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, OutputTypeBitcode, OutputTypeExe, OutputTypeObject};
20 use session::search_paths::PathKind;
22 use metadata::common::LinkMeta;
23 use metadata::filesearch::FileDoesntMatch;
24 use metadata::loader::METADATA_FILENAME;
25 use metadata::{encoder, cstore, filesearch, csearch, creader};
26 use middle::dependency_format::Linkage;
27 use middle::ty::{self, Ty};
28 use rustc::front::map::{PathElem, PathElems, PathName};
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;
36 use std::ffi::OsString;
37 use std::fs::{self, PathExt};
38 use std::io::{self, Read, Write};
40 use std::path::{Path, PathBuf};
41 use std::process::Command;
44 use serialize::hex::ToHex;
46 use syntax::codemap::Span;
47 use syntax::parse::token;
48 use syntax::attr::AttrMetaMethods;
49 use rustc_front::attr::AttrMetaMethods as FrontAttrMetaMethods;
53 // RLIB LLVM-BYTECODE OBJECT LAYOUT
56 // 0..10 "RUST_OBJECT" encoded in ASCII
57 // 11..14 format version as little-endian u32
58 // 15..22 size in bytes of deflate compressed LLVM bitcode as
60 // 23.. compressed LLVM bitcode
62 // This is the "magic number" expected at the beginning of a LLVM bytecode
64 pub const RLIB_BYTECODE_OBJECT_MAGIC: &'static [u8] = b"RUST_OBJECT";
66 // The version number this compiler will write to bytecode objects in rlibs
67 pub const RLIB_BYTECODE_OBJECT_VERSION: u32 = 1;
69 // The offset in bytes the bytecode object format version number can be found at
70 pub const RLIB_BYTECODE_OBJECT_VERSION_OFFSET: usize = 11;
72 // The offset in bytes the size of the compressed bytecode can be found at in
74 pub const RLIB_BYTECODE_OBJECT_V1_DATASIZE_OFFSET: usize =
75 RLIB_BYTECODE_OBJECT_VERSION_OFFSET + 4;
77 // The offset in bytes the compressed LLVM bytecode can be found at in format
79 pub const RLIB_BYTECODE_OBJECT_V1_DATA_OFFSET: usize =
80 RLIB_BYTECODE_OBJECT_V1_DATASIZE_OFFSET + 8;
84 * Name mangling and its relationship to metadata. This is complex. Read
87 * The semantic model of Rust linkage is, broadly, that "there's no global
88 * namespace" between crates. Our aim is to preserve the illusion of this
89 * model despite the fact that it's not *quite* possible to implement on
90 * modern linkers. We initially didn't use system linkers at all, but have
91 * been convinced of their utility.
93 * There are a few issues to handle:
95 * - Linkers operate on a flat namespace, so we have to flatten names.
96 * We do this using the C++ namespace-mangling technique. Foo::bar
99 * - Symbols with the same name but different types need to get different
100 * linkage-names. We do this by hashing a string-encoding of the type into
101 * a fixed-size (currently 16-byte hex) cryptographic hash function (CHF:
102 * we use SHA256) to "prevent collisions". This is not airtight but 16 hex
103 * digits on uniform probability means you're going to need 2**32 same-name
104 * symbols in the same process before you're even hitting birthday-paradox
105 * collision probability.
107 * - Symbols in different crates but with same names "within" the crate need
108 * to get different linkage-names.
110 * - The hash shown in the filename needs to be predictable and stable for
111 * build tooling integration. It also needs to be using a hash function
112 * which is easy to use from Python, make, etc.
114 * So here is what we do:
116 * - Consider the package id; every crate has one (specified with crate_id
117 * attribute). If a package id isn't provided explicitly, we infer a
118 * versionless one from the output name. The version will end up being 0.0
119 * in this case. CNAME and CVERS are taken from this package id. For
120 * example, github.com/mozilla/CNAME#CVERS.
122 * - Define CMH as SHA256(crateid).
124 * - Define CMH8 as the first 8 characters of CMH.
126 * - Compile our crate to lib CNAME-CMH8-CVERS.so
128 * - Define STH(sym) as SHA256(CMH, type_str(sym))
130 * - Suffix a mangled sym with ::STH@CVERS, so that it is unique in the
131 * name, non-name metadata, and type sense, and versioned in the way
132 * system linkers understand.
135 pub fn find_crate_name(sess: Option<&Session>,
136 attrs: &[ast::Attribute],
137 input: &Input) -> String {
138 let validate = |s: String, span: Option<Span>| {
139 creader::validate_crate_name(sess, &s[..], span);
143 // Look in attributes 100% of the time to make sure the attribute is marked
144 // as used. After doing this, however, we still prioritize a crate name from
145 // the command line over one found in the #[crate_name] attribute. If we
146 // find both we ensure that they're the same later on as well.
147 let attr_crate_name = attrs.iter().find(|at| at.check_name("crate_name"))
148 .and_then(|at| at.value_str().map(|s| (at, s)));
150 if let Some(sess) = sess {
151 if let Some(ref s) = sess.opts.crate_name {
152 if let Some((attr, ref name)) = attr_crate_name {
154 let msg = format!("--crate-name and #[crate_name] are \
155 required to match, but `{}` != `{}`",
157 sess.span_err(attr.span, &msg[..]);
160 return validate(s.clone(), None);
164 if let Some((attr, s)) = attr_crate_name {
165 return validate(s.to_string(), Some(attr.span));
167 if let Input::File(ref path) = *input {
168 if let Some(s) = path.file_stem().and_then(|s| s.to_str()) {
169 if s.starts_with("-") {
170 let msg = format!("crate names cannot start with a `-`, but \
171 `{}` has a leading hyphen", s);
172 if let Some(sess) = sess {
176 return validate(s.replace("-", "_"), None);
181 "rust_out".to_string()
184 pub fn build_link_meta(sess: &Session, krate: &hir::Crate,
185 name: String) -> LinkMeta {
188 crate_hash: Svh::calculate(&sess.opts.cg.metadata, krate),
194 fn truncated_hash_result(symbol_hasher: &mut Sha256) -> String {
195 let output = symbol_hasher.result_bytes();
196 // 64 bits should be enough to avoid collisions.
197 output[.. 8].to_hex().to_string()
201 // This calculates STH for a symbol, as defined above
202 fn symbol_hash<'tcx>(tcx: &ty::ctxt<'tcx>,
203 symbol_hasher: &mut Sha256,
205 link_meta: &LinkMeta)
207 // NB: do *not* use abbrevs here as we want the symbol names
208 // to be independent of one another in the crate.
210 symbol_hasher.reset();
211 symbol_hasher.input_str(&link_meta.crate_name);
212 symbol_hasher.input_str("-");
213 symbol_hasher.input_str(link_meta.crate_hash.as_str());
214 for meta in tcx.sess.crate_metadata.borrow().iter() {
215 symbol_hasher.input_str(&meta[..]);
217 symbol_hasher.input_str("-");
218 symbol_hasher.input_str(&encoder::encoded_ty(tcx, t));
219 // Prefix with 'h' so that it never blends into adjacent digits
220 let mut hash = String::from("h");
221 hash.push_str(&truncated_hash_result(symbol_hasher));
225 fn get_symbol_hash<'a, 'tcx>(ccx: &CrateContext<'a, 'tcx>, t: Ty<'tcx>) -> String {
226 match ccx.type_hashcodes().borrow().get(&t) {
227 Some(h) => return h.to_string(),
231 let mut symbol_hasher = ccx.symbol_hasher().borrow_mut();
232 let hash = symbol_hash(ccx.tcx(), &mut *symbol_hasher, t, ccx.link_meta());
233 ccx.type_hashcodes().borrow_mut().insert(t, hash.clone());
238 // Name sanitation. LLVM will happily accept identifiers with weird names, but
240 // gas accepts the following characters in symbols: a-z, A-Z, 0-9, ., _, $
241 pub fn sanitize(s: &str) -> String {
242 let mut result = String::new();
245 // Escape these with $ sequences
246 '@' => result.push_str("$SP$"),
247 '*' => result.push_str("$BP$"),
248 '&' => result.push_str("$RF$"),
249 '<' => result.push_str("$LT$"),
250 '>' => result.push_str("$GT$"),
251 '(' => result.push_str("$LP$"),
252 ')' => result.push_str("$RP$"),
253 ',' => result.push_str("$C$"),
255 // '.' doesn't occur in types and functions, so reuse it
257 '-' | ':' => result.push('.'),
259 // These are legal symbols
263 | '_' | '.' | '$' => result.push(c),
267 for c in c.escape_unicode().skip(1) {
270 '}' => result.push('$'),
278 // Underscore-qualify anything that didn't start as an ident.
279 if !result.is_empty() &&
280 result.as_bytes()[0] != '_' as u8 &&
281 ! (result.as_bytes()[0] as char).is_xid_start() {
282 return format!("_{}", &result[..]);
288 pub fn mangle<PI: Iterator<Item=PathElem>>(path: PI,
289 hash: Option<&str>) -> String {
290 // Follow C++ namespace-mangling style, see
291 // http://en.wikipedia.org/wiki/Name_mangling for more info.
293 // It turns out that on OSX you can actually have arbitrary symbols in
294 // function names (at least when given to LLVM), but this is not possible
295 // when using unix's linker. Perhaps one day when we just use a linker from LLVM
296 // we won't need to do this name mangling. The problem with name mangling is
297 // that it seriously limits the available characters. For example we can't
298 // have things like &T in symbol names when one would theoretically
299 // want them for things like impls of traits on that type.
301 // To be able to work on all platforms and get *some* reasonable output, we
302 // use C++ name-mangling.
304 let mut n = String::from("_ZN"); // _Z == Begin name-sequence, N == nested
306 fn push(n: &mut String, s: &str) {
307 let sani = sanitize(s);
308 n.push_str(&format!("{}{}", sani.len(), sani));
311 // First, connect each component with <len, name> pairs.
313 push(&mut n, &e.name().as_str())
317 Some(s) => push(&mut n, s),
321 n.push('E'); // End name-sequence.
325 pub fn exported_name(path: PathElems, hash: &str) -> String {
326 mangle(path, Some(hash))
329 pub fn mangle_exported_name<'a, 'tcx>(ccx: &CrateContext<'a, 'tcx>, path: PathElems,
330 t: Ty<'tcx>, id: ast::NodeId) -> String {
331 let mut hash = get_symbol_hash(ccx, t);
333 // Paths can be completely identical for different nodes,
334 // e.g. `fn foo() { { fn a() {} } { fn a() {} } }`, so we
335 // generate unique characters from the node id. For now
336 // hopefully 3 characters is enough to avoid collisions.
337 const EXTRA_CHARS: &'static str =
338 "abcdefghijklmnopqrstuvwxyz\
339 ABCDEFGHIJKLMNOPQRSTUVWXYZ\
341 let id = id as usize;
342 let extra1 = id % EXTRA_CHARS.len();
343 let id = id / EXTRA_CHARS.len();
344 let extra2 = id % EXTRA_CHARS.len();
345 let id = id / EXTRA_CHARS.len();
346 let extra3 = id % EXTRA_CHARS.len();
347 hash.push(EXTRA_CHARS.as_bytes()[extra1] as char);
348 hash.push(EXTRA_CHARS.as_bytes()[extra2] as char);
349 hash.push(EXTRA_CHARS.as_bytes()[extra3] as char);
351 exported_name(path, &hash[..])
354 pub fn mangle_internal_name_by_type_and_seq<'a, 'tcx>(ccx: &CrateContext<'a, 'tcx>,
356 name: &str) -> String {
357 let path = [PathName(token::intern(&t.to_string())),
359 let hash = get_symbol_hash(ccx, t);
360 mangle(path.iter().cloned(), Some(&hash[..]))
363 pub fn mangle_internal_name_by_path_and_seq(path: PathElems, flav: &str) -> String {
364 mangle(path.chain(Some(gensym_name(flav))), None)
367 pub fn get_linker(sess: &Session) -> (String, Command) {
368 if let Some(ref linker) = sess.opts.cg.linker {
369 (linker.clone(), Command::new(linker))
370 } else if sess.target.target.options.is_like_msvc {
371 ("link.exe".to_string(), msvc::link_exe_cmd(sess))
373 (sess.target.target.options.linker.clone(),
374 Command::new(&sess.target.target.options.linker))
378 pub fn get_ar_prog(sess: &Session) -> String {
379 sess.opts.cg.ar.clone().unwrap_or_else(|| {
380 sess.target.target.options.ar.clone()
384 fn command_path(sess: &Session) -> OsString {
385 // The compiler's sysroot often has some bundled tools, so add it to the
386 // PATH for the child.
387 let mut new_path = sess.host_filesearch(PathKind::All)
388 .get_tools_search_paths();
389 if let Some(path) = env::var_os("PATH") {
390 new_path.extend(env::split_paths(&path));
392 env::join_paths(new_path).unwrap()
395 pub fn remove(sess: &Session, path: &Path) {
396 match fs::remove_file(path) {
399 sess.err(&format!("failed to remove {}: {}",
406 /// Perform the linkage portion of the compilation phase. This will generate all
407 /// of the requested outputs for this compilation session.
408 pub fn link_binary(sess: &Session,
409 trans: &CrateTranslation,
410 outputs: &OutputFilenames,
411 crate_name: &str) -> Vec<PathBuf> {
412 let mut out_filenames = Vec::new();
413 for &crate_type in sess.crate_types.borrow().iter() {
414 if invalid_output_for_target(sess, crate_type) {
415 sess.bug(&format!("invalid output type `{:?}` for target os `{}`",
416 crate_type, sess.opts.target_triple));
418 let out_file = link_binary_output(sess, trans, crate_type, outputs,
420 out_filenames.push(out_file);
423 // Remove the temporary object file and metadata if we aren't saving temps
424 if !sess.opts.cg.save_temps {
425 for obj in object_filenames(sess, outputs) {
428 remove(sess, &outputs.with_extension("metadata.o"));
435 /// Returns default crate type for target
437 /// Default crate type is used when crate type isn't provided neither
438 /// through cmd line arguments nor through crate attributes
440 /// It is CrateTypeExecutable for all platforms but iOS as there is no
441 /// way to run iOS binaries anyway without jailbreaking and
442 /// interaction with Rust code through static library is the only
444 pub fn default_output_for_target(sess: &Session) -> config::CrateType {
445 if !sess.target.target.options.executables {
446 config::CrateTypeStaticlib
448 config::CrateTypeExecutable
452 /// Checks if target supports crate_type as output
453 pub fn invalid_output_for_target(sess: &Session,
454 crate_type: config::CrateType) -> bool {
455 match (sess.target.target.options.dynamic_linking,
456 sess.target.target.options.executables, crate_type) {
457 (false, _, config::CrateTypeDylib) => true,
458 (_, false, config::CrateTypeExecutable) => true,
463 fn is_writeable(p: &Path) -> bool {
466 Ok(m) => !m.permissions().readonly()
470 pub fn filename_for_input(sess: &Session,
471 crate_type: config::CrateType,
473 outputs: &OutputFilenames) -> PathBuf {
474 let libname = format!("{}{}", crate_name, sess.opts.cg.extra_filename);
476 config::CrateTypeRlib => {
477 outputs.out_directory.join(&format!("lib{}.rlib", libname))
479 config::CrateTypeDylib => {
480 let (prefix, suffix) = (&sess.target.target.options.dll_prefix,
481 &sess.target.target.options.dll_suffix);
482 outputs.out_directory.join(&format!("{}{}{}", prefix, libname,
485 config::CrateTypeStaticlib => {
486 outputs.out_directory.join(&format!("lib{}.a", libname))
488 config::CrateTypeExecutable => {
489 let suffix = &sess.target.target.options.exe_suffix;
490 let out_filename = outputs.path(OutputTypeExe);
491 if suffix.is_empty() {
492 out_filename.to_path_buf()
494 out_filename.with_extension(&suffix[1..])
500 pub fn each_linked_rlib(sess: &Session,
501 f: &mut FnMut(ast::CrateNum, &Path)) {
502 let crates = sess.cstore.get_used_crates(cstore::RequireStatic).into_iter();
503 let fmts = sess.dependency_formats.borrow();
504 let fmts = fmts.get(&config::CrateTypeExecutable).or_else(|| {
505 fmts.get(&config::CrateTypeStaticlib)
506 }).unwrap_or_else(|| {
507 sess.bug("could not find formats for rlibs")
509 for (cnum, path) in crates {
510 match fmts[cnum as usize - 1] {
511 Linkage::NotLinked | Linkage::IncludedFromDylib => continue,
514 let name = sess.cstore.get_crate_data(cnum).name.clone();
515 let path = match path {
518 sess.fatal(&format!("could not find rlib for: `{}`", name));
525 fn link_binary_output(sess: &Session,
526 trans: &CrateTranslation,
527 crate_type: config::CrateType,
528 outputs: &OutputFilenames,
529 crate_name: &str) -> PathBuf {
530 let objects = object_filenames(sess, outputs);
531 let out_filename = match outputs.single_output_file {
532 Some(ref file) => file.clone(),
533 None => filename_for_input(sess, crate_type, crate_name, outputs),
536 // Make sure files are writeable. Mac, FreeBSD, and Windows system linkers
537 // check this already -- however, the Linux linker will happily overwrite a
538 // read-only file. We should be consistent.
539 for file in objects.iter().chain(Some(&out_filename)) {
540 if !is_writeable(file) {
541 sess.fatal(&format!("output file {} is not writeable -- check its \
542 permissions", file.display()));
546 let tmpdir = TempDir::new("rustc").ok().expect("needs a temp dir");
548 config::CrateTypeRlib => {
549 link_rlib(sess, Some(trans), &objects, &out_filename,
550 tmpdir.path()).build();
552 config::CrateTypeStaticlib => {
553 link_staticlib(sess, &objects, &out_filename, tmpdir.path());
555 config::CrateTypeExecutable => {
556 link_natively(sess, false, &objects, &out_filename, trans, outputs,
559 config::CrateTypeDylib => {
560 link_natively(sess, true, &objects, &out_filename, trans, outputs,
568 fn object_filenames(sess: &Session, outputs: &OutputFilenames) -> Vec<PathBuf> {
569 (0..sess.opts.cg.codegen_units).map(|i| {
570 let ext = format!("{}.o", i);
571 outputs.temp_path(OutputTypeObject).with_extension(&ext)
575 fn archive_search_paths(sess: &Session) -> Vec<PathBuf> {
576 let mut search = Vec::new();
577 sess.target_filesearch(PathKind::Native).for_each_lib_search_path(|path, _| {
578 search.push(path.to_path_buf());
584 fn archive_config<'a>(sess: &'a Session,
586 input: Option<&Path>) -> ArchiveConfig<'a> {
589 dst: output.to_path_buf(),
590 src: input.map(|p| p.to_path_buf()),
591 lib_search_paths: archive_search_paths(sess),
592 ar_prog: get_ar_prog(sess),
593 command_path: command_path(sess),
599 // An rlib in its current incarnation is essentially a renamed .a file. The
600 // rlib primarily contains the object file of the crate, but it also contains
601 // all of the object files from native libraries. This is done by unzipping
602 // native libraries and inserting all of the contents into this archive.
603 fn link_rlib<'a>(sess: &'a Session,
604 trans: Option<&CrateTranslation>, // None == no metadata/bytecode
607 tmpdir: &Path) -> ArchiveBuilder<'a> {
608 info!("preparing rlib from {:?} to {:?}", objects, out_filename);
609 let mut ab = ArchiveBuilder::new(archive_config(sess, out_filename, None));
614 for &(ref l, kind) in sess.cstore.get_used_libraries().borrow().iter() {
616 cstore::NativeStatic => ab.add_native_library(&l).unwrap(),
617 cstore::NativeFramework | cstore::NativeUnknown => {}
621 // After adding all files to the archive, we need to update the
622 // symbol table of the archive.
625 // For OSX/iOS, we must be careful to update symbols only when adding
626 // object files. We're about to start adding non-object files, so run
627 // `ar` now to process the object files.
628 if sess.target.target.options.is_like_osx && !ab.using_llvm() {
632 // Note that it is important that we add all of our non-object "magical
633 // files" *after* all of the object files in the archive. The reason for
634 // this is as follows:
636 // * When performing LTO, this archive will be modified to remove
637 // objects from above. The reason for this is described below.
639 // * When the system linker looks at an archive, it will attempt to
640 // determine the architecture of the archive in order to see whether its
643 // The algorithm for this detection is: iterate over the files in the
644 // archive. Skip magical SYMDEF names. Interpret the first file as an
645 // object file. Read architecture from the object file.
647 // * As one can probably see, if "metadata" and "foo.bc" were placed
648 // before all of the objects, then the architecture of this archive would
649 // not be correctly inferred once 'foo.o' is removed.
651 // Basically, all this means is that this code should not move above the
655 // Instead of putting the metadata in an object file section, rlibs
656 // contain the metadata in a separate file. We use a temp directory
657 // here so concurrent builds in the same directory don't try to use
658 // the same filename for metadata (stomping over one another)
659 let metadata = tmpdir.join(METADATA_FILENAME);
660 match fs::File::create(&metadata).and_then(|mut f| {
661 f.write_all(&trans.metadata)
665 sess.fatal(&format!("failed to write {}: {}",
666 metadata.display(), e));
669 ab.add_file(&metadata);
671 // For LTO purposes, the bytecode of this library is also inserted
672 // into the archive. If codegen_units > 1, we insert each of the
675 // Note that we make sure that the bytecode filename in the
676 // archive is never exactly 16 bytes long by adding a 16 byte
677 // extension to it. This is to work around a bug in LLDB that
678 // would cause it to crash if the name of a file in an archive
679 // was exactly 16 bytes.
680 let bc_filename = obj.with_extension("bc");
681 let bc_deflated_filename = tmpdir.join({
682 obj.with_extension("bytecode.deflate").file_name().unwrap()
685 let mut bc_data = Vec::new();
686 match fs::File::open(&bc_filename).and_then(|mut f| {
687 f.read_to_end(&mut bc_data)
690 Err(e) => sess.fatal(&format!("failed to read bytecode: {}",
694 let bc_data_deflated = flate::deflate_bytes(&bc_data[..]);
696 let mut bc_file_deflated = match fs::File::create(&bc_deflated_filename) {
699 sess.fatal(&format!("failed to create compressed \
700 bytecode file: {}", e))
704 match write_rlib_bytecode_object_v1(&mut bc_file_deflated,
708 sess.fatal(&format!("failed to write compressed \
713 ab.add_file(&bc_deflated_filename);
715 // See the bottom of back::write::run_passes for an explanation
716 // of when we do and don't keep .0.bc files around.
717 let user_wants_numbered_bitcode =
718 sess.opts.output_types.contains(&OutputTypeBitcode) &&
719 sess.opts.cg.codegen_units > 1;
720 if !sess.opts.cg.save_temps && !user_wants_numbered_bitcode {
721 remove(sess, &bc_filename);
725 // After adding all files to the archive, we need to update the
726 // symbol table of the archive. This currently dies on OSX (see
727 // #11162), and isn't necessary there anyway
728 if !sess.target.target.options.is_like_osx || ab.using_llvm() {
739 fn write_rlib_bytecode_object_v1(writer: &mut Write,
740 bc_data_deflated: &[u8]) -> io::Result<()> {
741 let bc_data_deflated_size: u64 = bc_data_deflated.len() as u64;
743 try!(writer.write_all(RLIB_BYTECODE_OBJECT_MAGIC));
744 try!(writer.write_all(&[1, 0, 0, 0]));
745 try!(writer.write_all(&[
746 (bc_data_deflated_size >> 0) as u8,
747 (bc_data_deflated_size >> 8) as u8,
748 (bc_data_deflated_size >> 16) as u8,
749 (bc_data_deflated_size >> 24) as u8,
750 (bc_data_deflated_size >> 32) as u8,
751 (bc_data_deflated_size >> 40) as u8,
752 (bc_data_deflated_size >> 48) as u8,
753 (bc_data_deflated_size >> 56) as u8,
755 try!(writer.write_all(&bc_data_deflated));
757 let number_of_bytes_written_so_far =
758 RLIB_BYTECODE_OBJECT_MAGIC.len() + // magic id
759 mem::size_of_val(&RLIB_BYTECODE_OBJECT_VERSION) + // version
760 mem::size_of_val(&bc_data_deflated_size) + // data size field
761 bc_data_deflated_size as usize; // actual data
763 // If the number of bytes written to the object so far is odd, add a
764 // padding byte to make it even. This works around a crash bug in LLDB
765 // (see issue #15950)
766 if number_of_bytes_written_so_far % 2 == 1 {
767 try!(writer.write_all(&[0]));
773 // Create a static archive
775 // This is essentially the same thing as an rlib, but it also involves adding
776 // all of the upstream crates' objects into the archive. This will slurp in
777 // all of the native libraries of upstream dependencies as well.
779 // Additionally, there's no way for us to link dynamic libraries, so we warn
780 // about all dynamic library dependencies that they're not linked in.
782 // There's no need to include metadata in a static archive, so ensure to not
783 // link in the metadata object file (and also don't prepare the archive with a
785 fn link_staticlib(sess: &Session, objects: &[PathBuf], out_filename: &Path,
787 let mut ab = link_rlib(sess, None, objects, out_filename, tempdir);
788 if sess.target.target.options.is_like_osx && !ab.using_llvm() {
791 if !sess.target.target.options.no_compiler_rt {
792 ab.add_native_library("compiler-rt").unwrap();
795 let mut all_native_libs = vec![];
797 each_linked_rlib(sess, &mut |cnum, path| {
798 let name = sess.cstore.get_crate_data(cnum).name();
799 ab.add_rlib(path, &name, sess.lto()).unwrap();
801 let native_libs = csearch::get_native_libraries(&sess.cstore, cnum);
802 all_native_libs.extend(native_libs);
808 if !all_native_libs.is_empty() {
809 sess.note("link against the following native artifacts when linking against \
810 this static library");
811 sess.note("the order and any duplication can be significant on some platforms, \
812 and so may need to be preserved");
815 for &(kind, ref lib) in &all_native_libs {
816 let name = match kind {
817 cstore::NativeStatic => "static library",
818 cstore::NativeUnknown => "library",
819 cstore::NativeFramework => "framework",
821 sess.note(&format!("{}: {}", name, *lib));
825 // Create a dynamic library or executable
827 // This will invoke the system linker/cc to create the resulting file. This
828 // links to all upstream files as well.
829 fn link_natively(sess: &Session, dylib: bool,
830 objects: &[PathBuf], out_filename: &Path,
831 trans: &CrateTranslation,
832 outputs: &OutputFilenames,
834 info!("preparing dylib? ({}) from {:?} to {:?}", dylib, objects,
837 // The invocations of cc share some flags across platforms
838 let (pname, mut cmd) = get_linker(sess);
839 cmd.env("PATH", command_path(sess));
841 let root = sess.target_filesearch(PathKind::Native).get_lib_path();
842 cmd.args(&sess.target.target.options.pre_link_args);
843 for obj in &sess.target.target.options.pre_link_objects {
844 cmd.arg(root.join(obj));
848 let mut linker = if sess.target.target.options.is_like_msvc {
849 Box::new(MsvcLinker { cmd: &mut cmd, sess: &sess }) as Box<Linker>
851 Box::new(GnuLinker { cmd: &mut cmd, sess: &sess }) as Box<Linker>
853 link_args(&mut *linker, sess, dylib, tmpdir,
854 objects, out_filename, trans, outputs);
855 if !sess.target.target.options.no_compiler_rt {
856 linker.link_staticlib("compiler-rt");
859 for obj in &sess.target.target.options.post_link_objects {
860 cmd.arg(root.join(obj));
862 cmd.args(&sess.target.target.options.post_link_args);
864 if sess.opts.debugging_opts.print_link_args {
865 println!("{:?}", &cmd);
868 // May have not found libraries in the right formats.
869 sess.abort_if_errors();
871 // Invoke the system linker
873 let prog = time(sess.time_passes(), "running linker", || cmd.output());
876 if !prog.status.success() {
877 sess.err(&format!("linking with `{}` failed: {}",
880 sess.note(&format!("{:?}", &cmd));
881 let mut output = prog.stderr.clone();
882 output.push_all(&prog.stdout);
883 sess.note(str::from_utf8(&output[..]).unwrap());
884 sess.abort_if_errors();
886 info!("linker stderr:\n{}", String::from_utf8(prog.stderr).unwrap());
887 info!("linker stdout:\n{}", String::from_utf8(prog.stdout).unwrap());
890 sess.fatal(&format!("could not exec the linker `{}`: {}", pname, e));
895 // On OSX, debuggers need this utility to get run to do some munging of
897 if sess.target.target.options.is_like_osx && sess.opts.debuginfo != NoDebugInfo {
898 match Command::new("dsymutil").arg(out_filename).output() {
900 Err(e) => sess.fatal(&format!("failed to run dsymutil: {}", e)),
905 fn link_args(cmd: &mut Linker,
911 trans: &CrateTranslation,
912 outputs: &OutputFilenames) {
914 // The default library location, we need this to find the runtime.
915 // The location of crates will be determined as needed.
916 let lib_path = sess.target_filesearch(PathKind::All).get_lib_path();
919 let t = &sess.target.target;
921 cmd.include_path(&fix_windows_verbatim_for_gcc(&lib_path));
925 cmd.output_filename(out_filename);
927 // If we're building a dynamic library then some platforms need to make sure
928 // that all symbols are exported correctly from the dynamic library.
930 cmd.export_symbols(sess, trans, tmpdir);
933 // When linking a dynamic library, we put the metadata into a section of the
934 // executable. This metadata is in a separate object file from the main
935 // object file, so we link that in here.
937 cmd.add_object(&outputs.with_extension("metadata.o"));
940 // Try to strip as much out of the generated object by removing unused
941 // sections if possible. See more comments in linker.rs
942 cmd.gc_sections(dylib);
944 let used_link_args = sess.cstore.get_used_link_args().borrow();
946 if !dylib && t.options.position_independent_executables {
947 let empty_vec = Vec::new();
948 let empty_str = String::new();
949 let args = sess.opts.cg.link_args.as_ref().unwrap_or(&empty_vec);
950 let mut args = args.iter().chain(used_link_args.iter());
951 let relocation_model = sess.opts.cg.relocation_model.as_ref()
952 .unwrap_or(&empty_str);
953 if (t.options.relocation_model == "pic" || *relocation_model == "pic")
954 && !args.any(|x| *x == "-static") {
955 cmd.position_independent_executable();
959 // Pass optimization flags down to the linker.
962 // Pass debuginfo flags down to the linker.
965 // We want to prevent the compiler from accidentally leaking in any system
966 // libraries, so we explicitly ask gcc to not link to any libraries by
967 // default. Note that this does not happen for windows because windows pulls
968 // in some large number of libraries and I couldn't quite figure out which
970 cmd.no_default_libraries();
972 // Take careful note of the ordering of the arguments we pass to the linker
973 // here. Linkers will assume that things on the left depend on things to the
974 // right. Things on the right cannot depend on things on the left. This is
975 // all formally implemented in terms of resolving symbols (libs on the right
976 // resolve unknown symbols of libs on the left, but not vice versa).
978 // For this reason, we have organized the arguments we pass to the linker as
981 // 1. The local object that LLVM just generated
982 // 2. Upstream rust libraries
983 // 3. Local native libraries
984 // 4. Upstream native libraries
986 // This is generally fairly natural, but some may expect 2 and 3 to be
987 // swapped. The reason that all native libraries are put last is that it's
988 // not recommended for a native library to depend on a symbol from a rust
989 // crate. If this is the case then a staticlib crate is recommended, solving
992 // Additionally, it is occasionally the case that upstream rust libraries
993 // depend on a local native library. In the case of libraries such as
994 // lua/glfw/etc the name of the library isn't the same across all platforms,
995 // so only the consumer crate of a library knows the actual name. This means
996 // that downstream crates will provide the #[link] attribute which upstream
997 // crates will depend on. Hence local native libraries are after out
998 // upstream rust crates.
1000 // In theory this means that a symbol in an upstream native library will be
1001 // shadowed by a local native library when it wouldn't have been before, but
1002 // this kind of behavior is pretty platform specific and generally not
1003 // recommended anyway, so I don't think we're shooting ourself in the foot
1005 add_upstream_rust_crates(cmd, sess, dylib, tmpdir);
1006 add_local_native_libraries(cmd, sess);
1007 add_upstream_native_libraries(cmd, sess);
1009 // # Telling the linker what we're doing
1012 cmd.build_dylib(out_filename);
1015 // FIXME (#2397): At some point we want to rpath our guesses as to
1016 // where extern libraries might live, based on the
1017 // addl_lib_search_paths
1018 if sess.opts.cg.rpath {
1019 let sysroot = sess.sysroot();
1020 let target_triple = &sess.opts.target_triple;
1021 let mut get_install_prefix_lib_path = || {
1022 let install_prefix = option_env!("CFG_PREFIX").expect("CFG_PREFIX");
1023 let tlib = filesearch::relative_target_lib_path(sysroot, target_triple);
1024 let mut path = PathBuf::from(install_prefix);
1029 let mut rpath_config = RPathConfig {
1030 used_crates: sess.cstore.get_used_crates(cstore::RequireDynamic),
1031 out_filename: out_filename.to_path_buf(),
1032 has_rpath: sess.target.target.options.has_rpath,
1033 is_like_osx: sess.target.target.options.is_like_osx,
1034 get_install_prefix_lib_path: &mut get_install_prefix_lib_path,
1036 cmd.args(&rpath::get_rpath_flags(&mut rpath_config));
1039 // Finally add all the linker arguments provided on the command line along
1040 // with any #[link_args] attributes found inside the crate
1041 if let Some(ref args) = sess.opts.cg.link_args {
1044 cmd.args(&used_link_args);
1047 // # Native library linking
1049 // User-supplied library search paths (-L on the command line). These are
1050 // the same paths used to find Rust crates, so some of them may have been
1051 // added already by the previous crate linking code. This only allows them
1052 // to be found at compile time so it is still entirely up to outside
1053 // forces to make sure that library can be found at runtime.
1055 // Also note that the native libraries linked here are only the ones located
1056 // in the current crate. Upstream crates with native library dependencies
1057 // may have their native library pulled in above.
1058 fn add_local_native_libraries(cmd: &mut Linker, sess: &Session) {
1059 sess.target_filesearch(PathKind::All).for_each_lib_search_path(|path, k| {
1061 PathKind::Framework => { cmd.framework_path(path); }
1062 _ => { cmd.include_path(&fix_windows_verbatim_for_gcc(path)); }
1067 let libs = sess.cstore.get_used_libraries();
1068 let libs = libs.borrow();
1070 let staticlibs = libs.iter().filter_map(|&(ref l, kind)| {
1071 if kind == cstore::NativeStatic {Some(l)} else {None}
1073 let others = libs.iter().filter(|&&(_, kind)| {
1074 kind != cstore::NativeStatic
1077 // Some platforms take hints about whether a library is static or dynamic.
1078 // For those that support this, we ensure we pass the option if the library
1079 // was flagged "static" (most defaults are dynamic) to ensure that if
1080 // libfoo.a and libfoo.so both exist that the right one is chosen.
1083 let search_path = archive_search_paths(sess);
1084 for l in staticlibs {
1085 // Here we explicitly ask that the entire archive is included into the
1086 // result artifact. For more details see #15460, but the gist is that
1087 // the linker will strip away any unused objects in the archive if we
1088 // don't otherwise explicitly reference them. This can occur for
1089 // libraries which are just providing bindings, libraries with generic
1091 cmd.link_whole_staticlib(l, &search_path);
1096 for &(ref l, kind) in others {
1098 cstore::NativeUnknown => cmd.link_dylib(l),
1099 cstore::NativeFramework => cmd.link_framework(l),
1100 cstore::NativeStatic => unreachable!(),
1105 // # Rust Crate linking
1107 // Rust crates are not considered at all when creating an rlib output. All
1108 // dependencies will be linked when producing the final output (instead of
1109 // the intermediate rlib version)
1110 fn add_upstream_rust_crates(cmd: &mut Linker, sess: &Session,
1111 dylib: bool, tmpdir: &Path) {
1112 // All of the heavy lifting has previously been accomplished by the
1113 // dependency_format module of the compiler. This is just crawling the
1114 // output of that module, adding crates as necessary.
1116 // Linking to a rlib involves just passing it to the linker (the linker
1117 // will slurp up the object files inside), and linking to a dynamic library
1118 // involves just passing the right -l flag.
1120 let formats = sess.dependency_formats.borrow();
1121 let data = if dylib {
1122 formats.get(&config::CrateTypeDylib).unwrap()
1124 formats.get(&config::CrateTypeExecutable).unwrap()
1127 // Invoke get_used_crates to ensure that we get a topological sorting of
1129 let deps = sess.cstore.get_used_crates(cstore::RequireDynamic);
1131 for &(cnum, _) in &deps {
1132 // We may not pass all crates through to the linker. Some crates may
1133 // appear statically in an existing dylib, meaning we'll pick up all the
1134 // symbols from the dylib.
1135 let src = sess.cstore.get_used_crate_source(cnum).unwrap();
1136 match data[cnum as usize - 1] {
1137 Linkage::NotLinked |
1138 Linkage::IncludedFromDylib => {}
1139 Linkage::Static => {
1140 add_static_crate(cmd, sess, tmpdir, dylib, &src.rlib.unwrap().0)
1142 Linkage::Dynamic => {
1143 add_dynamic_crate(cmd, sess, &src.dylib.unwrap().0)
1148 // Converts a library file-stem into a cc -l argument
1149 fn unlib<'a>(config: &config::Config, stem: &'a str) -> &'a str {
1150 if stem.starts_with("lib") && !config.target.options.is_like_windows {
1157 // Adds the static "rlib" versions of all crates to the command line.
1158 // There's a bit of magic which happens here specifically related to LTO and
1159 // dynamic libraries. Specifically:
1161 // * For LTO, we remove upstream object files.
1162 // * For dylibs we remove metadata and bytecode from upstream rlibs
1164 // When performing LTO, all of the bytecode from the upstream libraries has
1165 // already been included in our object file output. As a result we need to
1166 // remove the object files in the upstream libraries so the linker doesn't
1167 // try to include them twice (or whine about duplicate symbols). We must
1168 // continue to include the rest of the rlib, however, as it may contain
1169 // static native libraries which must be linked in.
1171 // When making a dynamic library, linkers by default don't include any
1172 // object files in an archive if they're not necessary to resolve the link.
1173 // We basically want to convert the archive (rlib) to a dylib, though, so we
1174 // *do* want everything included in the output, regardless of whether the
1175 // linker thinks it's needed or not. As a result we must use the
1176 // --whole-archive option (or the platform equivalent). When using this
1177 // option the linker will fail if there are non-objects in the archive (such
1178 // as our own metadata and/or bytecode). All in all, for rlibs to be
1179 // entirely included in dylibs, we need to remove all non-object files.
1181 // Note, however, that if we're not doing LTO or we're not producing a dylib
1182 // (aka we're making an executable), we can just pass the rlib blindly to
1183 // the linker (fast) because it's fine if it's not actually included as
1184 // we're at the end of the dependency chain.
1185 fn add_static_crate(cmd: &mut Linker, sess: &Session, tmpdir: &Path,
1186 dylib: bool, cratepath: &Path) {
1187 if !sess.lto() && !dylib {
1188 cmd.link_rlib(&fix_windows_verbatim_for_gcc(cratepath));
1192 let dst = tmpdir.join(cratepath.file_name().unwrap());
1193 let name = cratepath.file_name().unwrap().to_str().unwrap();
1194 let name = &name[3..name.len() - 5]; // chop off lib/.rlib
1196 time(sess.time_passes(), &format!("altering {}.rlib", name), || {
1197 let cfg = archive_config(sess, &dst, Some(cratepath));
1198 let mut archive = ArchiveBuilder::new(cfg);
1199 archive.remove_file(METADATA_FILENAME);
1200 archive.update_symbols();
1202 let mut any_objects = false;
1203 for f in archive.src_files() {
1204 if f.ends_with("bytecode.deflate") {
1205 archive.remove_file(&f);
1208 let canonical = f.replace("-", "_");
1209 let canonical_name = name.replace("-", "_");
1210 if sess.lto() && canonical.starts_with(&canonical_name) &&
1211 canonical.ends_with(".o") {
1212 let num = &f[name.len()..f.len() - 2];
1213 if num.len() > 0 && num[1..].parse::<u32>().is_ok() {
1214 archive.remove_file(&f);
1223 cmd.link_whole_rlib(&fix_windows_verbatim_for_gcc(&dst));
1228 // Same thing as above, but for dynamic crates instead of static crates.
1229 fn add_dynamic_crate(cmd: &mut Linker, sess: &Session, cratepath: &Path) {
1230 // If we're performing LTO, then it should have been previously required
1231 // that all upstream rust dependencies were available in an rlib format.
1232 assert!(!sess.lto());
1234 // Just need to tell the linker about where the library lives and
1236 let parent = cratepath.parent();
1237 if let Some(dir) = parent {
1238 cmd.include_path(&fix_windows_verbatim_for_gcc(dir));
1240 let filestem = cratepath.file_stem().unwrap().to_str().unwrap();
1241 cmd.link_rust_dylib(&unlib(&sess.target, filestem),
1242 parent.unwrap_or(Path::new("")));
1246 // Link in all of our upstream crates' native dependencies. Remember that
1247 // all of these upstream native dependencies are all non-static
1248 // dependencies. We've got two cases then:
1250 // 1. The upstream crate is an rlib. In this case we *must* link in the
1251 // native dependency because the rlib is just an archive.
1253 // 2. The upstream crate is a dylib. In order to use the dylib, we have to
1254 // have the dependency present on the system somewhere. Thus, we don't
1255 // gain a whole lot from not linking in the dynamic dependency to this
1258 // The use case for this is a little subtle. In theory the native
1259 // dependencies of a crate are purely an implementation detail of the crate
1260 // itself, but the problem arises with generic and inlined functions. If a
1261 // generic function calls a native function, then the generic function must
1262 // be instantiated in the target crate, meaning that the native symbol must
1263 // also be resolved in the target crate.
1264 fn add_upstream_native_libraries(cmd: &mut Linker, sess: &Session) {
1265 // Be sure to use a topological sorting of crates because there may be
1266 // interdependencies between native libraries. When passing -nodefaultlibs,
1267 // for example, almost all native libraries depend on libc, so we have to
1268 // make sure that's all the way at the right (liblibc is near the base of
1269 // the dependency chain).
1271 // This passes RequireStatic, but the actual requirement doesn't matter,
1272 // we're just getting an ordering of crate numbers, we're not worried about
1274 let crates = sess.cstore.get_used_crates(cstore::RequireStatic);
1275 for (cnum, _) in crates {
1276 let libs = csearch::get_native_libraries(&sess.cstore, cnum);
1277 for &(kind, ref lib) in &libs {
1279 cstore::NativeUnknown => cmd.link_dylib(lib),
1280 cstore::NativeFramework => cmd.link_framework(lib),
1281 cstore::NativeStatic => {
1282 sess.bug("statics shouldn't be propagated");