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::def_id::DefId;
26 use middle::dependency_format::Linkage;
27 use middle::ty::TyCtxt;
28 use trans::CrateTranslation;
29 use util::common::time;
30 use util::fs::fix_windows_verbatim_for_gcc;
31 use rustc_back::tempdir::TempDir;
36 use std::ffi::OsString;
38 use std::io::{self, Read, Write};
40 use std::path::{Path, PathBuf};
41 use std::process::Command;
45 use syntax::codemap::Span;
46 use syntax::parse::token::InternedString;
47 use syntax::attr::AttrMetaMethods;
51 // RLIB LLVM-BYTECODE OBJECT LAYOUT
54 // 0..10 "RUST_OBJECT" encoded in ASCII
55 // 11..14 format version as little-endian u32
56 // 15..22 size in bytes of deflate compressed LLVM bitcode as
58 // 23.. compressed LLVM bitcode
60 // This is the "magic number" expected at the beginning of a LLVM bytecode
62 pub const RLIB_BYTECODE_OBJECT_MAGIC: &'static [u8] = b"RUST_OBJECT";
64 // The version number this compiler will write to bytecode objects in rlibs
65 pub const RLIB_BYTECODE_OBJECT_VERSION: u32 = 1;
67 // The offset in bytes the bytecode object format version number can be found at
68 pub const RLIB_BYTECODE_OBJECT_VERSION_OFFSET: usize = 11;
70 // The offset in bytes the size of the compressed bytecode can be found at in
72 pub const RLIB_BYTECODE_OBJECT_V1_DATASIZE_OFFSET: usize =
73 RLIB_BYTECODE_OBJECT_VERSION_OFFSET + 4;
75 // The offset in bytes the compressed LLVM bytecode can be found at in format
77 pub const RLIB_BYTECODE_OBJECT_V1_DATA_OFFSET: usize =
78 RLIB_BYTECODE_OBJECT_V1_DATASIZE_OFFSET + 8;
82 * Name mangling and its relationship to metadata. This is complex. Read
85 * The semantic model of Rust linkage is, broadly, that "there's no global
86 * namespace" between crates. Our aim is to preserve the illusion of this
87 * model despite the fact that it's not *quite* possible to implement on
88 * modern linkers. We initially didn't use system linkers at all, but have
89 * been convinced of their utility.
91 * There are a few issues to handle:
93 * - Linkers operate on a flat namespace, so we have to flatten names.
94 * We do this using the C++ namespace-mangling technique. Foo::bar
97 * - Symbols with the same name but different types need to get different
98 * linkage-names. We do this by hashing a string-encoding of the type into
99 * a fixed-size (currently 16-byte hex) cryptographic hash function (CHF:
100 * we use SHA256) to "prevent collisions". This is not airtight but 16 hex
101 * digits on uniform probability means you're going to need 2**32 same-name
102 * symbols in the same process before you're even hitting birthday-paradox
103 * collision probability.
105 * - Symbols in different crates but with same names "within" the crate need
106 * to get different linkage-names.
108 * - The hash shown in the filename needs to be predictable and stable for
109 * build tooling integration. It also needs to be using a hash function
110 * which is easy to use from Python, make, etc.
112 * So here is what we do:
114 * - Consider the package id; every crate has one (specified with crate_id
115 * attribute). If a package id isn't provided explicitly, we infer a
116 * versionless one from the output name. The version will end up being 0.0
117 * in this case. CNAME and CVERS are taken from this package id. For
118 * example, github.com/mozilla/CNAME#CVERS.
120 * - Define CMH as SHA256(crateid).
122 * - Define CMH8 as the first 8 characters of CMH.
124 * - Compile our crate to lib CNAME-CMH8-CVERS.so
126 * - Define STH(sym) as SHA256(CMH, type_str(sym))
128 * - Suffix a mangled sym with ::STH@CVERS, so that it is unique in the
129 * name, non-name metadata, and type sense, and versioned in the way
130 * system linkers understand.
133 pub fn find_crate_name(sess: Option<&Session>,
134 attrs: &[ast::Attribute],
135 input: &Input) -> String {
136 let validate = |s: String, span: Option<Span>| {
137 cstore::validate_crate_name(sess, &s[..], span);
141 // Look in attributes 100% of the time to make sure the attribute is marked
142 // as used. After doing this, however, we still prioritize a crate name from
143 // the command line over one found in the #[crate_name] attribute. If we
144 // find both we ensure that they're the same later on as well.
145 let attr_crate_name = attrs.iter().find(|at| at.check_name("crate_name"))
146 .and_then(|at| at.value_str().map(|s| (at, s)));
148 if let Some(sess) = sess {
149 if let Some(ref s) = sess.opts.crate_name {
150 if let Some((attr, ref name)) = attr_crate_name {
152 let msg = format!("--crate-name and #[crate_name] are \
153 required to match, but `{}` != `{}`",
155 sess.span_err(attr.span, &msg[..]);
158 return validate(s.clone(), None);
162 if let Some((attr, s)) = attr_crate_name {
163 return validate(s.to_string(), Some(attr.span));
165 if let Input::File(ref path) = *input {
166 if let Some(s) = path.file_stem().and_then(|s| s.to_str()) {
167 if s.starts_with("-") {
168 let msg = format!("crate names cannot start with a `-`, but \
169 `{}` has a leading hyphen", s);
170 if let Some(sess) = sess {
174 return validate(s.replace("-", "_"), None);
179 "rust_out".to_string()
182 pub fn build_link_meta(sess: &Session,
187 crate_name: name.to_owned(),
188 crate_hash: Svh::calculate(&sess.crate_disambiguator.borrow()[..], krate),
194 pub fn def_to_string(_tcx: &TyCtxt, did: DefId) -> String {
195 format!("{}:{}", did.krate, did.index.as_usize())
198 // Name sanitation. LLVM will happily accept identifiers with weird names, but
200 // gas accepts the following characters in symbols: a-z, A-Z, 0-9, ., _, $
201 pub fn sanitize(s: &str) -> String {
202 let mut result = String::new();
205 // Escape these with $ sequences
206 '@' => result.push_str("$SP$"),
207 '*' => result.push_str("$BP$"),
208 '&' => result.push_str("$RF$"),
209 '<' => result.push_str("$LT$"),
210 '>' => result.push_str("$GT$"),
211 '(' => result.push_str("$LP$"),
212 ')' => result.push_str("$RP$"),
213 ',' => result.push_str("$C$"),
215 // '.' doesn't occur in types and functions, so reuse it
217 '-' | ':' => result.push('.'),
219 // These are legal symbols
223 | '_' | '.' | '$' => result.push(c),
227 for c in c.escape_unicode().skip(1) {
230 '}' => result.push('$'),
238 // Underscore-qualify anything that didn't start as an ident.
239 if !result.is_empty() &&
240 result.as_bytes()[0] != '_' as u8 &&
241 ! (result.as_bytes()[0] as char).is_xid_start() {
242 return format!("_{}", &result[..]);
248 pub fn mangle<PI: Iterator<Item=InternedString>>(path: PI, hash: Option<&str>) -> String {
249 // Follow C++ namespace-mangling style, see
250 // http://en.wikipedia.org/wiki/Name_mangling for more info.
252 // It turns out that on OSX you can actually have arbitrary symbols in
253 // function names (at least when given to LLVM), but this is not possible
254 // when using unix's linker. Perhaps one day when we just use a linker from LLVM
255 // we won't need to do this name mangling. The problem with name mangling is
256 // that it seriously limits the available characters. For example we can't
257 // have things like &T in symbol names when one would theoretically
258 // want them for things like impls of traits on that type.
260 // To be able to work on all platforms and get *some* reasonable output, we
261 // use C++ name-mangling.
263 let mut n = String::from("_ZN"); // _Z == Begin name-sequence, N == nested
265 fn push(n: &mut String, s: &str) {
266 let sani = sanitize(s);
267 n.push_str(&format!("{}{}", sani.len(), sani));
270 // First, connect each component with <len, name> pairs.
275 if let Some(s) = hash {
279 n.push('E'); // End name-sequence.
283 pub fn get_linker(sess: &Session) -> (String, Command) {
284 if let Some(ref linker) = sess.opts.cg.linker {
285 (linker.clone(), Command::new(linker))
286 } else if sess.target.target.options.is_like_msvc {
287 ("link.exe".to_string(), msvc::link_exe_cmd(sess))
289 (sess.target.target.options.linker.clone(),
290 Command::new(&sess.target.target.options.linker))
294 pub fn get_ar_prog(sess: &Session) -> String {
295 sess.opts.cg.ar.clone().unwrap_or_else(|| {
296 sess.target.target.options.ar.clone()
300 fn command_path(sess: &Session) -> OsString {
301 // The compiler's sysroot often has some bundled tools, so add it to the
302 // PATH for the child.
303 let mut new_path = sess.host_filesearch(PathKind::All)
304 .get_tools_search_paths();
305 if let Some(path) = env::var_os("PATH") {
306 new_path.extend(env::split_paths(&path));
308 if sess.target.target.options.is_like_msvc {
309 new_path.extend(msvc::host_dll_path());
311 env::join_paths(new_path).unwrap()
314 pub fn remove(sess: &Session, path: &Path) {
315 match fs::remove_file(path) {
318 sess.err(&format!("failed to remove {}: {}",
325 /// Perform the linkage portion of the compilation phase. This will generate all
326 /// of the requested outputs for this compilation session.
327 pub fn link_binary(sess: &Session,
328 trans: &CrateTranslation,
329 outputs: &OutputFilenames,
330 crate_name: &str) -> Vec<PathBuf> {
331 let mut out_filenames = Vec::new();
332 for &crate_type in sess.crate_types.borrow().iter() {
333 if invalid_output_for_target(sess, crate_type) {
334 sess.bug(&format!("invalid output type `{:?}` for target os `{}`",
335 crate_type, sess.opts.target_triple));
337 let out_file = link_binary_output(sess, trans, crate_type, outputs,
339 out_filenames.push(out_file);
342 // Remove the temporary object file and metadata if we aren't saving temps
343 if !sess.opts.cg.save_temps {
344 for obj in object_filenames(sess, outputs) {
347 remove(sess, &outputs.with_extension("metadata.o"));
354 /// Returns default crate type for target
356 /// Default crate type is used when crate type isn't provided neither
357 /// through cmd line arguments nor through crate attributes
359 /// It is CrateTypeExecutable for all platforms but iOS as there is no
360 /// way to run iOS binaries anyway without jailbreaking and
361 /// interaction with Rust code through static library is the only
363 pub fn default_output_for_target(sess: &Session) -> config::CrateType {
364 if !sess.target.target.options.executables {
365 config::CrateTypeStaticlib
367 config::CrateTypeExecutable
371 /// Checks if target supports crate_type as output
372 pub fn invalid_output_for_target(sess: &Session,
373 crate_type: config::CrateType) -> bool {
374 match (sess.target.target.options.dynamic_linking,
375 sess.target.target.options.executables, crate_type) {
376 (false, _, config::CrateTypeDylib) => true,
377 (_, false, config::CrateTypeExecutable) => true,
382 fn is_writeable(p: &Path) -> bool {
385 Ok(m) => !m.permissions().readonly()
389 pub fn filename_for_input(sess: &Session,
390 crate_type: config::CrateType,
392 outputs: &OutputFilenames) -> PathBuf {
393 let libname = format!("{}{}", crate_name, sess.opts.cg.extra_filename);
395 config::CrateTypeRlib => {
396 outputs.out_directory.join(&format!("lib{}.rlib", libname))
398 config::CrateTypeDylib => {
399 let (prefix, suffix) = (&sess.target.target.options.dll_prefix,
400 &sess.target.target.options.dll_suffix);
401 outputs.out_directory.join(&format!("{}{}{}", prefix, libname,
404 config::CrateTypeStaticlib => {
405 let (prefix, suffix) = (&sess.target.target.options.staticlib_prefix,
406 &sess.target.target.options.staticlib_suffix);
407 outputs.out_directory.join(&format!("{}{}{}", prefix, libname,
410 config::CrateTypeExecutable => {
411 let suffix = &sess.target.target.options.exe_suffix;
412 let out_filename = outputs.path(OutputType::Exe);
413 if suffix.is_empty() {
414 out_filename.to_path_buf()
416 out_filename.with_extension(&suffix[1..])
422 pub fn each_linked_rlib(sess: &Session,
423 f: &mut FnMut(ast::CrateNum, &Path)) {
424 let crates = sess.cstore.used_crates(LinkagePreference::RequireStatic).into_iter();
425 let fmts = sess.dependency_formats.borrow();
426 let fmts = fmts.get(&config::CrateTypeExecutable).or_else(|| {
427 fmts.get(&config::CrateTypeStaticlib)
428 }).unwrap_or_else(|| {
429 sess.bug("could not find formats for rlibs")
431 for (cnum, path) in crates {
432 match fmts[cnum as usize - 1] {
433 Linkage::NotLinked | Linkage::IncludedFromDylib => continue,
436 let name = sess.cstore.crate_name(cnum).clone();
437 let path = match path {
440 sess.fatal(&format!("could not find rlib for: `{}`", name));
447 fn link_binary_output(sess: &Session,
448 trans: &CrateTranslation,
449 crate_type: config::CrateType,
450 outputs: &OutputFilenames,
451 crate_name: &str) -> PathBuf {
452 let objects = object_filenames(sess, outputs);
453 let default_filename = filename_for_input(sess, crate_type, crate_name,
455 let out_filename = outputs.outputs.get(&OutputType::Exe)
456 .and_then(|s| s.to_owned())
457 .or_else(|| outputs.single_output_file.clone())
458 .unwrap_or(default_filename);
460 // Make sure files are writeable. Mac, FreeBSD, and Windows system linkers
461 // check this already -- however, the Linux linker will happily overwrite a
462 // read-only file. We should be consistent.
463 for file in objects.iter().chain(Some(&out_filename)) {
464 if !is_writeable(file) {
465 sess.fatal(&format!("output file {} is not writeable -- check its \
466 permissions", file.display()));
470 let tmpdir = match TempDir::new("rustc") {
471 Ok(tmpdir) => tmpdir,
472 Err(err) => sess.fatal(&format!("couldn't create a temp dir: {}", err)),
476 config::CrateTypeRlib => {
477 link_rlib(sess, Some(trans), &objects, &out_filename,
478 tmpdir.path()).build();
480 config::CrateTypeStaticlib => {
481 link_staticlib(sess, &objects, &out_filename, tmpdir.path());
483 config::CrateTypeExecutable => {
484 link_natively(sess, false, &objects, &out_filename, trans, outputs,
487 config::CrateTypeDylib => {
488 link_natively(sess, true, &objects, &out_filename, trans, outputs,
496 fn object_filenames(sess: &Session, outputs: &OutputFilenames) -> Vec<PathBuf> {
497 (0..sess.opts.cg.codegen_units).map(|i| {
498 let ext = format!("{}.o", i);
499 outputs.temp_path(OutputType::Object).with_extension(&ext)
503 fn archive_search_paths(sess: &Session) -> Vec<PathBuf> {
504 let mut search = Vec::new();
505 sess.target_filesearch(PathKind::Native).for_each_lib_search_path(|path, _| {
506 search.push(path.to_path_buf());
511 fn archive_config<'a>(sess: &'a Session,
513 input: Option<&Path>) -> ArchiveConfig<'a> {
516 dst: output.to_path_buf(),
517 src: input.map(|p| p.to_path_buf()),
518 lib_search_paths: archive_search_paths(sess),
519 ar_prog: get_ar_prog(sess),
520 command_path: command_path(sess),
526 // An rlib in its current incarnation is essentially a renamed .a file. The
527 // rlib primarily contains the object file of the crate, but it also contains
528 // all of the object files from native libraries. This is done by unzipping
529 // native libraries and inserting all of the contents into this archive.
530 fn link_rlib<'a>(sess: &'a Session,
531 trans: Option<&CrateTranslation>, // None == no metadata/bytecode
534 tmpdir: &Path) -> ArchiveBuilder<'a> {
535 info!("preparing rlib from {:?} to {:?}", objects, out_filename);
536 let mut ab = ArchiveBuilder::new(archive_config(sess, out_filename, None));
541 for (l, kind) in sess.cstore.used_libraries() {
543 NativeLibraryKind::NativeStatic => ab.add_native_library(&l),
544 NativeLibraryKind::NativeFramework |
545 NativeLibraryKind::NativeUnknown => {}
549 // After adding all files to the archive, we need to update the
550 // symbol table of the archive.
553 // For OSX/iOS, we must be careful to update symbols only when adding
554 // object files. We're about to start adding non-object files, so run
555 // `ar` now to process the object files.
556 if sess.target.target.options.is_like_osx && !ab.using_llvm() {
560 // Note that it is important that we add all of our non-object "magical
561 // files" *after* all of the object files in the archive. The reason for
562 // this is as follows:
564 // * When performing LTO, this archive will be modified to remove
565 // objects from above. The reason for this is described below.
567 // * When the system linker looks at an archive, it will attempt to
568 // determine the architecture of the archive in order to see whether its
571 // The algorithm for this detection is: iterate over the files in the
572 // archive. Skip magical SYMDEF names. Interpret the first file as an
573 // object file. Read architecture from the object file.
575 // * As one can probably see, if "metadata" and "foo.bc" were placed
576 // before all of the objects, then the architecture of this archive would
577 // not be correctly inferred once 'foo.o' is removed.
579 // Basically, all this means is that this code should not move above the
583 // Instead of putting the metadata in an object file section, rlibs
584 // contain the metadata in a separate file. We use a temp directory
585 // here so concurrent builds in the same directory don't try to use
586 // the same filename for metadata (stomping over one another)
587 let metadata = tmpdir.join(sess.cstore.metadata_filename());
588 match fs::File::create(&metadata).and_then(|mut f| {
589 f.write_all(&trans.metadata)
593 sess.fatal(&format!("failed to write {}: {}",
594 metadata.display(), e));
597 ab.add_file(&metadata);
599 // For LTO purposes, the bytecode of this library is also inserted
600 // into the archive. If codegen_units > 1, we insert each of the
603 // Note that we make sure that the bytecode filename in the
604 // archive is never exactly 16 bytes long by adding a 16 byte
605 // extension to it. This is to work around a bug in LLDB that
606 // would cause it to crash if the name of a file in an archive
607 // was exactly 16 bytes.
608 let bc_filename = obj.with_extension("bc");
609 let bc_deflated_filename = tmpdir.join({
610 obj.with_extension("bytecode.deflate").file_name().unwrap()
613 let mut bc_data = Vec::new();
614 match fs::File::open(&bc_filename).and_then(|mut f| {
615 f.read_to_end(&mut bc_data)
618 Err(e) => sess.fatal(&format!("failed to read bytecode: {}",
622 let bc_data_deflated = flate::deflate_bytes(&bc_data[..]);
624 let mut bc_file_deflated = match fs::File::create(&bc_deflated_filename) {
627 sess.fatal(&format!("failed to create compressed \
628 bytecode file: {}", e))
632 match write_rlib_bytecode_object_v1(&mut bc_file_deflated,
636 sess.fatal(&format!("failed to write compressed \
641 ab.add_file(&bc_deflated_filename);
643 // See the bottom of back::write::run_passes for an explanation
644 // of when we do and don't keep .0.bc files around.
645 let user_wants_numbered_bitcode =
646 sess.opts.output_types.contains_key(&OutputType::Bitcode) &&
647 sess.opts.cg.codegen_units > 1;
648 if !sess.opts.cg.save_temps && !user_wants_numbered_bitcode {
649 remove(sess, &bc_filename);
653 // After adding all files to the archive, we need to update the
654 // symbol table of the archive. This currently dies on OSX (see
655 // #11162), and isn't necessary there anyway
656 if !sess.target.target.options.is_like_osx || ab.using_llvm() {
667 fn write_rlib_bytecode_object_v1(writer: &mut Write,
668 bc_data_deflated: &[u8]) -> io::Result<()> {
669 let bc_data_deflated_size: u64 = bc_data_deflated.len() as u64;
671 writer.write_all(RLIB_BYTECODE_OBJECT_MAGIC)?;
672 writer.write_all(&[1, 0, 0, 0])?;
674 (bc_data_deflated_size >> 0) as u8,
675 (bc_data_deflated_size >> 8) as u8,
676 (bc_data_deflated_size >> 16) as u8,
677 (bc_data_deflated_size >> 24) as u8,
678 (bc_data_deflated_size >> 32) as u8,
679 (bc_data_deflated_size >> 40) as u8,
680 (bc_data_deflated_size >> 48) as u8,
681 (bc_data_deflated_size >> 56) as u8,
683 writer.write_all(&bc_data_deflated)?;
685 let number_of_bytes_written_so_far =
686 RLIB_BYTECODE_OBJECT_MAGIC.len() + // magic id
687 mem::size_of_val(&RLIB_BYTECODE_OBJECT_VERSION) + // version
688 mem::size_of_val(&bc_data_deflated_size) + // data size field
689 bc_data_deflated_size as usize; // actual data
691 // If the number of bytes written to the object so far is odd, add a
692 // padding byte to make it even. This works around a crash bug in LLDB
693 // (see issue #15950)
694 if number_of_bytes_written_so_far % 2 == 1 {
695 writer.write_all(&[0])?;
701 // Create a static archive
703 // This is essentially the same thing as an rlib, but it also involves adding
704 // all of the upstream crates' objects into the archive. This will slurp in
705 // all of the native libraries of upstream dependencies as well.
707 // Additionally, there's no way for us to link dynamic libraries, so we warn
708 // about all dynamic library dependencies that they're not linked in.
710 // There's no need to include metadata in a static archive, so ensure to not
711 // link in the metadata object file (and also don't prepare the archive with a
713 fn link_staticlib(sess: &Session, objects: &[PathBuf], out_filename: &Path,
715 let mut ab = link_rlib(sess, None, objects, out_filename, tempdir);
716 if sess.target.target.options.is_like_osx && !ab.using_llvm() {
719 if !sess.target.target.options.no_compiler_rt {
720 ab.add_native_library("compiler-rt");
723 let mut all_native_libs = vec![];
725 each_linked_rlib(sess, &mut |cnum, path| {
726 let name = sess.cstore.crate_name(cnum);
727 ab.add_rlib(path, &name, sess.lto()).unwrap();
729 let native_libs = sess.cstore.native_libraries(cnum);
730 all_native_libs.extend(native_libs);
736 if !all_native_libs.is_empty() {
737 sess.note_without_error("link against the following native artifacts when linking against \
738 this static library");
739 sess.note_without_error("the order and any duplication can be significant on some \
740 platforms, and so may need to be preserved");
743 for &(kind, ref lib) in &all_native_libs {
744 let name = match kind {
745 NativeLibraryKind::NativeStatic => "static library",
746 NativeLibraryKind::NativeUnknown => "library",
747 NativeLibraryKind::NativeFramework => "framework",
749 sess.note_without_error(&format!("{}: {}", name, *lib));
753 // Create a dynamic library or executable
755 // This will invoke the system linker/cc to create the resulting file. This
756 // links to all upstream files as well.
757 fn link_natively(sess: &Session, dylib: bool,
758 objects: &[PathBuf], out_filename: &Path,
759 trans: &CrateTranslation,
760 outputs: &OutputFilenames,
762 info!("preparing dylib? ({}) from {:?} to {:?}", dylib, objects,
765 // The invocations of cc share some flags across platforms
766 let (pname, mut cmd) = get_linker(sess);
767 cmd.env("PATH", command_path(sess));
769 let root = sess.target_filesearch(PathKind::Native).get_lib_path();
770 cmd.args(&sess.target.target.options.pre_link_args);
772 let pre_link_objects = if dylib {
773 &sess.target.target.options.pre_link_objects_dll
775 &sess.target.target.options.pre_link_objects_exe
777 for obj in pre_link_objects {
778 cmd.arg(root.join(obj));
782 let mut linker = if sess.target.target.options.is_like_msvc {
783 Box::new(MsvcLinker { cmd: &mut cmd, sess: &sess }) as Box<Linker>
785 Box::new(GnuLinker { cmd: &mut cmd, sess: &sess }) as Box<Linker>
787 link_args(&mut *linker, sess, dylib, tmpdir,
788 objects, out_filename, trans, outputs);
789 if !sess.target.target.options.no_compiler_rt {
790 linker.link_staticlib("compiler-rt");
793 cmd.args(&sess.target.target.options.late_link_args);
794 for obj in &sess.target.target.options.post_link_objects {
795 cmd.arg(root.join(obj));
797 cmd.args(&sess.target.target.options.post_link_args);
799 if sess.opts.debugging_opts.print_link_args {
800 println!("{:?}", &cmd);
803 // May have not found libraries in the right formats.
804 sess.abort_if_errors();
806 // Invoke the system linker
808 let prog = time(sess.time_passes(), "running linker", || cmd.output());
811 fn escape_string(s: &[u8]) -> String {
812 str::from_utf8(s).map(|s| s.to_owned())
813 .unwrap_or_else(|_| {
814 let mut x = "Non-UTF-8 output: ".to_string();
816 .flat_map(|&b| ascii::escape_default(b))
817 .map(|b| char::from_u32(b as u32).unwrap()));
821 if !prog.status.success() {
822 let mut output = prog.stderr.clone();
823 output.extend_from_slice(&prog.stdout);
824 sess.struct_err(&format!("linking with `{}` failed: {}",
827 .note(&format!("{:?}", &cmd))
828 .note(&escape_string(&output[..]))
830 sess.abort_if_errors();
832 info!("linker stderr:\n{}", escape_string(&prog.stderr[..]));
833 info!("linker stdout:\n{}", escape_string(&prog.stdout[..]));
836 sess.fatal(&format!("could not exec the linker `{}`: {}", pname, e));
841 // On OSX, debuggers need this utility to get run to do some munging of
843 if sess.target.target.options.is_like_osx && sess.opts.debuginfo != NoDebugInfo {
844 match Command::new("dsymutil").arg(out_filename).output() {
846 Err(e) => sess.fatal(&format!("failed to run dsymutil: {}", e)),
851 fn link_args(cmd: &mut Linker,
857 trans: &CrateTranslation,
858 outputs: &OutputFilenames) {
860 // The default library location, we need this to find the runtime.
861 // The location of crates will be determined as needed.
862 let lib_path = sess.target_filesearch(PathKind::All).get_lib_path();
865 let t = &sess.target.target;
867 cmd.include_path(&fix_windows_verbatim_for_gcc(&lib_path));
871 cmd.output_filename(out_filename);
873 // If we're building a dynamic library then some platforms need to make sure
874 // that all symbols are exported correctly from the dynamic library.
876 cmd.export_symbols(sess, trans, tmpdir);
879 // When linking a dynamic library, we put the metadata into a section of the
880 // executable. This metadata is in a separate object file from the main
881 // object file, so we link that in here.
883 cmd.add_object(&outputs.with_extension("metadata.o"));
886 // Try to strip as much out of the generated object by removing unused
887 // sections if possible. See more comments in linker.rs
888 if !sess.opts.cg.link_dead_code {
889 cmd.gc_sections(dylib);
892 let used_link_args = sess.cstore.used_link_args();
894 if !dylib && t.options.position_independent_executables {
895 let empty_vec = Vec::new();
896 let empty_str = String::new();
897 let args = sess.opts.cg.link_args.as_ref().unwrap_or(&empty_vec);
898 let mut args = args.iter().chain(used_link_args.iter());
899 let relocation_model = sess.opts.cg.relocation_model.as_ref()
900 .unwrap_or(&empty_str);
901 if (t.options.relocation_model == "pic" || *relocation_model == "pic")
902 && !args.any(|x| *x == "-static") {
903 cmd.position_independent_executable();
907 // Pass optimization flags down to the linker.
910 // Pass debuginfo flags down to the linker.
913 // We want to prevent the compiler from accidentally leaking in any system
914 // libraries, so we explicitly ask gcc to not link to any libraries by
915 // default. Note that this does not happen for windows because windows pulls
916 // in some large number of libraries and I couldn't quite figure out which
918 if t.options.no_default_libraries {
919 cmd.no_default_libraries();
922 // Take careful note of the ordering of the arguments we pass to the linker
923 // here. Linkers will assume that things on the left depend on things to the
924 // right. Things on the right cannot depend on things on the left. This is
925 // all formally implemented in terms of resolving symbols (libs on the right
926 // resolve unknown symbols of libs on the left, but not vice versa).
928 // For this reason, we have organized the arguments we pass to the linker as
931 // 1. The local object that LLVM just generated
932 // 2. Local native libraries
933 // 3. Upstream rust libraries
934 // 4. Upstream native libraries
936 // The rationale behind this ordering is that those items lower down in the
937 // list can't depend on items higher up in the list. For example nothing can
938 // depend on what we just generated (e.g. that'd be a circular dependency).
939 // Upstream rust libraries are not allowed to depend on our local native
940 // libraries as that would violate the structure of the DAG, in that
941 // scenario they are required to link to them as well in a shared fashion.
943 // Note that upstream rust libraries may contain native dependencies as
944 // well, but they also can't depend on what we just started to add to the
945 // link line. And finally upstream native libraries can't depend on anything
946 // in this DAG so far because they're only dylibs and dylibs can only depend
947 // on other dylibs (e.g. other native deps).
948 add_local_native_libraries(cmd, sess);
949 add_upstream_rust_crates(cmd, sess, dylib, tmpdir);
950 add_upstream_native_libraries(cmd, sess);
952 // # Telling the linker what we're doing
955 cmd.build_dylib(out_filename);
958 // FIXME (#2397): At some point we want to rpath our guesses as to
959 // where extern libraries might live, based on the
960 // addl_lib_search_paths
961 if sess.opts.cg.rpath {
962 let sysroot = sess.sysroot();
963 let target_triple = &sess.opts.target_triple;
964 let mut get_install_prefix_lib_path = || {
965 let install_prefix = option_env!("CFG_PREFIX").expect("CFG_PREFIX");
966 let tlib = filesearch::relative_target_lib_path(sysroot, target_triple);
967 let mut path = PathBuf::from(install_prefix);
972 let mut rpath_config = RPathConfig {
973 used_crates: sess.cstore.used_crates(LinkagePreference::RequireDynamic),
974 out_filename: out_filename.to_path_buf(),
975 has_rpath: sess.target.target.options.has_rpath,
976 is_like_osx: sess.target.target.options.is_like_osx,
977 linker_is_gnu: sess.target.target.options.linker_is_gnu,
978 get_install_prefix_lib_path: &mut get_install_prefix_lib_path,
980 cmd.args(&rpath::get_rpath_flags(&mut rpath_config));
983 // Finally add all the linker arguments provided on the command line along
984 // with any #[link_args] attributes found inside the crate
985 if let Some(ref args) = sess.opts.cg.link_args {
988 cmd.args(&used_link_args);
991 // # Native library linking
993 // User-supplied library search paths (-L on the command line). These are
994 // the same paths used to find Rust crates, so some of them may have been
995 // added already by the previous crate linking code. This only allows them
996 // to be found at compile time so it is still entirely up to outside
997 // forces to make sure that library can be found at runtime.
999 // Also note that the native libraries linked here are only the ones located
1000 // in the current crate. Upstream crates with native library dependencies
1001 // may have their native library pulled in above.
1002 fn add_local_native_libraries(cmd: &mut Linker, sess: &Session) {
1003 sess.target_filesearch(PathKind::All).for_each_lib_search_path(|path, k| {
1005 PathKind::Framework => { cmd.framework_path(path); }
1006 _ => { cmd.include_path(&fix_windows_verbatim_for_gcc(path)); }
1010 let libs = sess.cstore.used_libraries();
1012 let staticlibs = libs.iter().filter_map(|&(ref l, kind)| {
1013 if kind == NativeLibraryKind::NativeStatic {Some(l)} else {None}
1015 let others = libs.iter().filter(|&&(_, kind)| {
1016 kind != NativeLibraryKind::NativeStatic
1019 // Some platforms take hints about whether a library is static or dynamic.
1020 // For those that support this, we ensure we pass the option if the library
1021 // was flagged "static" (most defaults are dynamic) to ensure that if
1022 // libfoo.a and libfoo.so both exist that the right one is chosen.
1025 let search_path = archive_search_paths(sess);
1026 for l in staticlibs {
1027 // Here we explicitly ask that the entire archive is included into the
1028 // result artifact. For more details see #15460, but the gist is that
1029 // the linker will strip away any unused objects in the archive if we
1030 // don't otherwise explicitly reference them. This can occur for
1031 // libraries which are just providing bindings, libraries with generic
1033 cmd.link_whole_staticlib(l, &search_path);
1038 for &(ref l, kind) in others {
1040 NativeLibraryKind::NativeUnknown => cmd.link_dylib(l),
1041 NativeLibraryKind::NativeFramework => cmd.link_framework(l),
1042 NativeLibraryKind::NativeStatic => unreachable!(),
1047 // # Rust Crate linking
1049 // Rust crates are not considered at all when creating an rlib output. All
1050 // dependencies will be linked when producing the final output (instead of
1051 // the intermediate rlib version)
1052 fn add_upstream_rust_crates(cmd: &mut Linker, sess: &Session,
1053 dylib: bool, tmpdir: &Path) {
1054 // All of the heavy lifting has previously been accomplished by the
1055 // dependency_format module of the compiler. This is just crawling the
1056 // output of that module, adding crates as necessary.
1058 // Linking to a rlib involves just passing it to the linker (the linker
1059 // will slurp up the object files inside), and linking to a dynamic library
1060 // involves just passing the right -l flag.
1062 let formats = sess.dependency_formats.borrow();
1063 let data = if dylib {
1064 formats.get(&config::CrateTypeDylib).unwrap()
1066 formats.get(&config::CrateTypeExecutable).unwrap()
1069 // Invoke get_used_crates to ensure that we get a topological sorting of
1071 let deps = sess.cstore.used_crates(LinkagePreference::RequireDynamic);
1073 for &(cnum, _) in &deps {
1074 // We may not pass all crates through to the linker. Some crates may
1075 // appear statically in an existing dylib, meaning we'll pick up all the
1076 // symbols from the dylib.
1077 let src = sess.cstore.used_crate_source(cnum);
1078 match data[cnum as usize - 1] {
1079 Linkage::NotLinked |
1080 Linkage::IncludedFromDylib => {}
1081 Linkage::Static => {
1082 add_static_crate(cmd, sess, tmpdir, dylib, &src.rlib.unwrap().0)
1084 Linkage::Dynamic => {
1085 add_dynamic_crate(cmd, sess, &src.dylib.unwrap().0)
1090 // Converts a library file-stem into a cc -l argument
1091 fn unlib<'a>(config: &config::Config, stem: &'a str) -> &'a str {
1092 if stem.starts_with("lib") && !config.target.options.is_like_windows {
1099 // Adds the static "rlib" versions of all crates to the command line.
1100 // There's a bit of magic which happens here specifically related to LTO and
1101 // dynamic libraries. Specifically:
1103 // * For LTO, we remove upstream object files.
1104 // * For dylibs we remove metadata and bytecode from upstream rlibs
1106 // When performing LTO, all of the bytecode from the upstream libraries has
1107 // already been included in our object file output. As a result we need to
1108 // remove the object files in the upstream libraries so the linker doesn't
1109 // try to include them twice (or whine about duplicate symbols). We must
1110 // continue to include the rest of the rlib, however, as it may contain
1111 // static native libraries which must be linked in.
1113 // When making a dynamic library, linkers by default don't include any
1114 // object files in an archive if they're not necessary to resolve the link.
1115 // We basically want to convert the archive (rlib) to a dylib, though, so we
1116 // *do* want everything included in the output, regardless of whether the
1117 // linker thinks it's needed or not. As a result we must use the
1118 // --whole-archive option (or the platform equivalent). When using this
1119 // option the linker will fail if there are non-objects in the archive (such
1120 // as our own metadata and/or bytecode). All in all, for rlibs to be
1121 // entirely included in dylibs, we need to remove all non-object files.
1123 // Note, however, that if we're not doing LTO or we're not producing a dylib
1124 // (aka we're making an executable), we can just pass the rlib blindly to
1125 // the linker (fast) because it's fine if it's not actually included as
1126 // we're at the end of the dependency chain.
1127 fn add_static_crate(cmd: &mut Linker, sess: &Session, tmpdir: &Path,
1128 dylib: bool, cratepath: &Path) {
1129 if !sess.lto() && !dylib {
1130 cmd.link_rlib(&fix_windows_verbatim_for_gcc(cratepath));
1134 let dst = tmpdir.join(cratepath.file_name().unwrap());
1135 let name = cratepath.file_name().unwrap().to_str().unwrap();
1136 let name = &name[3..name.len() - 5]; // chop off lib/.rlib
1138 time(sess.time_passes(), &format!("altering {}.rlib", name), || {
1139 let cfg = archive_config(sess, &dst, Some(cratepath));
1140 let mut archive = ArchiveBuilder::new(cfg);
1141 archive.remove_file(sess.cstore.metadata_filename());
1142 archive.update_symbols();
1144 let mut any_objects = false;
1145 for f in archive.src_files() {
1146 if f.ends_with("bytecode.deflate") {
1147 archive.remove_file(&f);
1150 let canonical = f.replace("-", "_");
1151 let canonical_name = name.replace("-", "_");
1152 if sess.lto() && canonical.starts_with(&canonical_name) &&
1153 canonical.ends_with(".o") {
1154 let num = &f[name.len()..f.len() - 2];
1155 if num.len() > 0 && num[1..].parse::<u32>().is_ok() {
1156 archive.remove_file(&f);
1166 cmd.link_whole_rlib(&fix_windows_verbatim_for_gcc(&dst));
1168 cmd.link_rlib(&fix_windows_verbatim_for_gcc(&dst));
1174 // Same thing as above, but for dynamic crates instead of static crates.
1175 fn add_dynamic_crate(cmd: &mut Linker, sess: &Session, cratepath: &Path) {
1176 // If we're performing LTO, then it should have been previously required
1177 // that all upstream rust dependencies were available in an rlib format.
1178 assert!(!sess.lto());
1180 // Just need to tell the linker about where the library lives and
1182 let parent = cratepath.parent();
1183 if let Some(dir) = parent {
1184 cmd.include_path(&fix_windows_verbatim_for_gcc(dir));
1186 let filestem = cratepath.file_stem().unwrap().to_str().unwrap();
1187 cmd.link_rust_dylib(&unlib(&sess.target, filestem),
1188 parent.unwrap_or(Path::new("")));
1192 // Link in all of our upstream crates' native dependencies. Remember that
1193 // all of these upstream native dependencies are all non-static
1194 // dependencies. We've got two cases then:
1196 // 1. The upstream crate is an rlib. In this case we *must* link in the
1197 // native dependency because the rlib is just an archive.
1199 // 2. The upstream crate is a dylib. In order to use the dylib, we have to
1200 // have the dependency present on the system somewhere. Thus, we don't
1201 // gain a whole lot from not linking in the dynamic dependency to this
1204 // The use case for this is a little subtle. In theory the native
1205 // dependencies of a crate are purely an implementation detail of the crate
1206 // itself, but the problem arises with generic and inlined functions. If a
1207 // generic function calls a native function, then the generic function must
1208 // be instantiated in the target crate, meaning that the native symbol must
1209 // also be resolved in the target crate.
1210 fn add_upstream_native_libraries(cmd: &mut Linker, sess: &Session) {
1211 // Be sure to use a topological sorting of crates because there may be
1212 // interdependencies between native libraries. When passing -nodefaultlibs,
1213 // for example, almost all native libraries depend on libc, so we have to
1214 // make sure that's all the way at the right (liblibc is near the base of
1215 // the dependency chain).
1217 // This passes RequireStatic, but the actual requirement doesn't matter,
1218 // we're just getting an ordering of crate numbers, we're not worried about
1220 let crates = sess.cstore.used_crates(LinkagePreference::RequireStatic);
1221 for (cnum, _) in crates {
1222 let libs = sess.cstore.native_libraries(cnum);
1223 for &(kind, ref lib) in &libs {
1225 NativeLibraryKind::NativeUnknown => cmd.link_dylib(lib),
1226 NativeLibraryKind::NativeFramework => cmd.link_framework(lib),
1227 NativeLibraryKind::NativeStatic => {
1228 sess.bug("statics shouldn't be propagated");