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 use super::archive::{ArchiveBuilder, ArchiveConfig};
12 use super::linker::Linker;
13 use super::rpath::RPathConfig;
17 use session::config::NoDebugInfo;
18 use session::config::{OutputFilenames, Input, OutputType};
19 use session::filesearch;
20 use session::search_paths::PathKind;
22 use middle::cstore::{self, LinkMeta, NativeLibrary};
23 use middle::cstore::{LinkagePreference, NativeLibraryKind};
24 use middle::dependency_format::Linkage;
26 use util::common::time;
27 use util::fs::fix_windows_verbatim_for_gcc;
28 use rustc::dep_graph::DepNode;
29 use rustc::hir::def_id::CrateNum;
30 use rustc::hir::svh::Svh;
31 use rustc_back::tempdir::TempDir;
32 use rustc_incremental::IncrementalHashesMap;
37 use std::ffi::OsString;
39 use std::io::{self, Read, Write};
41 use std::path::{Path, PathBuf};
42 use std::process::Command;
49 // RLIB LLVM-BYTECODE OBJECT LAYOUT
52 // 0..10 "RUST_OBJECT" encoded in ASCII
53 // 11..14 format version as little-endian u32
54 // 15..22 size in bytes of deflate compressed LLVM bitcode as
56 // 23.. compressed LLVM bitcode
58 // This is the "magic number" expected at the beginning of a LLVM bytecode
60 pub const RLIB_BYTECODE_OBJECT_MAGIC: &'static [u8] = b"RUST_OBJECT";
62 // The version number this compiler will write to bytecode objects in rlibs
63 pub const RLIB_BYTECODE_OBJECT_VERSION: u32 = 1;
65 // The offset in bytes the bytecode object format version number can be found at
66 pub const RLIB_BYTECODE_OBJECT_VERSION_OFFSET: usize = 11;
68 // The offset in bytes the size of the compressed bytecode can be found at in
70 pub const RLIB_BYTECODE_OBJECT_V1_DATASIZE_OFFSET: usize =
71 RLIB_BYTECODE_OBJECT_VERSION_OFFSET + 4;
73 // The offset in bytes the compressed LLVM bytecode can be found at in format
75 pub const RLIB_BYTECODE_OBJECT_V1_DATA_OFFSET: usize =
76 RLIB_BYTECODE_OBJECT_V1_DATASIZE_OFFSET + 8;
79 pub fn find_crate_name(sess: Option<&Session>,
80 attrs: &[ast::Attribute],
81 input: &Input) -> String {
82 let validate = |s: String, span: Option<Span>| {
83 cstore::validate_crate_name(sess, &s[..], span);
87 // Look in attributes 100% of the time to make sure the attribute is marked
88 // as used. After doing this, however, we still prioritize a crate name from
89 // the command line over one found in the #[crate_name] attribute. If we
90 // find both we ensure that they're the same later on as well.
91 let attr_crate_name = attrs.iter().find(|at| at.check_name("crate_name"))
92 .and_then(|at| at.value_str().map(|s| (at, s)));
94 if let Some(sess) = sess {
95 if let Some(ref s) = sess.opts.crate_name {
96 if let Some((attr, ref name)) = attr_crate_name {
98 let msg = format!("--crate-name and #[crate_name] are \
99 required to match, but `{}` != `{}`",
101 sess.span_err(attr.span, &msg[..]);
104 return validate(s.clone(), None);
108 if let Some((attr, s)) = attr_crate_name {
109 return validate(s.to_string(), Some(attr.span));
111 if let Input::File(ref path) = *input {
112 if let Some(s) = path.file_stem().and_then(|s| s.to_str()) {
113 if s.starts_with("-") {
114 let msg = format!("crate names cannot start with a `-`, but \
115 `{}` has a leading hyphen", s);
116 if let Some(sess) = sess {
120 return validate(s.replace("-", "_"), None);
125 "rust_out".to_string()
129 pub fn build_link_meta(incremental_hashes_map: &IncrementalHashesMap,
133 crate_name: name.to_owned(),
134 crate_hash: Svh::new(incremental_hashes_map[&DepNode::Krate].to_smaller_hash()),
140 // The third parameter is for an extra path to add to PATH for MSVC
141 // cross linkers for host toolchain DLL dependencies
142 pub fn get_linker(sess: &Session) -> (String, Command, Option<PathBuf>) {
143 if let Some(ref linker) = sess.opts.cg.linker {
144 (linker.clone(), Command::new(linker), None)
145 } else if sess.target.target.options.is_like_msvc {
146 let (cmd, host) = msvc::link_exe_cmd(sess);
147 ("link.exe".to_string(), cmd, host)
149 (sess.target.target.options.linker.clone(),
150 Command::new(&sess.target.target.options.linker), None)
154 pub fn get_ar_prog(sess: &Session) -> String {
155 sess.opts.cg.ar.clone().unwrap_or_else(|| {
156 sess.target.target.options.ar.clone()
160 fn command_path(sess: &Session, extra: Option<PathBuf>) -> OsString {
161 // The compiler's sysroot often has some bundled tools, so add it to the
162 // PATH for the child.
163 let mut new_path = sess.host_filesearch(PathKind::All)
164 .get_tools_search_paths();
165 if let Some(path) = env::var_os("PATH") {
166 new_path.extend(env::split_paths(&path));
168 new_path.extend(extra);
169 env::join_paths(new_path).unwrap()
172 pub fn remove(sess: &Session, path: &Path) {
173 match fs::remove_file(path) {
176 sess.err(&format!("failed to remove {}: {}",
183 /// Perform the linkage portion of the compilation phase. This will generate all
184 /// of the requested outputs for this compilation session.
185 pub fn link_binary(sess: &Session,
186 trans: &CrateTranslation,
187 outputs: &OutputFilenames,
188 crate_name: &str) -> Vec<PathBuf> {
189 let _task = sess.dep_graph.in_task(DepNode::LinkBinary);
191 let mut out_filenames = Vec::new();
192 for &crate_type in sess.crate_types.borrow().iter() {
193 // Ignore executable crates if we have -Z no-trans, as they will error.
194 if sess.opts.debugging_opts.no_trans &&
195 crate_type == config::CrateTypeExecutable {
199 if invalid_output_for_target(sess, crate_type) {
200 bug!("invalid output type `{:?}` for target os `{}`",
201 crate_type, sess.opts.target_triple);
203 let out_file = link_binary_output(sess, trans, crate_type, outputs,
205 out_filenames.push(out_file);
208 // Remove the temporary object file and metadata if we aren't saving temps
209 if !sess.opts.cg.save_temps {
210 for obj in object_filenames(trans, outputs) {
213 remove(sess, &outputs.with_extension("metadata.o"));
220 /// Returns default crate type for target
222 /// Default crate type is used when crate type isn't provided neither
223 /// through cmd line arguments nor through crate attributes
225 /// It is CrateTypeExecutable for all platforms but iOS as there is no
226 /// way to run iOS binaries anyway without jailbreaking and
227 /// interaction with Rust code through static library is the only
229 pub fn default_output_for_target(sess: &Session) -> config::CrateType {
230 if !sess.target.target.options.executables {
231 config::CrateTypeStaticlib
233 config::CrateTypeExecutable
237 /// Checks if target supports crate_type as output
238 pub fn invalid_output_for_target(sess: &Session,
239 crate_type: config::CrateType) -> bool {
240 match (sess.target.target.options.dynamic_linking,
241 sess.target.target.options.executables, crate_type) {
242 (false, _, config::CrateTypeCdylib) |
243 (false, _, config::CrateTypeProcMacro) |
244 (false, _, config::CrateTypeDylib) => true,
245 (_, false, config::CrateTypeExecutable) => true,
250 fn is_writeable(p: &Path) -> bool {
253 Ok(m) => !m.permissions().readonly()
257 pub fn filename_for_input(sess: &Session,
258 crate_type: config::CrateType,
260 outputs: &OutputFilenames) -> PathBuf {
261 let libname = format!("{}{}", crate_name, sess.opts.cg.extra_filename);
263 config::CrateTypeRlib => {
264 outputs.out_directory.join(&format!("lib{}.rlib", libname))
266 config::CrateTypeCdylib |
267 config::CrateTypeProcMacro |
268 config::CrateTypeDylib => {
269 let (prefix, suffix) = (&sess.target.target.options.dll_prefix,
270 &sess.target.target.options.dll_suffix);
271 outputs.out_directory.join(&format!("{}{}{}", prefix, libname,
274 config::CrateTypeStaticlib => {
275 let (prefix, suffix) = (&sess.target.target.options.staticlib_prefix,
276 &sess.target.target.options.staticlib_suffix);
277 outputs.out_directory.join(&format!("{}{}{}", prefix, libname,
280 config::CrateTypeExecutable => {
281 let suffix = &sess.target.target.options.exe_suffix;
282 let out_filename = outputs.path(OutputType::Exe);
283 if suffix.is_empty() {
284 out_filename.to_path_buf()
286 out_filename.with_extension(&suffix[1..])
292 pub fn each_linked_rlib(sess: &Session,
293 f: &mut FnMut(CrateNum, &Path)) {
294 let crates = sess.cstore.used_crates(LinkagePreference::RequireStatic).into_iter();
295 let fmts = sess.dependency_formats.borrow();
296 let fmts = fmts.get(&config::CrateTypeExecutable)
297 .or_else(|| fmts.get(&config::CrateTypeStaticlib))
298 .or_else(|| fmts.get(&config::CrateTypeCdylib))
299 .or_else(|| fmts.get(&config::CrateTypeProcMacro));
300 let fmts = fmts.unwrap_or_else(|| {
301 bug!("could not find formats for rlibs")
303 for (cnum, path) in crates {
304 match fmts[cnum.as_usize() - 1] {
305 Linkage::NotLinked | Linkage::IncludedFromDylib => continue,
308 let name = sess.cstore.crate_name(cnum).clone();
309 let path = match path {
312 sess.fatal(&format!("could not find rlib for: `{}`", name));
319 fn link_binary_output(sess: &Session,
320 trans: &CrateTranslation,
321 crate_type: config::CrateType,
322 outputs: &OutputFilenames,
323 crate_name: &str) -> PathBuf {
324 let objects = object_filenames(trans, outputs);
325 let default_filename = filename_for_input(sess, crate_type, crate_name,
327 let out_filename = outputs.outputs.get(&OutputType::Exe)
328 .and_then(|s| s.to_owned())
329 .or_else(|| outputs.single_output_file.clone())
330 .unwrap_or(default_filename);
332 // Make sure files are writeable. Mac, FreeBSD, and Windows system linkers
333 // check this already -- however, the Linux linker will happily overwrite a
334 // read-only file. We should be consistent.
335 for file in objects.iter().chain(Some(&out_filename)) {
336 if !is_writeable(file) {
337 sess.fatal(&format!("output file {} is not writeable -- check its \
338 permissions", file.display()));
342 let tmpdir = match TempDir::new("rustc") {
343 Ok(tmpdir) => tmpdir,
344 Err(err) => sess.fatal(&format!("couldn't create a temp dir: {}", err)),
348 config::CrateTypeRlib => {
349 link_rlib(sess, Some(trans), &objects, &out_filename,
350 tmpdir.path()).build();
352 config::CrateTypeStaticlib => {
353 link_staticlib(sess, &objects, &out_filename, tmpdir.path());
356 link_natively(sess, crate_type, &objects, &out_filename, trans,
357 outputs, tmpdir.path());
364 fn object_filenames(trans: &CrateTranslation,
365 outputs: &OutputFilenames)
367 trans.modules.iter().map(|module| {
368 outputs.temp_path(OutputType::Object, Some(&module.name[..]))
372 fn archive_search_paths(sess: &Session) -> Vec<PathBuf> {
373 let mut search = Vec::new();
374 sess.target_filesearch(PathKind::Native).for_each_lib_search_path(|path, _| {
375 search.push(path.to_path_buf());
380 fn archive_config<'a>(sess: &'a Session,
382 input: Option<&Path>) -> ArchiveConfig<'a> {
385 dst: output.to_path_buf(),
386 src: input.map(|p| p.to_path_buf()),
387 lib_search_paths: archive_search_paths(sess),
388 ar_prog: get_ar_prog(sess),
389 command_path: command_path(sess, None),
395 // An rlib in its current incarnation is essentially a renamed .a file. The
396 // rlib primarily contains the object file of the crate, but it also contains
397 // all of the object files from native libraries. This is done by unzipping
398 // native libraries and inserting all of the contents into this archive.
399 fn link_rlib<'a>(sess: &'a Session,
400 trans: Option<&CrateTranslation>, // None == no metadata/bytecode
403 tmpdir: &Path) -> ArchiveBuilder<'a> {
404 info!("preparing rlib from {:?} to {:?}", objects, out_filename);
405 let mut ab = ArchiveBuilder::new(archive_config(sess, out_filename, None));
410 // Note that in this loop we are ignoring the value of `lib.cfg`. That is,
411 // we may not be configured to actually include a static library if we're
412 // adding it here. That's because later when we consume this rlib we'll
413 // decide whether we actually needed the static library or not.
415 // To do this "correctly" we'd need to keep track of which libraries added
416 // which object files to the archive. We don't do that here, however. The
417 // #[link(cfg(..))] feature is unstable, though, and only intended to get
418 // liblibc working. In that sense the check below just indicates that if
419 // there are any libraries we want to omit object files for at link time we
420 // just exclude all custom object files.
422 // Eventually if we want to stabilize or flesh out the #[link(cfg(..))]
423 // feature then we'll need to figure out how to record what objects were
424 // loaded from the libraries found here and then encode that into the
425 // metadata of the rlib we're generating somehow.
426 for lib in sess.cstore.used_libraries() {
428 NativeLibraryKind::NativeStatic => {}
429 NativeLibraryKind::NativeFramework |
430 NativeLibraryKind::NativeUnknown => continue,
432 ab.add_native_library(&lib.name);
435 // After adding all files to the archive, we need to update the
436 // symbol table of the archive.
439 // Note that it is important that we add all of our non-object "magical
440 // files" *after* all of the object files in the archive. The reason for
441 // this is as follows:
443 // * When performing LTO, this archive will be modified to remove
444 // objects from above. The reason for this is described below.
446 // * When the system linker looks at an archive, it will attempt to
447 // determine the architecture of the archive in order to see whether its
450 // The algorithm for this detection is: iterate over the files in the
451 // archive. Skip magical SYMDEF names. Interpret the first file as an
452 // object file. Read architecture from the object file.
454 // * As one can probably see, if "metadata" and "foo.bc" were placed
455 // before all of the objects, then the architecture of this archive would
456 // not be correctly inferred once 'foo.o' is removed.
458 // Basically, all this means is that this code should not move above the
462 // Instead of putting the metadata in an object file section, rlibs
463 // contain the metadata in a separate file. We use a temp directory
464 // here so concurrent builds in the same directory don't try to use
465 // the same filename for metadata (stomping over one another)
466 let metadata = tmpdir.join(sess.cstore.metadata_filename());
467 match fs::File::create(&metadata).and_then(|mut f| {
468 f.write_all(&trans.metadata)
472 sess.fatal(&format!("failed to write {}: {}",
473 metadata.display(), e));
476 ab.add_file(&metadata);
478 // For LTO purposes, the bytecode of this library is also inserted
479 // into the archive. If codegen_units > 1, we insert each of the
482 // Note that we make sure that the bytecode filename in the
483 // archive is never exactly 16 bytes long by adding a 16 byte
484 // extension to it. This is to work around a bug in LLDB that
485 // would cause it to crash if the name of a file in an archive
486 // was exactly 16 bytes.
487 let bc_filename = obj.with_extension("bc");
488 let bc_deflated_filename = tmpdir.join({
489 obj.with_extension("bytecode.deflate").file_name().unwrap()
492 let mut bc_data = Vec::new();
493 match fs::File::open(&bc_filename).and_then(|mut f| {
494 f.read_to_end(&mut bc_data)
497 Err(e) => sess.fatal(&format!("failed to read bytecode: {}",
501 let bc_data_deflated = flate::deflate_bytes(&bc_data[..]);
503 let mut bc_file_deflated = match fs::File::create(&bc_deflated_filename) {
506 sess.fatal(&format!("failed to create compressed \
507 bytecode file: {}", e))
511 match write_rlib_bytecode_object_v1(&mut bc_file_deflated,
515 sess.fatal(&format!("failed to write compressed \
520 ab.add_file(&bc_deflated_filename);
522 // See the bottom of back::write::run_passes for an explanation
523 // of when we do and don't keep .#module-name#.bc files around.
524 let user_wants_numbered_bitcode =
525 sess.opts.output_types.contains_key(&OutputType::Bitcode) &&
526 sess.opts.cg.codegen_units > 1;
527 if !sess.opts.cg.save_temps && !user_wants_numbered_bitcode {
528 remove(sess, &bc_filename);
532 // After adding all files to the archive, we need to update the
533 // symbol table of the archive. This currently dies on OSX (see
534 // #11162), and isn't necessary there anyway
535 if !sess.target.target.options.is_like_osx {
546 fn write_rlib_bytecode_object_v1(writer: &mut Write,
547 bc_data_deflated: &[u8]) -> io::Result<()> {
548 let bc_data_deflated_size: u64 = bc_data_deflated.len() as u64;
550 writer.write_all(RLIB_BYTECODE_OBJECT_MAGIC)?;
551 writer.write_all(&[1, 0, 0, 0])?;
553 (bc_data_deflated_size >> 0) as u8,
554 (bc_data_deflated_size >> 8) as u8,
555 (bc_data_deflated_size >> 16) as u8,
556 (bc_data_deflated_size >> 24) as u8,
557 (bc_data_deflated_size >> 32) as u8,
558 (bc_data_deflated_size >> 40) as u8,
559 (bc_data_deflated_size >> 48) as u8,
560 (bc_data_deflated_size >> 56) as u8,
562 writer.write_all(&bc_data_deflated)?;
564 let number_of_bytes_written_so_far =
565 RLIB_BYTECODE_OBJECT_MAGIC.len() + // magic id
566 mem::size_of_val(&RLIB_BYTECODE_OBJECT_VERSION) + // version
567 mem::size_of_val(&bc_data_deflated_size) + // data size field
568 bc_data_deflated_size as usize; // actual data
570 // If the number of bytes written to the object so far is odd, add a
571 // padding byte to make it even. This works around a crash bug in LLDB
572 // (see issue #15950)
573 if number_of_bytes_written_so_far % 2 == 1 {
574 writer.write_all(&[0])?;
580 // Create a static archive
582 // This is essentially the same thing as an rlib, but it also involves adding
583 // all of the upstream crates' objects into the archive. This will slurp in
584 // all of the native libraries of upstream dependencies as well.
586 // Additionally, there's no way for us to link dynamic libraries, so we warn
587 // about all dynamic library dependencies that they're not linked in.
589 // There's no need to include metadata in a static archive, so ensure to not
590 // link in the metadata object file (and also don't prepare the archive with a
592 fn link_staticlib(sess: &Session, objects: &[PathBuf], out_filename: &Path,
594 let mut ab = link_rlib(sess, None, objects, out_filename, tempdir);
595 let mut all_native_libs = vec![];
597 each_linked_rlib(sess, &mut |cnum, path| {
598 let name = sess.cstore.crate_name(cnum);
599 let native_libs = sess.cstore.native_libraries(cnum);
601 // Here when we include the rlib into our staticlib we need to make a
602 // decision whether to include the extra object files along the way.
603 // These extra object files come from statically included native
604 // libraries, but they may be cfg'd away with #[link(cfg(..))].
606 // This unstable feature, though, only needs liblibc to work. The only
607 // use case there is where musl is statically included in liblibc.rlib,
608 // so if we don't want the included version we just need to skip it. As
609 // a result the logic here is that if *any* linked library is cfg'd away
610 // we just skip all object files.
612 // Clearly this is not sufficient for a general purpose feature, and
613 // we'd want to read from the library's metadata to determine which
614 // object files come from where and selectively skip them.
615 let skip_object_files = native_libs.iter().any(|lib| {
616 lib.kind == NativeLibraryKind::NativeStatic && !relevant_lib(sess, lib)
618 ab.add_rlib(path, &name, sess.lto(), skip_object_files).unwrap();
620 all_native_libs.extend(sess.cstore.native_libraries(cnum));
626 if !all_native_libs.is_empty() {
627 sess.note_without_error("link against the following native artifacts when linking against \
628 this static library");
629 sess.note_without_error("the order and any duplication can be significant on some \
630 platforms, and so may need to be preserved");
633 for lib in all_native_libs.iter().filter(|l| relevant_lib(sess, l)) {
634 let name = match lib.kind {
635 NativeLibraryKind::NativeUnknown => "library",
636 NativeLibraryKind::NativeFramework => "framework",
637 // These are included, no need to print them
638 NativeLibraryKind::NativeStatic => continue,
640 sess.note_without_error(&format!("{}: {}", name, lib.name));
644 // Create a dynamic library or executable
646 // This will invoke the system linker/cc to create the resulting file. This
647 // links to all upstream files as well.
648 fn link_natively(sess: &Session,
649 crate_type: config::CrateType,
652 trans: &CrateTranslation,
653 outputs: &OutputFilenames,
655 info!("preparing {:?} from {:?} to {:?}", crate_type, objects, out_filename);
657 // The invocations of cc share some flags across platforms
658 let (pname, mut cmd, extra) = get_linker(sess);
659 cmd.env("PATH", command_path(sess, extra));
661 let root = sess.target_filesearch(PathKind::Native).get_lib_path();
662 cmd.args(&sess.target.target.options.pre_link_args);
664 let pre_link_objects = if crate_type == config::CrateTypeExecutable {
665 &sess.target.target.options.pre_link_objects_exe
667 &sess.target.target.options.pre_link_objects_dll
669 for obj in pre_link_objects {
670 cmd.arg(root.join(obj));
674 let mut linker = trans.linker_info.to_linker(&mut cmd, &sess);
675 link_args(&mut *linker, sess, crate_type, tmpdir,
676 objects, out_filename, outputs, trans);
678 cmd.args(&sess.target.target.options.late_link_args);
679 for obj in &sess.target.target.options.post_link_objects {
680 cmd.arg(root.join(obj));
682 cmd.args(&sess.target.target.options.post_link_args);
684 if sess.opts.debugging_opts.print_link_args {
685 println!("{:?}", &cmd);
688 // May have not found libraries in the right formats.
689 sess.abort_if_errors();
691 // Invoke the system linker
693 let prog = time(sess.time_passes(), "running linker", || cmd.output());
696 fn escape_string(s: &[u8]) -> String {
697 str::from_utf8(s).map(|s| s.to_owned())
698 .unwrap_or_else(|_| {
699 let mut x = "Non-UTF-8 output: ".to_string();
701 .flat_map(|&b| ascii::escape_default(b))
702 .map(|b| char::from_u32(b as u32).unwrap()));
706 if !prog.status.success() {
707 let mut output = prog.stderr.clone();
708 output.extend_from_slice(&prog.stdout);
709 sess.struct_err(&format!("linking with `{}` failed: {}",
712 .note(&format!("{:?}", &cmd))
713 .note(&escape_string(&output[..]))
715 sess.abort_if_errors();
717 info!("linker stderr:\n{}", escape_string(&prog.stderr[..]));
718 info!("linker stdout:\n{}", escape_string(&prog.stdout[..]));
721 sess.struct_err(&format!("could not exec the linker `{}`: {}", pname, e))
722 .note(&format!("{:?}", &cmd))
724 if sess.target.target.options.is_like_msvc && e.kind() == io::ErrorKind::NotFound {
725 sess.note_without_error("the msvc targets depend on the msvc linker \
726 but `link.exe` was not found");
727 sess.note_without_error("please ensure that VS 2013 or VS 2015 was installed \
728 with the Visual C++ option");
730 sess.abort_if_errors();
735 // On OSX, debuggers need this utility to get run to do some munging of
737 if sess.target.target.options.is_like_osx && sess.opts.debuginfo != NoDebugInfo {
738 match Command::new("dsymutil").arg(out_filename).output() {
740 Err(e) => sess.fatal(&format!("failed to run dsymutil: {}", e)),
745 fn link_args(cmd: &mut Linker,
747 crate_type: config::CrateType,
751 outputs: &OutputFilenames,
752 trans: &CrateTranslation) {
754 // The default library location, we need this to find the runtime.
755 // The location of crates will be determined as needed.
756 let lib_path = sess.target_filesearch(PathKind::All).get_lib_path();
759 let t = &sess.target.target;
761 cmd.include_path(&fix_windows_verbatim_for_gcc(&lib_path));
765 cmd.output_filename(out_filename);
767 if crate_type == config::CrateTypeExecutable &&
768 sess.target.target.options.is_like_windows {
769 if let Some(ref s) = trans.windows_subsystem {
774 // If we're building a dynamic library then some platforms need to make sure
775 // that all symbols are exported correctly from the dynamic library.
776 if crate_type != config::CrateTypeExecutable {
777 cmd.export_symbols(tmpdir, crate_type);
780 // When linking a dynamic library, we put the metadata into a section of the
781 // executable. This metadata is in a separate object file from the main
782 // object file, so we link that in here.
783 if crate_type == config::CrateTypeDylib ||
784 crate_type == config::CrateTypeProcMacro {
785 cmd.add_object(&outputs.with_extension("metadata.o"));
788 // Try to strip as much out of the generated object by removing unused
789 // sections if possible. See more comments in linker.rs
790 if !sess.opts.cg.link_dead_code {
791 let keep_metadata = crate_type == config::CrateTypeDylib;
792 cmd.gc_sections(keep_metadata);
795 let used_link_args = sess.cstore.used_link_args();
797 if crate_type == config::CrateTypeExecutable &&
798 t.options.position_independent_executables {
799 let empty_vec = Vec::new();
800 let empty_str = String::new();
801 let args = sess.opts.cg.link_args.as_ref().unwrap_or(&empty_vec);
802 let more_args = &sess.opts.cg.link_arg;
803 let mut args = args.iter().chain(more_args.iter()).chain(used_link_args.iter());
804 let relocation_model = sess.opts.cg.relocation_model.as_ref()
805 .unwrap_or(&empty_str);
806 if (t.options.relocation_model == "pic" || *relocation_model == "pic")
807 && !args.any(|x| *x == "-static") {
808 cmd.position_independent_executable();
812 // Pass optimization flags down to the linker.
815 // Pass debuginfo flags down to the linker.
818 // We want to prevent the compiler from accidentally leaking in any system
819 // libraries, so we explicitly ask gcc to not link to any libraries by
820 // default. Note that this does not happen for windows because windows pulls
821 // in some large number of libraries and I couldn't quite figure out which
823 if t.options.no_default_libraries {
824 cmd.no_default_libraries();
827 // Take careful note of the ordering of the arguments we pass to the linker
828 // here. Linkers will assume that things on the left depend on things to the
829 // right. Things on the right cannot depend on things on the left. This is
830 // all formally implemented in terms of resolving symbols (libs on the right
831 // resolve unknown symbols of libs on the left, but not vice versa).
833 // For this reason, we have organized the arguments we pass to the linker as
836 // 1. The local object that LLVM just generated
837 // 2. Local native libraries
838 // 3. Upstream rust libraries
839 // 4. Upstream native libraries
841 // The rationale behind this ordering is that those items lower down in the
842 // list can't depend on items higher up in the list. For example nothing can
843 // depend on what we just generated (e.g. that'd be a circular dependency).
844 // Upstream rust libraries are not allowed to depend on our local native
845 // libraries as that would violate the structure of the DAG, in that
846 // scenario they are required to link to them as well in a shared fashion.
848 // Note that upstream rust libraries may contain native dependencies as
849 // well, but they also can't depend on what we just started to add to the
850 // link line. And finally upstream native libraries can't depend on anything
851 // in this DAG so far because they're only dylibs and dylibs can only depend
852 // on other dylibs (e.g. other native deps).
853 add_local_native_libraries(cmd, sess);
854 add_upstream_rust_crates(cmd, sess, crate_type, tmpdir);
855 add_upstream_native_libraries(cmd, sess);
857 // # Telling the linker what we're doing
859 if crate_type != config::CrateTypeExecutable {
860 cmd.build_dylib(out_filename);
863 // FIXME (#2397): At some point we want to rpath our guesses as to
864 // where extern libraries might live, based on the
865 // addl_lib_search_paths
866 if sess.opts.cg.rpath {
867 let sysroot = sess.sysroot();
868 let target_triple = &sess.opts.target_triple;
869 let mut get_install_prefix_lib_path = || {
870 let install_prefix = option_env!("CFG_PREFIX").expect("CFG_PREFIX");
871 let tlib = filesearch::relative_target_lib_path(sysroot, target_triple);
872 let mut path = PathBuf::from(install_prefix);
877 let mut rpath_config = RPathConfig {
878 used_crates: sess.cstore.used_crates(LinkagePreference::RequireDynamic),
879 out_filename: out_filename.to_path_buf(),
880 has_rpath: sess.target.target.options.has_rpath,
881 is_like_osx: sess.target.target.options.is_like_osx,
882 linker_is_gnu: sess.target.target.options.linker_is_gnu,
883 get_install_prefix_lib_path: &mut get_install_prefix_lib_path,
885 cmd.args(&rpath::get_rpath_flags(&mut rpath_config));
888 // Finally add all the linker arguments provided on the command line along
889 // with any #[link_args] attributes found inside the crate
890 if let Some(ref args) = sess.opts.cg.link_args {
893 cmd.args(&sess.opts.cg.link_arg);
894 cmd.args(&used_link_args);
897 // # Native library linking
899 // User-supplied library search paths (-L on the command line). These are
900 // the same paths used to find Rust crates, so some of them may have been
901 // added already by the previous crate linking code. This only allows them
902 // to be found at compile time so it is still entirely up to outside
903 // forces to make sure that library can be found at runtime.
905 // Also note that the native libraries linked here are only the ones located
906 // in the current crate. Upstream crates with native library dependencies
907 // may have their native library pulled in above.
908 fn add_local_native_libraries(cmd: &mut Linker, sess: &Session) {
909 sess.target_filesearch(PathKind::All).for_each_lib_search_path(|path, k| {
911 PathKind::Framework => { cmd.framework_path(path); }
912 _ => { cmd.include_path(&fix_windows_verbatim_for_gcc(path)); }
916 let pair = sess.cstore.used_libraries().into_iter().filter(|l| {
917 relevant_lib(sess, l)
919 lib.kind == NativeLibraryKind::NativeStatic
921 let (staticlibs, others): (Vec<_>, Vec<_>) = pair;
923 // Some platforms take hints about whether a library is static or dynamic.
924 // For those that support this, we ensure we pass the option if the library
925 // was flagged "static" (most defaults are dynamic) to ensure that if
926 // libfoo.a and libfoo.so both exist that the right one is chosen.
929 let search_path = archive_search_paths(sess);
930 for l in staticlibs {
931 // Here we explicitly ask that the entire archive is included into the
932 // result artifact. For more details see #15460, but the gist is that
933 // the linker will strip away any unused objects in the archive if we
934 // don't otherwise explicitly reference them. This can occur for
935 // libraries which are just providing bindings, libraries with generic
937 cmd.link_whole_staticlib(&l.name, &search_path);
944 NativeLibraryKind::NativeUnknown => cmd.link_dylib(&lib.name),
945 NativeLibraryKind::NativeFramework => cmd.link_framework(&lib.name),
946 NativeLibraryKind::NativeStatic => bug!(),
951 // # Rust Crate linking
953 // Rust crates are not considered at all when creating an rlib output. All
954 // dependencies will be linked when producing the final output (instead of
955 // the intermediate rlib version)
956 fn add_upstream_rust_crates(cmd: &mut Linker,
958 crate_type: config::CrateType,
960 // All of the heavy lifting has previously been accomplished by the
961 // dependency_format module of the compiler. This is just crawling the
962 // output of that module, adding crates as necessary.
964 // Linking to a rlib involves just passing it to the linker (the linker
965 // will slurp up the object files inside), and linking to a dynamic library
966 // involves just passing the right -l flag.
968 let formats = sess.dependency_formats.borrow();
969 let data = formats.get(&crate_type).unwrap();
971 // Invoke get_used_crates to ensure that we get a topological sorting of
973 let deps = sess.cstore.used_crates(LinkagePreference::RequireDynamic);
975 let mut compiler_builtins = None;
977 for &(cnum, _) in &deps {
978 // We may not pass all crates through to the linker. Some crates may
979 // appear statically in an existing dylib, meaning we'll pick up all the
980 // symbols from the dylib.
981 let src = sess.cstore.used_crate_source(cnum);
982 match data[cnum.as_usize() - 1] {
983 // compiler-builtins are always placed last to ensure that they're
985 _ if sess.cstore.is_compiler_builtins(cnum) => {
986 assert!(compiler_builtins.is_none());
987 compiler_builtins = Some(cnum);
990 Linkage::IncludedFromDylib => {}
992 add_static_crate(cmd, sess, tmpdir, crate_type, cnum);
994 Linkage::Dynamic => {
995 add_dynamic_crate(cmd, sess, &src.dylib.unwrap().0)
1000 // We must always link the `compiler_builtins` crate statically. Even if it
1001 // was already "included" in a dylib (e.g. `libstd` when `-C prefer-dynamic`
1003 if let Some(cnum) = compiler_builtins {
1004 add_static_crate(cmd, sess, tmpdir, crate_type, cnum);
1007 // Converts a library file-stem into a cc -l argument
1008 fn unlib<'a>(config: &config::Config, stem: &'a str) -> &'a str {
1009 if stem.starts_with("lib") && !config.target.options.is_like_windows {
1016 // Adds the static "rlib" versions of all crates to the command line.
1017 // There's a bit of magic which happens here specifically related to LTO and
1018 // dynamic libraries. Specifically:
1020 // * For LTO, we remove upstream object files.
1021 // * For dylibs we remove metadata and bytecode from upstream rlibs
1023 // When performing LTO, almost(*) all of the bytecode from the upstream
1024 // libraries has already been included in our object file output. As a
1025 // result we need to remove the object files in the upstream libraries so
1026 // the linker doesn't try to include them twice (or whine about duplicate
1027 // symbols). We must continue to include the rest of the rlib, however, as
1028 // it may contain static native libraries which must be linked in.
1030 // (*) Crates marked with `#![no_builtins]` don't participate in LTO and
1031 // their bytecode wasn't included. The object files in those libraries must
1032 // still be passed to the linker.
1034 // When making a dynamic library, linkers by default don't include any
1035 // object files in an archive if they're not necessary to resolve the link.
1036 // We basically want to convert the archive (rlib) to a dylib, though, so we
1037 // *do* want everything included in the output, regardless of whether the
1038 // linker thinks it's needed or not. As a result we must use the
1039 // --whole-archive option (or the platform equivalent). When using this
1040 // option the linker will fail if there are non-objects in the archive (such
1041 // as our own metadata and/or bytecode). All in all, for rlibs to be
1042 // entirely included in dylibs, we need to remove all non-object files.
1044 // Note, however, that if we're not doing LTO or we're not producing a dylib
1045 // (aka we're making an executable), we can just pass the rlib blindly to
1046 // the linker (fast) because it's fine if it's not actually included as
1047 // we're at the end of the dependency chain.
1048 fn add_static_crate(cmd: &mut Linker,
1051 crate_type: config::CrateType,
1053 let src = sess.cstore.used_crate_source(cnum);
1054 let cratepath = &src.rlib.unwrap().0;
1056 // See the comment above in `link_staticlib` and `link_rlib` for why if
1057 // there's a static library that's not relevant we skip all object
1059 let native_libs = sess.cstore.native_libraries(cnum);
1060 let skip_native = native_libs.iter().any(|lib| {
1061 lib.kind == NativeLibraryKind::NativeStatic && !relevant_lib(sess, lib)
1064 if !sess.lto() && crate_type != config::CrateTypeDylib && !skip_native {
1065 cmd.link_rlib(&fix_windows_verbatim_for_gcc(cratepath));
1069 let dst = tmpdir.join(cratepath.file_name().unwrap());
1070 let name = cratepath.file_name().unwrap().to_str().unwrap();
1071 let name = &name[3..name.len() - 5]; // chop off lib/.rlib
1073 time(sess.time_passes(), &format!("altering {}.rlib", name), || {
1074 let cfg = archive_config(sess, &dst, Some(cratepath));
1075 let mut archive = ArchiveBuilder::new(cfg);
1076 archive.update_symbols();
1078 let mut any_objects = false;
1079 for f in archive.src_files() {
1080 if f.ends_with("bytecode.deflate") ||
1081 f == sess.cstore.metadata_filename() {
1082 archive.remove_file(&f);
1086 let canonical = f.replace("-", "_");
1087 let canonical_name = name.replace("-", "_");
1089 let is_rust_object =
1090 canonical.starts_with(&canonical_name) && {
1091 let num = &f[name.len()..f.len() - 2];
1092 num.len() > 0 && num[1..].parse::<u32>().is_ok()
1095 // If we've been requested to skip all native object files
1096 // (those not generated by the rust compiler) then we can skip
1097 // this file. See above for why we may want to do this.
1098 let skip_because_cfg_say_so = skip_native && !is_rust_object;
1100 // If we're performing LTO and this is a rust-generated object
1101 // file, then we don't need the object file as it's part of the
1102 // LTO module. Note that `#![no_builtins]` is excluded from LTO,
1103 // though, so we let that object file slide.
1104 let skip_because_lto = sess.lto() && is_rust_object &&
1105 !sess.cstore.is_no_builtins(cnum);
1107 if skip_because_cfg_say_so || skip_because_lto {
1108 archive.remove_file(&f);
1119 // If we're creating a dylib, then we need to include the
1120 // whole of each object in our archive into that artifact. This is
1121 // because a `dylib` can be reused as an intermediate artifact.
1123 // Note, though, that we don't want to include the whole of a
1124 // compiler-builtins crate (e.g. compiler-rt) because it'll get
1125 // repeatedly linked anyway.
1126 if crate_type == config::CrateTypeDylib &&
1127 !sess.cstore.is_compiler_builtins(cnum) {
1128 cmd.link_whole_rlib(&fix_windows_verbatim_for_gcc(&dst));
1130 cmd.link_rlib(&fix_windows_verbatim_for_gcc(&dst));
1135 // Same thing as above, but for dynamic crates instead of static crates.
1136 fn add_dynamic_crate(cmd: &mut Linker, sess: &Session, cratepath: &Path) {
1137 // If we're performing LTO, then it should have been previously required
1138 // that all upstream rust dependencies were available in an rlib format.
1139 assert!(!sess.lto());
1141 // Just need to tell the linker about where the library lives and
1143 let parent = cratepath.parent();
1144 if let Some(dir) = parent {
1145 cmd.include_path(&fix_windows_verbatim_for_gcc(dir));
1147 let filestem = cratepath.file_stem().unwrap().to_str().unwrap();
1148 cmd.link_rust_dylib(&unlib(&sess.target, filestem),
1149 parent.unwrap_or(Path::new("")));
1153 // Link in all of our upstream crates' native dependencies. Remember that
1154 // all of these upstream native dependencies are all non-static
1155 // dependencies. We've got two cases then:
1157 // 1. The upstream crate is an rlib. In this case we *must* link in the
1158 // native dependency because the rlib is just an archive.
1160 // 2. The upstream crate is a dylib. In order to use the dylib, we have to
1161 // have the dependency present on the system somewhere. Thus, we don't
1162 // gain a whole lot from not linking in the dynamic dependency to this
1165 // The use case for this is a little subtle. In theory the native
1166 // dependencies of a crate are purely an implementation detail of the crate
1167 // itself, but the problem arises with generic and inlined functions. If a
1168 // generic function calls a native function, then the generic function must
1169 // be instantiated in the target crate, meaning that the native symbol must
1170 // also be resolved in the target crate.
1171 fn add_upstream_native_libraries(cmd: &mut Linker, sess: &Session) {
1172 // Be sure to use a topological sorting of crates because there may be
1173 // interdependencies between native libraries. When passing -nodefaultlibs,
1174 // for example, almost all native libraries depend on libc, so we have to
1175 // make sure that's all the way at the right (liblibc is near the base of
1176 // the dependency chain).
1178 // This passes RequireStatic, but the actual requirement doesn't matter,
1179 // we're just getting an ordering of crate numbers, we're not worried about
1181 let crates = sess.cstore.used_crates(LinkagePreference::RequireStatic);
1182 for (cnum, _) in crates {
1183 for lib in sess.cstore.native_libraries(cnum) {
1184 if !relevant_lib(sess, &lib) {
1188 NativeLibraryKind::NativeUnknown => cmd.link_dylib(&lib.name),
1189 NativeLibraryKind::NativeFramework => cmd.link_framework(&lib.name),
1191 // ignore statically included native libraries here as we've
1192 // already included them when we included the rust library
1194 NativeLibraryKind::NativeStatic => {}
1200 fn relevant_lib(sess: &Session, lib: &NativeLibrary) -> bool {
1202 Some(ref cfg) => attr::cfg_matches(cfg, &sess.parse_sess, None),