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::{Ty, TyCtxt};
28 use rustc::front::map::DefPath;
29 use trans::{CrateContext, CrateTranslation, gensym_name};
30 use util::common::time;
31 use util::sha2::{Digest, Sha256};
32 use util::fs::fix_windows_verbatim_for_gcc;
33 use rustc_back::tempdir::TempDir;
38 use std::ffi::OsString;
40 use std::io::{self, Read, Write};
43 use std::path::{Path, PathBuf};
44 use std::process::Command;
47 use serialize::hex::ToHex;
49 use syntax::codemap::Span;
50 use syntax::parse::token::{self, InternedString};
51 use syntax::attr::AttrMetaMethods;
55 // RLIB LLVM-BYTECODE OBJECT LAYOUT
58 // 0..10 "RUST_OBJECT" encoded in ASCII
59 // 11..14 format version as little-endian u32
60 // 15..22 size in bytes of deflate compressed LLVM bitcode as
62 // 23.. compressed LLVM bitcode
64 // This is the "magic number" expected at the beginning of a LLVM bytecode
66 pub const RLIB_BYTECODE_OBJECT_MAGIC: &'static [u8] = b"RUST_OBJECT";
68 // The version number this compiler will write to bytecode objects in rlibs
69 pub const RLIB_BYTECODE_OBJECT_VERSION: u32 = 1;
71 // The offset in bytes the bytecode object format version number can be found at
72 pub const RLIB_BYTECODE_OBJECT_VERSION_OFFSET: usize = 11;
74 // The offset in bytes the size of the compressed bytecode can be found at in
76 pub const RLIB_BYTECODE_OBJECT_V1_DATASIZE_OFFSET: usize =
77 RLIB_BYTECODE_OBJECT_VERSION_OFFSET + 4;
79 // The offset in bytes the compressed LLVM bytecode can be found at in format
81 pub const RLIB_BYTECODE_OBJECT_V1_DATA_OFFSET: usize =
82 RLIB_BYTECODE_OBJECT_V1_DATASIZE_OFFSET + 8;
86 * Name mangling and its relationship to metadata. This is complex. Read
89 * The semantic model of Rust linkage is, broadly, that "there's no global
90 * namespace" between crates. Our aim is to preserve the illusion of this
91 * model despite the fact that it's not *quite* possible to implement on
92 * modern linkers. We initially didn't use system linkers at all, but have
93 * been convinced of their utility.
95 * There are a few issues to handle:
97 * - Linkers operate on a flat namespace, so we have to flatten names.
98 * We do this using the C++ namespace-mangling technique. Foo::bar
101 * - Symbols with the same name but different types need to get different
102 * linkage-names. We do this by hashing a string-encoding of the type into
103 * a fixed-size (currently 16-byte hex) cryptographic hash function (CHF:
104 * we use SHA256) to "prevent collisions". This is not airtight but 16 hex
105 * digits on uniform probability means you're going to need 2**32 same-name
106 * symbols in the same process before you're even hitting birthday-paradox
107 * collision probability.
109 * - Symbols in different crates but with same names "within" the crate need
110 * to get different linkage-names.
112 * - The hash shown in the filename needs to be predictable and stable for
113 * build tooling integration. It also needs to be using a hash function
114 * which is easy to use from Python, make, etc.
116 * So here is what we do:
118 * - Consider the package id; every crate has one (specified with crate_id
119 * attribute). If a package id isn't provided explicitly, we infer a
120 * versionless one from the output name. The version will end up being 0.0
121 * in this case. CNAME and CVERS are taken from this package id. For
122 * example, github.com/mozilla/CNAME#CVERS.
124 * - Define CMH as SHA256(crateid).
126 * - Define CMH8 as the first 8 characters of CMH.
128 * - Compile our crate to lib CNAME-CMH8-CVERS.so
130 * - Define STH(sym) as SHA256(CMH, type_str(sym))
132 * - Suffix a mangled sym with ::STH@CVERS, so that it is unique in the
133 * name, non-name metadata, and type sense, and versioned in the way
134 * system linkers understand.
137 pub fn find_crate_name(sess: Option<&Session>,
138 attrs: &[ast::Attribute],
139 input: &Input) -> String {
140 let validate = |s: String, span: Option<Span>| {
141 cstore::validate_crate_name(sess, &s[..], span);
145 // Look in attributes 100% of the time to make sure the attribute is marked
146 // as used. After doing this, however, we still prioritize a crate name from
147 // the command line over one found in the #[crate_name] attribute. If we
148 // find both we ensure that they're the same later on as well.
149 let attr_crate_name = attrs.iter().find(|at| at.check_name("crate_name"))
150 .and_then(|at| at.value_str().map(|s| (at, s)));
152 if let Some(sess) = sess {
153 if let Some(ref s) = sess.opts.crate_name {
154 if let Some((attr, ref name)) = attr_crate_name {
156 let msg = format!("--crate-name and #[crate_name] are \
157 required to match, but `{}` != `{}`",
159 sess.span_err(attr.span, &msg[..]);
162 return validate(s.clone(), None);
166 if let Some((attr, s)) = attr_crate_name {
167 return validate(s.to_string(), Some(attr.span));
169 if let Input::File(ref path) = *input {
170 if let Some(s) = path.file_stem().and_then(|s| s.to_str()) {
171 if s.starts_with("-") {
172 let msg = format!("crate names cannot start with a `-`, but \
173 `{}` has a leading hyphen", s);
174 if let Some(sess) = sess {
178 return validate(s.replace("-", "_"), None);
183 "rust_out".to_string()
186 pub fn build_link_meta(sess: &Session,
191 crate_name: name.to_owned(),
192 crate_hash: Svh::calculate(&sess.crate_disambiguator.borrow()[..], krate),
198 fn truncated_hash_result(symbol_hasher: &mut Sha256) -> String {
199 let output = symbol_hasher.result_bytes();
200 // 64 bits should be enough to avoid collisions.
201 output[.. 8].to_hex().to_string()
204 pub fn def_to_string(_tcx: &TyCtxt, did: DefId) -> String {
205 format!("{}:{}", did.krate, did.index.as_usize())
208 // This calculates STH for a symbol, as defined above
209 fn symbol_hash<'tcx>(tcx: &TyCtxt<'tcx>,
210 symbol_hasher: &mut Sha256,
212 link_meta: &LinkMeta)
214 // NB: do *not* use abbrevs here as we want the symbol names
215 // to be independent of one another in the crate.
217 symbol_hasher.reset();
218 symbol_hasher.input_str(&link_meta.crate_name);
219 symbol_hasher.input_str("-");
220 symbol_hasher.input_str(link_meta.crate_hash.as_str());
221 symbol_hasher.input_str(&tcx.sess.crate_disambiguator.borrow()[..]);
222 symbol_hasher.input_str("-");
223 symbol_hasher.input(&tcx.sess.cstore.encode_type(tcx, t, def_to_string));
224 // Prefix with 'h' so that it never blends into adjacent digits
225 let mut hash = String::from("h");
226 hash.push_str(&truncated_hash_result(symbol_hasher));
230 fn get_symbol_hash<'a, 'tcx>(ccx: &CrateContext<'a, 'tcx>, t: Ty<'tcx>) -> String {
231 if let Some(h) = ccx.type_hashcodes().borrow().get(&t) {
235 let mut symbol_hasher = ccx.symbol_hasher().borrow_mut();
236 let hash = symbol_hash(ccx.tcx(), &mut *symbol_hasher, t, ccx.link_meta());
237 ccx.type_hashcodes().borrow_mut().insert(t, hash.clone());
242 // Name sanitation. LLVM will happily accept identifiers with weird names, but
244 // gas accepts the following characters in symbols: a-z, A-Z, 0-9, ., _, $
245 pub fn sanitize(s: &str) -> String {
246 let mut result = String::new();
249 // Escape these with $ sequences
250 '@' => result.push_str("$SP$"),
251 '*' => result.push_str("$BP$"),
252 '&' => result.push_str("$RF$"),
253 '<' => result.push_str("$LT$"),
254 '>' => result.push_str("$GT$"),
255 '(' => result.push_str("$LP$"),
256 ')' => result.push_str("$RP$"),
257 ',' => result.push_str("$C$"),
259 // '.' doesn't occur in types and functions, so reuse it
261 '-' | ':' => result.push('.'),
263 // These are legal symbols
267 | '_' | '.' | '$' => result.push(c),
271 for c in c.escape_unicode().skip(1) {
274 '}' => result.push('$'),
282 // Underscore-qualify anything that didn't start as an ident.
283 if !result.is_empty() &&
284 result.as_bytes()[0] != '_' as u8 &&
285 ! (result.as_bytes()[0] as char).is_xid_start() {
286 return format!("_{}", &result[..]);
292 pub fn mangle<PI: Iterator<Item=InternedString>>(path: PI, hash: Option<&str>) -> String {
293 // Follow C++ namespace-mangling style, see
294 // http://en.wikipedia.org/wiki/Name_mangling for more info.
296 // It turns out that on OSX you can actually have arbitrary symbols in
297 // function names (at least when given to LLVM), but this is not possible
298 // when using unix's linker. Perhaps one day when we just use a linker from LLVM
299 // we won't need to do this name mangling. The problem with name mangling is
300 // that it seriously limits the available characters. For example we can't
301 // have things like &T in symbol names when one would theoretically
302 // want them for things like impls of traits on that type.
304 // To be able to work on all platforms and get *some* reasonable output, we
305 // use C++ name-mangling.
307 let mut n = String::from("_ZN"); // _Z == Begin name-sequence, N == nested
309 fn push(n: &mut String, s: &str) {
310 let sani = sanitize(s);
311 n.push_str(&format!("{}{}", sani.len(), sani));
314 // First, connect each component with <len, name> pairs.
319 if let Some(s) = hash {
323 n.push('E'); // End name-sequence.
327 pub fn exported_name(path: DefPath, hash: &str) -> String {
328 let path = path.into_iter()
329 .map(|e| e.data.as_interned_str());
330 mangle(path, Some(hash))
333 pub fn mangle_exported_name<'a, 'tcx>(ccx: &CrateContext<'a, 'tcx>, path: DefPath,
334 t: Ty<'tcx>, id: ast::NodeId) -> String {
335 let mut hash = get_symbol_hash(ccx, t);
337 // Paths can be completely identical for different nodes,
338 // e.g. `fn foo() { { fn a() {} } { fn a() {} } }`, so we
339 // generate unique characters from the node id. For now
340 // hopefully 3 characters is enough to avoid collisions.
341 const EXTRA_CHARS: &'static str =
342 "abcdefghijklmnopqrstuvwxyz\
343 ABCDEFGHIJKLMNOPQRSTUVWXYZ\
345 let id = id as usize;
346 let extra1 = id % EXTRA_CHARS.len();
347 let id = id / EXTRA_CHARS.len();
348 let extra2 = id % EXTRA_CHARS.len();
349 let id = id / EXTRA_CHARS.len();
350 let extra3 = id % EXTRA_CHARS.len();
351 hash.push(EXTRA_CHARS.as_bytes()[extra1] as char);
352 hash.push(EXTRA_CHARS.as_bytes()[extra2] as char);
353 hash.push(EXTRA_CHARS.as_bytes()[extra3] as char);
355 exported_name(path, &hash[..])
358 pub fn mangle_internal_name_by_type_and_seq<'a, 'tcx>(ccx: &CrateContext<'a, 'tcx>,
360 name: &str) -> String {
361 let path = [token::intern(&t.to_string()).as_str(), gensym_name(name).as_str()];
362 let hash = get_symbol_hash(ccx, t);
363 mangle(path.iter().cloned(), Some(&hash[..]))
366 pub fn mangle_internal_name_by_path_and_seq(path: DefPath, flav: &str) -> String {
369 .map(|e| e.data.as_interned_str())
370 .chain(once(gensym_name(flav).as_str())); // append unique version of "flav"
374 pub fn get_linker(sess: &Session) -> (String, Command) {
375 if let Some(ref linker) = sess.opts.cg.linker {
376 (linker.clone(), Command::new(linker))
377 } else if sess.target.target.options.is_like_msvc {
378 ("link.exe".to_string(), msvc::link_exe_cmd(sess))
380 (sess.target.target.options.linker.clone(),
381 Command::new(&sess.target.target.options.linker))
385 pub fn get_ar_prog(sess: &Session) -> String {
386 sess.opts.cg.ar.clone().unwrap_or_else(|| {
387 sess.target.target.options.ar.clone()
391 fn command_path(sess: &Session) -> OsString {
392 // The compiler's sysroot often has some bundled tools, so add it to the
393 // PATH for the child.
394 let mut new_path = sess.host_filesearch(PathKind::All)
395 .get_tools_search_paths();
396 if let Some(path) = env::var_os("PATH") {
397 new_path.extend(env::split_paths(&path));
399 if sess.target.target.options.is_like_msvc {
400 new_path.extend(msvc::host_dll_path());
402 env::join_paths(new_path).unwrap()
405 pub fn remove(sess: &Session, path: &Path) {
406 match fs::remove_file(path) {
409 sess.err(&format!("failed to remove {}: {}",
416 /// Perform the linkage portion of the compilation phase. This will generate all
417 /// of the requested outputs for this compilation session.
418 pub fn link_binary(sess: &Session,
419 trans: &CrateTranslation,
420 outputs: &OutputFilenames,
421 crate_name: &str) -> Vec<PathBuf> {
422 let mut out_filenames = Vec::new();
423 for &crate_type in sess.crate_types.borrow().iter() {
424 if invalid_output_for_target(sess, crate_type) {
425 sess.bug(&format!("invalid output type `{:?}` for target os `{}`",
426 crate_type, sess.opts.target_triple));
428 let out_file = link_binary_output(sess, trans, crate_type, outputs,
430 out_filenames.push(out_file);
433 // Remove the temporary object file and metadata if we aren't saving temps
434 if !sess.opts.cg.save_temps {
435 for obj in object_filenames(sess, outputs) {
438 remove(sess, &outputs.with_extension("metadata.o"));
445 /// Returns default crate type for target
447 /// Default crate type is used when crate type isn't provided neither
448 /// through cmd line arguments nor through crate attributes
450 /// It is CrateTypeExecutable for all platforms but iOS as there is no
451 /// way to run iOS binaries anyway without jailbreaking and
452 /// interaction with Rust code through static library is the only
454 pub fn default_output_for_target(sess: &Session) -> config::CrateType {
455 if !sess.target.target.options.executables {
456 config::CrateTypeStaticlib
458 config::CrateTypeExecutable
462 /// Checks if target supports crate_type as output
463 pub fn invalid_output_for_target(sess: &Session,
464 crate_type: config::CrateType) -> bool {
465 match (sess.target.target.options.dynamic_linking,
466 sess.target.target.options.executables, crate_type) {
467 (false, _, config::CrateTypeDylib) => true,
468 (_, false, config::CrateTypeExecutable) => true,
473 fn is_writeable(p: &Path) -> bool {
476 Ok(m) => !m.permissions().readonly()
480 pub fn filename_for_input(sess: &Session,
481 crate_type: config::CrateType,
483 outputs: &OutputFilenames) -> PathBuf {
484 let libname = format!("{}{}", crate_name, sess.opts.cg.extra_filename);
486 config::CrateTypeRlib => {
487 outputs.out_directory.join(&format!("lib{}.rlib", libname))
489 config::CrateTypeDylib => {
490 let (prefix, suffix) = (&sess.target.target.options.dll_prefix,
491 &sess.target.target.options.dll_suffix);
492 outputs.out_directory.join(&format!("{}{}{}", prefix, libname,
495 config::CrateTypeStaticlib => {
496 let (prefix, suffix) = (&sess.target.target.options.staticlib_prefix,
497 &sess.target.target.options.staticlib_suffix);
498 outputs.out_directory.join(&format!("{}{}{}", prefix, libname,
501 config::CrateTypeExecutable => {
502 let suffix = &sess.target.target.options.exe_suffix;
503 let out_filename = outputs.path(OutputType::Exe);
504 if suffix.is_empty() {
505 out_filename.to_path_buf()
507 out_filename.with_extension(&suffix[1..])
513 pub fn each_linked_rlib(sess: &Session,
514 f: &mut FnMut(ast::CrateNum, &Path)) {
515 let crates = sess.cstore.used_crates(LinkagePreference::RequireStatic).into_iter();
516 let fmts = sess.dependency_formats.borrow();
517 let fmts = fmts.get(&config::CrateTypeExecutable).or_else(|| {
518 fmts.get(&config::CrateTypeStaticlib)
519 }).unwrap_or_else(|| {
520 sess.bug("could not find formats for rlibs")
522 for (cnum, path) in crates {
523 match fmts[cnum as usize - 1] {
524 Linkage::NotLinked | Linkage::IncludedFromDylib => continue,
527 let name = sess.cstore.crate_name(cnum).clone();
528 let path = match path {
531 sess.fatal(&format!("could not find rlib for: `{}`", name));
538 fn link_binary_output(sess: &Session,
539 trans: &CrateTranslation,
540 crate_type: config::CrateType,
541 outputs: &OutputFilenames,
542 crate_name: &str) -> PathBuf {
543 let objects = object_filenames(sess, outputs);
544 let default_filename = filename_for_input(sess, crate_type, crate_name,
546 let out_filename = outputs.outputs.get(&OutputType::Exe)
547 .and_then(|s| s.to_owned())
548 .or_else(|| outputs.single_output_file.clone())
549 .unwrap_or(default_filename);
551 // Make sure files are writeable. Mac, FreeBSD, and Windows system linkers
552 // check this already -- however, the Linux linker will happily overwrite a
553 // read-only file. We should be consistent.
554 for file in objects.iter().chain(Some(&out_filename)) {
555 if !is_writeable(file) {
556 sess.fatal(&format!("output file {} is not writeable -- check its \
557 permissions", file.display()));
561 let tmpdir = match TempDir::new("rustc") {
562 Ok(tmpdir) => tmpdir,
563 Err(err) => sess.fatal(&format!("couldn't create a temp dir: {}", err)),
567 config::CrateTypeRlib => {
568 link_rlib(sess, Some(trans), &objects, &out_filename,
569 tmpdir.path()).build();
571 config::CrateTypeStaticlib => {
572 link_staticlib(sess, &objects, &out_filename, tmpdir.path());
574 config::CrateTypeExecutable => {
575 link_natively(sess, false, &objects, &out_filename, trans, outputs,
578 config::CrateTypeDylib => {
579 link_natively(sess, true, &objects, &out_filename, trans, outputs,
587 fn object_filenames(sess: &Session, outputs: &OutputFilenames) -> Vec<PathBuf> {
588 (0..sess.opts.cg.codegen_units).map(|i| {
589 let ext = format!("{}.o", i);
590 outputs.temp_path(OutputType::Object).with_extension(&ext)
594 fn archive_search_paths(sess: &Session) -> Vec<PathBuf> {
595 let mut search = Vec::new();
596 sess.target_filesearch(PathKind::Native).for_each_lib_search_path(|path, _| {
597 search.push(path.to_path_buf());
602 fn archive_config<'a>(sess: &'a Session,
604 input: Option<&Path>) -> ArchiveConfig<'a> {
607 dst: output.to_path_buf(),
608 src: input.map(|p| p.to_path_buf()),
609 lib_search_paths: archive_search_paths(sess),
610 ar_prog: get_ar_prog(sess),
611 command_path: command_path(sess),
617 // An rlib in its current incarnation is essentially a renamed .a file. The
618 // rlib primarily contains the object file of the crate, but it also contains
619 // all of the object files from native libraries. This is done by unzipping
620 // native libraries and inserting all of the contents into this archive.
621 fn link_rlib<'a>(sess: &'a Session,
622 trans: Option<&CrateTranslation>, // None == no metadata/bytecode
625 tmpdir: &Path) -> ArchiveBuilder<'a> {
626 info!("preparing rlib from {:?} to {:?}", objects, out_filename);
627 let mut ab = ArchiveBuilder::new(archive_config(sess, out_filename, None));
632 for (l, kind) in sess.cstore.used_libraries() {
634 NativeLibraryKind::NativeStatic => ab.add_native_library(&l),
635 NativeLibraryKind::NativeFramework |
636 NativeLibraryKind::NativeUnknown => {}
640 // After adding all files to the archive, we need to update the
641 // symbol table of the archive.
644 // For OSX/iOS, we must be careful to update symbols only when adding
645 // object files. We're about to start adding non-object files, so run
646 // `ar` now to process the object files.
647 if sess.target.target.options.is_like_osx && !ab.using_llvm() {
651 // Note that it is important that we add all of our non-object "magical
652 // files" *after* all of the object files in the archive. The reason for
653 // this is as follows:
655 // * When performing LTO, this archive will be modified to remove
656 // objects from above. The reason for this is described below.
658 // * When the system linker looks at an archive, it will attempt to
659 // determine the architecture of the archive in order to see whether its
662 // The algorithm for this detection is: iterate over the files in the
663 // archive. Skip magical SYMDEF names. Interpret the first file as an
664 // object file. Read architecture from the object file.
666 // * As one can probably see, if "metadata" and "foo.bc" were placed
667 // before all of the objects, then the architecture of this archive would
668 // not be correctly inferred once 'foo.o' is removed.
670 // Basically, all this means is that this code should not move above the
674 // Instead of putting the metadata in an object file section, rlibs
675 // contain the metadata in a separate file. We use a temp directory
676 // here so concurrent builds in the same directory don't try to use
677 // the same filename for metadata (stomping over one another)
678 let metadata = tmpdir.join(sess.cstore.metadata_filename());
679 match fs::File::create(&metadata).and_then(|mut f| {
680 f.write_all(&trans.metadata)
684 sess.fatal(&format!("failed to write {}: {}",
685 metadata.display(), e));
688 ab.add_file(&metadata);
690 // For LTO purposes, the bytecode of this library is also inserted
691 // into the archive. If codegen_units > 1, we insert each of the
694 // Note that we make sure that the bytecode filename in the
695 // archive is never exactly 16 bytes long by adding a 16 byte
696 // extension to it. This is to work around a bug in LLDB that
697 // would cause it to crash if the name of a file in an archive
698 // was exactly 16 bytes.
699 let bc_filename = obj.with_extension("bc");
700 let bc_deflated_filename = tmpdir.join({
701 obj.with_extension("bytecode.deflate").file_name().unwrap()
704 let mut bc_data = Vec::new();
705 match fs::File::open(&bc_filename).and_then(|mut f| {
706 f.read_to_end(&mut bc_data)
709 Err(e) => sess.fatal(&format!("failed to read bytecode: {}",
713 let bc_data_deflated = flate::deflate_bytes(&bc_data[..]);
715 let mut bc_file_deflated = match fs::File::create(&bc_deflated_filename) {
718 sess.fatal(&format!("failed to create compressed \
719 bytecode file: {}", e))
723 match write_rlib_bytecode_object_v1(&mut bc_file_deflated,
727 sess.fatal(&format!("failed to write compressed \
732 ab.add_file(&bc_deflated_filename);
734 // See the bottom of back::write::run_passes for an explanation
735 // of when we do and don't keep .0.bc files around.
736 let user_wants_numbered_bitcode =
737 sess.opts.output_types.contains_key(&OutputType::Bitcode) &&
738 sess.opts.cg.codegen_units > 1;
739 if !sess.opts.cg.save_temps && !user_wants_numbered_bitcode {
740 remove(sess, &bc_filename);
744 // After adding all files to the archive, we need to update the
745 // symbol table of the archive. This currently dies on OSX (see
746 // #11162), and isn't necessary there anyway
747 if !sess.target.target.options.is_like_osx || ab.using_llvm() {
758 fn write_rlib_bytecode_object_v1(writer: &mut Write,
759 bc_data_deflated: &[u8]) -> io::Result<()> {
760 let bc_data_deflated_size: u64 = bc_data_deflated.len() as u64;
762 writer.write_all(RLIB_BYTECODE_OBJECT_MAGIC)?;
763 writer.write_all(&[1, 0, 0, 0])?;
765 (bc_data_deflated_size >> 0) as u8,
766 (bc_data_deflated_size >> 8) as u8,
767 (bc_data_deflated_size >> 16) as u8,
768 (bc_data_deflated_size >> 24) as u8,
769 (bc_data_deflated_size >> 32) as u8,
770 (bc_data_deflated_size >> 40) as u8,
771 (bc_data_deflated_size >> 48) as u8,
772 (bc_data_deflated_size >> 56) as u8,
774 writer.write_all(&bc_data_deflated)?;
776 let number_of_bytes_written_so_far =
777 RLIB_BYTECODE_OBJECT_MAGIC.len() + // magic id
778 mem::size_of_val(&RLIB_BYTECODE_OBJECT_VERSION) + // version
779 mem::size_of_val(&bc_data_deflated_size) + // data size field
780 bc_data_deflated_size as usize; // actual data
782 // If the number of bytes written to the object so far is odd, add a
783 // padding byte to make it even. This works around a crash bug in LLDB
784 // (see issue #15950)
785 if number_of_bytes_written_so_far % 2 == 1 {
786 writer.write_all(&[0])?;
792 // Create a static archive
794 // This is essentially the same thing as an rlib, but it also involves adding
795 // all of the upstream crates' objects into the archive. This will slurp in
796 // all of the native libraries of upstream dependencies as well.
798 // Additionally, there's no way for us to link dynamic libraries, so we warn
799 // about all dynamic library dependencies that they're not linked in.
801 // There's no need to include metadata in a static archive, so ensure to not
802 // link in the metadata object file (and also don't prepare the archive with a
804 fn link_staticlib(sess: &Session, objects: &[PathBuf], out_filename: &Path,
806 let mut ab = link_rlib(sess, None, objects, out_filename, tempdir);
807 if sess.target.target.options.is_like_osx && !ab.using_llvm() {
810 if !sess.target.target.options.no_compiler_rt {
811 ab.add_native_library("compiler-rt");
814 let mut all_native_libs = vec![];
816 each_linked_rlib(sess, &mut |cnum, path| {
817 let name = sess.cstore.crate_name(cnum);
818 ab.add_rlib(path, &name, sess.lto()).unwrap();
820 let native_libs = sess.cstore.native_libraries(cnum);
821 all_native_libs.extend(native_libs);
827 if !all_native_libs.is_empty() {
828 sess.note_without_error("link against the following native artifacts when linking against \
829 this static library");
830 sess.note_without_error("the order and any duplication can be significant on some \
831 platforms, and so may need to be preserved");
834 for &(kind, ref lib) in &all_native_libs {
835 let name = match kind {
836 NativeLibraryKind::NativeStatic => "static library",
837 NativeLibraryKind::NativeUnknown => "library",
838 NativeLibraryKind::NativeFramework => "framework",
840 sess.note_without_error(&format!("{}: {}", name, *lib));
844 // Create a dynamic library or executable
846 // This will invoke the system linker/cc to create the resulting file. This
847 // links to all upstream files as well.
848 fn link_natively(sess: &Session, dylib: bool,
849 objects: &[PathBuf], out_filename: &Path,
850 trans: &CrateTranslation,
851 outputs: &OutputFilenames,
853 info!("preparing dylib? ({}) from {:?} to {:?}", dylib, objects,
856 // The invocations of cc share some flags across platforms
857 let (pname, mut cmd) = get_linker(sess);
858 cmd.env("PATH", command_path(sess));
860 let root = sess.target_filesearch(PathKind::Native).get_lib_path();
861 cmd.args(&sess.target.target.options.pre_link_args);
863 let pre_link_objects = if dylib {
864 &sess.target.target.options.pre_link_objects_dll
866 &sess.target.target.options.pre_link_objects_exe
868 for obj in pre_link_objects {
869 cmd.arg(root.join(obj));
873 let mut linker = if sess.target.target.options.is_like_msvc {
874 Box::new(MsvcLinker { cmd: &mut cmd, sess: &sess }) as Box<Linker>
876 Box::new(GnuLinker { cmd: &mut cmd, sess: &sess }) as Box<Linker>
878 link_args(&mut *linker, sess, dylib, tmpdir,
879 objects, out_filename, trans, outputs);
880 if !sess.target.target.options.no_compiler_rt {
881 linker.link_staticlib("compiler-rt");
884 cmd.args(&sess.target.target.options.late_link_args);
885 for obj in &sess.target.target.options.post_link_objects {
886 cmd.arg(root.join(obj));
888 cmd.args(&sess.target.target.options.post_link_args);
890 if sess.opts.debugging_opts.print_link_args {
891 println!("{:?}", &cmd);
894 // May have not found libraries in the right formats.
895 sess.abort_if_errors();
897 // Invoke the system linker
899 let prog = time(sess.time_passes(), "running linker", || cmd.output());
902 fn escape_string(s: &[u8]) -> String {
903 str::from_utf8(s).map(|s| s.to_owned())
904 .unwrap_or_else(|_| {
905 let mut x = "Non-UTF-8 output: ".to_string();
907 .flat_map(|&b| ascii::escape_default(b))
908 .map(|b| char::from_u32(b as u32).unwrap()));
912 if !prog.status.success() {
913 let mut output = prog.stderr.clone();
914 output.extend_from_slice(&prog.stdout);
915 sess.struct_err(&format!("linking with `{}` failed: {}",
918 .note(&format!("{:?}", &cmd))
919 .note(&escape_string(&output[..]))
921 sess.abort_if_errors();
923 info!("linker stderr:\n{}", escape_string(&prog.stderr[..]));
924 info!("linker stdout:\n{}", escape_string(&prog.stdout[..]));
927 sess.fatal(&format!("could not exec the linker `{}`: {}", pname, e));
932 // On OSX, debuggers need this utility to get run to do some munging of
934 if sess.target.target.options.is_like_osx && sess.opts.debuginfo != NoDebugInfo {
935 match Command::new("dsymutil").arg(out_filename).output() {
937 Err(e) => sess.fatal(&format!("failed to run dsymutil: {}", e)),
942 fn link_args(cmd: &mut Linker,
948 trans: &CrateTranslation,
949 outputs: &OutputFilenames) {
951 // The default library location, we need this to find the runtime.
952 // The location of crates will be determined as needed.
953 let lib_path = sess.target_filesearch(PathKind::All).get_lib_path();
956 let t = &sess.target.target;
958 cmd.include_path(&fix_windows_verbatim_for_gcc(&lib_path));
962 cmd.output_filename(out_filename);
964 // If we're building a dynamic library then some platforms need to make sure
965 // that all symbols are exported correctly from the dynamic library.
967 cmd.export_symbols(sess, trans, tmpdir);
970 // When linking a dynamic library, we put the metadata into a section of the
971 // executable. This metadata is in a separate object file from the main
972 // object file, so we link that in here.
974 cmd.add_object(&outputs.with_extension("metadata.o"));
977 // Try to strip as much out of the generated object by removing unused
978 // sections if possible. See more comments in linker.rs
979 if !sess.opts.cg.link_dead_code {
980 cmd.gc_sections(dylib);
983 let used_link_args = sess.cstore.used_link_args();
985 if !dylib && t.options.position_independent_executables {
986 let empty_vec = Vec::new();
987 let empty_str = String::new();
988 let args = sess.opts.cg.link_args.as_ref().unwrap_or(&empty_vec);
989 let mut args = args.iter().chain(used_link_args.iter());
990 let relocation_model = sess.opts.cg.relocation_model.as_ref()
991 .unwrap_or(&empty_str);
992 if (t.options.relocation_model == "pic" || *relocation_model == "pic")
993 && !args.any(|x| *x == "-static") {
994 cmd.position_independent_executable();
998 // Pass optimization flags down to the linker.
1001 // Pass debuginfo flags down to the linker.
1004 // We want to prevent the compiler from accidentally leaking in any system
1005 // libraries, so we explicitly ask gcc to not link to any libraries by
1006 // default. Note that this does not happen for windows because windows pulls
1007 // in some large number of libraries and I couldn't quite figure out which
1008 // subset we wanted.
1009 if t.options.no_default_libraries {
1010 cmd.no_default_libraries();
1013 // Take careful note of the ordering of the arguments we pass to the linker
1014 // here. Linkers will assume that things on the left depend on things to the
1015 // right. Things on the right cannot depend on things on the left. This is
1016 // all formally implemented in terms of resolving symbols (libs on the right
1017 // resolve unknown symbols of libs on the left, but not vice versa).
1019 // For this reason, we have organized the arguments we pass to the linker as
1022 // 1. The local object that LLVM just generated
1023 // 2. Local native libraries
1024 // 3. Upstream rust libraries
1025 // 4. Upstream native libraries
1027 // The rationale behind this ordering is that those items lower down in the
1028 // list can't depend on items higher up in the list. For example nothing can
1029 // depend on what we just generated (e.g. that'd be a circular dependency).
1030 // Upstream rust libraries are not allowed to depend on our local native
1031 // libraries as that would violate the structure of the DAG, in that
1032 // scenario they are required to link to them as well in a shared fashion.
1034 // Note that upstream rust libraries may contain native dependencies as
1035 // well, but they also can't depend on what we just started to add to the
1036 // link line. And finally upstream native libraries can't depend on anything
1037 // in this DAG so far because they're only dylibs and dylibs can only depend
1038 // on other dylibs (e.g. other native deps).
1039 add_local_native_libraries(cmd, sess);
1040 add_upstream_rust_crates(cmd, sess, dylib, tmpdir);
1041 add_upstream_native_libraries(cmd, sess);
1043 // # Telling the linker what we're doing
1046 cmd.build_dylib(out_filename);
1049 // FIXME (#2397): At some point we want to rpath our guesses as to
1050 // where extern libraries might live, based on the
1051 // addl_lib_search_paths
1052 if sess.opts.cg.rpath {
1053 let sysroot = sess.sysroot();
1054 let target_triple = &sess.opts.target_triple;
1055 let mut get_install_prefix_lib_path = || {
1056 let install_prefix = option_env!("CFG_PREFIX").expect("CFG_PREFIX");
1057 let tlib = filesearch::relative_target_lib_path(sysroot, target_triple);
1058 let mut path = PathBuf::from(install_prefix);
1063 let mut rpath_config = RPathConfig {
1064 used_crates: sess.cstore.used_crates(LinkagePreference::RequireDynamic),
1065 out_filename: out_filename.to_path_buf(),
1066 has_rpath: sess.target.target.options.has_rpath,
1067 is_like_osx: sess.target.target.options.is_like_osx,
1068 linker_is_gnu: sess.target.target.options.linker_is_gnu,
1069 get_install_prefix_lib_path: &mut get_install_prefix_lib_path,
1071 cmd.args(&rpath::get_rpath_flags(&mut rpath_config));
1074 // Finally add all the linker arguments provided on the command line along
1075 // with any #[link_args] attributes found inside the crate
1076 if let Some(ref args) = sess.opts.cg.link_args {
1079 cmd.args(&used_link_args);
1082 // # Native library linking
1084 // User-supplied library search paths (-L on the command line). These are
1085 // the same paths used to find Rust crates, so some of them may have been
1086 // added already by the previous crate linking code. This only allows them
1087 // to be found at compile time so it is still entirely up to outside
1088 // forces to make sure that library can be found at runtime.
1090 // Also note that the native libraries linked here are only the ones located
1091 // in the current crate. Upstream crates with native library dependencies
1092 // may have their native library pulled in above.
1093 fn add_local_native_libraries(cmd: &mut Linker, sess: &Session) {
1094 sess.target_filesearch(PathKind::All).for_each_lib_search_path(|path, k| {
1096 PathKind::Framework => { cmd.framework_path(path); }
1097 _ => { cmd.include_path(&fix_windows_verbatim_for_gcc(path)); }
1101 let libs = sess.cstore.used_libraries();
1103 let staticlibs = libs.iter().filter_map(|&(ref l, kind)| {
1104 if kind == NativeLibraryKind::NativeStatic {Some(l)} else {None}
1106 let others = libs.iter().filter(|&&(_, kind)| {
1107 kind != NativeLibraryKind::NativeStatic
1110 // Some platforms take hints about whether a library is static or dynamic.
1111 // For those that support this, we ensure we pass the option if the library
1112 // was flagged "static" (most defaults are dynamic) to ensure that if
1113 // libfoo.a and libfoo.so both exist that the right one is chosen.
1116 let search_path = archive_search_paths(sess);
1117 for l in staticlibs {
1118 // Here we explicitly ask that the entire archive is included into the
1119 // result artifact. For more details see #15460, but the gist is that
1120 // the linker will strip away any unused objects in the archive if we
1121 // don't otherwise explicitly reference them. This can occur for
1122 // libraries which are just providing bindings, libraries with generic
1124 cmd.link_whole_staticlib(l, &search_path);
1129 for &(ref l, kind) in others {
1131 NativeLibraryKind::NativeUnknown => cmd.link_dylib(l),
1132 NativeLibraryKind::NativeFramework => cmd.link_framework(l),
1133 NativeLibraryKind::NativeStatic => unreachable!(),
1138 // # Rust Crate linking
1140 // Rust crates are not considered at all when creating an rlib output. All
1141 // dependencies will be linked when producing the final output (instead of
1142 // the intermediate rlib version)
1143 fn add_upstream_rust_crates(cmd: &mut Linker, sess: &Session,
1144 dylib: bool, tmpdir: &Path) {
1145 // All of the heavy lifting has previously been accomplished by the
1146 // dependency_format module of the compiler. This is just crawling the
1147 // output of that module, adding crates as necessary.
1149 // Linking to a rlib involves just passing it to the linker (the linker
1150 // will slurp up the object files inside), and linking to a dynamic library
1151 // involves just passing the right -l flag.
1153 let formats = sess.dependency_formats.borrow();
1154 let data = if dylib {
1155 formats.get(&config::CrateTypeDylib).unwrap()
1157 formats.get(&config::CrateTypeExecutable).unwrap()
1160 // Invoke get_used_crates to ensure that we get a topological sorting of
1162 let deps = sess.cstore.used_crates(LinkagePreference::RequireDynamic);
1164 for &(cnum, _) in &deps {
1165 // We may not pass all crates through to the linker. Some crates may
1166 // appear statically in an existing dylib, meaning we'll pick up all the
1167 // symbols from the dylib.
1168 let src = sess.cstore.used_crate_source(cnum);
1169 match data[cnum as usize - 1] {
1170 Linkage::NotLinked |
1171 Linkage::IncludedFromDylib => {}
1172 Linkage::Static => {
1173 add_static_crate(cmd, sess, tmpdir, dylib, &src.rlib.unwrap().0)
1175 Linkage::Dynamic => {
1176 add_dynamic_crate(cmd, sess, &src.dylib.unwrap().0)
1181 // Converts a library file-stem into a cc -l argument
1182 fn unlib<'a>(config: &config::Config, stem: &'a str) -> &'a str {
1183 if stem.starts_with("lib") && !config.target.options.is_like_windows {
1190 // Adds the static "rlib" versions of all crates to the command line.
1191 // There's a bit of magic which happens here specifically related to LTO and
1192 // dynamic libraries. Specifically:
1194 // * For LTO, we remove upstream object files.
1195 // * For dylibs we remove metadata and bytecode from upstream rlibs
1197 // When performing LTO, all of the bytecode from the upstream libraries has
1198 // already been included in our object file output. As a result we need to
1199 // remove the object files in the upstream libraries so the linker doesn't
1200 // try to include them twice (or whine about duplicate symbols). We must
1201 // continue to include the rest of the rlib, however, as it may contain
1202 // static native libraries which must be linked in.
1204 // When making a dynamic library, linkers by default don't include any
1205 // object files in an archive if they're not necessary to resolve the link.
1206 // We basically want to convert the archive (rlib) to a dylib, though, so we
1207 // *do* want everything included in the output, regardless of whether the
1208 // linker thinks it's needed or not. As a result we must use the
1209 // --whole-archive option (or the platform equivalent). When using this
1210 // option the linker will fail if there are non-objects in the archive (such
1211 // as our own metadata and/or bytecode). All in all, for rlibs to be
1212 // entirely included in dylibs, we need to remove all non-object files.
1214 // Note, however, that if we're not doing LTO or we're not producing a dylib
1215 // (aka we're making an executable), we can just pass the rlib blindly to
1216 // the linker (fast) because it's fine if it's not actually included as
1217 // we're at the end of the dependency chain.
1218 fn add_static_crate(cmd: &mut Linker, sess: &Session, tmpdir: &Path,
1219 dylib: bool, cratepath: &Path) {
1220 if !sess.lto() && !dylib {
1221 cmd.link_rlib(&fix_windows_verbatim_for_gcc(cratepath));
1225 let dst = tmpdir.join(cratepath.file_name().unwrap());
1226 let name = cratepath.file_name().unwrap().to_str().unwrap();
1227 let name = &name[3..name.len() - 5]; // chop off lib/.rlib
1229 time(sess.time_passes(), &format!("altering {}.rlib", name), || {
1230 let cfg = archive_config(sess, &dst, Some(cratepath));
1231 let mut archive = ArchiveBuilder::new(cfg);
1232 archive.remove_file(sess.cstore.metadata_filename());
1233 archive.update_symbols();
1235 let mut any_objects = false;
1236 for f in archive.src_files() {
1237 if f.ends_with("bytecode.deflate") {
1238 archive.remove_file(&f);
1241 let canonical = f.replace("-", "_");
1242 let canonical_name = name.replace("-", "_");
1243 if sess.lto() && canonical.starts_with(&canonical_name) &&
1244 canonical.ends_with(".o") {
1245 let num = &f[name.len()..f.len() - 2];
1246 if num.len() > 0 && num[1..].parse::<u32>().is_ok() {
1247 archive.remove_file(&f);
1257 cmd.link_whole_rlib(&fix_windows_verbatim_for_gcc(&dst));
1259 cmd.link_rlib(&fix_windows_verbatim_for_gcc(&dst));
1265 // Same thing as above, but for dynamic crates instead of static crates.
1266 fn add_dynamic_crate(cmd: &mut Linker, sess: &Session, cratepath: &Path) {
1267 // If we're performing LTO, then it should have been previously required
1268 // that all upstream rust dependencies were available in an rlib format.
1269 assert!(!sess.lto());
1271 // Just need to tell the linker about where the library lives and
1273 let parent = cratepath.parent();
1274 if let Some(dir) = parent {
1275 cmd.include_path(&fix_windows_verbatim_for_gcc(dir));
1277 let filestem = cratepath.file_stem().unwrap().to_str().unwrap();
1278 cmd.link_rust_dylib(&unlib(&sess.target, filestem),
1279 parent.unwrap_or(Path::new("")));
1283 // Link in all of our upstream crates' native dependencies. Remember that
1284 // all of these upstream native dependencies are all non-static
1285 // dependencies. We've got two cases then:
1287 // 1. The upstream crate is an rlib. In this case we *must* link in the
1288 // native dependency because the rlib is just an archive.
1290 // 2. The upstream crate is a dylib. In order to use the dylib, we have to
1291 // have the dependency present on the system somewhere. Thus, we don't
1292 // gain a whole lot from not linking in the dynamic dependency to this
1295 // The use case for this is a little subtle. In theory the native
1296 // dependencies of a crate are purely an implementation detail of the crate
1297 // itself, but the problem arises with generic and inlined functions. If a
1298 // generic function calls a native function, then the generic function must
1299 // be instantiated in the target crate, meaning that the native symbol must
1300 // also be resolved in the target crate.
1301 fn add_upstream_native_libraries(cmd: &mut Linker, sess: &Session) {
1302 // Be sure to use a topological sorting of crates because there may be
1303 // interdependencies between native libraries. When passing -nodefaultlibs,
1304 // for example, almost all native libraries depend on libc, so we have to
1305 // make sure that's all the way at the right (liblibc is near the base of
1306 // the dependency chain).
1308 // This passes RequireStatic, but the actual requirement doesn't matter,
1309 // we're just getting an ordering of crate numbers, we're not worried about
1311 let crates = sess.cstore.used_crates(LinkagePreference::RequireStatic);
1312 for (cnum, _) in crates {
1313 let libs = sess.cstore.native_libraries(cnum);
1314 for &(kind, ref lib) in &libs {
1316 NativeLibraryKind::NativeUnknown => cmd.link_dylib(lib),
1317 NativeLibraryKind::NativeFramework => cmd.link_framework(lib),
1318 NativeLibraryKind::NativeStatic => {
1319 sess.bug("statics shouldn't be propagated");