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;
52 // RLIB LLVM-BYTECODE OBJECT LAYOUT
55 // 0..10 "RUST_OBJECT" encoded in ASCII
56 // 11..14 format version as little-endian u32
57 // 15..22 size in bytes of deflate compressed LLVM bitcode as
59 // 23.. compressed LLVM bitcode
61 // This is the "magic number" expected at the beginning of a LLVM bytecode
63 pub const RLIB_BYTECODE_OBJECT_MAGIC: &'static [u8] = b"RUST_OBJECT";
65 // The version number this compiler will write to bytecode objects in rlibs
66 pub const RLIB_BYTECODE_OBJECT_VERSION: u32 = 1;
68 // The offset in bytes the bytecode object format version number can be found at
69 pub const RLIB_BYTECODE_OBJECT_VERSION_OFFSET: usize = 11;
71 // The offset in bytes the size of the compressed bytecode can be found at in
73 pub const RLIB_BYTECODE_OBJECT_V1_DATASIZE_OFFSET: usize =
74 RLIB_BYTECODE_OBJECT_VERSION_OFFSET + 4;
76 // The offset in bytes the compressed LLVM bytecode can be found at in format
78 pub const RLIB_BYTECODE_OBJECT_V1_DATA_OFFSET: usize =
79 RLIB_BYTECODE_OBJECT_V1_DATASIZE_OFFSET + 8;
83 * Name mangling and its relationship to metadata. This is complex. Read
86 * The semantic model of Rust linkage is, broadly, that "there's no global
87 * namespace" between crates. Our aim is to preserve the illusion of this
88 * model despite the fact that it's not *quite* possible to implement on
89 * modern linkers. We initially didn't use system linkers at all, but have
90 * been convinced of their utility.
92 * There are a few issues to handle:
94 * - Linkers operate on a flat namespace, so we have to flatten names.
95 * We do this using the C++ namespace-mangling technique. Foo::bar
98 * - Symbols with the same name but different types need to get different
99 * linkage-names. We do this by hashing a string-encoding of the type into
100 * a fixed-size (currently 16-byte hex) cryptographic hash function (CHF:
101 * we use SHA256) to "prevent collisions". This is not airtight but 16 hex
102 * digits on uniform probability means you're going to need 2**32 same-name
103 * symbols in the same process before you're even hitting birthday-paradox
104 * collision probability.
106 * - Symbols in different crates but with same names "within" the crate need
107 * to get different linkage-names.
109 * - The hash shown in the filename needs to be predictable and stable for
110 * build tooling integration. It also needs to be using a hash function
111 * which is easy to use from Python, make, etc.
113 * So here is what we do:
115 * - Consider the package id; every crate has one (specified with crate_id
116 * attribute). If a package id isn't provided explicitly, we infer a
117 * versionless one from the output name. The version will end up being 0.0
118 * in this case. CNAME and CVERS are taken from this package id. For
119 * example, github.com/mozilla/CNAME#CVERS.
121 * - Define CMH as SHA256(crateid).
123 * - Define CMH8 as the first 8 characters of CMH.
125 * - Compile our crate to lib CNAME-CMH8-CVERS.so
127 * - Define STH(sym) as SHA256(CMH, type_str(sym))
129 * - Suffix a mangled sym with ::STH@CVERS, so that it is unique in the
130 * name, non-name metadata, and type sense, and versioned in the way
131 * system linkers understand.
134 pub fn find_crate_name(sess: Option<&Session>,
135 attrs: &[ast::Attribute],
136 input: &Input) -> String {
137 let validate = |s: String, span: Option<Span>| {
138 creader::validate_crate_name(sess, &s[..], span);
142 // Look in attributes 100% of the time to make sure the attribute is marked
143 // as used. After doing this, however, we still prioritize a crate name from
144 // the command line over one found in the #[crate_name] attribute. If we
145 // find both we ensure that they're the same later on as well.
146 let attr_crate_name = attrs.iter().find(|at| at.check_name("crate_name"))
147 .and_then(|at| at.value_str().map(|s| (at, s)));
149 if let Some(sess) = sess {
150 if let Some(ref s) = sess.opts.crate_name {
151 if let Some((attr, ref name)) = attr_crate_name {
153 let msg = format!("--crate-name and #[crate_name] are \
154 required to match, but `{}` != `{}`",
156 sess.span_err(attr.span, &msg[..]);
159 return validate(s.clone(), None);
163 if let Some((attr, s)) = attr_crate_name {
164 return validate(s.to_string(), Some(attr.span));
166 if let Input::File(ref path) = *input {
167 if let Some(s) = path.file_stem().and_then(|s| s.to_str()) {
168 if s.starts_with("-") {
169 let msg = format!("crate names cannot start with a `-`, but \
170 `{}` has a leading hyphen", s);
171 if let Some(sess) = sess {
175 return validate(s.replace("-", "_"), None);
180 "rust_out".to_string()
183 pub fn build_link_meta(sess: &Session, krate: &hir::Crate,
184 name: String) -> LinkMeta {
187 crate_hash: Svh::calculate(&sess.opts.cg.metadata, krate),
193 fn truncated_hash_result(symbol_hasher: &mut Sha256) -> String {
194 let output = symbol_hasher.result_bytes();
195 // 64 bits should be enough to avoid collisions.
196 output[.. 8].to_hex().to_string()
200 // This calculates STH for a symbol, as defined above
201 fn symbol_hash<'tcx>(tcx: &ty::ctxt<'tcx>,
202 symbol_hasher: &mut Sha256,
204 link_meta: &LinkMeta)
206 // NB: do *not* use abbrevs here as we want the symbol names
207 // to be independent of one another in the crate.
209 symbol_hasher.reset();
210 symbol_hasher.input_str(&link_meta.crate_name);
211 symbol_hasher.input_str("-");
212 symbol_hasher.input_str(link_meta.crate_hash.as_str());
213 for meta in tcx.sess.crate_metadata.borrow().iter() {
214 symbol_hasher.input_str(&meta[..]);
216 symbol_hasher.input_str("-");
217 symbol_hasher.input_str(&encoder::encoded_ty(tcx, t));
218 // Prefix with 'h' so that it never blends into adjacent digits
219 let mut hash = String::from("h");
220 hash.push_str(&truncated_hash_result(symbol_hasher));
224 fn get_symbol_hash<'a, 'tcx>(ccx: &CrateContext<'a, 'tcx>, t: Ty<'tcx>) -> String {
225 match ccx.type_hashcodes().borrow().get(&t) {
226 Some(h) => return h.to_string(),
230 let mut symbol_hasher = ccx.symbol_hasher().borrow_mut();
231 let hash = symbol_hash(ccx.tcx(), &mut *symbol_hasher, t, ccx.link_meta());
232 ccx.type_hashcodes().borrow_mut().insert(t, hash.clone());
237 // Name sanitation. LLVM will happily accept identifiers with weird names, but
239 // gas accepts the following characters in symbols: a-z, A-Z, 0-9, ., _, $
240 pub fn sanitize(s: &str) -> String {
241 let mut result = String::new();
244 // Escape these with $ sequences
245 '@' => result.push_str("$SP$"),
246 '*' => result.push_str("$BP$"),
247 '&' => result.push_str("$RF$"),
248 '<' => result.push_str("$LT$"),
249 '>' => result.push_str("$GT$"),
250 '(' => result.push_str("$LP$"),
251 ')' => result.push_str("$RP$"),
252 ',' => result.push_str("$C$"),
254 // '.' doesn't occur in types and functions, so reuse it
256 '-' | ':' => result.push('.'),
258 // These are legal symbols
262 | '_' | '.' | '$' => result.push(c),
266 for c in c.escape_unicode().skip(1) {
269 '}' => result.push('$'),
277 // Underscore-qualify anything that didn't start as an ident.
278 if !result.is_empty() &&
279 result.as_bytes()[0] != '_' as u8 &&
280 ! (result.as_bytes()[0] as char).is_xid_start() {
281 return format!("_{}", &result[..]);
287 pub fn mangle<PI: Iterator<Item=PathElem>>(path: PI,
288 hash: Option<&str>) -> String {
289 // Follow C++ namespace-mangling style, see
290 // http://en.wikipedia.org/wiki/Name_mangling for more info.
292 // It turns out that on OSX you can actually have arbitrary symbols in
293 // function names (at least when given to LLVM), but this is not possible
294 // when using unix's linker. Perhaps one day when we just use a linker from LLVM
295 // we won't need to do this name mangling. The problem with name mangling is
296 // that it seriously limits the available characters. For example we can't
297 // have things like &T in symbol names when one would theoretically
298 // want them for things like impls of traits on that type.
300 // To be able to work on all platforms and get *some* reasonable output, we
301 // use C++ name-mangling.
303 let mut n = String::from("_ZN"); // _Z == Begin name-sequence, N == nested
305 fn push(n: &mut String, s: &str) {
306 let sani = sanitize(s);
307 n.push_str(&format!("{}{}", sani.len(), sani));
310 // First, connect each component with <len, name> pairs.
312 push(&mut n, &e.name().as_str())
316 Some(s) => push(&mut n, s),
320 n.push('E'); // End name-sequence.
324 pub fn exported_name(path: PathElems, hash: &str) -> String {
325 mangle(path, Some(hash))
328 pub fn mangle_exported_name<'a, 'tcx>(ccx: &CrateContext<'a, 'tcx>, path: PathElems,
329 t: Ty<'tcx>, id: ast::NodeId) -> String {
330 let mut hash = get_symbol_hash(ccx, t);
332 // Paths can be completely identical for different nodes,
333 // e.g. `fn foo() { { fn a() {} } { fn a() {} } }`, so we
334 // generate unique characters from the node id. For now
335 // hopefully 3 characters is enough to avoid collisions.
336 const EXTRA_CHARS: &'static str =
337 "abcdefghijklmnopqrstuvwxyz\
338 ABCDEFGHIJKLMNOPQRSTUVWXYZ\
340 let id = id as usize;
341 let extra1 = id % EXTRA_CHARS.len();
342 let id = id / EXTRA_CHARS.len();
343 let extra2 = id % EXTRA_CHARS.len();
344 let id = id / EXTRA_CHARS.len();
345 let extra3 = id % EXTRA_CHARS.len();
346 hash.push(EXTRA_CHARS.as_bytes()[extra1] as char);
347 hash.push(EXTRA_CHARS.as_bytes()[extra2] as char);
348 hash.push(EXTRA_CHARS.as_bytes()[extra3] as char);
350 exported_name(path, &hash[..])
353 pub fn mangle_internal_name_by_type_and_seq<'a, 'tcx>(ccx: &CrateContext<'a, 'tcx>,
355 name: &str) -> String {
356 let path = [PathName(token::intern(&t.to_string())),
358 let hash = get_symbol_hash(ccx, t);
359 mangle(path.iter().cloned(), Some(&hash[..]))
362 pub fn mangle_internal_name_by_path_and_seq(path: PathElems, flav: &str) -> String {
363 mangle(path.chain(Some(gensym_name(flav))), None)
366 pub fn get_linker(sess: &Session) -> (String, Command) {
367 if let Some(ref linker) = sess.opts.cg.linker {
368 (linker.clone(), Command::new(linker))
369 } else if sess.target.target.options.is_like_msvc {
370 ("link.exe".to_string(), msvc::link_exe_cmd(sess))
372 (sess.target.target.options.linker.clone(),
373 Command::new(&sess.target.target.options.linker))
377 pub fn get_ar_prog(sess: &Session) -> String {
378 sess.opts.cg.ar.clone().unwrap_or_else(|| {
379 sess.target.target.options.ar.clone()
383 fn command_path(sess: &Session) -> OsString {
384 // The compiler's sysroot often has some bundled tools, so add it to the
385 // PATH for the child.
386 let mut new_path = sess.host_filesearch(PathKind::All)
387 .get_tools_search_paths();
388 if let Some(path) = env::var_os("PATH") {
389 new_path.extend(env::split_paths(&path));
391 env::join_paths(new_path).unwrap()
394 pub fn remove(sess: &Session, path: &Path) {
395 match fs::remove_file(path) {
398 sess.err(&format!("failed to remove {}: {}",
405 /// Perform the linkage portion of the compilation phase. This will generate all
406 /// of the requested outputs for this compilation session.
407 pub fn link_binary(sess: &Session,
408 trans: &CrateTranslation,
409 outputs: &OutputFilenames,
410 crate_name: &str) -> Vec<PathBuf> {
411 let mut out_filenames = Vec::new();
412 for &crate_type in sess.crate_types.borrow().iter() {
413 if invalid_output_for_target(sess, crate_type) {
414 sess.bug(&format!("invalid output type `{:?}` for target os `{}`",
415 crate_type, sess.opts.target_triple));
417 let out_file = link_binary_output(sess, trans, crate_type, outputs,
419 out_filenames.push(out_file);
422 // Remove the temporary object file and metadata if we aren't saving temps
423 if !sess.opts.cg.save_temps {
424 for obj in object_filenames(sess, outputs) {
427 remove(sess, &outputs.with_extension("metadata.o"));
434 /// Returns default crate type for target
436 /// Default crate type is used when crate type isn't provided neither
437 /// through cmd line arguments nor through crate attributes
439 /// It is CrateTypeExecutable for all platforms but iOS as there is no
440 /// way to run iOS binaries anyway without jailbreaking and
441 /// interaction with Rust code through static library is the only
443 pub fn default_output_for_target(sess: &Session) -> config::CrateType {
444 if !sess.target.target.options.executables {
445 config::CrateTypeStaticlib
447 config::CrateTypeExecutable
451 /// Checks if target supports crate_type as output
452 pub fn invalid_output_for_target(sess: &Session,
453 crate_type: config::CrateType) -> bool {
454 match (sess.target.target.options.dynamic_linking,
455 sess.target.target.options.executables, crate_type) {
456 (false, _, config::CrateTypeDylib) => true,
457 (_, false, config::CrateTypeExecutable) => true,
462 fn is_writeable(p: &Path) -> bool {
465 Ok(m) => !m.permissions().readonly()
469 pub fn filename_for_input(sess: &Session,
470 crate_type: config::CrateType,
472 outputs: &OutputFilenames) -> PathBuf {
473 let libname = format!("{}{}", crate_name, sess.opts.cg.extra_filename);
475 config::CrateTypeRlib => {
476 outputs.out_directory.join(&format!("lib{}.rlib", libname))
478 config::CrateTypeDylib => {
479 let (prefix, suffix) = (&sess.target.target.options.dll_prefix,
480 &sess.target.target.options.dll_suffix);
481 outputs.out_directory.join(&format!("{}{}{}", prefix, libname,
484 config::CrateTypeStaticlib => {
485 outputs.out_directory.join(&format!("lib{}.a", libname))
487 config::CrateTypeExecutable => {
488 let suffix = &sess.target.target.options.exe_suffix;
489 let out_filename = outputs.path(OutputTypeExe);
490 if suffix.is_empty() {
491 out_filename.to_path_buf()
493 out_filename.with_extension(&suffix[1..])
499 pub fn each_linked_rlib(sess: &Session,
500 f: &mut FnMut(ast::CrateNum, &Path)) {
501 let crates = sess.cstore.get_used_crates(cstore::RequireStatic).into_iter();
502 let fmts = sess.dependency_formats.borrow();
503 let fmts = fmts.get(&config::CrateTypeExecutable).or_else(|| {
504 fmts.get(&config::CrateTypeStaticlib)
505 }).unwrap_or_else(|| {
506 sess.bug("could not find formats for rlibs")
508 for (cnum, path) in crates {
509 match fmts[cnum as usize - 1] {
510 Linkage::NotLinked | Linkage::IncludedFromDylib => continue,
513 let name = sess.cstore.get_crate_data(cnum).name.clone();
514 let path = match path {
517 sess.fatal(&format!("could not find rlib for: `{}`", name));
524 fn link_binary_output(sess: &Session,
525 trans: &CrateTranslation,
526 crate_type: config::CrateType,
527 outputs: &OutputFilenames,
528 crate_name: &str) -> PathBuf {
529 let objects = object_filenames(sess, outputs);
530 let out_filename = match outputs.single_output_file {
531 Some(ref file) => file.clone(),
532 None => filename_for_input(sess, crate_type, crate_name, outputs),
535 // Make sure files are writeable. Mac, FreeBSD, and Windows system linkers
536 // check this already -- however, the Linux linker will happily overwrite a
537 // read-only file. We should be consistent.
538 for file in objects.iter().chain(Some(&out_filename)) {
539 if !is_writeable(file) {
540 sess.fatal(&format!("output file {} is not writeable -- check its \
541 permissions", file.display()));
545 let tmpdir = TempDir::new("rustc").ok().expect("needs a temp dir");
547 config::CrateTypeRlib => {
548 link_rlib(sess, Some(trans), &objects, &out_filename,
549 tmpdir.path()).build();
551 config::CrateTypeStaticlib => {
552 link_staticlib(sess, &objects, &out_filename, tmpdir.path());
554 config::CrateTypeExecutable => {
555 link_natively(sess, false, &objects, &out_filename, trans, outputs,
558 config::CrateTypeDylib => {
559 link_natively(sess, true, &objects, &out_filename, trans, outputs,
567 fn object_filenames(sess: &Session, outputs: &OutputFilenames) -> Vec<PathBuf> {
568 (0..sess.opts.cg.codegen_units).map(|i| {
569 let ext = format!("{}.o", i);
570 outputs.temp_path(OutputTypeObject).with_extension(&ext)
574 fn archive_search_paths(sess: &Session) -> Vec<PathBuf> {
575 let mut search = Vec::new();
576 sess.target_filesearch(PathKind::Native).for_each_lib_search_path(|path, _| {
577 search.push(path.to_path_buf());
583 fn archive_config<'a>(sess: &'a Session,
585 input: Option<&Path>) -> ArchiveConfig<'a> {
588 dst: output.to_path_buf(),
589 src: input.map(|p| p.to_path_buf()),
590 lib_search_paths: archive_search_paths(sess),
591 ar_prog: get_ar_prog(sess),
592 command_path: command_path(sess),
598 // An rlib in its current incarnation is essentially a renamed .a file. The
599 // rlib primarily contains the object file of the crate, but it also contains
600 // all of the object files from native libraries. This is done by unzipping
601 // native libraries and inserting all of the contents into this archive.
602 fn link_rlib<'a>(sess: &'a Session,
603 trans: Option<&CrateTranslation>, // None == no metadata/bytecode
606 tmpdir: &Path) -> ArchiveBuilder<'a> {
607 info!("preparing rlib from {:?} to {:?}", objects, out_filename);
608 let mut ab = ArchiveBuilder::new(archive_config(sess, out_filename, None));
613 for &(ref l, kind) in sess.cstore.get_used_libraries().borrow().iter() {
615 cstore::NativeStatic => ab.add_native_library(&l).unwrap(),
616 cstore::NativeFramework | cstore::NativeUnknown => {}
620 // After adding all files to the archive, we need to update the
621 // symbol table of the archive.
624 // For OSX/iOS, we must be careful to update symbols only when adding
625 // object files. We're about to start adding non-object files, so run
626 // `ar` now to process the object files.
627 if sess.target.target.options.is_like_osx && !ab.using_llvm() {
631 // Note that it is important that we add all of our non-object "magical
632 // files" *after* all of the object files in the archive. The reason for
633 // this is as follows:
635 // * When performing LTO, this archive will be modified to remove
636 // objects from above. The reason for this is described below.
638 // * When the system linker looks at an archive, it will attempt to
639 // determine the architecture of the archive in order to see whether its
642 // The algorithm for this detection is: iterate over the files in the
643 // archive. Skip magical SYMDEF names. Interpret the first file as an
644 // object file. Read architecture from the object file.
646 // * As one can probably see, if "metadata" and "foo.bc" were placed
647 // before all of the objects, then the architecture of this archive would
648 // not be correctly inferred once 'foo.o' is removed.
650 // Basically, all this means is that this code should not move above the
654 // Instead of putting the metadata in an object file section, rlibs
655 // contain the metadata in a separate file. We use a temp directory
656 // here so concurrent builds in the same directory don't try to use
657 // the same filename for metadata (stomping over one another)
658 let metadata = tmpdir.join(METADATA_FILENAME);
659 match fs::File::create(&metadata).and_then(|mut f| {
660 f.write_all(&trans.metadata)
664 sess.fatal(&format!("failed to write {}: {}",
665 metadata.display(), e));
668 ab.add_file(&metadata);
670 // For LTO purposes, the bytecode of this library is also inserted
671 // into the archive. If codegen_units > 1, we insert each of the
674 // Note that we make sure that the bytecode filename in the
675 // archive is never exactly 16 bytes long by adding a 16 byte
676 // extension to it. This is to work around a bug in LLDB that
677 // would cause it to crash if the name of a file in an archive
678 // was exactly 16 bytes.
679 let bc_filename = obj.with_extension("bc");
680 let bc_deflated_filename = tmpdir.join({
681 obj.with_extension("bytecode.deflate").file_name().unwrap()
684 let mut bc_data = Vec::new();
685 match fs::File::open(&bc_filename).and_then(|mut f| {
686 f.read_to_end(&mut bc_data)
689 Err(e) => sess.fatal(&format!("failed to read bytecode: {}",
693 let bc_data_deflated = flate::deflate_bytes(&bc_data[..]);
695 let mut bc_file_deflated = match fs::File::create(&bc_deflated_filename) {
698 sess.fatal(&format!("failed to create compressed \
699 bytecode file: {}", e))
703 match write_rlib_bytecode_object_v1(&mut bc_file_deflated,
707 sess.fatal(&format!("failed to write compressed \
712 ab.add_file(&bc_deflated_filename);
714 // See the bottom of back::write::run_passes for an explanation
715 // of when we do and don't keep .0.bc files around.
716 let user_wants_numbered_bitcode =
717 sess.opts.output_types.contains(&OutputTypeBitcode) &&
718 sess.opts.cg.codegen_units > 1;
719 if !sess.opts.cg.save_temps && !user_wants_numbered_bitcode {
720 remove(sess, &bc_filename);
724 // After adding all files to the archive, we need to update the
725 // symbol table of the archive. This currently dies on OSX (see
726 // #11162), and isn't necessary there anyway
727 if !sess.target.target.options.is_like_osx || ab.using_llvm() {
738 fn write_rlib_bytecode_object_v1(writer: &mut Write,
739 bc_data_deflated: &[u8]) -> io::Result<()> {
740 let bc_data_deflated_size: u64 = bc_data_deflated.len() as u64;
742 try!(writer.write_all(RLIB_BYTECODE_OBJECT_MAGIC));
743 try!(writer.write_all(&[1, 0, 0, 0]));
744 try!(writer.write_all(&[
745 (bc_data_deflated_size >> 0) as u8,
746 (bc_data_deflated_size >> 8) as u8,
747 (bc_data_deflated_size >> 16) as u8,
748 (bc_data_deflated_size >> 24) as u8,
749 (bc_data_deflated_size >> 32) as u8,
750 (bc_data_deflated_size >> 40) as u8,
751 (bc_data_deflated_size >> 48) as u8,
752 (bc_data_deflated_size >> 56) as u8,
754 try!(writer.write_all(&bc_data_deflated));
756 let number_of_bytes_written_so_far =
757 RLIB_BYTECODE_OBJECT_MAGIC.len() + // magic id
758 mem::size_of_val(&RLIB_BYTECODE_OBJECT_VERSION) + // version
759 mem::size_of_val(&bc_data_deflated_size) + // data size field
760 bc_data_deflated_size as usize; // actual data
762 // If the number of bytes written to the object so far is odd, add a
763 // padding byte to make it even. This works around a crash bug in LLDB
764 // (see issue #15950)
765 if number_of_bytes_written_so_far % 2 == 1 {
766 try!(writer.write_all(&[0]));
772 // Create a static archive
774 // This is essentially the same thing as an rlib, but it also involves adding
775 // all of the upstream crates' objects into the archive. This will slurp in
776 // all of the native libraries of upstream dependencies as well.
778 // Additionally, there's no way for us to link dynamic libraries, so we warn
779 // about all dynamic library dependencies that they're not linked in.
781 // There's no need to include metadata in a static archive, so ensure to not
782 // link in the metadata object file (and also don't prepare the archive with a
784 fn link_staticlib(sess: &Session, objects: &[PathBuf], out_filename: &Path,
786 let mut ab = link_rlib(sess, None, objects, out_filename, tempdir);
787 if sess.target.target.options.is_like_osx && !ab.using_llvm() {
790 if !sess.target.target.options.no_compiler_rt {
791 ab.add_native_library("compiler-rt").unwrap();
794 let mut all_native_libs = vec![];
796 each_linked_rlib(sess, &mut |cnum, path| {
797 let name = sess.cstore.get_crate_data(cnum).name();
798 ab.add_rlib(path, &name, sess.lto()).unwrap();
800 let native_libs = csearch::get_native_libraries(&sess.cstore, cnum);
801 all_native_libs.extend(native_libs);
807 if !all_native_libs.is_empty() {
808 sess.note("link against the following native artifacts when linking against \
809 this static library");
810 sess.note("the order and any duplication can be significant on some platforms, \
811 and so may need to be preserved");
814 for &(kind, ref lib) in &all_native_libs {
815 let name = match kind {
816 cstore::NativeStatic => "static library",
817 cstore::NativeUnknown => "library",
818 cstore::NativeFramework => "framework",
820 sess.note(&format!("{}: {}", name, *lib));
824 // Create a dynamic library or executable
826 // This will invoke the system linker/cc to create the resulting file. This
827 // links to all upstream files as well.
828 fn link_natively(sess: &Session, dylib: bool,
829 objects: &[PathBuf], out_filename: &Path,
830 trans: &CrateTranslation,
831 outputs: &OutputFilenames,
833 info!("preparing dylib? ({}) from {:?} to {:?}", dylib, objects,
836 // The invocations of cc share some flags across platforms
837 let (pname, mut cmd) = get_linker(sess);
838 cmd.env("PATH", command_path(sess));
840 let root = sess.target_filesearch(PathKind::Native).get_lib_path();
841 cmd.args(&sess.target.target.options.pre_link_args);
842 for obj in &sess.target.target.options.pre_link_objects {
843 cmd.arg(root.join(obj));
847 let mut linker = if sess.target.target.options.is_like_msvc {
848 Box::new(MsvcLinker { cmd: &mut cmd, sess: &sess }) as Box<Linker>
850 Box::new(GnuLinker { cmd: &mut cmd, sess: &sess }) as Box<Linker>
852 link_args(&mut *linker, sess, dylib, tmpdir,
853 objects, out_filename, trans, outputs);
854 if !sess.target.target.options.no_compiler_rt {
855 linker.link_staticlib("compiler-rt");
858 for obj in &sess.target.target.options.post_link_objects {
859 cmd.arg(root.join(obj));
861 cmd.args(&sess.target.target.options.post_link_args);
863 if sess.opts.debugging_opts.print_link_args {
864 println!("{:?}", &cmd);
867 // May have not found libraries in the right formats.
868 sess.abort_if_errors();
870 // Invoke the system linker
872 let prog = time(sess.time_passes(), "running linker", || cmd.output());
875 if !prog.status.success() {
876 sess.err(&format!("linking with `{}` failed: {}",
879 sess.note(&format!("{:?}", &cmd));
880 let mut output = prog.stderr.clone();
881 output.push_all(&prog.stdout);
882 sess.note(str::from_utf8(&output[..]).unwrap());
883 sess.abort_if_errors();
885 info!("linker stderr:\n{}", String::from_utf8(prog.stderr).unwrap());
886 info!("linker stdout:\n{}", String::from_utf8(prog.stdout).unwrap());
889 sess.fatal(&format!("could not exec the linker `{}`: {}", pname, e));
894 // On OSX, debuggers need this utility to get run to do some munging of
896 if sess.target.target.options.is_like_osx && sess.opts.debuginfo != NoDebugInfo {
897 match Command::new("dsymutil").arg(out_filename).output() {
899 Err(e) => sess.fatal(&format!("failed to run dsymutil: {}", e)),
904 fn link_args(cmd: &mut Linker,
910 trans: &CrateTranslation,
911 outputs: &OutputFilenames) {
913 // The default library location, we need this to find the runtime.
914 // The location of crates will be determined as needed.
915 let lib_path = sess.target_filesearch(PathKind::All).get_lib_path();
918 let t = &sess.target.target;
920 cmd.include_path(&fix_windows_verbatim_for_gcc(&lib_path));
924 cmd.output_filename(out_filename);
926 // If we're building a dynamic library then some platforms need to make sure
927 // that all symbols are exported correctly from the dynamic library.
929 cmd.export_symbols(sess, trans, tmpdir);
932 // When linking a dynamic library, we put the metadata into a section of the
933 // executable. This metadata is in a separate object file from the main
934 // object file, so we link that in here.
936 cmd.add_object(&outputs.with_extension("metadata.o"));
939 // Try to strip as much out of the generated object by removing unused
940 // sections if possible. See more comments in linker.rs
941 cmd.gc_sections(dylib);
943 let used_link_args = sess.cstore.get_used_link_args().borrow();
945 if !dylib && t.options.position_independent_executables {
946 let empty_vec = Vec::new();
947 let empty_str = String::new();
948 let args = sess.opts.cg.link_args.as_ref().unwrap_or(&empty_vec);
949 let mut args = args.iter().chain(used_link_args.iter());
950 let relocation_model = sess.opts.cg.relocation_model.as_ref()
951 .unwrap_or(&empty_str);
952 if (t.options.relocation_model == "pic" || *relocation_model == "pic")
953 && !args.any(|x| *x == "-static") {
954 cmd.position_independent_executable();
958 // Pass optimization flags down to the linker.
961 // Pass debuginfo flags down to the linker.
964 // We want to prevent the compiler from accidentally leaking in any system
965 // libraries, so we explicitly ask gcc to not link to any libraries by
966 // default. Note that this does not happen for windows because windows pulls
967 // in some large number of libraries and I couldn't quite figure out which
969 cmd.no_default_libraries();
971 // Take careful note of the ordering of the arguments we pass to the linker
972 // here. Linkers will assume that things on the left depend on things to the
973 // right. Things on the right cannot depend on things on the left. This is
974 // all formally implemented in terms of resolving symbols (libs on the right
975 // resolve unknown symbols of libs on the left, but not vice versa).
977 // For this reason, we have organized the arguments we pass to the linker as
980 // 1. The local object that LLVM just generated
981 // 2. Upstream rust libraries
982 // 3. Local native libraries
983 // 4. Upstream native libraries
985 // This is generally fairly natural, but some may expect 2 and 3 to be
986 // swapped. The reason that all native libraries are put last is that it's
987 // not recommended for a native library to depend on a symbol from a rust
988 // crate. If this is the case then a staticlib crate is recommended, solving
991 // Additionally, it is occasionally the case that upstream rust libraries
992 // depend on a local native library. In the case of libraries such as
993 // lua/glfw/etc the name of the library isn't the same across all platforms,
994 // so only the consumer crate of a library knows the actual name. This means
995 // that downstream crates will provide the #[link] attribute which upstream
996 // crates will depend on. Hence local native libraries are after out
997 // upstream rust crates.
999 // In theory this means that a symbol in an upstream native library will be
1000 // shadowed by a local native library when it wouldn't have been before, but
1001 // this kind of behavior is pretty platform specific and generally not
1002 // recommended anyway, so I don't think we're shooting ourself in the foot
1004 add_upstream_rust_crates(cmd, sess, dylib, tmpdir);
1005 add_local_native_libraries(cmd, sess);
1006 add_upstream_native_libraries(cmd, sess);
1008 // # Telling the linker what we're doing
1011 cmd.build_dylib(out_filename);
1014 // FIXME (#2397): At some point we want to rpath our guesses as to
1015 // where extern libraries might live, based on the
1016 // addl_lib_search_paths
1017 if sess.opts.cg.rpath {
1018 let sysroot = sess.sysroot();
1019 let target_triple = &sess.opts.target_triple;
1020 let mut get_install_prefix_lib_path = || {
1021 let install_prefix = option_env!("CFG_PREFIX").expect("CFG_PREFIX");
1022 let tlib = filesearch::relative_target_lib_path(sysroot, target_triple);
1023 let mut path = PathBuf::from(install_prefix);
1028 let mut rpath_config = RPathConfig {
1029 used_crates: sess.cstore.get_used_crates(cstore::RequireDynamic),
1030 out_filename: out_filename.to_path_buf(),
1031 has_rpath: sess.target.target.options.has_rpath,
1032 is_like_osx: sess.target.target.options.is_like_osx,
1033 get_install_prefix_lib_path: &mut get_install_prefix_lib_path,
1035 cmd.args(&rpath::get_rpath_flags(&mut rpath_config));
1038 // Finally add all the linker arguments provided on the command line along
1039 // with any #[link_args] attributes found inside the crate
1040 if let Some(ref args) = sess.opts.cg.link_args {
1043 cmd.args(&used_link_args);
1046 // # Native library linking
1048 // User-supplied library search paths (-L on the command line). These are
1049 // the same paths used to find Rust crates, so some of them may have been
1050 // added already by the previous crate linking code. This only allows them
1051 // to be found at compile time so it is still entirely up to outside
1052 // forces to make sure that library can be found at runtime.
1054 // Also note that the native libraries linked here are only the ones located
1055 // in the current crate. Upstream crates with native library dependencies
1056 // may have their native library pulled in above.
1057 fn add_local_native_libraries(cmd: &mut Linker, sess: &Session) {
1058 sess.target_filesearch(PathKind::All).for_each_lib_search_path(|path, k| {
1060 PathKind::Framework => { cmd.framework_path(path); }
1061 _ => { cmd.include_path(&fix_windows_verbatim_for_gcc(path)); }
1066 let libs = sess.cstore.get_used_libraries();
1067 let libs = libs.borrow();
1069 let staticlibs = libs.iter().filter_map(|&(ref l, kind)| {
1070 if kind == cstore::NativeStatic {Some(l)} else {None}
1072 let others = libs.iter().filter(|&&(_, kind)| {
1073 kind != cstore::NativeStatic
1076 // Some platforms take hints about whether a library is static or dynamic.
1077 // For those that support this, we ensure we pass the option if the library
1078 // was flagged "static" (most defaults are dynamic) to ensure that if
1079 // libfoo.a and libfoo.so both exist that the right one is chosen.
1082 let search_path = archive_search_paths(sess);
1083 for l in staticlibs {
1084 // Here we explicitly ask that the entire archive is included into the
1085 // result artifact. For more details see #15460, but the gist is that
1086 // the linker will strip away any unused objects in the archive if we
1087 // don't otherwise explicitly reference them. This can occur for
1088 // libraries which are just providing bindings, libraries with generic
1090 cmd.link_whole_staticlib(l, &search_path);
1095 for &(ref l, kind) in others {
1097 cstore::NativeUnknown => cmd.link_dylib(l),
1098 cstore::NativeFramework => cmd.link_framework(l),
1099 cstore::NativeStatic => unreachable!(),
1104 // # Rust Crate linking
1106 // Rust crates are not considered at all when creating an rlib output. All
1107 // dependencies will be linked when producing the final output (instead of
1108 // the intermediate rlib version)
1109 fn add_upstream_rust_crates(cmd: &mut Linker, sess: &Session,
1110 dylib: bool, tmpdir: &Path) {
1111 // All of the heavy lifting has previously been accomplished by the
1112 // dependency_format module of the compiler. This is just crawling the
1113 // output of that module, adding crates as necessary.
1115 // Linking to a rlib involves just passing it to the linker (the linker
1116 // will slurp up the object files inside), and linking to a dynamic library
1117 // involves just passing the right -l flag.
1119 let formats = sess.dependency_formats.borrow();
1120 let data = if dylib {
1121 formats.get(&config::CrateTypeDylib).unwrap()
1123 formats.get(&config::CrateTypeExecutable).unwrap()
1126 // Invoke get_used_crates to ensure that we get a topological sorting of
1128 let deps = sess.cstore.get_used_crates(cstore::RequireDynamic);
1130 for &(cnum, _) in &deps {
1131 // We may not pass all crates through to the linker. Some crates may
1132 // appear statically in an existing dylib, meaning we'll pick up all the
1133 // symbols from the dylib.
1134 let src = sess.cstore.get_used_crate_source(cnum).unwrap();
1135 match data[cnum as usize - 1] {
1136 Linkage::NotLinked |
1137 Linkage::IncludedFromDylib => {}
1138 Linkage::Static => {
1139 add_static_crate(cmd, sess, tmpdir, dylib, &src.rlib.unwrap().0)
1141 Linkage::Dynamic => {
1142 add_dynamic_crate(cmd, sess, &src.dylib.unwrap().0)
1147 // Converts a library file-stem into a cc -l argument
1148 fn unlib<'a>(config: &config::Config, stem: &'a str) -> &'a str {
1149 if stem.starts_with("lib") && !config.target.options.is_like_windows {
1156 // Adds the static "rlib" versions of all crates to the command line.
1157 // There's a bit of magic which happens here specifically related to LTO and
1158 // dynamic libraries. Specifically:
1160 // * For LTO, we remove upstream object files.
1161 // * For dylibs we remove metadata and bytecode from upstream rlibs
1163 // When performing LTO, all of the bytecode from the upstream libraries has
1164 // already been included in our object file output. As a result we need to
1165 // remove the object files in the upstream libraries so the linker doesn't
1166 // try to include them twice (or whine about duplicate symbols). We must
1167 // continue to include the rest of the rlib, however, as it may contain
1168 // static native libraries which must be linked in.
1170 // When making a dynamic library, linkers by default don't include any
1171 // object files in an archive if they're not necessary to resolve the link.
1172 // We basically want to convert the archive (rlib) to a dylib, though, so we
1173 // *do* want everything included in the output, regardless of whether the
1174 // linker thinks it's needed or not. As a result we must use the
1175 // --whole-archive option (or the platform equivalent). When using this
1176 // option the linker will fail if there are non-objects in the archive (such
1177 // as our own metadata and/or bytecode). All in all, for rlibs to be
1178 // entirely included in dylibs, we need to remove all non-object files.
1180 // Note, however, that if we're not doing LTO or we're not producing a dylib
1181 // (aka we're making an executable), we can just pass the rlib blindly to
1182 // the linker (fast) because it's fine if it's not actually included as
1183 // we're at the end of the dependency chain.
1184 fn add_static_crate(cmd: &mut Linker, sess: &Session, tmpdir: &Path,
1185 dylib: bool, cratepath: &Path) {
1186 if !sess.lto() && !dylib {
1187 cmd.link_rlib(&fix_windows_verbatim_for_gcc(cratepath));
1191 let dst = tmpdir.join(cratepath.file_name().unwrap());
1192 let name = cratepath.file_name().unwrap().to_str().unwrap();
1193 let name = &name[3..name.len() - 5]; // chop off lib/.rlib
1195 time(sess.time_passes(), &format!("altering {}.rlib", name), || {
1196 let cfg = archive_config(sess, &dst, Some(cratepath));
1197 let mut archive = ArchiveBuilder::new(cfg);
1198 archive.remove_file(METADATA_FILENAME);
1199 archive.update_symbols();
1201 let mut any_objects = false;
1202 for f in archive.src_files() {
1203 if f.ends_with("bytecode.deflate") {
1204 archive.remove_file(&f);
1207 let canonical = f.replace("-", "_");
1208 let canonical_name = name.replace("-", "_");
1209 if sess.lto() && canonical.starts_with(&canonical_name) &&
1210 canonical.ends_with(".o") {
1211 let num = &f[name.len()..f.len() - 2];
1212 if num.len() > 0 && num[1..].parse::<u32>().is_ok() {
1213 archive.remove_file(&f);
1222 cmd.link_whole_rlib(&fix_windows_verbatim_for_gcc(&dst));
1227 // Same thing as above, but for dynamic crates instead of static crates.
1228 fn add_dynamic_crate(cmd: &mut Linker, sess: &Session, cratepath: &Path) {
1229 // If we're performing LTO, then it should have been previously required
1230 // that all upstream rust dependencies were available in an rlib format.
1231 assert!(!sess.lto());
1233 // Just need to tell the linker about where the library lives and
1235 let parent = cratepath.parent();
1236 if let Some(dir) = parent {
1237 cmd.include_path(&fix_windows_verbatim_for_gcc(dir));
1239 let filestem = cratepath.file_stem().unwrap().to_str().unwrap();
1240 cmd.link_rust_dylib(&unlib(&sess.target, filestem),
1241 parent.unwrap_or(Path::new("")));
1245 // Link in all of our upstream crates' native dependencies. Remember that
1246 // all of these upstream native dependencies are all non-static
1247 // dependencies. We've got two cases then:
1249 // 1. The upstream crate is an rlib. In this case we *must* link in the
1250 // native dependency because the rlib is just an archive.
1252 // 2. The upstream crate is a dylib. In order to use the dylib, we have to
1253 // have the dependency present on the system somewhere. Thus, we don't
1254 // gain a whole lot from not linking in the dynamic dependency to this
1257 // The use case for this is a little subtle. In theory the native
1258 // dependencies of a crate are purely an implementation detail of the crate
1259 // itself, but the problem arises with generic and inlined functions. If a
1260 // generic function calls a native function, then the generic function must
1261 // be instantiated in the target crate, meaning that the native symbol must
1262 // also be resolved in the target crate.
1263 fn add_upstream_native_libraries(cmd: &mut Linker, sess: &Session) {
1264 // Be sure to use a topological sorting of crates because there may be
1265 // interdependencies between native libraries. When passing -nodefaultlibs,
1266 // for example, almost all native libraries depend on libc, so we have to
1267 // make sure that's all the way at the right (liblibc is near the base of
1268 // the dependency chain).
1270 // This passes RequireStatic, but the actual requirement doesn't matter,
1271 // we're just getting an ordering of crate numbers, we're not worried about
1273 let crates = sess.cstore.get_used_crates(cstore::RequireStatic);
1274 for (cnum, _) in crates {
1275 let libs = csearch::get_native_libraries(&sess.cstore, cnum);
1276 for &(kind, ref lib) in &libs {
1278 cstore::NativeUnknown => cmd.link_dylib(lib),
1279 cstore::NativeFramework => cmd.link_framework(lib),
1280 cstore::NativeStatic => {
1281 sess.bug("statics shouldn't be propagated");