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::{Archive, ArchiveBuilder, ArchiveConfig, METADATA_FILENAME};
14 use super::rpath::RPathConfig;
17 use session::config::NoDebugInfo;
18 use session::config::{OutputFilenames, Input, OutputTypeBitcode, OutputTypeExe, OutputTypeObject};
19 use session::search_paths::PathKind;
21 use metadata::common::LinkMeta;
22 use metadata::{encoder, cstore, filesearch, csearch, creader};
23 use metadata::filesearch::FileDoesntMatch;
24 use trans::{CrateContext, CrateTranslation, gensym_name};
25 use middle::ty::{self, Ty};
26 use util::common::time;
28 use util::sha2::{Digest, Sha256};
29 use rustc_back::tempdir::TempDir;
31 use std::ffi::OsString;
32 use std::fs::{self, PathExt};
33 use std::io::{self, Read, Write};
35 use std::path::{self, Path, PathBuf};
36 use std::process::Command;
39 use serialize::hex::ToHex;
41 use syntax::ast_map::{PathElem, PathElems, PathName};
42 use syntax::attr::AttrMetaMethods;
43 use syntax::codemap::Span;
44 use syntax::parse::token;
46 // RLIB LLVM-BYTECODE OBJECT LAYOUT
49 // 0..10 "RUST_OBJECT" encoded in ASCII
50 // 11..14 format version as little-endian u32
51 // 15..22 size in bytes of deflate compressed LLVM bitcode as
53 // 23.. compressed LLVM bitcode
55 // This is the "magic number" expected at the beginning of a LLVM bytecode
57 pub const RLIB_BYTECODE_OBJECT_MAGIC: &'static [u8] = b"RUST_OBJECT";
59 // The version number this compiler will write to bytecode objects in rlibs
60 pub const RLIB_BYTECODE_OBJECT_VERSION: u32 = 1;
62 // The offset in bytes the bytecode object format version number can be found at
63 pub const RLIB_BYTECODE_OBJECT_VERSION_OFFSET: usize = 11;
65 // The offset in bytes the size of the compressed bytecode can be found at in
67 pub const RLIB_BYTECODE_OBJECT_V1_DATASIZE_OFFSET: usize =
68 RLIB_BYTECODE_OBJECT_VERSION_OFFSET + 4;
70 // The offset in bytes the compressed LLVM bytecode can be found at in format
72 pub const RLIB_BYTECODE_OBJECT_V1_DATA_OFFSET: usize =
73 RLIB_BYTECODE_OBJECT_V1_DATASIZE_OFFSET + 8;
77 * Name mangling and its relationship to metadata. This is complex. Read
80 * The semantic model of Rust linkage is, broadly, that "there's no global
81 * namespace" between crates. Our aim is to preserve the illusion of this
82 * model despite the fact that it's not *quite* possible to implement on
83 * modern linkers. We initially didn't use system linkers at all, but have
84 * been convinced of their utility.
86 * There are a few issues to handle:
88 * - Linkers operate on a flat namespace, so we have to flatten names.
89 * We do this using the C++ namespace-mangling technique. Foo::bar
92 * - Symbols with the same name but different types need to get different
93 * linkage-names. We do this by hashing a string-encoding of the type into
94 * a fixed-size (currently 16-byte hex) cryptographic hash function (CHF:
95 * we use SHA256) to "prevent collisions". This is not airtight but 16 hex
96 * digits on uniform probability means you're going to need 2**32 same-name
97 * symbols in the same process before you're even hitting birthday-paradox
98 * collision probability.
100 * - Symbols in different crates but with same names "within" the crate need
101 * to get different linkage-names.
103 * - The hash shown in the filename needs to be predictable and stable for
104 * build tooling integration. It also needs to be using a hash function
105 * which is easy to use from Python, make, etc.
107 * So here is what we do:
109 * - Consider the package id; every crate has one (specified with crate_id
110 * attribute). If a package id isn't provided explicitly, we infer a
111 * versionless one from the output name. The version will end up being 0.0
112 * in this case. CNAME and CVERS are taken from this package id. For
113 * example, github.com/mozilla/CNAME#CVERS.
115 * - Define CMH as SHA256(crateid).
117 * - Define CMH8 as the first 8 characters of CMH.
119 * - Compile our crate to lib CNAME-CMH8-CVERS.so
121 * - Define STH(sym) as SHA256(CMH, type_str(sym))
123 * - Suffix a mangled sym with ::STH@CVERS, so that it is unique in the
124 * name, non-name metadata, and type sense, and versioned in the way
125 * system linkers understand.
128 pub fn find_crate_name(sess: Option<&Session>,
129 attrs: &[ast::Attribute],
130 input: &Input) -> String {
131 let validate = |s: String, span: Option<Span>| {
132 creader::validate_crate_name(sess, &s[..], span);
136 // Look in attributes 100% of the time to make sure the attribute is marked
137 // as used. After doing this, however, we still prioritize a crate name from
138 // the command line over one found in the #[crate_name] attribute. If we
139 // find both we ensure that they're the same later on as well.
140 let attr_crate_name = attrs.iter().find(|at| at.check_name("crate_name"))
141 .and_then(|at| at.value_str().map(|s| (at, s)));
143 if let Some(sess) = sess {
144 if let Some(ref s) = sess.opts.crate_name {
145 if let Some((attr, ref name)) = attr_crate_name {
147 let msg = format!("--crate-name and #[crate_name] are \
148 required to match, but `{}` != `{}`",
150 sess.span_err(attr.span, &msg[..]);
153 return validate(s.clone(), None);
157 if let Some((attr, s)) = attr_crate_name {
158 return validate(s.to_string(), Some(attr.span));
160 if let Input::File(ref path) = *input {
161 if let Some(s) = path.file_stem().and_then(|s| s.to_str()) {
162 if s.starts_with("-") {
163 let msg = format!("crate names cannot start with a `-`, but \
164 `{}` has a leading hyphen", s);
165 if let Some(sess) = sess {
169 return validate(s.replace("-", "_"), None);
174 "rust_out".to_string()
177 pub fn build_link_meta(sess: &Session, krate: &ast::Crate,
178 name: String) -> LinkMeta {
181 crate_hash: Svh::calculate(&sess.opts.cg.metadata, krate),
187 fn truncated_hash_result(symbol_hasher: &mut Sha256) -> String {
188 let output = symbol_hasher.result_bytes();
189 // 64 bits should be enough to avoid collisions.
190 output[.. 8].to_hex().to_string()
194 // This calculates STH for a symbol, as defined above
195 fn symbol_hash<'tcx>(tcx: &ty::ctxt<'tcx>,
196 symbol_hasher: &mut Sha256,
198 link_meta: &LinkMeta)
200 // NB: do *not* use abbrevs here as we want the symbol names
201 // to be independent of one another in the crate.
203 symbol_hasher.reset();
204 symbol_hasher.input_str(&link_meta.crate_name);
205 symbol_hasher.input_str("-");
206 symbol_hasher.input_str(link_meta.crate_hash.as_str());
207 for meta in &*tcx.sess.crate_metadata.borrow() {
208 symbol_hasher.input_str(&meta[..]);
210 symbol_hasher.input_str("-");
211 symbol_hasher.input_str(&encoder::encoded_ty(tcx, t));
212 // Prefix with 'h' so that it never blends into adjacent digits
213 let mut hash = String::from_str("h");
214 hash.push_str(&truncated_hash_result(symbol_hasher));
218 fn get_symbol_hash<'a, 'tcx>(ccx: &CrateContext<'a, 'tcx>, t: Ty<'tcx>) -> String {
219 match ccx.type_hashcodes().borrow().get(&t) {
220 Some(h) => return h.to_string(),
224 let mut symbol_hasher = ccx.symbol_hasher().borrow_mut();
225 let hash = symbol_hash(ccx.tcx(), &mut *symbol_hasher, t, ccx.link_meta());
226 ccx.type_hashcodes().borrow_mut().insert(t, hash.clone());
231 // Name sanitation. LLVM will happily accept identifiers with weird names, but
233 // gas accepts the following characters in symbols: a-z, A-Z, 0-9, ., _, $
234 pub fn sanitize(s: &str) -> String {
235 let mut result = String::new();
238 // Escape these with $ sequences
239 '@' => result.push_str("$SP$"),
240 '*' => result.push_str("$BP$"),
241 '&' => result.push_str("$RF$"),
242 '<' => result.push_str("$LT$"),
243 '>' => result.push_str("$GT$"),
244 '(' => result.push_str("$LP$"),
245 ')' => result.push_str("$RP$"),
246 ',' => result.push_str("$C$"),
248 // '.' doesn't occur in types and functions, so reuse it
250 '-' | ':' => result.push('.'),
252 // These are legal symbols
256 | '_' | '.' | '$' => result.push(c),
260 for c in c.escape_unicode().skip(1) {
263 '}' => result.push('$'),
271 // Underscore-qualify anything that didn't start as an ident.
272 if !result.is_empty() &&
273 result.as_bytes()[0] != '_' as u8 &&
274 ! (result.as_bytes()[0] as char).is_xid_start() {
275 return format!("_{}", &result[..]);
281 pub fn mangle<PI: Iterator<Item=PathElem>>(path: PI,
282 hash: Option<&str>) -> String {
283 // Follow C++ namespace-mangling style, see
284 // http://en.wikipedia.org/wiki/Name_mangling for more info.
286 // It turns out that on OSX you can actually have arbitrary symbols in
287 // function names (at least when given to LLVM), but this is not possible
288 // when using unix's linker. Perhaps one day when we just use a linker from LLVM
289 // we won't need to do this name mangling. The problem with name mangling is
290 // that it seriously limits the available characters. For example we can't
291 // have things like &T or ~[T] in symbol names when one would theoretically
292 // want them for things like impls of traits on that type.
294 // To be able to work on all platforms and get *some* reasonable output, we
295 // use C++ name-mangling.
297 let mut n = String::from_str("_ZN"); // _Z == Begin name-sequence, N == nested
299 fn push(n: &mut String, s: &str) {
300 let sani = sanitize(s);
301 n.push_str(&format!("{}{}", sani.len(), sani));
304 // First, connect each component with <len, name> pairs.
306 push(&mut n, &token::get_name(e.name()))
310 Some(s) => push(&mut n, s),
314 n.push('E'); // End name-sequence.
318 pub fn exported_name(path: PathElems, hash: &str) -> String {
319 mangle(path, Some(hash))
322 pub fn mangle_exported_name<'a, 'tcx>(ccx: &CrateContext<'a, 'tcx>, path: PathElems,
323 t: Ty<'tcx>, id: ast::NodeId) -> String {
324 let mut hash = get_symbol_hash(ccx, t);
326 // Paths can be completely identical for different nodes,
327 // e.g. `fn foo() { { fn a() {} } { fn a() {} } }`, so we
328 // generate unique characters from the node id. For now
329 // hopefully 3 characters is enough to avoid collisions.
330 const EXTRA_CHARS: &'static str =
331 "abcdefghijklmnopqrstuvwxyz\
332 ABCDEFGHIJKLMNOPQRSTUVWXYZ\
334 let id = id as usize;
335 let extra1 = id % EXTRA_CHARS.len();
336 let id = id / EXTRA_CHARS.len();
337 let extra2 = id % EXTRA_CHARS.len();
338 let id = id / EXTRA_CHARS.len();
339 let extra3 = id % EXTRA_CHARS.len();
340 hash.push(EXTRA_CHARS.as_bytes()[extra1] as char);
341 hash.push(EXTRA_CHARS.as_bytes()[extra2] as char);
342 hash.push(EXTRA_CHARS.as_bytes()[extra3] as char);
344 exported_name(path, &hash[..])
347 pub fn mangle_internal_name_by_type_and_seq<'a, 'tcx>(ccx: &CrateContext<'a, 'tcx>,
349 name: &str) -> String {
350 let s = ppaux::ty_to_string(ccx.tcx(), t);
351 let path = [PathName(token::intern(&s[..])),
353 let hash = get_symbol_hash(ccx, t);
354 mangle(path.iter().cloned(), Some(&hash[..]))
357 pub fn mangle_internal_name_by_path_and_seq(path: PathElems, flav: &str) -> String {
358 mangle(path.chain(Some(gensym_name(flav)).into_iter()), None)
361 pub fn get_cc_prog(sess: &Session) -> String {
362 match sess.opts.cg.linker {
363 Some(ref linker) => return linker.to_string(),
364 None => sess.target.target.options.linker.clone(),
368 pub fn remove(sess: &Session, path: &Path) {
369 match fs::remove_file(path) {
372 sess.err(&format!("failed to remove {}: {}",
379 /// Perform the linkage portion of the compilation phase. This will generate all
380 /// of the requested outputs for this compilation session.
381 pub fn link_binary(sess: &Session,
382 trans: &CrateTranslation,
383 outputs: &OutputFilenames,
384 crate_name: &str) -> Vec<PathBuf> {
385 let mut out_filenames = Vec::new();
386 for &crate_type in &*sess.crate_types.borrow() {
387 if invalid_output_for_target(sess, crate_type) {
388 sess.bug(&format!("invalid output type `{:?}` for target os `{}`",
389 crate_type, sess.opts.target_triple));
391 let out_file = link_binary_output(sess, trans, crate_type, outputs,
393 out_filenames.push(out_file);
396 // Remove the temporary object file and metadata if we aren't saving temps
397 if !sess.opts.cg.save_temps {
398 let obj_filename = outputs.temp_path(OutputTypeObject);
399 if !sess.opts.output_types.contains(&OutputTypeObject) {
400 remove(sess, &obj_filename);
402 remove(sess, &obj_filename.with_extension("metadata.o"));
409 /// Returns default crate type for target
411 /// Default crate type is used when crate type isn't provided neither
412 /// through cmd line arguments nor through crate attributes
414 /// It is CrateTypeExecutable for all platforms but iOS as there is no
415 /// way to run iOS binaries anyway without jailbreaking and
416 /// interaction with Rust code through static library is the only
418 pub fn default_output_for_target(sess: &Session) -> config::CrateType {
419 if !sess.target.target.options.executables {
420 config::CrateTypeStaticlib
422 config::CrateTypeExecutable
426 /// Checks if target supports crate_type as output
427 pub fn invalid_output_for_target(sess: &Session,
428 crate_type: config::CrateType) -> bool {
429 match (sess.target.target.options.dynamic_linking,
430 sess.target.target.options.executables, crate_type) {
431 (false, _, config::CrateTypeDylib) => true,
432 (_, false, config::CrateTypeExecutable) => true,
437 fn is_writeable(p: &Path) -> bool {
440 Ok(m) => !m.permissions().readonly()
444 pub fn filename_for_input(sess: &Session,
445 crate_type: config::CrateType,
447 out_filename: &Path) -> PathBuf {
448 let libname = format!("{}{}", name, sess.opts.cg.extra_filename);
450 config::CrateTypeRlib => {
451 out_filename.with_file_name(&format!("lib{}.rlib", libname))
453 config::CrateTypeDylib => {
454 let (prefix, suffix) = (&sess.target.target.options.dll_prefix,
455 &sess.target.target.options.dll_suffix);
456 out_filename.with_file_name(&format!("{}{}{}",
461 config::CrateTypeStaticlib => {
462 out_filename.with_file_name(&format!("lib{}.a", libname))
464 config::CrateTypeExecutable => {
465 let suffix = &sess.target.target.options.exe_suffix;
466 if suffix.is_empty() {
467 out_filename.to_path_buf()
469 out_filename.with_extension(&suffix[1..])
475 fn link_binary_output(sess: &Session,
476 trans: &CrateTranslation,
477 crate_type: config::CrateType,
478 outputs: &OutputFilenames,
479 crate_name: &str) -> PathBuf {
480 let obj_filename = outputs.temp_path(OutputTypeObject);
481 let out_filename = match outputs.single_output_file {
482 Some(ref file) => file.clone(),
484 let out_filename = outputs.path(OutputTypeExe);
485 filename_for_input(sess, crate_type, crate_name, &out_filename)
489 // Make sure the output and obj_filename are both writeable.
490 // Mac, FreeBSD, and Windows system linkers check this already --
491 // however, the Linux linker will happily overwrite a read-only file.
492 // We should be consistent.
493 let obj_is_writeable = is_writeable(&obj_filename);
494 let out_is_writeable = is_writeable(&out_filename);
495 if !out_is_writeable {
496 sess.fatal(&format!("output file {} is not writeable -- check its \
498 out_filename.display()));
500 else if !obj_is_writeable {
501 sess.fatal(&format!("object file {} is not writeable -- check its \
503 obj_filename.display()));
507 config::CrateTypeRlib => {
508 link_rlib(sess, Some(trans), &obj_filename, &out_filename).build();
510 config::CrateTypeStaticlib => {
511 link_staticlib(sess, &obj_filename, &out_filename);
513 config::CrateTypeExecutable => {
514 link_natively(sess, trans, false, &obj_filename, &out_filename);
516 config::CrateTypeDylib => {
517 link_natively(sess, trans, true, &obj_filename, &out_filename);
524 fn archive_search_paths(sess: &Session) -> Vec<PathBuf> {
525 let mut search = Vec::new();
526 sess.target_filesearch(PathKind::Native).for_each_lib_search_path(|path, _| {
527 search.push(path.to_path_buf());
535 // An rlib in its current incarnation is essentially a renamed .a file. The
536 // rlib primarily contains the object file of the crate, but it also contains
537 // all of the object files from native libraries. This is done by unzipping
538 // native libraries and inserting all of the contents into this archive.
539 fn link_rlib<'a>(sess: &'a Session,
540 trans: Option<&CrateTranslation>, // None == no metadata/bytecode
542 out_filename: &Path) -> ArchiveBuilder<'a> {
543 let handler = &sess.diagnostic().handler;
544 let config = ArchiveConfig {
546 dst: out_filename.to_path_buf(),
547 lib_search_paths: archive_search_paths(sess),
548 slib_prefix: sess.target.target.options.staticlib_prefix.clone(),
549 slib_suffix: sess.target.target.options.staticlib_suffix.clone(),
550 maybe_ar_prog: sess.opts.cg.ar.clone()
552 let mut ab = ArchiveBuilder::create(config);
553 ab.add_file(obj_filename).unwrap();
555 for &(ref l, kind) in &*sess.cstore.get_used_libraries().borrow() {
557 cstore::NativeStatic => {
558 ab.add_native_library(&l[..]).unwrap();
560 cstore::NativeFramework | cstore::NativeUnknown => {}
564 // After adding all files to the archive, we need to update the
565 // symbol table of the archive.
568 let mut ab = match sess.target.target.options.is_like_osx {
569 // For OSX/iOS, we must be careful to update symbols only when adding
570 // object files. We're about to start adding non-object files, so run
571 // `ar` now to process the object files.
572 true => ab.build().extend(),
576 // Note that it is important that we add all of our non-object "magical
577 // files" *after* all of the object files in the archive. The reason for
578 // this is as follows:
580 // * When performing LTO, this archive will be modified to remove
581 // obj_filename from above. The reason for this is described below.
583 // * When the system linker looks at an archive, it will attempt to
584 // determine the architecture of the archive in order to see whether its
587 // The algorithm for this detection is: iterate over the files in the
588 // archive. Skip magical SYMDEF names. Interpret the first file as an
589 // object file. Read architecture from the object file.
591 // * As one can probably see, if "metadata" and "foo.bc" were placed
592 // before all of the objects, then the architecture of this archive would
593 // not be correctly inferred once 'foo.o' is removed.
595 // Basically, all this means is that this code should not move above the
599 // Instead of putting the metadata in an object file section, rlibs
600 // contain the metadata in a separate file. We use a temp directory
601 // here so concurrent builds in the same directory don't try to use
602 // the same filename for metadata (stomping over one another)
603 let tmpdir = TempDir::new("rustc").ok().expect("needs a temp dir");
604 let metadata = tmpdir.path().join(METADATA_FILENAME);
605 match fs::File::create(&metadata).and_then(|mut f| {
606 f.write_all(&trans.metadata)
610 sess.err(&format!("failed to write {}: {}",
613 sess.abort_if_errors();
616 ab.add_file(&metadata).unwrap();
617 remove(sess, &metadata);
619 // For LTO purposes, the bytecode of this library is also inserted
620 // into the archive. If codegen_units > 1, we insert each of the
622 for i in 0..sess.opts.cg.codegen_units {
623 // Note that we make sure that the bytecode filename in the
624 // archive is never exactly 16 bytes long by adding a 16 byte
625 // extension to it. This is to work around a bug in LLDB that
626 // would cause it to crash if the name of a file in an archive
627 // was exactly 16 bytes.
628 let bc_filename = obj_filename.with_extension(&format!("{}.bc", i));
629 let bc_deflated_filename = obj_filename.with_extension(
630 &format!("{}.bytecode.deflate", i));
632 let mut bc_data = Vec::new();
633 match fs::File::open(&bc_filename).and_then(|mut f| {
634 f.read_to_end(&mut bc_data)
637 Err(e) => sess.fatal(&format!("failed to read bytecode: {}",
641 let bc_data_deflated = flate::deflate_bytes(&bc_data[..]);
643 let mut bc_file_deflated = match fs::File::create(&bc_deflated_filename) {
646 sess.fatal(&format!("failed to create compressed \
647 bytecode file: {}", e))
651 match write_rlib_bytecode_object_v1(&mut bc_file_deflated,
655 sess.err(&format!("failed to write compressed bytecode: \
657 sess.abort_if_errors()
661 ab.add_file(&bc_deflated_filename).unwrap();
662 remove(sess, &bc_deflated_filename);
664 // See the bottom of back::write::run_passes for an explanation
665 // of when we do and don't keep .0.bc files around.
666 let user_wants_numbered_bitcode =
667 sess.opts.output_types.contains(&OutputTypeBitcode) &&
668 sess.opts.cg.codegen_units > 1;
669 if !sess.opts.cg.save_temps && !user_wants_numbered_bitcode {
670 remove(sess, &bc_filename);
674 // After adding all files to the archive, we need to update the
675 // symbol table of the archive. This currently dies on OSX (see
676 // #11162), and isn't necessary there anyway
677 if !sess.target.target.options.is_like_osx {
688 fn write_rlib_bytecode_object_v1(writer: &mut Write,
689 bc_data_deflated: &[u8]) -> io::Result<()> {
690 let bc_data_deflated_size: u64 = bc_data_deflated.len() as u64;
692 try!(writer.write_all(RLIB_BYTECODE_OBJECT_MAGIC));
693 try!(writer.write_all(&[1, 0, 0, 0]));
694 try!(writer.write_all(&[
695 (bc_data_deflated_size >> 0) as u8,
696 (bc_data_deflated_size >> 8) as u8,
697 (bc_data_deflated_size >> 16) as u8,
698 (bc_data_deflated_size >> 24) as u8,
699 (bc_data_deflated_size >> 32) as u8,
700 (bc_data_deflated_size >> 40) as u8,
701 (bc_data_deflated_size >> 48) as u8,
702 (bc_data_deflated_size >> 56) as u8,
704 try!(writer.write_all(&bc_data_deflated));
706 let number_of_bytes_written_so_far =
707 RLIB_BYTECODE_OBJECT_MAGIC.len() + // magic id
708 mem::size_of_val(&RLIB_BYTECODE_OBJECT_VERSION) + // version
709 mem::size_of_val(&bc_data_deflated_size) + // data size field
710 bc_data_deflated_size as usize; // actual data
712 // If the number of bytes written to the object so far is odd, add a
713 // padding byte to make it even. This works around a crash bug in LLDB
714 // (see issue #15950)
715 if number_of_bytes_written_so_far % 2 == 1 {
716 try!(writer.write_all(&[0]));
722 // Create a static archive
724 // This is essentially the same thing as an rlib, but it also involves adding
725 // all of the upstream crates' objects into the archive. This will slurp in
726 // all of the native libraries of upstream dependencies as well.
728 // Additionally, there's no way for us to link dynamic libraries, so we warn
729 // about all dynamic library dependencies that they're not linked in.
731 // There's no need to include metadata in a static archive, so ensure to not
732 // link in the metadata object file (and also don't prepare the archive with a
734 fn link_staticlib(sess: &Session, obj_filename: &Path, out_filename: &Path) {
735 let ab = link_rlib(sess, None, obj_filename, out_filename);
736 let mut ab = match sess.target.target.options.is_like_osx {
737 true => ab.build().extend(),
740 if sess.target.target.options.morestack {
741 ab.add_native_library("morestack").unwrap();
743 if !sess.target.target.options.no_compiler_rt {
744 ab.add_native_library("compiler-rt").unwrap();
747 let crates = sess.cstore.get_used_crates(cstore::RequireStatic);
748 let mut all_native_libs = vec![];
750 for &(cnum, ref path) in &crates {
751 let ref name = sess.cstore.get_crate_data(cnum).name;
752 let p = match *path {
753 Some(ref p) => p.clone(), None => {
754 sess.err(&format!("could not find rlib for: `{}`",
759 ab.add_rlib(&p, &name[..], sess.lto()).unwrap();
761 let native_libs = csearch::get_native_libraries(&sess.cstore, cnum);
762 all_native_libs.extend(native_libs.into_iter());
768 if !all_native_libs.is_empty() {
769 sess.note("link against the following native artifacts when linking against \
770 this static library");
771 sess.note("the order and any duplication can be significant on some platforms, \
772 and so may need to be preserved");
775 for &(kind, ref lib) in &all_native_libs {
776 let name = match kind {
777 cstore::NativeStatic => "static library",
778 cstore::NativeUnknown => "library",
779 cstore::NativeFramework => "framework",
781 sess.note(&format!("{}: {}", name, *lib));
785 // Create a dynamic library or executable
787 // This will invoke the system linker/cc to create the resulting file. This
788 // links to all upstream files as well.
789 fn link_natively(sess: &Session, trans: &CrateTranslation, dylib: bool,
790 obj_filename: &Path, out_filename: &Path) {
791 let tmpdir = TempDir::new("rustc").ok().expect("needs a temp dir");
793 // The invocations of cc share some flags across platforms
794 let pname = get_cc_prog(sess);
795 let mut cmd = Command::new(&pname[..]);
797 let root = sess.target_filesearch(PathKind::Native).get_lib_path();
798 cmd.args(&sess.target.target.options.pre_link_args);
799 for obj in &sess.target.target.options.pre_link_objects {
800 cmd.arg(root.join(obj));
803 link_args(&mut cmd, sess, dylib, tmpdir.path(),
804 trans, obj_filename, out_filename);
805 if !sess.target.target.options.no_compiler_rt {
806 cmd.arg("-lcompiler-rt");
808 for obj in &sess.target.target.options.post_link_objects {
809 cmd.arg(root.join(obj));
811 cmd.args(&sess.target.target.options.post_link_args);
813 if sess.opts.debugging_opts.print_link_args {
814 println!("{:?}", &cmd);
817 // May have not found libraries in the right formats.
818 sess.abort_if_errors();
820 // Invoke the system linker
821 debug!("{:?}", &cmd);
822 let prog = time(sess.time_passes(), "running linker", (), |()| cmd.output());
825 if !prog.status.success() {
826 sess.err(&format!("linking with `{}` failed: {}",
829 sess.note(&format!("{:?}", &cmd));
830 let mut output = prog.stderr.clone();
831 output.push_all(&prog.stdout);
832 sess.note(str::from_utf8(&output[..]).unwrap());
833 sess.abort_if_errors();
835 debug!("linker stderr:\n{}", String::from_utf8(prog.stderr).unwrap());
836 debug!("linker stdout:\n{}", String::from_utf8(prog.stdout).unwrap());
839 sess.err(&format!("could not exec the linker `{}`: {}",
842 sess.abort_if_errors();
847 // On OSX, debuggers need this utility to get run to do some munging of
849 if sess.target.target.options.is_like_osx && sess.opts.debuginfo != NoDebugInfo {
850 match Command::new("dsymutil").arg(out_filename).output() {
853 sess.err(&format!("failed to run dsymutil: {}", e));
854 sess.abort_if_errors();
860 fn link_args(cmd: &mut Command,
864 trans: &CrateTranslation,
866 out_filename: &Path) {
868 // The default library location, we need this to find the runtime.
869 // The location of crates will be determined as needed.
870 let lib_path = sess.target_filesearch(PathKind::All).get_lib_path();
873 let t = &sess.target.target;
875 cmd.arg("-L").arg(&fix_windows_verbatim_for_gcc(&lib_path));
877 cmd.arg("-o").arg(out_filename).arg(obj_filename);
880 // Stack growth requires statically linking a __morestack function. Note
881 // that this is listed *before* all other libraries. Due to the usage of the
882 // --as-needed flag below, the standard library may only be useful for its
883 // rust_stack_exhausted function. In this case, we must ensure that the
884 // libmorestack.a file appears *before* the standard library (so we put it
885 // at the very front).
887 // Most of the time this is sufficient, except for when LLVM gets super
888 // clever. If, for example, we have a main function `fn main() {}`, LLVM
889 // will optimize out calls to `__morestack` entirely because the function
890 // doesn't need any stack at all!
892 // To get around this snag, we specially tell the linker to always include
893 // all contents of this library. This way we're guaranteed that the linker
894 // will include the __morestack symbol 100% of the time, always resolving
895 // references to it even if the object above didn't use it.
896 if t.options.morestack {
897 if t.options.is_like_osx {
898 let morestack = lib_path.join("libmorestack.a");
900 let mut v = OsString::from("-Wl,-force_load,");
904 cmd.args(&["-Wl,--whole-archive", "-lmorestack", "-Wl,--no-whole-archive"]);
908 // When linking a dynamic library, we put the metadata into a section of the
909 // executable. This metadata is in a separate object file from the main
910 // object file, so we link that in here.
912 cmd.arg(&obj_filename.with_extension("metadata.o"));
915 if t.options.is_like_osx {
916 // The dead_strip option to the linker specifies that functions and data
917 // unreachable by the entry point will be removed. This is quite useful
918 // with Rust's compilation model of compiling libraries at a time into
919 // one object file. For example, this brings hello world from 1.7MB to
922 // Note that this is done for both executables and dynamic libraries. We
923 // won't get much benefit from dylibs because LLVM will have already
924 // stripped away as much as it could. This has not been seen to impact
925 // link times negatively.
927 // -dead_strip can't be part of the pre_link_args because it's also used
928 // for partial linking when using multiple codegen units (-r). So we
930 cmd.arg("-Wl,-dead_strip");
933 // If we're building a dylib, we don't use --gc-sections because LLVM has
934 // already done the best it can do, and we also don't want to eliminate the
935 // metadata. If we're building an executable, however, --gc-sections drops
936 // the size of hello world from 1.8MB to 597K, a 67% reduction.
937 if !dylib && !t.options.is_like_osx {
938 cmd.arg("-Wl,--gc-sections");
941 let used_link_args = sess.cstore.get_used_link_args().borrow();
943 if t.options.position_independent_executables {
944 let empty_vec = Vec::new();
945 let empty_str = String::new();
946 let args = sess.opts.cg.link_args.as_ref().unwrap_or(&empty_vec);
947 let mut args = args.iter().chain(used_link_args.iter());
949 && (t.options.relocation_model == "pic"
950 || *sess.opts.cg.relocation_model.as_ref()
951 .unwrap_or(&empty_str) == "pic")
952 && !args.any(|x| *x == "-static") {
957 if t.options.linker_is_gnu {
958 // GNU-style linkers support optimization with -O. GNU ld doesn't need a
959 // numeric argument, but other linkers do.
960 if sess.opts.optimize == config::Default ||
961 sess.opts.optimize == config::Aggressive {
966 // We want to prevent the compiler from accidentally leaking in any system
967 // libraries, so we explicitly ask gcc to not link to any libraries by
968 // default. Note that this does not happen for windows because windows pulls
969 // in some large number of libraries and I couldn't quite figure out which
971 if !t.options.is_like_windows {
972 cmd.arg("-nodefaultlibs");
975 // Mark all dynamic libraries and executables as compatible with ASLR
976 // FIXME #17098: ASLR breaks gdb
977 if t.options.is_like_windows && sess.opts.debuginfo == NoDebugInfo {
978 // cmd.arg("-Wl,--dynamicbase");
981 // Take careful note of the ordering of the arguments we pass to the linker
982 // here. Linkers will assume that things on the left depend on things to the
983 // right. Things on the right cannot depend on things on the left. This is
984 // all formally implemented in terms of resolving symbols (libs on the right
985 // resolve unknown symbols of libs on the left, but not vice versa).
987 // For this reason, we have organized the arguments we pass to the linker as
990 // 1. The local object that LLVM just generated
991 // 2. Upstream rust libraries
992 // 3. Local native libraries
993 // 4. Upstream native libraries
995 // This is generally fairly natural, but some may expect 2 and 3 to be
996 // swapped. The reason that all native libraries are put last is that it's
997 // not recommended for a native library to depend on a symbol from a rust
998 // crate. If this is the case then a staticlib crate is recommended, solving
1001 // Additionally, it is occasionally the case that upstream rust libraries
1002 // depend on a local native library. In the case of libraries such as
1003 // lua/glfw/etc the name of the library isn't the same across all platforms,
1004 // so only the consumer crate of a library knows the actual name. This means
1005 // that downstream crates will provide the #[link] attribute which upstream
1006 // crates will depend on. Hence local native libraries are after out
1007 // upstream rust crates.
1009 // In theory this means that a symbol in an upstream native library will be
1010 // shadowed by a local native library when it wouldn't have been before, but
1011 // this kind of behavior is pretty platform specific and generally not
1012 // recommended anyway, so I don't think we're shooting ourself in the foot
1014 add_upstream_rust_crates(cmd, sess, dylib, tmpdir, trans);
1015 add_local_native_libraries(cmd, sess);
1016 add_upstream_native_libraries(cmd, sess);
1018 // # Telling the linker what we're doing
1021 // On mac we need to tell the linker to let this library be rpathed
1022 if sess.target.target.options.is_like_osx {
1023 cmd.args(&["-dynamiclib", "-Wl,-dylib"]);
1025 if sess.opts.cg.rpath {
1026 let mut v = OsString::from("-Wl,-install_name,@rpath/");
1027 v.push(out_filename.file_name().unwrap());
1035 // FIXME (#2397): At some point we want to rpath our guesses as to
1036 // where extern libraries might live, based on the
1037 // addl_lib_search_paths
1038 if sess.opts.cg.rpath {
1039 let sysroot = sess.sysroot();
1040 let target_triple = &sess.opts.target_triple;
1041 let mut get_install_prefix_lib_path = || {
1042 let install_prefix = option_env!("CFG_PREFIX").expect("CFG_PREFIX");
1043 let tlib = filesearch::relative_target_lib_path(sysroot, target_triple);
1044 let mut path = PathBuf::from(install_prefix);
1049 let mut rpath_config = RPathConfig {
1050 used_crates: sess.cstore.get_used_crates(cstore::RequireDynamic),
1051 out_filename: out_filename.to_path_buf(),
1052 has_rpath: sess.target.target.options.has_rpath,
1053 is_like_osx: sess.target.target.options.is_like_osx,
1054 get_install_prefix_lib_path: &mut get_install_prefix_lib_path,
1056 cmd.args(&rpath::get_rpath_flags(&mut rpath_config));
1059 // Finally add all the linker arguments provided on the command line along
1060 // with any #[link_args] attributes found inside the crate
1061 let empty = Vec::new();
1062 cmd.args(&sess.opts.cg.link_args.as_ref().unwrap_or(&empty));
1063 cmd.args(&used_link_args[..]);
1066 // # Native library linking
1068 // User-supplied library search paths (-L on the command line). These are
1069 // the same paths used to find Rust crates, so some of them may have been
1070 // added already by the previous crate linking code. This only allows them
1071 // to be found at compile time so it is still entirely up to outside
1072 // forces to make sure that library can be found at runtime.
1074 // Also note that the native libraries linked here are only the ones located
1075 // in the current crate. Upstream crates with native library dependencies
1076 // may have their native library pulled in above.
1077 fn add_local_native_libraries(cmd: &mut Command, sess: &Session) {
1078 sess.target_filesearch(PathKind::All).for_each_lib_search_path(|path, k| {
1080 PathKind::Framework => { cmd.arg("-F").arg(path); }
1081 _ => { cmd.arg("-L").arg(path); }
1086 // Some platforms take hints about whether a library is static or dynamic.
1087 // For those that support this, we ensure we pass the option if the library
1088 // was flagged "static" (most defaults are dynamic) to ensure that if
1089 // libfoo.a and libfoo.so both exist that the right one is chosen.
1090 let takes_hints = !sess.target.target.options.is_like_osx;
1092 let libs = sess.cstore.get_used_libraries();
1093 let libs = libs.borrow();
1095 let staticlibs = libs.iter().filter_map(|&(ref l, kind)| {
1096 if kind == cstore::NativeStatic {Some(l)} else {None}
1098 let others = libs.iter().filter(|&&(_, kind)| {
1099 kind != cstore::NativeStatic
1102 // Platforms that take hints generally also support the --whole-archive
1103 // flag. We need to pass this flag when linking static native libraries to
1104 // ensure the entire library is included.
1106 // For more details see #15460, but the gist is that the linker will strip
1107 // away any unused objects in the archive if we don't otherwise explicitly
1108 // reference them. This can occur for libraries which are just providing
1109 // bindings, libraries with generic functions, etc.
1111 cmd.arg("-Wl,--whole-archive").arg("-Wl,-Bstatic");
1113 let search_path = archive_search_paths(sess);
1114 for l in staticlibs {
1116 cmd.arg(&format!("-l{}", l));
1118 // -force_load is the OSX equivalent of --whole-archive, but it
1119 // involves passing the full path to the library to link.
1120 let lib = archive::find_library(&l[..],
1121 &sess.target.target.options.staticlib_prefix,
1122 &sess.target.target.options.staticlib_suffix,
1124 &sess.diagnostic().handler);
1125 let mut v = OsString::from("-Wl,-force_load,");
1131 cmd.arg("-Wl,--no-whole-archive").arg("-Wl,-Bdynamic");
1134 for &(ref l, kind) in others {
1136 cstore::NativeUnknown => {
1137 cmd.arg(&format!("-l{}", l));
1139 cstore::NativeFramework => {
1140 cmd.arg("-framework").arg(&l[..]);
1142 cstore::NativeStatic => unreachable!(),
1147 // # Rust Crate linking
1149 // Rust crates are not considered at all when creating an rlib output. All
1150 // dependencies will be linked when producing the final output (instead of
1151 // the intermediate rlib version)
1152 fn add_upstream_rust_crates(cmd: &mut Command, sess: &Session,
1153 dylib: bool, tmpdir: &Path,
1154 trans: &CrateTranslation) {
1155 // All of the heavy lifting has previously been accomplished by the
1156 // dependency_format module of the compiler. This is just crawling the
1157 // output of that module, adding crates as necessary.
1159 // Linking to a rlib involves just passing it to the linker (the linker
1160 // will slurp up the object files inside), and linking to a dynamic library
1161 // involves just passing the right -l flag.
1163 let data = if dylib {
1164 trans.crate_formats.get(&config::CrateTypeDylib).unwrap()
1166 trans.crate_formats.get(&config::CrateTypeExecutable).unwrap()
1169 // Invoke get_used_crates to ensure that we get a topological sorting of
1171 let deps = sess.cstore.get_used_crates(cstore::RequireDynamic);
1173 for &(cnum, _) in &deps {
1174 // We may not pass all crates through to the linker. Some crates may
1175 // appear statically in an existing dylib, meaning we'll pick up all the
1176 // symbols from the dylib.
1177 let kind = match data[cnum as usize - 1] {
1181 let src = sess.cstore.get_used_crate_source(cnum).unwrap();
1183 cstore::RequireDynamic => {
1184 add_dynamic_crate(cmd, sess, &src.dylib.unwrap().0)
1186 cstore::RequireStatic => {
1187 add_static_crate(cmd, sess, tmpdir, &src.rlib.unwrap().0)
1193 // Converts a library file-stem into a cc -l argument
1194 fn unlib<'a>(config: &config::Config, stem: &'a str) -> &'a str {
1195 if stem.starts_with("lib") && !config.target.options.is_like_windows {
1202 // Adds the static "rlib" versions of all crates to the command line.
1203 fn add_static_crate(cmd: &mut Command, sess: &Session, tmpdir: &Path,
1205 // When performing LTO on an executable output, all of the
1206 // bytecode from the upstream libraries has already been
1207 // included in our object file output. We need to modify all of
1208 // the upstream archives to remove their corresponding object
1209 // file to make sure we don't pull the same code in twice.
1211 // We must continue to link to the upstream archives to be sure
1212 // to pull in native static dependencies. As the final caveat,
1213 // on Linux it is apparently illegal to link to a blank archive,
1214 // so if an archive no longer has any object files in it after
1215 // we remove `lib.o`, then don't link against it at all.
1217 // If we're not doing LTO, then our job is simply to just link
1218 // against the archive.
1220 let name = cratepath.file_name().unwrap().to_str().unwrap();
1221 let name = &name[3..name.len() - 5]; // chop off lib/.rlib
1222 time(sess.time_passes(),
1223 &format!("altering {}.rlib", name),
1225 let dst = tmpdir.join(cratepath.file_name().unwrap());
1226 match fs::copy(&cratepath, &dst) {
1229 sess.err(&format!("failed to copy {} to {}: {}",
1230 cratepath.display(),
1233 sess.abort_if_errors();
1236 // Fix up permissions of the copy, as fs::copy() preserves
1237 // permissions, but the original file may have been installed
1238 // by a package manager and may be read-only.
1239 match fs::metadata(&dst).and_then(|m| {
1240 let mut perms = m.permissions();
1241 perms.set_readonly(false);
1242 fs::set_permissions(&dst, perms)
1246 sess.err(&format!("failed to chmod {} when preparing \
1247 for LTO: {}", dst.display(),
1249 sess.abort_if_errors();
1252 let handler = &sess.diagnostic().handler;
1253 let config = ArchiveConfig {
1256 lib_search_paths: archive_search_paths(sess),
1257 slib_prefix: sess.target.target.options.staticlib_prefix.clone(),
1258 slib_suffix: sess.target.target.options.staticlib_suffix.clone(),
1259 maybe_ar_prog: sess.opts.cg.ar.clone()
1261 let mut archive = Archive::open(config);
1262 archive.remove_file(&format!("{}.o", name));
1263 let files = archive.files();
1264 if files.iter().any(|s| s.ends_with(".o")) {
1269 cmd.arg(&fix_windows_verbatim_for_gcc(cratepath));
1273 // Same thing as above, but for dynamic crates instead of static crates.
1274 fn add_dynamic_crate(cmd: &mut Command, sess: &Session, cratepath: &Path) {
1275 // If we're performing LTO, then it should have been previously required
1276 // that all upstream rust dependencies were available in an rlib format.
1277 assert!(!sess.lto());
1279 // Just need to tell the linker about where the library lives and
1281 if let Some(dir) = cratepath.parent() {
1282 cmd.arg("-L").arg(&fix_windows_verbatim_for_gcc(dir));
1284 let filestem = cratepath.file_stem().unwrap().to_str().unwrap();
1285 cmd.arg(&format!("-l{}", unlib(&sess.target, filestem)));
1289 // Link in all of our upstream crates' native dependencies. Remember that
1290 // all of these upstream native dependencies are all non-static
1291 // dependencies. We've got two cases then:
1293 // 1. The upstream crate is an rlib. In this case we *must* link in the
1294 // native dependency because the rlib is just an archive.
1296 // 2. The upstream crate is a dylib. In order to use the dylib, we have to
1297 // have the dependency present on the system somewhere. Thus, we don't
1298 // gain a whole lot from not linking in the dynamic dependency to this
1301 // The use case for this is a little subtle. In theory the native
1302 // dependencies of a crate are purely an implementation detail of the crate
1303 // itself, but the problem arises with generic and inlined functions. If a
1304 // generic function calls a native function, then the generic function must
1305 // be instantiated in the target crate, meaning that the native symbol must
1306 // also be resolved in the target crate.
1307 fn add_upstream_native_libraries(cmd: &mut Command, sess: &Session) {
1308 // Be sure to use a topological sorting of crates because there may be
1309 // interdependencies between native libraries. When passing -nodefaultlibs,
1310 // for example, almost all native libraries depend on libc, so we have to
1311 // make sure that's all the way at the right (liblibc is near the base of
1312 // the dependency chain).
1314 // This passes RequireStatic, but the actual requirement doesn't matter,
1315 // we're just getting an ordering of crate numbers, we're not worried about
1317 let crates = sess.cstore.get_used_crates(cstore::RequireStatic);
1318 for (cnum, _) in crates {
1319 let libs = csearch::get_native_libraries(&sess.cstore, cnum);
1320 for &(kind, ref lib) in &libs {
1322 cstore::NativeUnknown => {
1323 cmd.arg(&format!("-l{}", *lib));
1325 cstore::NativeFramework => {
1326 cmd.arg("-framework");
1329 cstore::NativeStatic => {
1330 sess.bug("statics shouldn't be propagated");
1337 // Unfortunately, on windows, gcc cannot accept paths of the form `\\?\C:\...`
1338 // (a verbatim path). This form of path is generally pretty rare, but the
1339 // implementation of `fs::canonicalize` currently generates paths of this form,
1340 // meaning that we're going to be passing quite a few of these down to gcc.
1342 // For now we just strip the "verbatim prefix" of `\\?\` from the path. This
1343 // will probably lose information in some cases, but there's not a whole lot
1344 // more we can do with a buggy gcc...
1345 fn fix_windows_verbatim_for_gcc(p: &Path) -> PathBuf {
1347 return p.to_path_buf()
1349 let mut components = p.components();
1350 let prefix = match components.next() {
1351 Some(path::Component::Prefix(p)) => p,
1352 _ => return p.to_path_buf(),
1354 let disk = match prefix.kind() {
1355 path::Prefix::VerbatimDisk(disk) => disk,
1356 _ => return p.to_path_buf(),
1358 let mut base = OsString::from(format!("{}:", disk as char));
1359 base.push(components.as_path());