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, GnuLinker, MsvcLinker};
13 use super::rpath::RPathConfig;
18 use session::config::NoDebugInfo;
19 use session::config::{OutputFilenames, Input, OutputType};
20 use session::filesearch;
21 use session::search_paths::PathKind;
23 use middle::cstore::{self, CrateStore, LinkMeta};
24 use middle::cstore::{LinkagePreference, NativeLibraryKind};
25 use middle::dependency_format::Linkage;
26 use trans::CrateTranslation;
27 use util::common::time;
28 use util::fs::fix_windows_verbatim_for_gcc;
29 use rustc_back::tempdir::TempDir;
34 use std::ffi::OsString;
36 use std::io::{self, Read, Write};
38 use std::path::{Path, PathBuf};
39 use std::process::Command;
43 use syntax::codemap::Span;
44 use syntax::attr::AttrMetaMethods;
48 // RLIB LLVM-BYTECODE OBJECT LAYOUT
51 // 0..10 "RUST_OBJECT" encoded in ASCII
52 // 11..14 format version as little-endian u32
53 // 15..22 size in bytes of deflate compressed LLVM bitcode as
55 // 23.. compressed LLVM bitcode
57 // This is the "magic number" expected at the beginning of a LLVM bytecode
59 pub const RLIB_BYTECODE_OBJECT_MAGIC: &'static [u8] = b"RUST_OBJECT";
61 // The version number this compiler will write to bytecode objects in rlibs
62 pub const RLIB_BYTECODE_OBJECT_VERSION: u32 = 1;
64 // The offset in bytes the bytecode object format version number can be found at
65 pub const RLIB_BYTECODE_OBJECT_VERSION_OFFSET: usize = 11;
67 // The offset in bytes the size of the compressed bytecode can be found at in
69 pub const RLIB_BYTECODE_OBJECT_V1_DATASIZE_OFFSET: usize =
70 RLIB_BYTECODE_OBJECT_VERSION_OFFSET + 4;
72 // The offset in bytes the compressed LLVM bytecode can be found at in format
74 pub const RLIB_BYTECODE_OBJECT_V1_DATA_OFFSET: usize =
75 RLIB_BYTECODE_OBJECT_V1_DATASIZE_OFFSET + 8;
78 pub fn find_crate_name(sess: Option<&Session>,
79 attrs: &[ast::Attribute],
80 input: &Input) -> String {
81 let validate = |s: String, span: Option<Span>| {
82 cstore::validate_crate_name(sess, &s[..], span);
86 // Look in attributes 100% of the time to make sure the attribute is marked
87 // as used. After doing this, however, we still prioritize a crate name from
88 // the command line over one found in the #[crate_name] attribute. If we
89 // find both we ensure that they're the same later on as well.
90 let attr_crate_name = attrs.iter().find(|at| at.check_name("crate_name"))
91 .and_then(|at| at.value_str().map(|s| (at, s)));
93 if let Some(sess) = sess {
94 if let Some(ref s) = sess.opts.crate_name {
95 if let Some((attr, ref name)) = attr_crate_name {
97 let msg = format!("--crate-name and #[crate_name] are \
98 required to match, but `{}` != `{}`",
100 sess.span_err(attr.span, &msg[..]);
103 return validate(s.clone(), None);
107 if let Some((attr, s)) = attr_crate_name {
108 return validate(s.to_string(), Some(attr.span));
110 if let Input::File(ref path) = *input {
111 if let Some(s) = path.file_stem().and_then(|s| s.to_str()) {
112 if s.starts_with("-") {
113 let msg = format!("crate names cannot start with a `-`, but \
114 `{}` has a leading hyphen", s);
115 if let Some(sess) = sess {
119 return validate(s.replace("-", "_"), None);
124 "rust_out".to_string()
127 pub fn build_link_meta(sess: &Session,
132 crate_name: name.to_owned(),
133 crate_hash: Svh::calculate(&sess.crate_disambiguator.borrow()[..], krate),
139 pub fn get_linker(sess: &Session) -> (String, Command) {
140 if let Some(ref linker) = sess.opts.cg.linker {
141 (linker.clone(), Command::new(linker))
142 } else if sess.target.target.options.is_like_msvc {
143 ("link.exe".to_string(), msvc::link_exe_cmd(sess))
145 (sess.target.target.options.linker.clone(),
146 Command::new(&sess.target.target.options.linker))
150 pub fn get_ar_prog(sess: &Session) -> String {
151 sess.opts.cg.ar.clone().unwrap_or_else(|| {
152 sess.target.target.options.ar.clone()
156 fn command_path(sess: &Session) -> OsString {
157 // The compiler's sysroot often has some bundled tools, so add it to the
158 // PATH for the child.
159 let mut new_path = sess.host_filesearch(PathKind::All)
160 .get_tools_search_paths();
161 if let Some(path) = env::var_os("PATH") {
162 new_path.extend(env::split_paths(&path));
164 if sess.target.target.options.is_like_msvc {
165 new_path.extend(msvc::host_dll_path());
167 env::join_paths(new_path).unwrap()
170 pub fn remove(sess: &Session, path: &Path) {
171 match fs::remove_file(path) {
174 sess.err(&format!("failed to remove {}: {}",
181 /// Perform the linkage portion of the compilation phase. This will generate all
182 /// of the requested outputs for this compilation session.
183 pub fn link_binary(sess: &Session,
184 trans: &CrateTranslation,
185 outputs: &OutputFilenames,
186 crate_name: &str) -> Vec<PathBuf> {
187 let mut out_filenames = Vec::new();
188 for &crate_type in sess.crate_types.borrow().iter() {
189 if invalid_output_for_target(sess, crate_type) {
190 sess.bug(&format!("invalid output type `{:?}` for target os `{}`",
191 crate_type, sess.opts.target_triple));
193 let out_file = link_binary_output(sess, trans, crate_type, outputs,
195 out_filenames.push(out_file);
198 // Remove the temporary object file and metadata if we aren't saving temps
199 if !sess.opts.cg.save_temps {
200 for obj in object_filenames(sess, outputs) {
203 remove(sess, &outputs.with_extension("metadata.o"));
210 /// Returns default crate type for target
212 /// Default crate type is used when crate type isn't provided neither
213 /// through cmd line arguments nor through crate attributes
215 /// It is CrateTypeExecutable for all platforms but iOS as there is no
216 /// way to run iOS binaries anyway without jailbreaking and
217 /// interaction with Rust code through static library is the only
219 pub fn default_output_for_target(sess: &Session) -> config::CrateType {
220 if !sess.target.target.options.executables {
221 config::CrateTypeStaticlib
223 config::CrateTypeExecutable
227 /// Checks if target supports crate_type as output
228 pub fn invalid_output_for_target(sess: &Session,
229 crate_type: config::CrateType) -> bool {
230 match (sess.target.target.options.dynamic_linking,
231 sess.target.target.options.executables, crate_type) {
232 (false, _, config::CrateTypeDylib) => true,
233 (_, false, config::CrateTypeExecutable) => true,
238 fn is_writeable(p: &Path) -> bool {
241 Ok(m) => !m.permissions().readonly()
245 pub fn filename_for_input(sess: &Session,
246 crate_type: config::CrateType,
248 outputs: &OutputFilenames) -> PathBuf {
249 let libname = format!("{}{}", crate_name, sess.opts.cg.extra_filename);
251 config::CrateTypeRlib => {
252 outputs.out_directory.join(&format!("lib{}.rlib", libname))
254 config::CrateTypeDylib => {
255 let (prefix, suffix) = (&sess.target.target.options.dll_prefix,
256 &sess.target.target.options.dll_suffix);
257 outputs.out_directory.join(&format!("{}{}{}", prefix, libname,
260 config::CrateTypeStaticlib => {
261 let (prefix, suffix) = (&sess.target.target.options.staticlib_prefix,
262 &sess.target.target.options.staticlib_suffix);
263 outputs.out_directory.join(&format!("{}{}{}", prefix, libname,
266 config::CrateTypeExecutable => {
267 let suffix = &sess.target.target.options.exe_suffix;
268 let out_filename = outputs.path(OutputType::Exe);
269 if suffix.is_empty() {
270 out_filename.to_path_buf()
272 out_filename.with_extension(&suffix[1..])
278 pub fn each_linked_rlib(sess: &Session,
279 f: &mut FnMut(ast::CrateNum, &Path)) {
280 let crates = sess.cstore.used_crates(LinkagePreference::RequireStatic).into_iter();
281 let fmts = sess.dependency_formats.borrow();
282 let fmts = fmts.get(&config::CrateTypeExecutable).or_else(|| {
283 fmts.get(&config::CrateTypeStaticlib)
284 }).unwrap_or_else(|| {
285 sess.bug("could not find formats for rlibs")
287 for (cnum, path) in crates {
288 match fmts[cnum as usize - 1] {
289 Linkage::NotLinked | Linkage::IncludedFromDylib => continue,
292 let name = sess.cstore.crate_name(cnum).clone();
293 let path = match path {
296 sess.fatal(&format!("could not find rlib for: `{}`", name));
303 fn link_binary_output(sess: &Session,
304 trans: &CrateTranslation,
305 crate_type: config::CrateType,
306 outputs: &OutputFilenames,
307 crate_name: &str) -> PathBuf {
308 let objects = object_filenames(sess, outputs);
309 let default_filename = filename_for_input(sess, crate_type, crate_name,
311 let out_filename = outputs.outputs.get(&OutputType::Exe)
312 .and_then(|s| s.to_owned())
313 .or_else(|| outputs.single_output_file.clone())
314 .unwrap_or(default_filename);
316 // Make sure files are writeable. Mac, FreeBSD, and Windows system linkers
317 // check this already -- however, the Linux linker will happily overwrite a
318 // read-only file. We should be consistent.
319 for file in objects.iter().chain(Some(&out_filename)) {
320 if !is_writeable(file) {
321 sess.fatal(&format!("output file {} is not writeable -- check its \
322 permissions", file.display()));
326 let tmpdir = match TempDir::new("rustc") {
327 Ok(tmpdir) => tmpdir,
328 Err(err) => sess.fatal(&format!("couldn't create a temp dir: {}", err)),
332 config::CrateTypeRlib => {
333 link_rlib(sess, Some(trans), &objects, &out_filename,
334 tmpdir.path()).build();
336 config::CrateTypeStaticlib => {
337 link_staticlib(sess, &objects, &out_filename, tmpdir.path());
339 config::CrateTypeExecutable => {
340 link_natively(sess, false, &objects, &out_filename, trans, outputs,
343 config::CrateTypeDylib => {
344 link_natively(sess, true, &objects, &out_filename, trans, outputs,
352 fn object_filenames(sess: &Session, outputs: &OutputFilenames) -> Vec<PathBuf> {
353 (0..sess.opts.cg.codegen_units).map(|i| {
354 let ext = format!("{}.o", i);
355 outputs.temp_path(OutputType::Object).with_extension(&ext)
359 fn archive_search_paths(sess: &Session) -> Vec<PathBuf> {
360 let mut search = Vec::new();
361 sess.target_filesearch(PathKind::Native).for_each_lib_search_path(|path, _| {
362 search.push(path.to_path_buf());
367 fn archive_config<'a>(sess: &'a Session,
369 input: Option<&Path>) -> ArchiveConfig<'a> {
372 dst: output.to_path_buf(),
373 src: input.map(|p| p.to_path_buf()),
374 lib_search_paths: archive_search_paths(sess),
375 ar_prog: get_ar_prog(sess),
376 command_path: command_path(sess),
382 // An rlib in its current incarnation is essentially a renamed .a file. The
383 // rlib primarily contains the object file of the crate, but it also contains
384 // all of the object files from native libraries. This is done by unzipping
385 // native libraries and inserting all of the contents into this archive.
386 fn link_rlib<'a>(sess: &'a Session,
387 trans: Option<&CrateTranslation>, // None == no metadata/bytecode
390 tmpdir: &Path) -> ArchiveBuilder<'a> {
391 info!("preparing rlib from {:?} to {:?}", objects, out_filename);
392 let mut ab = ArchiveBuilder::new(archive_config(sess, out_filename, None));
397 for (l, kind) in sess.cstore.used_libraries() {
399 NativeLibraryKind::NativeStatic => ab.add_native_library(&l),
400 NativeLibraryKind::NativeFramework |
401 NativeLibraryKind::NativeUnknown => {}
405 // After adding all files to the archive, we need to update the
406 // symbol table of the archive.
409 // For OSX/iOS, we must be careful to update symbols only when adding
410 // object files. We're about to start adding non-object files, so run
411 // `ar` now to process the object files.
412 if sess.target.target.options.is_like_osx && !ab.using_llvm() {
416 // Note that it is important that we add all of our non-object "magical
417 // files" *after* all of the object files in the archive. The reason for
418 // this is as follows:
420 // * When performing LTO, this archive will be modified to remove
421 // objects from above. The reason for this is described below.
423 // * When the system linker looks at an archive, it will attempt to
424 // determine the architecture of the archive in order to see whether its
427 // The algorithm for this detection is: iterate over the files in the
428 // archive. Skip magical SYMDEF names. Interpret the first file as an
429 // object file. Read architecture from the object file.
431 // * As one can probably see, if "metadata" and "foo.bc" were placed
432 // before all of the objects, then the architecture of this archive would
433 // not be correctly inferred once 'foo.o' is removed.
435 // Basically, all this means is that this code should not move above the
439 // Instead of putting the metadata in an object file section, rlibs
440 // contain the metadata in a separate file. We use a temp directory
441 // here so concurrent builds in the same directory don't try to use
442 // the same filename for metadata (stomping over one another)
443 let metadata = tmpdir.join(sess.cstore.metadata_filename());
444 match fs::File::create(&metadata).and_then(|mut f| {
445 f.write_all(&trans.metadata)
449 sess.fatal(&format!("failed to write {}: {}",
450 metadata.display(), e));
453 ab.add_file(&metadata);
455 // For LTO purposes, the bytecode of this library is also inserted
456 // into the archive. If codegen_units > 1, we insert each of the
459 // Note that we make sure that the bytecode filename in the
460 // archive is never exactly 16 bytes long by adding a 16 byte
461 // extension to it. This is to work around a bug in LLDB that
462 // would cause it to crash if the name of a file in an archive
463 // was exactly 16 bytes.
464 let bc_filename = obj.with_extension("bc");
465 let bc_deflated_filename = tmpdir.join({
466 obj.with_extension("bytecode.deflate").file_name().unwrap()
469 let mut bc_data = Vec::new();
470 match fs::File::open(&bc_filename).and_then(|mut f| {
471 f.read_to_end(&mut bc_data)
474 Err(e) => sess.fatal(&format!("failed to read bytecode: {}",
478 let bc_data_deflated = flate::deflate_bytes(&bc_data[..]);
480 let mut bc_file_deflated = match fs::File::create(&bc_deflated_filename) {
483 sess.fatal(&format!("failed to create compressed \
484 bytecode file: {}", e))
488 match write_rlib_bytecode_object_v1(&mut bc_file_deflated,
492 sess.fatal(&format!("failed to write compressed \
497 ab.add_file(&bc_deflated_filename);
499 // See the bottom of back::write::run_passes for an explanation
500 // of when we do and don't keep .0.bc files around.
501 let user_wants_numbered_bitcode =
502 sess.opts.output_types.contains_key(&OutputType::Bitcode) &&
503 sess.opts.cg.codegen_units > 1;
504 if !sess.opts.cg.save_temps && !user_wants_numbered_bitcode {
505 remove(sess, &bc_filename);
509 // After adding all files to the archive, we need to update the
510 // symbol table of the archive. This currently dies on OSX (see
511 // #11162), and isn't necessary there anyway
512 if !sess.target.target.options.is_like_osx || ab.using_llvm() {
523 fn write_rlib_bytecode_object_v1(writer: &mut Write,
524 bc_data_deflated: &[u8]) -> io::Result<()> {
525 let bc_data_deflated_size: u64 = bc_data_deflated.len() as u64;
527 writer.write_all(RLIB_BYTECODE_OBJECT_MAGIC)?;
528 writer.write_all(&[1, 0, 0, 0])?;
530 (bc_data_deflated_size >> 0) as u8,
531 (bc_data_deflated_size >> 8) as u8,
532 (bc_data_deflated_size >> 16) as u8,
533 (bc_data_deflated_size >> 24) as u8,
534 (bc_data_deflated_size >> 32) as u8,
535 (bc_data_deflated_size >> 40) as u8,
536 (bc_data_deflated_size >> 48) as u8,
537 (bc_data_deflated_size >> 56) as u8,
539 writer.write_all(&bc_data_deflated)?;
541 let number_of_bytes_written_so_far =
542 RLIB_BYTECODE_OBJECT_MAGIC.len() + // magic id
543 mem::size_of_val(&RLIB_BYTECODE_OBJECT_VERSION) + // version
544 mem::size_of_val(&bc_data_deflated_size) + // data size field
545 bc_data_deflated_size as usize; // actual data
547 // If the number of bytes written to the object so far is odd, add a
548 // padding byte to make it even. This works around a crash bug in LLDB
549 // (see issue #15950)
550 if number_of_bytes_written_so_far % 2 == 1 {
551 writer.write_all(&[0])?;
557 // Create a static archive
559 // This is essentially the same thing as an rlib, but it also involves adding
560 // all of the upstream crates' objects into the archive. This will slurp in
561 // all of the native libraries of upstream dependencies as well.
563 // Additionally, there's no way for us to link dynamic libraries, so we warn
564 // about all dynamic library dependencies that they're not linked in.
566 // There's no need to include metadata in a static archive, so ensure to not
567 // link in the metadata object file (and also don't prepare the archive with a
569 fn link_staticlib(sess: &Session, objects: &[PathBuf], out_filename: &Path,
571 let mut ab = link_rlib(sess, None, objects, out_filename, tempdir);
572 if sess.target.target.options.is_like_osx && !ab.using_llvm() {
575 if !sess.target.target.options.no_compiler_rt {
576 ab.add_native_library("compiler-rt");
579 let mut all_native_libs = vec![];
581 each_linked_rlib(sess, &mut |cnum, path| {
582 let name = sess.cstore.crate_name(cnum);
583 ab.add_rlib(path, &name, sess.lto()).unwrap();
585 let native_libs = sess.cstore.native_libraries(cnum);
586 all_native_libs.extend(native_libs);
592 if !all_native_libs.is_empty() {
593 sess.note_without_error("link against the following native artifacts when linking against \
594 this static library");
595 sess.note_without_error("the order and any duplication can be significant on some \
596 platforms, and so may need to be preserved");
599 for &(kind, ref lib) in &all_native_libs {
600 let name = match kind {
601 NativeLibraryKind::NativeStatic => "static library",
602 NativeLibraryKind::NativeUnknown => "library",
603 NativeLibraryKind::NativeFramework => "framework",
605 sess.note_without_error(&format!("{}: {}", name, *lib));
609 // Create a dynamic library or executable
611 // This will invoke the system linker/cc to create the resulting file. This
612 // links to all upstream files as well.
613 fn link_natively(sess: &Session, dylib: bool,
614 objects: &[PathBuf], out_filename: &Path,
615 trans: &CrateTranslation,
616 outputs: &OutputFilenames,
618 info!("preparing dylib? ({}) from {:?} to {:?}", dylib, objects,
621 // The invocations of cc share some flags across platforms
622 let (pname, mut cmd) = get_linker(sess);
623 cmd.env("PATH", command_path(sess));
625 let root = sess.target_filesearch(PathKind::Native).get_lib_path();
626 cmd.args(&sess.target.target.options.pre_link_args);
628 let pre_link_objects = if dylib {
629 &sess.target.target.options.pre_link_objects_dll
631 &sess.target.target.options.pre_link_objects_exe
633 for obj in pre_link_objects {
634 cmd.arg(root.join(obj));
638 let mut linker = if sess.target.target.options.is_like_msvc {
639 Box::new(MsvcLinker { cmd: &mut cmd, sess: &sess }) as Box<Linker>
641 Box::new(GnuLinker { cmd: &mut cmd, sess: &sess }) as Box<Linker>
643 link_args(&mut *linker, sess, dylib, tmpdir,
644 objects, out_filename, trans, outputs);
645 if !sess.target.target.options.no_compiler_rt {
646 linker.link_staticlib("compiler-rt");
649 cmd.args(&sess.target.target.options.late_link_args);
650 for obj in &sess.target.target.options.post_link_objects {
651 cmd.arg(root.join(obj));
653 cmd.args(&sess.target.target.options.post_link_args);
655 if sess.opts.debugging_opts.print_link_args {
656 println!("{:?}", &cmd);
659 // May have not found libraries in the right formats.
660 sess.abort_if_errors();
662 // Invoke the system linker
664 let prog = time(sess.time_passes(), "running linker", || cmd.output());
667 fn escape_string(s: &[u8]) -> String {
668 str::from_utf8(s).map(|s| s.to_owned())
669 .unwrap_or_else(|_| {
670 let mut x = "Non-UTF-8 output: ".to_string();
672 .flat_map(|&b| ascii::escape_default(b))
673 .map(|b| char::from_u32(b as u32).unwrap()));
677 if !prog.status.success() {
678 let mut output = prog.stderr.clone();
679 output.extend_from_slice(&prog.stdout);
680 sess.struct_err(&format!("linking with `{}` failed: {}",
683 .note(&format!("{:?}", &cmd))
684 .note(&escape_string(&output[..]))
686 sess.abort_if_errors();
688 info!("linker stderr:\n{}", escape_string(&prog.stderr[..]));
689 info!("linker stdout:\n{}", escape_string(&prog.stdout[..]));
692 sess.fatal(&format!("could not exec the linker `{}`: {}", pname, e));
697 // On OSX, debuggers need this utility to get run to do some munging of
699 if sess.target.target.options.is_like_osx && sess.opts.debuginfo != NoDebugInfo {
700 match Command::new("dsymutil").arg(out_filename).output() {
702 Err(e) => sess.fatal(&format!("failed to run dsymutil: {}", e)),
707 fn link_args(cmd: &mut Linker,
713 trans: &CrateTranslation,
714 outputs: &OutputFilenames) {
716 // The default library location, we need this to find the runtime.
717 // The location of crates will be determined as needed.
718 let lib_path = sess.target_filesearch(PathKind::All).get_lib_path();
721 let t = &sess.target.target;
723 cmd.include_path(&fix_windows_verbatim_for_gcc(&lib_path));
727 cmd.output_filename(out_filename);
729 // If we're building a dynamic library then some platforms need to make sure
730 // that all symbols are exported correctly from the dynamic library.
732 cmd.export_symbols(sess, trans, tmpdir);
735 // When linking a dynamic library, we put the metadata into a section of the
736 // executable. This metadata is in a separate object file from the main
737 // object file, so we link that in here.
739 cmd.add_object(&outputs.with_extension("metadata.o"));
742 // Try to strip as much out of the generated object by removing unused
743 // sections if possible. See more comments in linker.rs
744 if !sess.opts.cg.link_dead_code {
745 cmd.gc_sections(dylib);
748 let used_link_args = sess.cstore.used_link_args();
750 if !dylib && t.options.position_independent_executables {
751 let empty_vec = Vec::new();
752 let empty_str = String::new();
753 let args = sess.opts.cg.link_args.as_ref().unwrap_or(&empty_vec);
754 let mut args = args.iter().chain(used_link_args.iter());
755 let relocation_model = sess.opts.cg.relocation_model.as_ref()
756 .unwrap_or(&empty_str);
757 if (t.options.relocation_model == "pic" || *relocation_model == "pic")
758 && !args.any(|x| *x == "-static") {
759 cmd.position_independent_executable();
763 // Pass optimization flags down to the linker.
766 // Pass debuginfo flags down to the linker.
769 // We want to prevent the compiler from accidentally leaking in any system
770 // libraries, so we explicitly ask gcc to not link to any libraries by
771 // default. Note that this does not happen for windows because windows pulls
772 // in some large number of libraries and I couldn't quite figure out which
774 if t.options.no_default_libraries {
775 cmd.no_default_libraries();
778 // Take careful note of the ordering of the arguments we pass to the linker
779 // here. Linkers will assume that things on the left depend on things to the
780 // right. Things on the right cannot depend on things on the left. This is
781 // all formally implemented in terms of resolving symbols (libs on the right
782 // resolve unknown symbols of libs on the left, but not vice versa).
784 // For this reason, we have organized the arguments we pass to the linker as
787 // 1. The local object that LLVM just generated
788 // 2. Local native libraries
789 // 3. Upstream rust libraries
790 // 4. Upstream native libraries
792 // The rationale behind this ordering is that those items lower down in the
793 // list can't depend on items higher up in the list. For example nothing can
794 // depend on what we just generated (e.g. that'd be a circular dependency).
795 // Upstream rust libraries are not allowed to depend on our local native
796 // libraries as that would violate the structure of the DAG, in that
797 // scenario they are required to link to them as well in a shared fashion.
799 // Note that upstream rust libraries may contain native dependencies as
800 // well, but they also can't depend on what we just started to add to the
801 // link line. And finally upstream native libraries can't depend on anything
802 // in this DAG so far because they're only dylibs and dylibs can only depend
803 // on other dylibs (e.g. other native deps).
804 add_local_native_libraries(cmd, sess);
805 add_upstream_rust_crates(cmd, sess, dylib, tmpdir);
806 add_upstream_native_libraries(cmd, sess);
808 // # Telling the linker what we're doing
811 cmd.build_dylib(out_filename);
814 // FIXME (#2397): At some point we want to rpath our guesses as to
815 // where extern libraries might live, based on the
816 // addl_lib_search_paths
817 if sess.opts.cg.rpath {
818 let sysroot = sess.sysroot();
819 let target_triple = &sess.opts.target_triple;
820 let mut get_install_prefix_lib_path = || {
821 let install_prefix = option_env!("CFG_PREFIX").expect("CFG_PREFIX");
822 let tlib = filesearch::relative_target_lib_path(sysroot, target_triple);
823 let mut path = PathBuf::from(install_prefix);
828 let mut rpath_config = RPathConfig {
829 used_crates: sess.cstore.used_crates(LinkagePreference::RequireDynamic),
830 out_filename: out_filename.to_path_buf(),
831 has_rpath: sess.target.target.options.has_rpath,
832 is_like_osx: sess.target.target.options.is_like_osx,
833 linker_is_gnu: sess.target.target.options.linker_is_gnu,
834 get_install_prefix_lib_path: &mut get_install_prefix_lib_path,
836 cmd.args(&rpath::get_rpath_flags(&mut rpath_config));
839 // Finally add all the linker arguments provided on the command line along
840 // with any #[link_args] attributes found inside the crate
841 if let Some(ref args) = sess.opts.cg.link_args {
844 cmd.args(&used_link_args);
847 // # Native library linking
849 // User-supplied library search paths (-L on the command line). These are
850 // the same paths used to find Rust crates, so some of them may have been
851 // added already by the previous crate linking code. This only allows them
852 // to be found at compile time so it is still entirely up to outside
853 // forces to make sure that library can be found at runtime.
855 // Also note that the native libraries linked here are only the ones located
856 // in the current crate. Upstream crates with native library dependencies
857 // may have their native library pulled in above.
858 fn add_local_native_libraries(cmd: &mut Linker, sess: &Session) {
859 sess.target_filesearch(PathKind::All).for_each_lib_search_path(|path, k| {
861 PathKind::Framework => { cmd.framework_path(path); }
862 _ => { cmd.include_path(&fix_windows_verbatim_for_gcc(path)); }
866 let libs = sess.cstore.used_libraries();
868 let staticlibs = libs.iter().filter_map(|&(ref l, kind)| {
869 if kind == NativeLibraryKind::NativeStatic {Some(l)} else {None}
871 let others = libs.iter().filter(|&&(_, kind)| {
872 kind != NativeLibraryKind::NativeStatic
875 // Some platforms take hints about whether a library is static or dynamic.
876 // For those that support this, we ensure we pass the option if the library
877 // was flagged "static" (most defaults are dynamic) to ensure that if
878 // libfoo.a and libfoo.so both exist that the right one is chosen.
881 let search_path = archive_search_paths(sess);
882 for l in staticlibs {
883 // Here we explicitly ask that the entire archive is included into the
884 // result artifact. For more details see #15460, but the gist is that
885 // the linker will strip away any unused objects in the archive if we
886 // don't otherwise explicitly reference them. This can occur for
887 // libraries which are just providing bindings, libraries with generic
889 cmd.link_whole_staticlib(l, &search_path);
894 for &(ref l, kind) in others {
896 NativeLibraryKind::NativeUnknown => cmd.link_dylib(l),
897 NativeLibraryKind::NativeFramework => cmd.link_framework(l),
898 NativeLibraryKind::NativeStatic => unreachable!(),
903 // # Rust Crate linking
905 // Rust crates are not considered at all when creating an rlib output. All
906 // dependencies will be linked when producing the final output (instead of
907 // the intermediate rlib version)
908 fn add_upstream_rust_crates(cmd: &mut Linker, sess: &Session,
909 dylib: bool, tmpdir: &Path) {
910 // All of the heavy lifting has previously been accomplished by the
911 // dependency_format module of the compiler. This is just crawling the
912 // output of that module, adding crates as necessary.
914 // Linking to a rlib involves just passing it to the linker (the linker
915 // will slurp up the object files inside), and linking to a dynamic library
916 // involves just passing the right -l flag.
918 let formats = sess.dependency_formats.borrow();
919 let data = if dylib {
920 formats.get(&config::CrateTypeDylib).unwrap()
922 formats.get(&config::CrateTypeExecutable).unwrap()
925 // Invoke get_used_crates to ensure that we get a topological sorting of
927 let deps = sess.cstore.used_crates(LinkagePreference::RequireDynamic);
929 for &(cnum, _) in &deps {
930 // We may not pass all crates through to the linker. Some crates may
931 // appear statically in an existing dylib, meaning we'll pick up all the
932 // symbols from the dylib.
933 let src = sess.cstore.used_crate_source(cnum);
934 match data[cnum as usize - 1] {
936 Linkage::IncludedFromDylib => {}
938 add_static_crate(cmd, sess, tmpdir, dylib, &src.rlib.unwrap().0)
940 Linkage::Dynamic => {
941 add_dynamic_crate(cmd, sess, &src.dylib.unwrap().0)
946 // Converts a library file-stem into a cc -l argument
947 fn unlib<'a>(config: &config::Config, stem: &'a str) -> &'a str {
948 if stem.starts_with("lib") && !config.target.options.is_like_windows {
955 // Adds the static "rlib" versions of all crates to the command line.
956 // There's a bit of magic which happens here specifically related to LTO and
957 // dynamic libraries. Specifically:
959 // * For LTO, we remove upstream object files.
960 // * For dylibs we remove metadata and bytecode from upstream rlibs
962 // When performing LTO, all of the bytecode from the upstream libraries has
963 // already been included in our object file output. As a result we need to
964 // remove the object files in the upstream libraries so the linker doesn't
965 // try to include them twice (or whine about duplicate symbols). We must
966 // continue to include the rest of the rlib, however, as it may contain
967 // static native libraries which must be linked in.
969 // When making a dynamic library, linkers by default don't include any
970 // object files in an archive if they're not necessary to resolve the link.
971 // We basically want to convert the archive (rlib) to a dylib, though, so we
972 // *do* want everything included in the output, regardless of whether the
973 // linker thinks it's needed or not. As a result we must use the
974 // --whole-archive option (or the platform equivalent). When using this
975 // option the linker will fail if there are non-objects in the archive (such
976 // as our own metadata and/or bytecode). All in all, for rlibs to be
977 // entirely included in dylibs, we need to remove all non-object files.
979 // Note, however, that if we're not doing LTO or we're not producing a dylib
980 // (aka we're making an executable), we can just pass the rlib blindly to
981 // the linker (fast) because it's fine if it's not actually included as
982 // we're at the end of the dependency chain.
983 fn add_static_crate(cmd: &mut Linker, sess: &Session, tmpdir: &Path,
984 dylib: bool, cratepath: &Path) {
985 if !sess.lto() && !dylib {
986 cmd.link_rlib(&fix_windows_verbatim_for_gcc(cratepath));
990 let dst = tmpdir.join(cratepath.file_name().unwrap());
991 let name = cratepath.file_name().unwrap().to_str().unwrap();
992 let name = &name[3..name.len() - 5]; // chop off lib/.rlib
994 time(sess.time_passes(), &format!("altering {}.rlib", name), || {
995 let cfg = archive_config(sess, &dst, Some(cratepath));
996 let mut archive = ArchiveBuilder::new(cfg);
997 archive.remove_file(sess.cstore.metadata_filename());
998 archive.update_symbols();
1000 let mut any_objects = false;
1001 for f in archive.src_files() {
1002 if f.ends_with("bytecode.deflate") {
1003 archive.remove_file(&f);
1006 let canonical = f.replace("-", "_");
1007 let canonical_name = name.replace("-", "_");
1008 if sess.lto() && canonical.starts_with(&canonical_name) &&
1009 canonical.ends_with(".o") {
1010 let num = &f[name.len()..f.len() - 2];
1011 if num.len() > 0 && num[1..].parse::<u32>().is_ok() {
1012 archive.remove_file(&f);
1022 cmd.link_whole_rlib(&fix_windows_verbatim_for_gcc(&dst));
1024 cmd.link_rlib(&fix_windows_verbatim_for_gcc(&dst));
1030 // Same thing as above, but for dynamic crates instead of static crates.
1031 fn add_dynamic_crate(cmd: &mut Linker, sess: &Session, cratepath: &Path) {
1032 // If we're performing LTO, then it should have been previously required
1033 // that all upstream rust dependencies were available in an rlib format.
1034 assert!(!sess.lto());
1036 // Just need to tell the linker about where the library lives and
1038 let parent = cratepath.parent();
1039 if let Some(dir) = parent {
1040 cmd.include_path(&fix_windows_verbatim_for_gcc(dir));
1042 let filestem = cratepath.file_stem().unwrap().to_str().unwrap();
1043 cmd.link_rust_dylib(&unlib(&sess.target, filestem),
1044 parent.unwrap_or(Path::new("")));
1048 // Link in all of our upstream crates' native dependencies. Remember that
1049 // all of these upstream native dependencies are all non-static
1050 // dependencies. We've got two cases then:
1052 // 1. The upstream crate is an rlib. In this case we *must* link in the
1053 // native dependency because the rlib is just an archive.
1055 // 2. The upstream crate is a dylib. In order to use the dylib, we have to
1056 // have the dependency present on the system somewhere. Thus, we don't
1057 // gain a whole lot from not linking in the dynamic dependency to this
1060 // The use case for this is a little subtle. In theory the native
1061 // dependencies of a crate are purely an implementation detail of the crate
1062 // itself, but the problem arises with generic and inlined functions. If a
1063 // generic function calls a native function, then the generic function must
1064 // be instantiated in the target crate, meaning that the native symbol must
1065 // also be resolved in the target crate.
1066 fn add_upstream_native_libraries(cmd: &mut Linker, sess: &Session) {
1067 // Be sure to use a topological sorting of crates because there may be
1068 // interdependencies between native libraries. When passing -nodefaultlibs,
1069 // for example, almost all native libraries depend on libc, so we have to
1070 // make sure that's all the way at the right (liblibc is near the base of
1071 // the dependency chain).
1073 // This passes RequireStatic, but the actual requirement doesn't matter,
1074 // we're just getting an ordering of crate numbers, we're not worried about
1076 let crates = sess.cstore.used_crates(LinkagePreference::RequireStatic);
1077 for (cnum, _) in crates {
1078 let libs = sess.cstore.native_libraries(cnum);
1079 for &(kind, ref lib) in &libs {
1081 NativeLibraryKind::NativeUnknown => cmd.link_dylib(lib),
1082 NativeLibraryKind::NativeFramework => cmd.link_framework(lib),
1083 NativeLibraryKind::NativeStatic => {
1084 sess.bug("statics shouldn't be propagated");