1 // Copyright 2012-2014 The Rust Project Developers. See the COPYRIGHT
2 // file at the top-level directory of this distribution and at
3 // http://rust-lang.org/COPYRIGHT.
5 // Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
6 // http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
7 // <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
8 // option. This file may not be copied, modified, or distributed
9 // except according to those terms.
11 extern crate rustc_trans_utils;
13 use super::archive::{ArchiveBuilder, ArchiveConfig};
14 use super::linker::Linker;
15 use super::rpath::RPathConfig;
17 use metadata::METADATA_FILENAME;
18 use rustc::session::config::{self, NoDebugInfo, OutputFilenames, OutputType, PrintRequest};
19 use rustc::session::filesearch;
20 use rustc::session::search_paths::PathKind;
21 use rustc::session::Session;
22 use rustc::middle::cstore::{LinkMeta, NativeLibrary, LibSource, LinkagePreference,
24 use rustc::middle::dependency_format::Linkage;
25 use {CrateTranslation, CrateInfo};
26 use rustc::util::common::time;
27 use rustc::util::fs::fix_windows_verbatim_for_gcc;
28 use rustc::dep_graph::{DepKind, DepNode};
29 use rustc::hir::def_id::CrateNum;
30 use rustc::hir::svh::Svh;
31 use rustc_back::tempdir::TempDir;
32 use rustc_back::{PanicStrategy, RelroLevel};
33 use rustc_incremental::IncrementalHashesMap;
34 use context::get_reloc_model;
40 use std::ffi::OsString;
42 use std::io::{self, Read, Write};
44 use std::path::{Path, PathBuf};
45 use std::process::Command;
47 use flate2::Compression;
48 use flate2::write::DeflateEncoder;
51 /// The LLVM module name containing crate-metadata. This includes a `.` on
52 /// purpose, so it cannot clash with the name of a user-defined module.
53 pub const METADATA_MODULE_NAME: &'static str = "crate.metadata";
54 /// The name of the crate-metadata object file the compiler generates. Must
55 /// match up with `METADATA_MODULE_NAME`.
56 pub const METADATA_OBJ_NAME: &'static str = "crate.metadata.o";
58 // same as for metadata above, but for allocator shim
59 pub const ALLOCATOR_MODULE_NAME: &'static str = "crate.allocator";
60 pub const ALLOCATOR_OBJ_NAME: &'static str = "crate.allocator.o";
62 // RLIB LLVM-BYTECODE OBJECT LAYOUT
65 // 0..10 "RUST_OBJECT" encoded in ASCII
66 // 11..14 format version as little-endian u32
67 // 15..22 size in bytes of deflate compressed LLVM bitcode as
69 // 23.. compressed LLVM bitcode
71 // This is the "magic number" expected at the beginning of a LLVM bytecode
73 pub const RLIB_BYTECODE_OBJECT_MAGIC: &'static [u8] = b"RUST_OBJECT";
75 // The version number this compiler will write to bytecode objects in rlibs
76 pub const RLIB_BYTECODE_OBJECT_VERSION: u32 = 1;
78 // The offset in bytes the bytecode object format version number can be found at
79 pub const RLIB_BYTECODE_OBJECT_VERSION_OFFSET: usize = 11;
81 // The offset in bytes the size of the compressed bytecode can be found at in
83 pub const RLIB_BYTECODE_OBJECT_V1_DATASIZE_OFFSET: usize =
84 RLIB_BYTECODE_OBJECT_VERSION_OFFSET + 4;
86 // The offset in bytes the compressed LLVM bytecode can be found at in format
88 pub const RLIB_BYTECODE_OBJECT_V1_DATA_OFFSET: usize =
89 RLIB_BYTECODE_OBJECT_V1_DATASIZE_OFFSET + 8;
91 pub use self::rustc_trans_utils::link::{find_crate_name, filename_for_input,
92 default_output_for_target, invalid_output_for_target};
94 pub fn build_link_meta(incremental_hashes_map: &IncrementalHashesMap) -> LinkMeta {
95 let krate_dep_node = &DepNode::new_no_params(DepKind::Krate);
97 crate_hash: Svh::new(incremental_hashes_map[krate_dep_node].to_smaller_hash()),
103 // The third parameter is for env vars, used on windows to set up the
104 // path for MSVC to find its DLLs, and gcc to find its bundled
106 pub fn get_linker(sess: &Session) -> (String, Command, Vec<(OsString, OsString)>) {
107 let envs = vec![("PATH".into(), command_path(sess))];
109 if let Some(ref linker) = sess.opts.cg.linker {
110 (linker.clone(), Command::new(linker), envs)
111 } else if sess.target.target.options.is_like_msvc {
112 let (cmd, envs) = msvc_link_exe_cmd(sess);
113 ("link.exe".to_string(), cmd, envs)
115 let linker = &sess.target.target.options.linker;
116 (linker.clone(), Command::new(&linker), envs)
121 pub fn msvc_link_exe_cmd(sess: &Session) -> (Command, Vec<(OsString, OsString)>) {
122 use gcc::windows_registry;
124 let target = &sess.opts.target_triple;
125 let tool = windows_registry::find_tool(target, "link.exe");
127 if let Some(tool) = tool {
128 let envs = tool.env().to_vec();
129 (tool.to_command(), envs)
131 debug!("Failed to locate linker.");
132 (Command::new("link.exe"), vec![])
137 pub fn msvc_link_exe_cmd(_sess: &Session) -> (Command, Vec<(OsString, OsString)>) {
138 (Command::new("link.exe"), vec![])
141 fn command_path(sess: &Session) -> OsString {
142 // The compiler's sysroot often has some bundled tools, so add it to the
143 // PATH for the child.
144 let mut new_path = sess.host_filesearch(PathKind::All)
145 .get_tools_search_paths();
146 if let Some(path) = env::var_os("PATH") {
147 new_path.extend(env::split_paths(&path));
149 env::join_paths(new_path).unwrap()
152 pub fn remove(sess: &Session, path: &Path) {
153 match fs::remove_file(path) {
156 sess.err(&format!("failed to remove {}: {}",
163 /// Perform the linkage portion of the compilation phase. This will generate all
164 /// of the requested outputs for this compilation session.
165 pub fn link_binary(sess: &Session,
166 trans: &CrateTranslation,
167 outputs: &OutputFilenames,
168 crate_name: &str) -> Vec<PathBuf> {
169 let mut out_filenames = Vec::new();
170 for &crate_type in sess.crate_types.borrow().iter() {
171 // Ignore executable crates if we have -Z no-trans, as they will error.
172 if (sess.opts.debugging_opts.no_trans ||
173 !sess.opts.output_types.should_trans()) &&
174 crate_type == config::CrateTypeExecutable {
178 if invalid_output_for_target(sess, crate_type) {
179 bug!("invalid output type `{:?}` for target os `{}`",
180 crate_type, sess.opts.target_triple);
182 let mut out_files = link_binary_output(sess, trans, crate_type, outputs, crate_name);
183 out_filenames.append(&mut out_files);
186 // Remove the temporary object file and metadata if we aren't saving temps
187 if !sess.opts.cg.save_temps {
188 if sess.opts.output_types.should_trans() {
189 for obj in object_filenames(trans, outputs) {
193 remove(sess, &outputs.with_extension(METADATA_OBJ_NAME));
194 if trans.allocator_module.is_some() {
195 remove(sess, &outputs.with_extension(ALLOCATOR_OBJ_NAME));
202 fn is_writeable(p: &Path) -> bool {
205 Ok(m) => !m.permissions().readonly()
209 fn filename_for_metadata(sess: &Session, crate_name: &str, outputs: &OutputFilenames) -> PathBuf {
210 let out_filename = outputs.single_output_file.clone()
213 .join(&format!("lib{}{}.rmeta", crate_name, sess.opts.cg.extra_filename)));
214 check_file_is_writeable(&out_filename, sess);
218 pub fn each_linked_rlib(sess: &Session,
219 f: &mut FnMut(CrateNum, &Path)) -> Result<(), String> {
220 let crates = sess.cstore.used_crates(LinkagePreference::RequireStatic).into_iter();
221 let fmts = sess.dependency_formats.borrow();
222 let fmts = fmts.get(&config::CrateTypeExecutable)
223 .or_else(|| fmts.get(&config::CrateTypeStaticlib))
224 .or_else(|| fmts.get(&config::CrateTypeCdylib))
225 .or_else(|| fmts.get(&config::CrateTypeProcMacro));
226 let fmts = match fmts {
228 None => return Err(format!("could not find formats for rlibs"))
230 for (cnum, path) in crates {
231 match fmts.get(cnum.as_usize() - 1) {
232 Some(&Linkage::NotLinked) |
233 Some(&Linkage::IncludedFromDylib) => continue,
235 None => return Err(format!("could not find formats for rlibs"))
237 let name = sess.cstore.crate_name(cnum).clone();
238 let path = match path {
239 LibSource::Some(p) => p,
240 LibSource::MetadataOnly => {
241 return Err(format!("could not find rlib for: `{}`, found rmeta (metadata) file",
245 return Err(format!("could not find rlib for: `{}`", name))
253 /// Returns a boolean indicating whether the specified crate should be ignored
256 /// Crates ignored during LTO are not lumped together in the "massive object
257 /// file" that we create and are linked in their normal rlib states. See
258 /// comments below for what crates do not participate in LTO.
260 /// It's unusual for a crate to not participate in LTO. Typically only
261 /// compiler-specific and unstable crates have a reason to not participate in
263 pub fn ignored_for_lto(info: &CrateInfo, cnum: CrateNum) -> bool {
264 // `#![no_builtins]` crates don't participate in LTO because the state
265 // of builtins gets messed up (our crate isn't tagged with no builtins).
266 // Similarly `#![compiler_builtins]` doesn't participate because we want
268 info.is_no_builtins.contains(&cnum) || info.compiler_builtins == Some(cnum)
271 fn out_filename(sess: &Session,
272 crate_type: config::CrateType,
273 outputs: &OutputFilenames,
276 let default_filename = filename_for_input(sess, crate_type, crate_name, outputs);
277 let out_filename = outputs.outputs.get(&OutputType::Exe)
278 .and_then(|s| s.to_owned())
279 .or_else(|| outputs.single_output_file.clone())
280 .unwrap_or(default_filename);
282 check_file_is_writeable(&out_filename, sess);
287 // Make sure files are writeable. Mac, FreeBSD, and Windows system linkers
288 // check this already -- however, the Linux linker will happily overwrite a
289 // read-only file. We should be consistent.
290 fn check_file_is_writeable(file: &Path, sess: &Session) {
291 if !is_writeable(file) {
292 sess.fatal(&format!("output file {} is not writeable -- check its \
293 permissions", file.display()));
297 fn link_binary_output(sess: &Session,
298 trans: &CrateTranslation,
299 crate_type: config::CrateType,
300 outputs: &OutputFilenames,
301 crate_name: &str) -> Vec<PathBuf> {
302 let objects = object_filenames(trans, outputs);
304 for file in &objects {
305 check_file_is_writeable(file, sess);
308 let tmpdir = match TempDir::new("rustc") {
309 Ok(tmpdir) => tmpdir,
310 Err(err) => sess.fatal(&format!("couldn't create a temp dir: {}", err)),
313 let mut out_filenames = vec![];
315 if outputs.outputs.contains_key(&OutputType::Metadata) {
316 let out_filename = filename_for_metadata(sess, crate_name, outputs);
317 emit_metadata(sess, trans, &out_filename);
318 out_filenames.push(out_filename);
321 if outputs.outputs.should_trans() {
322 let out_filename = out_filename(sess, crate_type, outputs, crate_name);
324 config::CrateTypeRlib => {
331 tmpdir.path()).build();
333 config::CrateTypeStaticlib => {
342 link_natively(sess, crate_type, &objects, &out_filename, trans,
343 outputs, tmpdir.path());
346 out_filenames.push(out_filename);
349 if sess.opts.cg.save_temps {
350 let _ = tmpdir.into_path();
356 fn object_filenames(trans: &CrateTranslation,
357 outputs: &OutputFilenames)
359 trans.modules.iter().map(|module| {
360 outputs.temp_path(OutputType::Object, Some(&module.name))
364 fn archive_search_paths(sess: &Session) -> Vec<PathBuf> {
365 let mut search = Vec::new();
366 sess.target_filesearch(PathKind::Native).for_each_lib_search_path(|path, _| {
367 search.push(path.to_path_buf());
372 fn archive_config<'a>(sess: &'a Session,
374 input: Option<&Path>) -> ArchiveConfig<'a> {
377 dst: output.to_path_buf(),
378 src: input.map(|p| p.to_path_buf()),
379 lib_search_paths: archive_search_paths(sess),
383 fn emit_metadata<'a>(sess: &'a Session, trans: &CrateTranslation, out_filename: &Path) {
384 let result = fs::File::create(out_filename).and_then(|mut f| {
385 f.write_all(&trans.metadata.raw_data)
388 if let Err(e) = result {
389 sess.fatal(&format!("failed to write {}: {}", out_filename.display(), e));
400 // An rlib in its current incarnation is essentially a renamed .a file. The
401 // rlib primarily contains the object file of the crate, but it also contains
402 // all of the object files from native libraries. This is done by unzipping
403 // native libraries and inserting all of the contents into this archive.
404 fn link_rlib<'a>(sess: &'a Session,
405 trans: &CrateTranslation,
408 outputs: &OutputFilenames,
410 tmpdir: &Path) -> ArchiveBuilder<'a> {
411 info!("preparing rlib from {:?} to {:?}", objects, out_filename);
412 let mut ab = ArchiveBuilder::new(archive_config(sess, out_filename, None));
418 // Note that in this loop we are ignoring the value of `lib.cfg`. That is,
419 // we may not be configured to actually include a static library if we're
420 // adding it here. That's because later when we consume this rlib we'll
421 // decide whether we actually needed the static library or not.
423 // To do this "correctly" we'd need to keep track of which libraries added
424 // which object files to the archive. We don't do that here, however. The
425 // #[link(cfg(..))] feature is unstable, though, and only intended to get
426 // liblibc working. In that sense the check below just indicates that if
427 // there are any libraries we want to omit object files for at link time we
428 // just exclude all custom object files.
430 // Eventually if we want to stabilize or flesh out the #[link(cfg(..))]
431 // feature then we'll need to figure out how to record what objects were
432 // loaded from the libraries found here and then encode that into the
433 // metadata of the rlib we're generating somehow.
434 for lib in sess.cstore.used_libraries() {
436 NativeLibraryKind::NativeStatic => {}
437 NativeLibraryKind::NativeStaticNobundle |
438 NativeLibraryKind::NativeFramework |
439 NativeLibraryKind::NativeUnknown => continue,
441 ab.add_native_library(&lib.name.as_str());
444 // After adding all files to the archive, we need to update the
445 // symbol table of the archive.
448 // Note that it is important that we add all of our non-object "magical
449 // files" *after* all of the object files in the archive. The reason for
450 // this is as follows:
452 // * When performing LTO, this archive will be modified to remove
453 // objects from above. The reason for this is described below.
455 // * When the system linker looks at an archive, it will attempt to
456 // determine the architecture of the archive in order to see whether its
459 // The algorithm for this detection is: iterate over the files in the
460 // archive. Skip magical SYMDEF names. Interpret the first file as an
461 // object file. Read architecture from the object file.
463 // * As one can probably see, if "metadata" and "foo.bc" were placed
464 // before all of the objects, then the architecture of this archive would
465 // not be correctly inferred once 'foo.o' is removed.
467 // Basically, all this means is that this code should not move above the
470 RlibFlavor::Normal => {
471 // Instead of putting the metadata in an object file section, rlibs
472 // contain the metadata in a separate file. We use a temp directory
473 // here so concurrent builds in the same directory don't try to use
474 // the same filename for metadata (stomping over one another)
475 let metadata = tmpdir.join(METADATA_FILENAME);
476 emit_metadata(sess, trans, &metadata);
477 ab.add_file(&metadata);
479 // For LTO purposes, the bytecode of this library is also inserted
480 // into the archive. If codegen_units > 1, we insert each of the
483 // Note that we make sure that the bytecode filename in the
484 // archive is never exactly 16 bytes long by adding a 16 byte
485 // extension to it. This is to work around a bug in LLDB that
486 // would cause it to crash if the name of a file in an archive
487 // was exactly 16 bytes.
488 let bc_filename = obj.with_extension("bc");
489 let bc_deflated_filename = tmpdir.join({
490 obj.with_extension("bytecode.deflate").file_name().unwrap()
493 let mut bc_data = Vec::new();
494 match fs::File::open(&bc_filename).and_then(|mut f| {
495 f.read_to_end(&mut bc_data)
498 Err(e) => sess.fatal(&format!("failed to read bytecode: {}",
502 let mut bc_data_deflated = Vec::new();
503 DeflateEncoder::new(&mut bc_data_deflated, Compression::Fast)
504 .write_all(&bc_data).unwrap();
506 let mut bc_file_deflated = match fs::File::create(&bc_deflated_filename) {
509 sess.fatal(&format!("failed to create compressed \
510 bytecode file: {}", e))
514 match write_rlib_bytecode_object_v1(&mut bc_file_deflated,
518 sess.fatal(&format!("failed to write compressed \
523 ab.add_file(&bc_deflated_filename);
525 // See the bottom of back::write::run_passes for an explanation
526 // of when we do and don't keep .#module-name#.bc files around.
527 let user_wants_numbered_bitcode =
528 sess.opts.output_types.contains_key(&OutputType::Bitcode) &&
529 sess.opts.cg.codegen_units > 1;
530 if !sess.opts.cg.save_temps && !user_wants_numbered_bitcode {
531 remove(sess, &bc_filename);
535 // After adding all files to the archive, we need to update the
536 // symbol table of the archive. This currently dies on macOS (see
537 // #11162), and isn't necessary there anyway
538 if !sess.target.target.options.is_like_osx {
543 RlibFlavor::StaticlibBase => {
544 if trans.allocator_module.is_some() {
545 ab.add_file(&outputs.with_extension(ALLOCATOR_OBJ_NAME));
553 fn write_rlib_bytecode_object_v1(writer: &mut Write,
554 bc_data_deflated: &[u8]) -> io::Result<()> {
555 let bc_data_deflated_size: u64 = bc_data_deflated.len() as u64;
557 writer.write_all(RLIB_BYTECODE_OBJECT_MAGIC)?;
558 writer.write_all(&[1, 0, 0, 0])?;
560 (bc_data_deflated_size >> 0) as u8,
561 (bc_data_deflated_size >> 8) as u8,
562 (bc_data_deflated_size >> 16) as u8,
563 (bc_data_deflated_size >> 24) as u8,
564 (bc_data_deflated_size >> 32) as u8,
565 (bc_data_deflated_size >> 40) as u8,
566 (bc_data_deflated_size >> 48) as u8,
567 (bc_data_deflated_size >> 56) as u8,
569 writer.write_all(&bc_data_deflated)?;
571 let number_of_bytes_written_so_far =
572 RLIB_BYTECODE_OBJECT_MAGIC.len() + // magic id
573 mem::size_of_val(&RLIB_BYTECODE_OBJECT_VERSION) + // version
574 mem::size_of_val(&bc_data_deflated_size) + // data size field
575 bc_data_deflated_size as usize; // actual data
577 // If the number of bytes written to the object so far is odd, add a
578 // padding byte to make it even. This works around a crash bug in LLDB
579 // (see issue #15950)
580 if number_of_bytes_written_so_far % 2 == 1 {
581 writer.write_all(&[0])?;
587 // Create a static archive
589 // This is essentially the same thing as an rlib, but it also involves adding
590 // all of the upstream crates' objects into the archive. This will slurp in
591 // all of the native libraries of upstream dependencies as well.
593 // Additionally, there's no way for us to link dynamic libraries, so we warn
594 // about all dynamic library dependencies that they're not linked in.
596 // There's no need to include metadata in a static archive, so ensure to not
597 // link in the metadata object file (and also don't prepare the archive with a
599 fn link_staticlib(sess: &Session,
600 trans: &CrateTranslation,
601 outputs: &OutputFilenames,
605 let mut ab = link_rlib(sess,
607 RlibFlavor::StaticlibBase,
612 let mut all_native_libs = vec![];
614 let res = each_linked_rlib(sess, &mut |cnum, path| {
615 let name = sess.cstore.crate_name(cnum);
616 let native_libs = &trans.crate_info.native_libraries[&cnum];
618 // Here when we include the rlib into our staticlib we need to make a
619 // decision whether to include the extra object files along the way.
620 // These extra object files come from statically included native
621 // libraries, but they may be cfg'd away with #[link(cfg(..))].
623 // This unstable feature, though, only needs liblibc to work. The only
624 // use case there is where musl is statically included in liblibc.rlib,
625 // so if we don't want the included version we just need to skip it. As
626 // a result the logic here is that if *any* linked library is cfg'd away
627 // we just skip all object files.
629 // Clearly this is not sufficient for a general purpose feature, and
630 // we'd want to read from the library's metadata to determine which
631 // object files come from where and selectively skip them.
632 let skip_object_files = native_libs.iter().any(|lib| {
633 lib.kind == NativeLibraryKind::NativeStatic && !relevant_lib(sess, lib)
637 sess.lto() && !ignored_for_lto(&trans.crate_info, cnum),
638 skip_object_files).unwrap();
640 all_native_libs.extend(trans.crate_info.native_libraries[&cnum].iter().cloned());
642 if let Err(e) = res {
649 if !all_native_libs.is_empty() {
650 if sess.opts.prints.contains(&PrintRequest::NativeStaticLibs) {
651 print_native_static_libs(sess, &all_native_libs);
653 // Fallback for backwards compatibility only
654 print_native_static_libs_legacy(sess, &all_native_libs);
659 fn print_native_static_libs_legacy(sess: &Session, all_native_libs: &[NativeLibrary]) {
660 sess.note_without_error("link against the following native artifacts when linking against \
661 this static library");
662 sess.note_without_error("This list will not be printed by default. \
663 Please add --print=native-static-libs if you need this information");
665 for lib in all_native_libs.iter().filter(|l| relevant_lib(sess, l)) {
666 let name = match lib.kind {
667 NativeLibraryKind::NativeStaticNobundle |
668 NativeLibraryKind::NativeUnknown => "library",
669 NativeLibraryKind::NativeFramework => "framework",
670 // These are included, no need to print them
671 NativeLibraryKind::NativeStatic => continue,
673 sess.note_without_error(&format!("{}: {}", name, lib.name));
677 fn print_native_static_libs(sess: &Session, all_native_libs: &[NativeLibrary]) {
678 let lib_args: Vec<_> = all_native_libs.iter()
679 .filter(|l| relevant_lib(sess, l))
680 .filter_map(|lib| match lib.kind {
681 NativeLibraryKind::NativeStaticNobundle |
682 NativeLibraryKind::NativeUnknown => {
683 if sess.target.target.options.is_like_msvc {
684 Some(format!("{}.lib", lib.name))
686 Some(format!("-l{}", lib.name))
689 NativeLibraryKind::NativeFramework => {
690 // ld-only syntax, since there are no frameworks in MSVC
691 Some(format!("-framework {}", lib.name))
693 // These are included, no need to print them
694 NativeLibraryKind::NativeStatic => None,
697 if !lib_args.is_empty() {
698 sess.note_without_error("Link against the following native artifacts when linking \
699 against this static library. The order and any duplication \
700 can be significant on some platforms.");
701 // Prefix for greppability
702 sess.note_without_error(&format!("native-static-libs: {}", &lib_args.join(" ")));
706 // Create a dynamic library or executable
708 // This will invoke the system linker/cc to create the resulting file. This
709 // links to all upstream files as well.
710 fn link_natively(sess: &Session,
711 crate_type: config::CrateType,
714 trans: &CrateTranslation,
715 outputs: &OutputFilenames,
717 info!("preparing {:?} from {:?} to {:?}", crate_type, objects, out_filename);
718 let flavor = sess.linker_flavor();
720 // The invocations of cc share some flags across platforms
721 let (pname, mut cmd, envs) = get_linker(sess);
722 // This will set PATH on windows
725 let root = sess.target_filesearch(PathKind::Native).get_lib_path();
726 if let Some(args) = sess.target.target.options.pre_link_args.get(&flavor) {
729 if let Some(ref args) = sess.opts.debugging_opts.pre_link_args {
732 cmd.args(&sess.opts.debugging_opts.pre_link_arg);
734 let pre_link_objects = if crate_type == config::CrateTypeExecutable {
735 &sess.target.target.options.pre_link_objects_exe
737 &sess.target.target.options.pre_link_objects_dll
739 for obj in pre_link_objects {
740 cmd.arg(root.join(obj));
743 if sess.target.target.options.is_like_emscripten {
745 cmd.arg(if sess.panic_strategy() == PanicStrategy::Abort {
746 "DISABLE_EXCEPTION_CATCHING=1"
748 "DISABLE_EXCEPTION_CATCHING=0"
753 let mut linker = trans.linker_info.to_linker(cmd, &sess);
754 link_args(&mut *linker, sess, crate_type, tmpdir,
755 objects, out_filename, outputs, trans);
756 cmd = linker.finalize();
758 if let Some(args) = sess.target.target.options.late_link_args.get(&flavor) {
761 for obj in &sess.target.target.options.post_link_objects {
762 cmd.arg(root.join(obj));
764 if let Some(args) = sess.target.target.options.post_link_args.get(&flavor) {
767 for &(ref k, ref v) in &sess.target.target.options.link_env {
771 if sess.opts.debugging_opts.print_link_args {
772 println!("{:?}", &cmd);
775 // May have not found libraries in the right formats.
776 sess.abort_if_errors();
778 // Invoke the system linker
780 // Note that there's a terribly awful hack that really shouldn't be present
781 // in any compiler. Here an environment variable is supported to
782 // automatically retry the linker invocation if the linker looks like it
785 // Gee that seems odd, normally segfaults are things we want to know about!
786 // Unfortunately though in rust-lang/rust#38878 we're experiencing the
787 // linker segfaulting on Travis quite a bit which is causing quite a bit of
788 // pain to land PRs when they spuriously fail due to a segfault.
790 // The issue #38878 has some more debugging information on it as well, but
791 // this unfortunately looks like it's just a race condition in macOS's linker
792 // with some thread pool working in the background. It seems that no one
793 // currently knows a fix for this so in the meantime we're left with this...
795 let retry_on_segfault = env::var("RUSTC_RETRY_LINKER_ON_SEGFAULT").is_ok();
800 prog = time(sess.time_passes(), "running linker", || cmd.output());
801 if !retry_on_segfault || i > 3 {
804 let output = match prog {
805 Ok(ref output) => output,
808 if output.status.success() {
811 let mut out = output.stderr.clone();
812 out.extend(&output.stdout);
813 let out = String::from_utf8_lossy(&out);
814 let msg = "clang: error: unable to execute command: \
815 Segmentation fault: 11";
816 if !out.contains(msg) {
820 sess.struct_warn("looks like the linker segfaulted when we tried to \
821 call it, automatically retrying again")
822 .note(&format!("{:?}", cmd))
829 fn escape_string(s: &[u8]) -> String {
830 str::from_utf8(s).map(|s| s.to_owned())
831 .unwrap_or_else(|_| {
832 let mut x = "Non-UTF-8 output: ".to_string();
834 .flat_map(|&b| ascii::escape_default(b))
835 .map(|b| char::from_u32(b as u32).unwrap()));
839 if !prog.status.success() {
840 let mut output = prog.stderr.clone();
841 output.extend_from_slice(&prog.stdout);
842 sess.struct_err(&format!("linking with `{}` failed: {}",
845 .note(&format!("{:?}", &cmd))
846 .note(&escape_string(&output))
848 sess.abort_if_errors();
850 info!("linker stderr:\n{}", escape_string(&prog.stderr));
851 info!("linker stdout:\n{}", escape_string(&prog.stdout));
854 sess.struct_err(&format!("could not exec the linker `{}`: {}", pname, e))
855 .note(&format!("{:?}", &cmd))
857 if sess.target.target.options.is_like_msvc && e.kind() == io::ErrorKind::NotFound {
858 sess.note_without_error("the msvc targets depend on the msvc linker \
859 but `link.exe` was not found");
860 sess.note_without_error("please ensure that VS 2013 or VS 2015 was installed \
861 with the Visual C++ option");
863 sess.abort_if_errors();
868 // On macOS, debuggers need this utility to get run to do some munging of
870 if sess.target.target.options.is_like_osx && sess.opts.debuginfo != NoDebugInfo {
871 match Command::new("dsymutil").arg(out_filename).output() {
873 Err(e) => sess.fatal(&format!("failed to run dsymutil: {}", e)),
878 fn link_args(cmd: &mut Linker,
880 crate_type: config::CrateType,
884 outputs: &OutputFilenames,
885 trans: &CrateTranslation) {
887 // The default library location, we need this to find the runtime.
888 // The location of crates will be determined as needed.
889 let lib_path = sess.target_filesearch(PathKind::All).get_lib_path();
892 let t = &sess.target.target;
894 cmd.include_path(&fix_windows_verbatim_for_gcc(&lib_path));
898 cmd.output_filename(out_filename);
900 if crate_type == config::CrateTypeExecutable &&
901 sess.target.target.options.is_like_windows {
902 if let Some(ref s) = trans.windows_subsystem {
907 // If we're building a dynamic library then some platforms need to make sure
908 // that all symbols are exported correctly from the dynamic library.
909 if crate_type != config::CrateTypeExecutable ||
910 sess.target.target.options.is_like_emscripten {
911 cmd.export_symbols(tmpdir, crate_type);
914 // When linking a dynamic library, we put the metadata into a section of the
915 // executable. This metadata is in a separate object file from the main
916 // object file, so we link that in here.
917 if crate_type == config::CrateTypeDylib ||
918 crate_type == config::CrateTypeProcMacro {
919 cmd.add_object(&outputs.with_extension(METADATA_OBJ_NAME));
922 if trans.allocator_module.is_some() {
923 cmd.add_object(&outputs.with_extension(ALLOCATOR_OBJ_NAME));
926 // Try to strip as much out of the generated object by removing unused
927 // sections if possible. See more comments in linker.rs
928 if !sess.opts.cg.link_dead_code {
929 let keep_metadata = crate_type == config::CrateTypeDylib;
930 cmd.gc_sections(keep_metadata);
933 let used_link_args = sess.cstore.used_link_args();
935 if crate_type == config::CrateTypeExecutable &&
936 t.options.position_independent_executables {
937 let empty_vec = Vec::new();
938 let args = sess.opts.cg.link_args.as_ref().unwrap_or(&empty_vec);
939 let more_args = &sess.opts.cg.link_arg;
940 let mut args = args.iter().chain(more_args.iter()).chain(used_link_args.iter());
942 if get_reloc_model(sess) == llvm::RelocMode::PIC
943 && !sess.crt_static() && !args.any(|x| *x == "-static") {
944 cmd.position_independent_executable();
948 let relro_level = match sess.opts.debugging_opts.relro_level {
949 Some(level) => level,
950 None => t.options.relro_level,
953 RelroLevel::Full => {
956 RelroLevel::Partial => {
959 RelroLevel::Off => {},
962 // Pass optimization flags down to the linker.
965 // Pass debuginfo flags down to the linker.
968 // We want to prevent the compiler from accidentally leaking in any system
969 // libraries, so we explicitly ask gcc to not link to any libraries by
970 // default. Note that this does not happen for windows because windows pulls
971 // in some large number of libraries and I couldn't quite figure out which
973 if t.options.no_default_libraries {
974 cmd.no_default_libraries();
977 // Take careful note of the ordering of the arguments we pass to the linker
978 // here. Linkers will assume that things on the left depend on things to the
979 // right. Things on the right cannot depend on things on the left. This is
980 // all formally implemented in terms of resolving symbols (libs on the right
981 // resolve unknown symbols of libs on the left, but not vice versa).
983 // For this reason, we have organized the arguments we pass to the linker as
986 // 1. The local object that LLVM just generated
987 // 2. Local native libraries
988 // 3. Upstream rust libraries
989 // 4. Upstream native libraries
991 // The rationale behind this ordering is that those items lower down in the
992 // list can't depend on items higher up in the list. For example nothing can
993 // depend on what we just generated (e.g. that'd be a circular dependency).
994 // Upstream rust libraries are not allowed to depend on our local native
995 // libraries as that would violate the structure of the DAG, in that
996 // scenario they are required to link to them as well in a shared fashion.
998 // Note that upstream rust libraries may contain native dependencies as
999 // well, but they also can't depend on what we just started to add to the
1000 // link line. And finally upstream native libraries can't depend on anything
1001 // in this DAG so far because they're only dylibs and dylibs can only depend
1002 // on other dylibs (e.g. other native deps).
1003 add_local_native_libraries(cmd, sess);
1004 add_upstream_rust_crates(cmd, sess, trans, crate_type, tmpdir);
1005 add_upstream_native_libraries(cmd, sess, trans, crate_type);
1007 // Tell the linker what we're doing.
1008 if crate_type != config::CrateTypeExecutable {
1009 cmd.build_dylib(out_filename);
1011 if crate_type == config::CrateTypeExecutable && sess.crt_static() {
1012 cmd.build_static_executable();
1015 // FIXME (#2397): At some point we want to rpath our guesses as to
1016 // where extern libraries might live, based on the
1017 // addl_lib_search_paths
1018 if sess.opts.cg.rpath {
1019 let sysroot = sess.sysroot();
1020 let target_triple = &sess.opts.target_triple;
1021 let mut get_install_prefix_lib_path = || {
1022 let install_prefix = option_env!("CFG_PREFIX").expect("CFG_PREFIX");
1023 let tlib = filesearch::relative_target_lib_path(sysroot, target_triple);
1024 let mut path = PathBuf::from(install_prefix);
1029 let mut rpath_config = RPathConfig {
1030 used_crates: sess.cstore.used_crates(LinkagePreference::RequireDynamic),
1031 out_filename: out_filename.to_path_buf(),
1032 has_rpath: sess.target.target.options.has_rpath,
1033 is_like_osx: sess.target.target.options.is_like_osx,
1034 linker_is_gnu: sess.target.target.options.linker_is_gnu,
1035 get_install_prefix_lib_path: &mut get_install_prefix_lib_path,
1037 cmd.args(&rpath::get_rpath_flags(&mut rpath_config));
1040 // Finally add all the linker arguments provided on the command line along
1041 // with any #[link_args] attributes found inside the crate
1042 if let Some(ref args) = sess.opts.cg.link_args {
1045 cmd.args(&sess.opts.cg.link_arg);
1046 cmd.args(&used_link_args);
1049 // # Native library linking
1051 // User-supplied library search paths (-L on the command line). These are
1052 // the same paths used to find Rust crates, so some of them may have been
1053 // added already by the previous crate linking code. This only allows them
1054 // to be found at compile time so it is still entirely up to outside
1055 // forces to make sure that library can be found at runtime.
1057 // Also note that the native libraries linked here are only the ones located
1058 // in the current crate. Upstream crates with native library dependencies
1059 // may have their native library pulled in above.
1060 fn add_local_native_libraries(cmd: &mut Linker, sess: &Session) {
1061 sess.target_filesearch(PathKind::All).for_each_lib_search_path(|path, k| {
1063 PathKind::Framework => { cmd.framework_path(path); }
1064 _ => { cmd.include_path(&fix_windows_verbatim_for_gcc(path)); }
1068 let relevant_libs = sess.cstore.used_libraries().into_iter().filter(|l| {
1069 relevant_lib(sess, l)
1072 let search_path = archive_search_paths(sess);
1073 for lib in relevant_libs {
1075 NativeLibraryKind::NativeUnknown => cmd.link_dylib(&lib.name.as_str()),
1076 NativeLibraryKind::NativeFramework => cmd.link_framework(&lib.name.as_str()),
1077 NativeLibraryKind::NativeStaticNobundle => cmd.link_staticlib(&lib.name.as_str()),
1078 NativeLibraryKind::NativeStatic => cmd.link_whole_staticlib(&lib.name.as_str(),
1084 // # Rust Crate linking
1086 // Rust crates are not considered at all when creating an rlib output. All
1087 // dependencies will be linked when producing the final output (instead of
1088 // the intermediate rlib version)
1089 fn add_upstream_rust_crates(cmd: &mut Linker,
1091 trans: &CrateTranslation,
1092 crate_type: config::CrateType,
1094 // All of the heavy lifting has previously been accomplished by the
1095 // dependency_format module of the compiler. This is just crawling the
1096 // output of that module, adding crates as necessary.
1098 // Linking to a rlib involves just passing it to the linker (the linker
1099 // will slurp up the object files inside), and linking to a dynamic library
1100 // involves just passing the right -l flag.
1102 let formats = sess.dependency_formats.borrow();
1103 let data = formats.get(&crate_type).unwrap();
1105 // Invoke get_used_crates to ensure that we get a topological sorting of
1107 let deps = sess.cstore.used_crates(LinkagePreference::RequireDynamic);
1109 let mut compiler_builtins = None;
1111 for &(cnum, _) in &deps {
1112 // We may not pass all crates through to the linker. Some crates may
1113 // appear statically in an existing dylib, meaning we'll pick up all the
1114 // symbols from the dylib.
1115 let src = sess.cstore.used_crate_source(cnum);
1116 match data[cnum.as_usize() - 1] {
1117 _ if trans.crate_info.profiler_runtime == Some(cnum) => {
1118 add_static_crate(cmd, sess, trans, tmpdir, crate_type, cnum);
1120 _ if trans.crate_info.sanitizer_runtime == Some(cnum) => {
1121 link_sanitizer_runtime(cmd, sess, tmpdir, cnum);
1123 // compiler-builtins are always placed last to ensure that they're
1124 // linked correctly.
1125 _ if trans.crate_info.compiler_builtins == Some(cnum) => {
1126 assert!(compiler_builtins.is_none());
1127 compiler_builtins = Some(cnum);
1129 Linkage::NotLinked |
1130 Linkage::IncludedFromDylib => {}
1131 Linkage::Static => {
1132 add_static_crate(cmd, sess, trans, tmpdir, crate_type, cnum);
1134 Linkage::Dynamic => {
1135 add_dynamic_crate(cmd, sess, &src.dylib.unwrap().0)
1140 // compiler-builtins are always placed last to ensure that they're
1141 // linked correctly.
1142 // We must always link the `compiler_builtins` crate statically. Even if it
1143 // was already "included" in a dylib (e.g. `libstd` when `-C prefer-dynamic`
1145 if let Some(cnum) = compiler_builtins {
1146 add_static_crate(cmd, sess, trans, tmpdir, crate_type, cnum);
1149 // Converts a library file-stem into a cc -l argument
1150 fn unlib<'a>(config: &config::Config, stem: &'a str) -> &'a str {
1151 if stem.starts_with("lib") && !config.target.options.is_like_windows {
1158 // We must link the sanitizer runtime using -Wl,--whole-archive but since
1159 // it's packed in a .rlib, it contains stuff that are not objects that will
1160 // make the linker error. So we must remove those bits from the .rlib before
1162 fn link_sanitizer_runtime(cmd: &mut Linker,
1166 let src = sess.cstore.used_crate_source(cnum);
1167 let cratepath = &src.rlib.unwrap().0;
1169 if sess.target.target.options.is_like_osx {
1170 // On Apple platforms, the sanitizer is always built as a dylib, and
1171 // LLVM will link to `@rpath/*.dylib`, so we need to specify an
1172 // rpath to the library as well (the rpath should be absolute, see
1173 // PR #41352 for details).
1175 // FIXME: Remove this logic into librustc_*san once Cargo supports it
1176 let rpath = cratepath.parent().unwrap();
1177 let rpath = rpath.to_str().expect("non-utf8 component in path");
1178 cmd.args(&["-Wl,-rpath".into(), "-Xlinker".into(), rpath.into()]);
1181 let dst = tmpdir.join(cratepath.file_name().unwrap());
1182 let cfg = archive_config(sess, &dst, Some(cratepath));
1183 let mut archive = ArchiveBuilder::new(cfg);
1184 archive.update_symbols();
1186 for f in archive.src_files() {
1187 if f.ends_with("bytecode.deflate") || f == METADATA_FILENAME {
1188 archive.remove_file(&f);
1195 cmd.link_whole_rlib(&dst);
1198 // Adds the static "rlib" versions of all crates to the command line.
1199 // There's a bit of magic which happens here specifically related to LTO and
1200 // dynamic libraries. Specifically:
1202 // * For LTO, we remove upstream object files.
1203 // * For dylibs we remove metadata and bytecode from upstream rlibs
1205 // When performing LTO, almost(*) all of the bytecode from the upstream
1206 // libraries has already been included in our object file output. As a
1207 // result we need to remove the object files in the upstream libraries so
1208 // the linker doesn't try to include them twice (or whine about duplicate
1209 // symbols). We must continue to include the rest of the rlib, however, as
1210 // it may contain static native libraries which must be linked in.
1212 // (*) Crates marked with `#![no_builtins]` don't participate in LTO and
1213 // their bytecode wasn't included. The object files in those libraries must
1214 // still be passed to the linker.
1216 // When making a dynamic library, linkers by default don't include any
1217 // object files in an archive if they're not necessary to resolve the link.
1218 // We basically want to convert the archive (rlib) to a dylib, though, so we
1219 // *do* want everything included in the output, regardless of whether the
1220 // linker thinks it's needed or not. As a result we must use the
1221 // --whole-archive option (or the platform equivalent). When using this
1222 // option the linker will fail if there are non-objects in the archive (such
1223 // as our own metadata and/or bytecode). All in all, for rlibs to be
1224 // entirely included in dylibs, we need to remove all non-object files.
1226 // Note, however, that if we're not doing LTO or we're not producing a dylib
1227 // (aka we're making an executable), we can just pass the rlib blindly to
1228 // the linker (fast) because it's fine if it's not actually included as
1229 // we're at the end of the dependency chain.
1230 fn add_static_crate(cmd: &mut Linker,
1232 trans: &CrateTranslation,
1234 crate_type: config::CrateType,
1236 let src = sess.cstore.used_crate_source(cnum);
1237 let cratepath = &src.rlib.unwrap().0;
1239 // See the comment above in `link_staticlib` and `link_rlib` for why if
1240 // there's a static library that's not relevant we skip all object
1242 let native_libs = &trans.crate_info.native_libraries[&cnum];
1243 let skip_native = native_libs.iter().any(|lib| {
1244 lib.kind == NativeLibraryKind::NativeStatic && !relevant_lib(sess, lib)
1247 if (!sess.lto() || ignored_for_lto(&trans.crate_info, cnum)) &&
1248 crate_type != config::CrateTypeDylib &&
1250 cmd.link_rlib(&fix_windows_verbatim_for_gcc(cratepath));
1254 let dst = tmpdir.join(cratepath.file_name().unwrap());
1255 let name = cratepath.file_name().unwrap().to_str().unwrap();
1256 let name = &name[3..name.len() - 5]; // chop off lib/.rlib
1258 time(sess.time_passes(), &format!("altering {}.rlib", name), || {
1259 let cfg = archive_config(sess, &dst, Some(cratepath));
1260 let mut archive = ArchiveBuilder::new(cfg);
1261 archive.update_symbols();
1263 let mut any_objects = false;
1264 for f in archive.src_files() {
1265 if f.ends_with("bytecode.deflate") || f == METADATA_FILENAME {
1266 archive.remove_file(&f);
1270 let canonical = f.replace("-", "_");
1271 let canonical_name = name.replace("-", "_");
1273 let is_rust_object =
1274 canonical.starts_with(&canonical_name) && {
1275 let num = &f[name.len()..f.len() - 2];
1276 num.len() > 0 && num[1..].parse::<u32>().is_ok()
1279 // If we've been requested to skip all native object files
1280 // (those not generated by the rust compiler) then we can skip
1281 // this file. See above for why we may want to do this.
1282 let skip_because_cfg_say_so = skip_native && !is_rust_object;
1284 // If we're performing LTO and this is a rust-generated object
1285 // file, then we don't need the object file as it's part of the
1286 // LTO module. Note that `#![no_builtins]` is excluded from LTO,
1287 // though, so we let that object file slide.
1288 let skip_because_lto = sess.lto() && is_rust_object &&
1289 !trans.crate_info.is_no_builtins.contains(&cnum);
1291 if skip_because_cfg_say_so || skip_because_lto {
1292 archive.remove_file(&f);
1303 // If we're creating a dylib, then we need to include the
1304 // whole of each object in our archive into that artifact. This is
1305 // because a `dylib` can be reused as an intermediate artifact.
1307 // Note, though, that we don't want to include the whole of a
1308 // compiler-builtins crate (e.g. compiler-rt) because it'll get
1309 // repeatedly linked anyway.
1310 if crate_type == config::CrateTypeDylib &&
1311 trans.crate_info.compiler_builtins != Some(cnum) {
1312 cmd.link_whole_rlib(&fix_windows_verbatim_for_gcc(&dst));
1314 cmd.link_rlib(&fix_windows_verbatim_for_gcc(&dst));
1319 // Same thing as above, but for dynamic crates instead of static crates.
1320 fn add_dynamic_crate(cmd: &mut Linker, sess: &Session, cratepath: &Path) {
1321 // If we're performing LTO, then it should have been previously required
1322 // that all upstream rust dependencies were available in an rlib format.
1323 assert!(!sess.lto());
1325 // Just need to tell the linker about where the library lives and
1327 let parent = cratepath.parent();
1328 if let Some(dir) = parent {
1329 cmd.include_path(&fix_windows_verbatim_for_gcc(dir));
1331 let filestem = cratepath.file_stem().unwrap().to_str().unwrap();
1332 cmd.link_rust_dylib(&unlib(&sess.target, filestem),
1333 parent.unwrap_or(Path::new("")));
1337 // Link in all of our upstream crates' native dependencies. Remember that
1338 // all of these upstream native dependencies are all non-static
1339 // dependencies. We've got two cases then:
1341 // 1. The upstream crate is an rlib. In this case we *must* link in the
1342 // native dependency because the rlib is just an archive.
1344 // 2. The upstream crate is a dylib. In order to use the dylib, we have to
1345 // have the dependency present on the system somewhere. Thus, we don't
1346 // gain a whole lot from not linking in the dynamic dependency to this
1349 // The use case for this is a little subtle. In theory the native
1350 // dependencies of a crate are purely an implementation detail of the crate
1351 // itself, but the problem arises with generic and inlined functions. If a
1352 // generic function calls a native function, then the generic function must
1353 // be instantiated in the target crate, meaning that the native symbol must
1354 // also be resolved in the target crate.
1355 fn add_upstream_native_libraries(cmd: &mut Linker,
1357 trans: &CrateTranslation,
1358 crate_type: config::CrateType) {
1359 // Be sure to use a topological sorting of crates because there may be
1360 // interdependencies between native libraries. When passing -nodefaultlibs,
1361 // for example, almost all native libraries depend on libc, so we have to
1362 // make sure that's all the way at the right (liblibc is near the base of
1363 // the dependency chain).
1365 // This passes RequireStatic, but the actual requirement doesn't matter,
1366 // we're just getting an ordering of crate numbers, we're not worried about
1368 let formats = sess.dependency_formats.borrow();
1369 let data = formats.get(&crate_type).unwrap();
1371 let crates = sess.cstore.used_crates(LinkagePreference::RequireStatic);
1372 for (cnum, _) in crates {
1373 for lib in trans.crate_info.native_libraries[&cnum].iter() {
1374 if !relevant_lib(sess, &lib) {
1378 NativeLibraryKind::NativeUnknown => cmd.link_dylib(&lib.name.as_str()),
1379 NativeLibraryKind::NativeFramework => cmd.link_framework(&lib.name.as_str()),
1380 NativeLibraryKind::NativeStaticNobundle => {
1381 // Link "static-nobundle" native libs only if the crate they originate from
1382 // is being linked statically to the current crate. If it's linked dynamically
1383 // or is an rlib already included via some other dylib crate, the symbols from
1384 // native libs will have already been included in that dylib.
1385 if data[cnum.as_usize() - 1] == Linkage::Static {
1386 cmd.link_staticlib(&lib.name.as_str())
1389 // ignore statically included native libraries here as we've
1390 // already included them when we included the rust library
1392 NativeLibraryKind::NativeStatic => {}
1398 fn relevant_lib(sess: &Session, lib: &NativeLibrary) -> bool {
1400 Some(ref cfg) => attr::cfg_matches(cfg, &sess.parse_sess, None),