. So we must remove those bits from the .rlib before - // linking it. - fn link_sanitizer_runtime<'a, B: ArchiveBuilder<'a>>(cmd: &mut dyn Linker, - sess: &'a Session, - codegen_results: &CodegenResults, - tmpdir: &Path, - cnum: CrateNum) { - let src = &codegen_results.crate_info.used_crate_source[&cnum]; - let cratepath = &src.rlib.as_ref().unwrap().0; - - if sess.target.target.options.is_like_osx { - // On Apple platforms, the sanitizer is always built as a dylib, and - // LLVM will link to `@rpath/*.dylib`, so we need to specify an - // rpath to the library as well (the rpath should be absolute, see - // PR #41352 for details). - // - // FIXME: Remove this logic into librustc_*san once Cargo supports it - let rpath = cratepath.parent().unwrap(); - let rpath = rpath.to_str().expect("non-utf8 component in path"); - cmd.args(&["-Wl,-rpath".into(), "-Xlinker".into(), rpath.into()]); - } - - let dst = tmpdir.join(cratepath.file_name().unwrap()); - let mut archive = ::new(sess, &dst, Some(cratepath)); - archive.update_symbols(); - - for f in archive.src_files() { - if f.ends_with(RLIB_BYTECODE_EXTENSION) || f == METADATA_FILENAME { - archive.remove_file(&f); - } - } - - archive.build(); - - cmd.link_whole_rlib(&dst); - } - - // Adds the static "rlib" versions of all crates to the command line. - // There's a bit of magic which happens here specifically related to LTO and - // dynamic libraries. Specifically: - // - // * For LTO, we remove upstream object files. - // * For dylibs we remove metadata and bytecode from upstream rlibs - // - // When performing LTO, almost(*) all of the bytecode from the upstream - // libraries has already been included in our object file output. As a - // result we need to remove the object files in the upstream libraries so - // the linker doesn't try to include them twice (or whine about duplicate - // symbols). We must continue to include the rest of the rlib, however, as - // it may contain static native libraries which must be linked in. - // - // (*) Crates marked with `#![no_builtins]` don't participate in LTO and - // their bytecode wasn't included. The object files in those libraries must - // still be passed to the linker. - // - // When making a dynamic library, linkers by default don't include any - // object files in an archive if they're not necessary to resolve the link. - // We basically want to convert the archive (rlib) to a dylib, though, so we - // *do* want everything included in the output, regardless of whether the - // linker thinks it's needed or not. As a result we must use the - // --whole-archive option (or the platform equivalent). When using this - // option the linker will fail if there are non-objects in the archive (such - // as our own metadata and/or bytecode). All in all, for rlibs to be - // entirely included in dylibs, we need to remove all non-object files. - // - // Note, however, that if we're not doing LTO or we're not producing a dylib - // (aka we're making an executable), we can just pass the rlib blindly to - // the linker (fast) because it's fine if it's not actually included as - // we're at the end of the dependency chain. - fn add_static_crate<'a, B: ArchiveBuilder<'a>>(cmd: &mut dyn Linker, - sess: &'a Session, - codegen_results: &CodegenResults, - tmpdir: &Path, - crate_type: config::CrateType, - cnum: CrateNum) { - let src = &codegen_results.crate_info.used_crate_source[&cnum]; - let cratepath = &src.rlib.as_ref().unwrap().0; - - // See the comment above in `link_staticlib` and `link_rlib` for why if - // there's a static library that's not relevant we skip all object - // files. - let native_libs = &codegen_results.crate_info.native_libraries[&cnum]; - let skip_native = native_libs.iter().any(|lib| { - lib.kind == NativeLibraryKind::NativeStatic && !relevant_lib(sess, lib) - }); - - if (!are_upstream_rust_objects_already_included(sess) || - ignored_for_lto(sess, &codegen_results.crate_info, cnum)) && - crate_type != config::CrateType::Dylib && - !skip_native { - cmd.link_rlib(&fix_windows_verbatim_for_gcc(cratepath)); - return - } - - let dst = tmpdir.join(cratepath.file_name().unwrap()); - let name = cratepath.file_name().unwrap().to_str().unwrap(); - let name = &name[3..name.len() - 5]; // chop off lib/.rlib - - time_ext(sess.time_extended(), Some(sess), &format!("altering {}.rlib", name), || { - let mut archive = ::new(sess, &dst, Some(cratepath)); - archive.update_symbols(); - - let mut any_objects = false; - for f in archive.src_files() { - if f.ends_with(RLIB_BYTECODE_EXTENSION) || f == METADATA_FILENAME { - archive.remove_file(&f); - continue - } - - let canonical = f.replace("-", "_"); - let canonical_name = name.replace("-", "_"); - - // Look for `.rcgu.o` at the end of the filename to conclude - // that this is a Rust-related object file. - fn looks_like_rust(s: &str) -> bool { - let path = Path::new(s); - let ext = path.extension().and_then(|s| s.to_str()); - if ext != Some(OutputType::Object.extension()) { - return false - } - let ext2 = path.file_stem() - .and_then(|s| Path::new(s).extension()) - .and_then(|s| s.to_str()); - ext2 == Some(RUST_CGU_EXT) - } - - let is_rust_object = - canonical.starts_with(&canonical_name) && - looks_like_rust(&f); - - // If we've been requested to skip all native object files - // (those not generated by the rust compiler) then we can skip - // this file. See above for why we may want to do this. - let skip_because_cfg_say_so = skip_native && !is_rust_object; - - // If we're performing LTO and this is a rust-generated object - // file, then we don't need the object file as it's part of the - // LTO module. Note that `#![no_builtins]` is excluded from LTO, - // though, so we let that object file slide. - let skip_because_lto = are_upstream_rust_objects_already_included(sess) && - is_rust_object && - (sess.target.target.options.no_builtins || - !codegen_results.crate_info.is_no_builtins.contains(&cnum)); - - if skip_because_cfg_say_so || skip_because_lto { - archive.remove_file(&f); - } else { - any_objects = true; - } - } - - if !any_objects { - return - } - archive.build(); - - // If we're creating a dylib, then we need to include the - // whole of each object in our archive into that artifact. This is - // because a `dylib` can be reused as an intermediate artifact. - // - // Note, though, that we don't want to include the whole of a - // compiler-builtins crate (e.g., compiler-rt) because it'll get - // repeatedly linked anyway. - if crate_type == config::CrateType::Dylib && - codegen_results.crate_info.compiler_builtins != Some(cnum) { - cmd.link_whole_rlib(&fix_windows_verbatim_for_gcc(&dst)); - } else { - cmd.link_rlib(&fix_windows_verbatim_for_gcc(&dst)); - } - }); - } - - // Same thing as above, but for dynamic crates instead of static crates. - fn add_dynamic_crate(cmd: &mut dyn Linker, sess: &Session, cratepath: &Path) { - // Just need to tell the linker about where the library lives and - // what its name is - let parent = cratepath.parent(); - if let Some(dir) = parent { - cmd.include_path(&fix_windows_verbatim_for_gcc(dir)); - } - let filestem = cratepath.file_stem().unwrap().to_str().unwrap(); - cmd.link_rust_dylib(&unlib(&sess.target, filestem), - parent.unwrap_or(Path::new(""))); - } -} - -fn is_pic(sess: &Session) -> bool { - let reloc_model_arg = match sess.opts.cg.relocation_model { - Some(ref s) => &s[..], - None => &sess.target.target.options.relocation_model[..], - }; - - reloc_model_arg == "pic" + outputs: &OutputFilenames, + crate_name: &str, +) -> Vec { + let target_cpu = crate::llvm_util::target_cpu(sess); + rustc_codegen_ssa::back::link::link_binary::>( + sess, + codegen_results, + outputs, + crate_name, + target_cpu, + ) } diff --git a/src/librustc_codegen_llvm/lib.rs b/src/librustc_codegen_llvm/lib.rs index c2eee59fbb0..8283d1aa1b5 100644 --- a/src/librustc_codegen_llvm/lib.rs +++ b/src/librustc_codegen_llvm/lib.rs @@ -44,8 +44,6 @@ extern crate rustc_fs_util; #[macro_use] extern crate syntax; extern crate syntax_pos; extern crate rustc_errors as errors; -extern crate serialize; -extern crate tempfile; use rustc_codegen_ssa::traits::*; use rustc_codegen_ssa::back::write::{CodegenContext, ModuleConfig, FatLTOInput}; @@ -78,8 +76,6 @@ mod back { pub mod link; pub mod lto; pub mod write; - mod rpath; - pub mod wasm; } mod abi; diff --git a/src/librustc_codegen_ssa/Cargo.toml b/src/librustc_codegen_ssa/Cargo.toml index 4702e34aa19..af99d39182c 100644 --- a/src/librustc_codegen_ssa/Cargo.toml +++ b/src/librustc_codegen_ssa/Cargo.toml @@ -20,6 +20,7 @@ log = "0.4.5" libc = "0.2.44" jobserver = "0.1.11" parking_lot = "0.7" +tempfile = "3.0.5" serialize = { path = "../libserialize" } syntax = { path = "../libsyntax" } diff --git a/src/librustc_codegen_ssa/back/link.rs b/src/librustc_codegen_ssa/back/link.rs index f97f78b7feb..acd2237617f 100644 --- a/src/librustc_codegen_ssa/back/link.rs +++ b/src/librustc_codegen_ssa/back/link.rs @@ -1,24 +1,36 @@ /// For all the linkers we support, and information they might /// need out of the shared crate context before we get rid of it. -use rustc::session::{Session, config}; +use rustc::session::{Session, filesearch}; +use rustc::session::config::{ + self, RUST_CGU_EXT, DebugInfo, OutputFilenames, OutputType, PrintRequest, Sanitizer +}; use rustc::session::search_paths::PathKind; use rustc::middle::dependency_format::Linkage; use rustc::middle::cstore::{LibSource, NativeLibrary, NativeLibraryKind}; -use rustc_target::spec::LinkerFlavor; +use rustc::util::common::{time, time_ext}; use rustc::hir::def_id::CrateNum; +use rustc_data_structures::fx::FxHashSet; use rustc_fs_util::fix_windows_verbatim_for_gcc; +use rustc_target::spec::{PanicStrategy, RelroLevel, LinkerFlavor}; +use crate::{METADATA_FILENAME, RLIB_BYTECODE_EXTENSION, CrateInfo, CodegenResults}; +use super::archive::ArchiveBuilder; use super::command::Command; -use crate::{CrateInfo, CodegenResults}; -use crate::back::linker::Linker; +use super::linker::Linker; +use super::rpath::{self, RPathConfig}; use cc::windows_registry; +use tempfile::{Builder as TempFileBuilder, TempDir}; + +use std::ascii; +use std::char; use std::fmt; use std::fs; use std::io; use std::path::{Path, PathBuf}; use std::process::{Output, Stdio}; +use std::str; use std::env; pub use rustc_codegen_utils::link::*; @@ -31,6 +43,122 @@ pub fn remove(sess: &Session, path: &Path) { } } +/// Performs the linkage portion of the compilation phase. This will generate all +/// of the requested outputs for this compilation session. +pub fn link_binary<'a, B: ArchiveBuilder<'a>>(sess: &'a Session, + codegen_results: &CodegenResults, + outputs: &OutputFilenames, + crate_name: &str, + target_cpu: &str) -> Vec { + let mut out_filenames = Vec::new(); + for &crate_type in sess.crate_types.borrow().iter() { + // Ignore executable crates if we have -Z no-codegen, as they will error. + let output_metadata = sess.opts.output_types.contains_key(&OutputType::Metadata); + if (sess.opts.debugging_opts.no_codegen || !sess.opts.output_types.should_codegen()) && + !output_metadata && + crate_type == config::CrateType::Executable { + continue; + } + + if invalid_output_for_target(sess, crate_type) { + bug!("invalid output type `{:?}` for target os `{}`", + crate_type, sess.opts.target_triple); + } + let out_files = link_binary_output::(sess, + codegen_results, + crate_type, + outputs, + crate_name, + target_cpu); + out_filenames.extend(out_files); + } + + // Remove the temporary object file and metadata if we aren't saving temps + if !sess.opts.cg.save_temps { + if sess.opts.output_types.should_codegen() && !preserve_objects_for_their_debuginfo(sess) { + for obj in codegen_results.modules.iter().filter_map(|m| m.object.as_ref()) { + remove(sess, obj); + } + } + for obj in codegen_results.modules.iter().filter_map(|m| m.bytecode_compressed.as_ref()) { + remove(sess, obj); + } + if let Some(ref obj) = codegen_results.metadata_module.object { + remove(sess, obj); + } + if let Some(ref allocator) = codegen_results.allocator_module { + if let Some(ref obj) = allocator.object { + remove(sess, obj); + } + if let Some(ref bc) = allocator.bytecode_compressed { + remove(sess, bc); + } + } + } + + out_filenames +} + +fn link_binary_output<'a, B: ArchiveBuilder<'a>>(sess: &'a Session, + codegen_results: &CodegenResults, + crate_type: config::CrateType, + outputs: &OutputFilenames, + crate_name: &str, + target_cpu: &str) -> Vec { + for obj in codegen_results.modules.iter().filter_map(|m| m.object.as_ref()) { + check_file_is_writeable(obj, sess); + } + + let mut out_filenames = vec![]; + + if outputs.outputs.contains_key(&OutputType::Metadata) { + let out_filename = filename_for_metadata(sess, crate_name, outputs); + // To avoid races with another rustc process scanning the output directory, + // we need to write the file somewhere else and atomically move it to its + // final destination, with a `fs::rename` call. In order for the rename to + // always succeed, the temporary file needs to be on the same filesystem, + // which is why we create it inside the output directory specifically. + let metadata_tmpdir = TempFileBuilder::new() + .prefix("rmeta") + .tempdir_in(out_filename.parent().unwrap()) + .unwrap_or_else(|err| sess.fatal(&format!("couldn't create a temp dir: {}", err))); + let metadata = emit_metadata(sess, codegen_results, &metadata_tmpdir); + if let Err(e) = fs::rename(metadata, &out_filename) { + sess.fatal(&format!("failed to write {}: {}", out_filename.display(), e)); + } + out_filenames.push(out_filename); + } + + let tmpdir = TempFileBuilder::new().prefix("rustc").tempdir().unwrap_or_else(|err| + sess.fatal(&format!("couldn't create a temp dir: {}", err))); + + if outputs.outputs.should_codegen() { + let out_filename = out_filename(sess, crate_type, outputs, crate_name); + match crate_type { + config::CrateType::Rlib => { + link_rlib::(sess, + codegen_results, + RlibFlavor::Normal, + &out_filename, + &tmpdir).build(); + } + config::CrateType::Staticlib => { + link_staticlib::(sess, codegen_results, &out_filename, &tmpdir); + } + _ => { + link_natively::(sess, crate_type, &out_filename, codegen_results, tmpdir.path(), target_cpu); + } + } + out_filenames.push(out_filename); + } + + if sess.opts.cg.save_temps { + let _ = tmpdir.into_path(); + } + + out_filenames +} + // The third parameter is for env vars, used on windows to set up the // path for MSVC to find its DLLs, and gcc to find its bundled // toolchain @@ -123,6 +251,444 @@ pub fn each_linked_rlib(sess: &Session, Ok(()) } +/// We use a temp directory here to avoid races between concurrent rustc processes, +/// such as builds in the same directory using the same filename for metadata while +/// building an `.rlib` (stomping over one another), or writing an `.rmeta` into a +/// directory being searched for `extern crate` (observing an incomplete file). +/// The returned path is the temporary file containing the complete metadata. +fn emit_metadata<'a>( + sess: &'a Session, + codegen_results: &CodegenResults, + tmpdir: &TempDir +) -> PathBuf { + let out_filename = tmpdir.path().join(METADATA_FILENAME); + let result = fs::write(&out_filename, &codegen_results.metadata.raw_data); + + if let Err(e) = result { + sess.fatal(&format!("failed to write {}: {}", out_filename.display(), e)); + } + + out_filename +} + +// Create an 'rlib' +// +// An rlib in its current incarnation is essentially a renamed .a file. The +// rlib primarily contains the object file of the crate, but it also contains +// all of the object files from native libraries. This is done by unzipping +// native libraries and inserting all of the contents into this archive. +fn link_rlib<'a, B: ArchiveBuilder<'a>>(sess: &'a Session, + codegen_results: &CodegenResults, + flavor: RlibFlavor, + out_filename: &Path, + tmpdir: &TempDir) -> B { + info!("preparing rlib to {:?}", out_filename); + let mut ab = ::new(sess, out_filename, None); + + for obj in codegen_results.modules.iter().filter_map(|m| m.object.as_ref()) { + ab.add_file(obj); + } + + // Note that in this loop we are ignoring the value of `lib.cfg`. That is, + // we may not be configured to actually include a static library if we're + // adding it here. That's because later when we consume this rlib we'll + // decide whether we actually needed the static library or not. + // + // To do this "correctly" we'd need to keep track of which libraries added + // which object files to the archive. We don't do that here, however. The + // #[link(cfg(..))] feature is unstable, though, and only intended to get + // liblibc working. In that sense the check below just indicates that if + // there are any libraries we want to omit object files for at link time we + // just exclude all custom object files. + // + // Eventually if we want to stabilize or flesh out the #[link(cfg(..))] + // feature then we'll need to figure out how to record what objects were + // loaded from the libraries found here and then encode that into the + // metadata of the rlib we're generating somehow. + for lib in codegen_results.crate_info.used_libraries.iter() { + match lib.kind { + NativeLibraryKind::NativeStatic => {} + NativeLibraryKind::NativeStaticNobundle | + NativeLibraryKind::NativeFramework | + NativeLibraryKind::NativeUnknown => continue, + } + if let Some(name) = lib.name { + ab.add_native_library(&name.as_str()); + } + } + + // After adding all files to the archive, we need to update the + // symbol table of the archive. + ab.update_symbols(); + + // Note that it is important that we add all of our non-object "magical + // files" *after* all of the object files in the archive. The reason for + // this is as follows: + // + // * When performing LTO, this archive will be modified to remove + // objects from above. The reason for this is described below. + // + // * When the system linker looks at an archive, it will attempt to + // determine the architecture of the archive in order to see whether its + // linkable. + // + // The algorithm for this detection is: iterate over the files in the + // archive. Skip magical SYMDEF names. Interpret the first file as an + // object file. Read architecture from the object file. + // + // * As one can probably see, if "metadata" and "foo.bc" were placed + // before all of the objects, then the architecture of this archive would + // not be correctly inferred once 'foo.o' is removed. + // + // Basically, all this means is that this code should not move above the + // code above. + match flavor { + RlibFlavor::Normal => { + // Instead of putting the metadata in an object file section, rlibs + // contain the metadata in a separate file. + ab.add_file(&emit_metadata(sess, codegen_results, tmpdir)); + + // For LTO purposes, the bytecode of this library is also inserted + // into the archive. + for bytecode in codegen_results + .modules + .iter() + .filter_map(|m| m.bytecode_compressed.as_ref()) + { + ab.add_file(bytecode); + } + + // After adding all files to the archive, we need to update the + // symbol table of the archive. This currently dies on macOS (see + // #11162), and isn't necessary there anyway + if !sess.target.target.options.is_like_osx { + ab.update_symbols(); + } + } + + RlibFlavor::StaticlibBase => { + let obj = codegen_results.allocator_module + .as_ref() + .and_then(|m| m.object.as_ref()); + if let Some(obj) = obj { + ab.add_file(obj); + } + } + } + + ab +} + +// Create a static archive +// +// This is essentially the same thing as an rlib, but it also involves adding +// all of the upstream crates' objects into the archive. This will slurp in +// all of the native libraries of upstream dependencies as well. +// +// Additionally, there's no way for us to link dynamic libraries, so we warn +// about all dynamic library dependencies that they're not linked in. +// +// There's no need to include metadata in a static archive, so ensure to not +// link in the metadata object file (and also don't prepare the archive with a +// metadata file). +fn link_staticlib<'a, B: ArchiveBuilder<'a>>(sess: &'a Session, + codegen_results: &CodegenResults, + out_filename: &Path, + tempdir: &TempDir) { + let mut ab = link_rlib::(sess, + codegen_results, + RlibFlavor::StaticlibBase, + out_filename, + tempdir); + let mut all_native_libs = vec![]; + + let res = each_linked_rlib(sess, &codegen_results.crate_info, &mut |cnum, path| { + let name = &codegen_results.crate_info.crate_name[&cnum]; + let native_libs = &codegen_results.crate_info.native_libraries[&cnum]; + + // Here when we include the rlib into our staticlib we need to make a + // decision whether to include the extra object files along the way. + // These extra object files come from statically included native + // libraries, but they may be cfg'd away with #[link(cfg(..))]. + // + // This unstable feature, though, only needs liblibc to work. The only + // use case there is where musl is statically included in liblibc.rlib, + // so if we don't want the included version we just need to skip it. As + // a result the logic here is that if *any* linked library is cfg'd away + // we just skip all object files. + // + // Clearly this is not sufficient for a general purpose feature, and + // we'd want to read from the library's metadata to determine which + // object files come from where and selectively skip them. + let skip_object_files = native_libs.iter().any(|lib| { + lib.kind == NativeLibraryKind::NativeStatic && !relevant_lib(sess, lib) + }); + ab.add_rlib(path, + &name.as_str(), + are_upstream_rust_objects_already_included(sess) && + !ignored_for_lto(sess, &codegen_results.crate_info, cnum), + skip_object_files).unwrap(); + + all_native_libs.extend(codegen_results.crate_info.native_libraries[&cnum].iter().cloned()); + }); + if let Err(e) = res { + sess.fatal(&e); + } + + ab.update_symbols(); + ab.build(); + + if !all_native_libs.is_empty() { + if sess.opts.prints.contains(&PrintRequest::NativeStaticLibs) { + print_native_static_libs(sess, &all_native_libs); + } + } +} + +// Create a dynamic library or executable +// +// This will invoke the system linker/cc to create the resulting file. This +// links to all upstream files as well. +fn link_natively<'a, B: ArchiveBuilder<'a>>(sess: &'a Session, + crate_type: config::CrateType, + out_filename: &Path, + codegen_results: &CodegenResults, + tmpdir: &Path, + target_cpu: &str) { + info!("preparing {:?} to {:?}", crate_type, out_filename); + let (linker, flavor) = linker_and_flavor(sess); + + // The invocations of cc share some flags across platforms + let (pname, mut cmd) = get_linker(sess, &linker, flavor); + + if let Some(args) = sess.target.target.options.pre_link_args.get(&flavor) { + cmd.args(args); + } + if let Some(args) = sess.target.target.options.pre_link_args_crt.get(&flavor) { + if sess.crt_static() { + cmd.args(args); + } + } + if let Some(ref args) = sess.opts.debugging_opts.pre_link_args { + cmd.args(args); + } + cmd.args(&sess.opts.debugging_opts.pre_link_arg); + + if sess.target.target.options.is_like_fuchsia { + let prefix = match sess.opts.debugging_opts.sanitizer { + Some(Sanitizer::Address) => "asan/", + _ => "", + }; + cmd.arg(format!("--dynamic-linker={}ld.so.1", prefix)); + } + + let pre_link_objects = if crate_type == config::CrateType::Executable { + &sess.target.target.options.pre_link_objects_exe + } else { + &sess.target.target.options.pre_link_objects_dll + }; + for obj in pre_link_objects { + cmd.arg(get_file_path(sess, obj)); + } + + if crate_type == config::CrateType::Executable && sess.crt_static() { + for obj in &sess.target.target.options.pre_link_objects_exe_crt { + cmd.arg(get_file_path(sess, obj)); + } + } + + if sess.target.target.options.is_like_emscripten { + cmd.arg("-s"); + cmd.arg(if sess.panic_strategy() == PanicStrategy::Abort { + "DISABLE_EXCEPTION_CATCHING=1" + } else { + "DISABLE_EXCEPTION_CATCHING=0" + }); + } + + { + let mut linker = codegen_results.linker_info.to_linker(cmd, &sess, flavor, target_cpu); + link_args::(&mut *linker, flavor, sess, crate_type, tmpdir, + out_filename, codegen_results); + cmd = linker.finalize(); + } + if let Some(args) = sess.target.target.options.late_link_args.get(&flavor) { + cmd.args(args); + } + for obj in &sess.target.target.options.post_link_objects { + cmd.arg(get_file_path(sess, obj)); + } + if sess.crt_static() { + for obj in &sess.target.target.options.post_link_objects_crt { + cmd.arg(get_file_path(sess, obj)); + } + } + if let Some(args) = sess.target.target.options.post_link_args.get(&flavor) { + cmd.args(args); + } + for &(ref k, ref v) in &sess.target.target.options.link_env { + cmd.env(k, v); + } + + if sess.opts.debugging_opts.print_link_args { + println!("{:?}", &cmd); + } + + // May have not found libraries in the right formats. + sess.abort_if_errors(); + + // Invoke the system linker + // + // Note that there's a terribly awful hack that really shouldn't be present + // in any compiler. Here an environment variable is supported to + // automatically retry the linker invocation if the linker looks like it + // segfaulted. + // + // Gee that seems odd, normally segfaults are things we want to know about! + // Unfortunately though in rust-lang/rust#38878 we're experiencing the + // linker segfaulting on Travis quite a bit which is causing quite a bit of + // pain to land PRs when they spuriously fail due to a segfault. + // + // The issue #38878 has some more debugging information on it as well, but + // this unfortunately looks like it's just a race condition in macOS's linker + // with some thread pool working in the background. It seems that no one + // currently knows a fix for this so in the meantime we're left with this... + info!("{:?}", &cmd); + let retry_on_segfault = env::var("RUSTC_RETRY_LINKER_ON_SEGFAULT").is_ok(); + let mut prog; + let mut i = 0; + loop { + i += 1; + prog = time(sess, "running linker", || { + exec_linker(sess, &mut cmd, out_filename, tmpdir) + }); + let output = match prog { + Ok(ref output) => output, + Err(_) => break, + }; + if output.status.success() { + break + } + let mut out = output.stderr.clone(); + out.extend(&output.stdout); + let out = String::from_utf8_lossy(&out); + + // Check to see if the link failed with "unrecognized command line option: + // '-no-pie'" for gcc or "unknown argument: '-no-pie'" for clang. If so, + // reperform the link step without the -no-pie option. This is safe because + // if the linker doesn't support -no-pie then it should not default to + // linking executables as pie. Different versions of gcc seem to use + // different quotes in the error message so don't check for them. + if sess.target.target.options.linker_is_gnu && + flavor != LinkerFlavor::Ld && + (out.contains("unrecognized command line option") || + out.contains("unknown argument")) && + out.contains("-no-pie") && + cmd.get_args().iter().any(|e| e.to_string_lossy() == "-no-pie") { + info!("linker output: {:?}", out); + warn!("Linker does not support -no-pie command line option. Retrying without."); + for arg in cmd.take_args() { + if arg.to_string_lossy() != "-no-pie" { + cmd.arg(arg); + } + } + info!("{:?}", &cmd); + continue; + } + if !retry_on_segfault || i > 3 { + break + } + let msg_segv = "clang: error: unable to execute command: Segmentation fault: 11"; + let msg_bus = "clang: error: unable to execute command: Bus error: 10"; + if !(out.contains(msg_segv) || out.contains(msg_bus)) { + break + } + + warn!( + "looks like the linker segfaulted when we tried to call it, \ + automatically retrying again. cmd = {:?}, out = {}.", + cmd, + out, + ); + } + + match prog { + Ok(prog) => { + fn escape_string(s: &[u8]) -> String { + str::from_utf8(s).map(|s| s.to_owned()) + .unwrap_or_else(|_| { + let mut x = "Non-UTF-8 output: ".to_string(); + x.extend(s.iter() + .flat_map(|&b| ascii::escape_default(b)) + .map(char::from)); + x + }) + } + if !prog.status.success() { + let mut output = prog.stderr.clone(); + output.extend_from_slice(&prog.stdout); + sess.struct_err(&format!("linking with `{}` failed: {}", + pname.display(), + prog.status)) + .note(&format!("{:?}", &cmd)) + .note(&escape_string(&output)) + .emit(); + sess.abort_if_errors(); + } + info!("linker stderr:\n{}", escape_string(&prog.stderr)); + info!("linker stdout:\n{}", escape_string(&prog.stdout)); + }, + Err(e) => { + let linker_not_found = e.kind() == io::ErrorKind::NotFound; + + let mut linker_error = { + if linker_not_found { + sess.struct_err(&format!("linker `{}` not found", pname.display())) + } else { + sess.struct_err(&format!("could not exec the linker `{}`", pname.display())) + } + }; + + linker_error.note(&e.to_string()); + + if !linker_not_found { + linker_error.note(&format!("{:?}", &cmd)); + } + + linker_error.emit(); + + if sess.target.target.options.is_like_msvc && linker_not_found { + sess.note_without_error("the msvc targets depend on the msvc linker \ + but `link.exe` was not found"); + sess.note_without_error("please ensure that VS 2013, VS 2015 or VS 2017 \ + was installed with the Visual C++ option"); + } + sess.abort_if_errors(); + } + } + + + // On macOS, debuggers need this utility to get run to do some munging of + // the symbols. Note, though, that if the object files are being preserved + // for their debug information there's no need for us to run dsymutil. + if sess.target.target.options.is_like_osx && + sess.opts.debuginfo != DebugInfo::None && + !preserve_objects_for_their_debuginfo(sess) + { + if let Err(e) = Command::new("dsymutil").arg(out_filename).output() { + sess.fatal(&format!("failed to run dsymutil: {}", e)) + } + } + + if sess.opts.target_triple.triple() == "wasm32-unknown-unknown" { + super::wasm::add_producer_section( + &out_filename, + &sess.edition().to_string(), + option_env!("CFG_VERSION").unwrap_or("unknown"), + ); + } +} + /// Returns a boolean indicating whether the specified crate should be ignored /// during LTO. /// @@ -258,7 +824,7 @@ pub fn archive_search_paths(sess: &Session) -> Vec { sess.target_filesearch(PathKind::Native).search_path_dirs() } -pub enum RlibFlavor { +enum RlibFlavor { Normal, StaticlibBase, } @@ -451,6 +1017,209 @@ pub fn exec_linker(sess: &Session, cmd: &mut Command, out_filename: &Path, tmpdi } } +fn link_args<'a, B: ArchiveBuilder<'a>>(cmd: &mut dyn Linker, + flavor: LinkerFlavor, + sess: &'a Session, + crate_type: config::CrateType, + tmpdir: &Path, + out_filename: &Path, + codegen_results: &CodegenResults) { + + // Linker plugins should be specified early in the list of arguments + cmd.linker_plugin_lto(); + + // The default library location, we need this to find the runtime. + // The location of crates will be determined as needed. + let lib_path = sess.target_filesearch(PathKind::All).get_lib_path(); + + // target descriptor + let t = &sess.target.target; + + cmd.include_path(&fix_windows_verbatim_for_gcc(&lib_path)); + for obj in codegen_results.modules.iter().filter_map(|m| m.object.as_ref()) { + cmd.add_object(obj); + } + cmd.output_filename(out_filename); + + if crate_type == config::CrateType::Executable && + sess.target.target.options.is_like_windows { + if let Some(ref s) = codegen_results.windows_subsystem { + cmd.subsystem(s); + } + } + + // If we're building a dynamic library then some platforms need to make sure + // that all symbols are exported correctly from the dynamic library. + if crate_type != config::CrateType::Executable || + sess.target.target.options.is_like_emscripten { + cmd.export_symbols(tmpdir, crate_type); + } + + // When linking a dynamic library, we put the metadata into a section of the + // executable. This metadata is in a separate object file from the main + // object file, so we link that in here. + if crate_type == config::CrateType::Dylib || + crate_type == config::CrateType::ProcMacro { + if let Some(obj) = codegen_results.metadata_module.object.as_ref() { + cmd.add_object(obj); + } + } + + let obj = codegen_results.allocator_module + .as_ref() + .and_then(|m| m.object.as_ref()); + if let Some(obj) = obj { + cmd.add_object(obj); + } + + // Try to strip as much out of the generated object by removing unused + // sections if possible. See more comments in linker.rs + if !sess.opts.cg.link_dead_code { + let keep_metadata = crate_type == config::CrateType::Dylib; + cmd.gc_sections(keep_metadata); + } + + let used_link_args = &codegen_results.crate_info.link_args; + + if crate_type == config::CrateType::Executable { + let mut position_independent_executable = false; + + if t.options.position_independent_executables { + let empty_vec = Vec::new(); + let args = sess.opts.cg.link_args.as_ref().unwrap_or(&empty_vec); + let more_args = &sess.opts.cg.link_arg; + let mut args = args.iter().chain(more_args.iter()).chain(used_link_args.iter()); + + if is_pic(sess) && !sess.crt_static() && !args.any(|x| *x == "-static") { + position_independent_executable = true; + } + } + + if position_independent_executable { + cmd.position_independent_executable(); + } else { + // recent versions of gcc can be configured to generate position + // independent executables by default. We have to pass -no-pie to + // explicitly turn that off. Not applicable to ld. + if sess.target.target.options.linker_is_gnu + && flavor != LinkerFlavor::Ld { + cmd.no_position_independent_executable(); + } + } + } + + let relro_level = match sess.opts.debugging_opts.relro_level { + Some(level) => level, + None => t.options.relro_level, + }; + match relro_level { + RelroLevel::Full => { + cmd.full_relro(); + }, + RelroLevel::Partial => { + cmd.partial_relro(); + }, + RelroLevel::Off => { + cmd.no_relro(); + }, + RelroLevel::None => { + }, + } + + // Pass optimization flags down to the linker. + cmd.optimize(); + + // Pass debuginfo flags down to the linker. + cmd.debuginfo(); + + // We want to, by default, prevent the compiler from accidentally leaking in + // any system libraries, so we may explicitly ask linkers to not link to any + // libraries by default. Note that this does not happen for windows because + // windows pulls in some large number of libraries and I couldn't quite + // figure out which subset we wanted. + // + // This is all naturally configurable via the standard methods as well. + if !sess.opts.cg.default_linker_libraries.unwrap_or(false) && + t.options.no_default_libraries + { + cmd.no_default_libraries(); + } + + // Take careful note of the ordering of the arguments we pass to the linker + // here. Linkers will assume that things on the left depend on things to the + // right. Things on the right cannot depend on things on the left. This is + // all formally implemented in terms of resolving symbols (libs on the right + // resolve unknown symbols of libs on the left, but not vice versa). + // + // For this reason, we have organized the arguments we pass to the linker as + // such: + // + // 1. The local object that LLVM just generated + // 2. Local native libraries + // 3. Upstream rust libraries + // 4. Upstream native libraries + // + // The rationale behind this ordering is that those items lower down in the + // list can't depend on items higher up in the list. For example nothing can + // depend on what we just generated (e.g., that'd be a circular dependency). + // Upstream rust libraries are not allowed to depend on our local native + // libraries as that would violate the structure of the DAG, in that + // scenario they are required to link to them as well in a shared fashion. + // + // Note that upstream rust libraries may contain native dependencies as + // well, but they also can't depend on what we just started to add to the + // link line. And finally upstream native libraries can't depend on anything + // in this DAG so far because they're only dylibs and dylibs can only depend + // on other dylibs (e.g., other native deps). + add_local_native_libraries(cmd, sess, codegen_results); + add_upstream_rust_crates::(cmd, sess, codegen_results, crate_type, tmpdir); + add_upstream_native_libraries(cmd, sess, codegen_results, crate_type); + + // Tell the linker what we're doing. + if crate_type != config::CrateType::Executable { + cmd.build_dylib(out_filename); + } + if crate_type == config::CrateType::Executable && sess.crt_static() { + cmd.build_static_executable(); + } + + if sess.opts.debugging_opts.pgo_gen.enabled() { + cmd.pgo_gen(); + } + + // FIXME (#2397): At some point we want to rpath our guesses as to + // where extern libraries might live, based on the + // addl_lib_search_paths + if sess.opts.cg.rpath { + let target_triple = sess.opts.target_triple.triple(); + let mut get_install_prefix_lib_path = || { + let install_prefix = option_env!("CFG_PREFIX").expect("CFG_PREFIX"); + let tlib = filesearch::relative_target_lib_path(&sess.sysroot, target_triple); + let mut path = PathBuf::from(install_prefix); + path.push(&tlib); + + path + }; + let mut rpath_config = RPathConfig { + used_crates: &codegen_results.crate_info.used_crates_dynamic, + out_filename: out_filename.to_path_buf(), + has_rpath: sess.target.target.options.has_rpath, + is_like_osx: sess.target.target.options.is_like_osx, + linker_is_gnu: sess.target.target.options.linker_is_gnu, + get_install_prefix_lib_path: &mut get_install_prefix_lib_path, + }; + cmd.args(&rpath::get_rpath_flags(&mut rpath_config)); + } + + // Finally add all the linker arguments provided on the command line along + // with any #[link_args] attributes found inside the crate + if let Some(ref args) = sess.opts.cg.link_args { + cmd.args(args); + } + cmd.args(&sess.opts.cg.link_arg); + cmd.args(&used_link_args); +} + // # Native library linking // // User-supplied library search paths (-L on the command line). These are @@ -493,6 +1262,319 @@ pub fn add_local_native_libraries(cmd: &mut dyn Linker, } } +// # Rust Crate linking +// +// Rust crates are not considered at all when creating an rlib output. All +// dependencies will be linked when producing the final output (instead of +// the intermediate rlib version) +fn add_upstream_rust_crates<'a, B: ArchiveBuilder<'a>>(cmd: &mut dyn Linker, + sess: &'a Session, + codegen_results: &CodegenResults, + crate_type: config::CrateType, + tmpdir: &Path) { + // All of the heavy lifting has previously been accomplished by the + // dependency_format module of the compiler. This is just crawling the + // output of that module, adding crates as necessary. + // + // Linking to a rlib involves just passing it to the linker (the linker + // will slurp up the object files inside), and linking to a dynamic library + // involves just passing the right -l flag. + + let formats = sess.dependency_formats.borrow(); + let data = formats.get(&crate_type).unwrap(); + + // Invoke get_used_crates to ensure that we get a topological sorting of + // crates. + let deps = &codegen_results.crate_info.used_crates_dynamic; + + // There's a few internal crates in the standard library (aka libcore and + // libstd) which actually have a circular dependence upon one another. This + // currently arises through "weak lang items" where libcore requires things + // like `rust_begin_unwind` but libstd ends up defining it. To get this + // circular dependence to work correctly in all situations we'll need to be + // sure to correctly apply the `--start-group` and `--end-group` options to + // GNU linkers, otherwise if we don't use any other symbol from the standard + // library it'll get discarded and the whole application won't link. + // + // In this loop we're calculating the `group_end`, after which crate to + // pass `--end-group` and `group_start`, before which crate to pass + // `--start-group`. We currently do this by passing `--end-group` after + // the first crate (when iterating backwards) that requires a lang item + // defined somewhere else. Once that's set then when we've defined all the + // necessary lang items we'll pass `--start-group`. + // + // Note that this isn't amazing logic for now but it should do the trick + // for the current implementation of the standard library. + let mut group_end = None; + let mut group_start = None; + let mut end_with = FxHashSet::default(); + let info = &codegen_results.crate_info; + for &(cnum, _) in deps.iter().rev() { + if let Some(missing) = info.missing_lang_items.get(&cnum) { + end_with.extend(missing.iter().cloned()); + if end_with.len() > 0 && group_end.is_none() { + group_end = Some(cnum); + } + } + end_with.retain(|item| info.lang_item_to_crate.get(item) != Some(&cnum)); + if end_with.len() == 0 && group_end.is_some() { + group_start = Some(cnum); + break + } + } + + // If we didn't end up filling in all lang items from upstream crates then + // we'll be filling it in with our crate. This probably means we're the + // standard library itself, so skip this for now. + if group_end.is_some() && group_start.is_none() { + group_end = None; + } + + let mut compiler_builtins = None; + + for &(cnum, _) in deps.iter() { + if group_start == Some(cnum) { + cmd.group_start(); + } + + // We may not pass all crates through to the linker. Some crates may + // appear statically in an existing dylib, meaning we'll pick up all the + // symbols from the dylib. + let src = &codegen_results.crate_info.used_crate_source[&cnum]; + match data[cnum.as_usize() - 1] { + _ if codegen_results.crate_info.profiler_runtime == Some(cnum) => { + add_static_crate::(cmd, sess, codegen_results, tmpdir, crate_type, cnum); + } + _ if codegen_results.crate_info.sanitizer_runtime == Some(cnum) => { + link_sanitizer_runtime::(cmd, sess, codegen_results, tmpdir, cnum); + } + // compiler-builtins are always placed last to ensure that they're + // linked correctly. + _ if codegen_results.crate_info.compiler_builtins == Some(cnum) => { + assert!(compiler_builtins.is_none()); + compiler_builtins = Some(cnum); + } + Linkage::NotLinked | + Linkage::IncludedFromDylib => {} + Linkage::Static => { + add_static_crate::(cmd, sess, codegen_results, tmpdir, crate_type, cnum); + } + Linkage::Dynamic => { + add_dynamic_crate(cmd, sess, &src.dylib.as_ref().unwrap().0) + } + } + + if group_end == Some(cnum) { + cmd.group_end(); + } + } + + // compiler-builtins are always placed last to ensure that they're + // linked correctly. + // We must always link the `compiler_builtins` crate statically. Even if it + // was already "included" in a dylib (e.g., `libstd` when `-C prefer-dynamic` + // is used) + if let Some(cnum) = compiler_builtins { + add_static_crate::(cmd, sess, codegen_results, tmpdir, crate_type, cnum); + } + + // Converts a library file-stem into a cc -l argument + fn unlib<'a>(config: &config::Config, stem: &'a str) -> &'a str { + if stem.starts_with("lib") && !config.target.options.is_like_windows { + &stem[3..] + } else { + stem + } + } + + // We must link the sanitizer runtime using -Wl,--whole-archive but since + // it's packed in a .rlib, it contains stuff that are not objects that will + // make the linker error. So we must remove those bits from the .rlib before + // linking it. + fn link_sanitizer_runtime<'a, B: ArchiveBuilder<'a>>(cmd: &mut dyn Linker, + sess: &'a Session, + codegen_results: &CodegenResults, + tmpdir: &Path, + cnum: CrateNum) { + let src = &codegen_results.crate_info.used_crate_source[&cnum]; + let cratepath = &src.rlib.as_ref().unwrap().0; + + if sess.target.target.options.is_like_osx { + // On Apple platforms, the sanitizer is always built as a dylib, and + // LLVM will link to `@rpath/*.dylib`, so we need to specify an + // rpath to the library as well (the rpath should be absolute, see + // PR #41352 for details). + // + // FIXME: Remove this logic into librustc_*san once Cargo supports it + let rpath = cratepath.parent().unwrap(); + let rpath = rpath.to_str().expect("non-utf8 component in path"); + cmd.args(&["-Wl,-rpath".into(), "-Xlinker".into(), rpath.into()]); + } + + let dst = tmpdir.join(cratepath.file_name().unwrap()); + let mut archive = ::new(sess, &dst, Some(cratepath)); + archive.update_symbols(); + + for f in archive.src_files() { + if f.ends_with(RLIB_BYTECODE_EXTENSION) || f == METADATA_FILENAME { + archive.remove_file(&f); + } + } + + archive.build(); + + cmd.link_whole_rlib(&dst); + } + + // Adds the static "rlib" versions of all crates to the command line. + // There's a bit of magic which happens here specifically related to LTO and + // dynamic libraries. Specifically: + // + // * For LTO, we remove upstream object files. + // * For dylibs we remove metadata and bytecode from upstream rlibs + // + // When performing LTO, almost(*) all of the bytecode from the upstream + // libraries has already been included in our object file output. As a + // result we need to remove the object files in the upstream libraries so + // the linker doesn't try to include them twice (or whine about duplicate + // symbols). We must continue to include the rest of the rlib, however, as + // it may contain static native libraries which must be linked in. + // + // (*) Crates marked with `#![no_builtins]` don't participate in LTO and + // their bytecode wasn't included. The object files in those libraries must + // still be passed to the linker. + // + // When making a dynamic library, linkers by default don't include any + // object files in an archive if they're not necessary to resolve the link. + // We basically want to convert the archive (rlib) to a dylib, though, so we + // *do* want everything included in the output, regardless of whether the + // linker thinks it's needed or not. As a result we must use the + // --whole-archive option (or the platform equivalent). When using this + // option the linker will fail if there are non-objects in the archive (such + // as our own metadata and/or bytecode). All in all, for rlibs to be + // entirely included in dylibs, we need to remove all non-object files. + // + // Note, however, that if we're not doing LTO or we're not producing a dylib + // (aka we're making an executable), we can just pass the rlib blindly to + // the linker (fast) because it's fine if it's not actually included as + // we're at the end of the dependency chain. + fn add_static_crate<'a, B: ArchiveBuilder<'a>>(cmd: &mut dyn Linker, + sess: &'a Session, + codegen_results: &CodegenResults, + tmpdir: &Path, + crate_type: config::CrateType, + cnum: CrateNum) { + let src = &codegen_results.crate_info.used_crate_source[&cnum]; + let cratepath = &src.rlib.as_ref().unwrap().0; + + // See the comment above in `link_staticlib` and `link_rlib` for why if + // there's a static library that's not relevant we skip all object + // files. + let native_libs = &codegen_results.crate_info.native_libraries[&cnum]; + let skip_native = native_libs.iter().any(|lib| { + lib.kind == NativeLibraryKind::NativeStatic && !relevant_lib(sess, lib) + }); + + if (!are_upstream_rust_objects_already_included(sess) || + ignored_for_lto(sess, &codegen_results.crate_info, cnum)) && + crate_type != config::CrateType::Dylib && + !skip_native { + cmd.link_rlib(&fix_windows_verbatim_for_gcc(cratepath)); + return + } + + let dst = tmpdir.join(cratepath.file_name().unwrap()); + let name = cratepath.file_name().unwrap().to_str().unwrap(); + let name = &name[3..name.len() - 5]; // chop off lib/.rlib + + time_ext(sess.time_extended(), Some(sess), &format!("altering {}.rlib", name), || { + let mut archive = ::new(sess, &dst, Some(cratepath)); + archive.update_symbols(); + + let mut any_objects = false; + for f in archive.src_files() { + if f.ends_with(RLIB_BYTECODE_EXTENSION) || f == METADATA_FILENAME { + archive.remove_file(&f); + continue + } + + let canonical = f.replace("-", "_"); + let canonical_name = name.replace("-", "_"); + + // Look for `.rcgu.o` at the end of the filename to conclude + // that this is a Rust-related object file. + fn looks_like_rust(s: &str) -> bool { + let path = Path::new(s); + let ext = path.extension().and_then(|s| s.to_str()); + if ext != Some(OutputType::Object.extension()) { + return false + } + let ext2 = path.file_stem() + .and_then(|s| Path::new(s).extension()) + .and_then(|s| s.to_str()); + ext2 == Some(RUST_CGU_EXT) + } + + let is_rust_object = + canonical.starts_with(&canonical_name) && + looks_like_rust(&f); + + // If we've been requested to skip all native object files + // (those not generated by the rust compiler) then we can skip + // this file. See above for why we may want to do this. + let skip_because_cfg_say_so = skip_native && !is_rust_object; + + // If we're performing LTO and this is a rust-generated object + // file, then we don't need the object file as it's part of the + // LTO module. Note that `#![no_builtins]` is excluded from LTO, + // though, so we let that object file slide. + let skip_because_lto = are_upstream_rust_objects_already_included(sess) && + is_rust_object && + (sess.target.target.options.no_builtins || + !codegen_results.crate_info.is_no_builtins.contains(&cnum)); + + if skip_because_cfg_say_so || skip_because_lto { + archive.remove_file(&f); + } else { + any_objects = true; + } + } + + if !any_objects { + return + } + archive.build(); + + // If we're creating a dylib, then we need to include the + // whole of each object in our archive into that artifact. This is + // because a `dylib` can be reused as an intermediate artifact. + // + // Note, though, that we don't want to include the whole of a + // compiler-builtins crate (e.g., compiler-rt) because it'll get + // repeatedly linked anyway. + if crate_type == config::CrateType::Dylib && + codegen_results.crate_info.compiler_builtins != Some(cnum) { + cmd.link_whole_rlib(&fix_windows_verbatim_for_gcc(&dst)); + } else { + cmd.link_rlib(&fix_windows_verbatim_for_gcc(&dst)); + } + }); + } + + // Same thing as above, but for dynamic crates instead of static crates. + fn add_dynamic_crate(cmd: &mut dyn Linker, sess: &Session, cratepath: &Path) { + // Just need to tell the linker about where the library lives and + // what its name is + let parent = cratepath.parent(); + if let Some(dir) = parent { + cmd.include_path(&fix_windows_verbatim_for_gcc(dir)); + } + let filestem = cratepath.file_stem().unwrap().to_str().unwrap(); + cmd.link_rust_dylib(&unlib(&sess.target, filestem), + parent.unwrap_or(Path::new(""))); + } +} + // Link in all of our upstream crates' native dependencies. Remember that // all of these upstream native dependencies are all non-static // dependencies. We've got two cases then: @@ -577,3 +1659,12 @@ pub fn are_upstream_rust_objects_already_included(sess: &Session) -> bool { config::Lto::ThinLocal => false, } } + +fn is_pic(sess: &Session) -> bool { + let reloc_model_arg = match sess.opts.cg.relocation_model { + Some(ref s) => &s[..], + None => &sess.target.target.options.relocation_model[..], + }; + + reloc_model_arg == "pic" +} diff --git a/src/librustc_codegen_ssa/back/mod.rs b/src/librustc_codegen_ssa/back/mod.rs index 888108408fb..a16d099ee3e 100644 --- a/src/librustc_codegen_ssa/back/mod.rs +++ b/src/librustc_codegen_ssa/back/mod.rs @@ -5,3 +5,5 @@ pub mod link; pub mod command; pub mod symbol_export; pub mod archive; +pub mod rpath; +pub mod wasm; diff --git a/src/librustc_codegen_llvm/back/rpath.rs b/src/librustc_codegen_ssa/back/rpath.rs similarity index 100% rename from src/librustc_codegen_llvm/back/rpath.rs rename to src/librustc_codegen_ssa/back/rpath.rs diff --git a/src/librustc_codegen_llvm/back/wasm.rs b/src/librustc_codegen_ssa/back/wasm.rs similarity index 100% rename from src/librustc_codegen_llvm/back/wasm.rs rename to src/librustc_codegen_ssa/back/wasm.rs