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 back::archive::{Archive, METADATA_FILENAME};
14 use driver::driver::{CrateTranslation, OutputFilenames};
15 use driver::session::{NoDebugInfo, Session};
18 use lib::llvm::ModuleRef;
20 use metadata::common::LinkMeta;
21 use metadata::{encoder, cstore, filesearch, csearch};
22 use middle::trans::context::CrateContext;
23 use middle::trans::common::gensym_name;
25 use util::common::time;
27 use util::sha2::{Digest, Sha256};
29 use std::c_str::{ToCStr, CString};
31 use std::os::consts::{macos, freebsd, linux, android, win32};
35 use std::io::{fs, TempDir, Process};
37 use serialize::hex::ToHex;
40 use syntax::ast_map::{PathElem, PathElems, PathName};
43 use syntax::attr::AttrMetaMethods;
44 use syntax::crateid::CrateId;
45 use syntax::parse::token;
47 #[deriving(Clone, Eq, Ord, TotalOrd, TotalEq)]
51 OutputTypeLlvmAssembly,
56 pub fn llvm_err(sess: &Session, msg: ~str) -> ! {
58 let cstr = llvm::LLVMRustGetLastError();
59 if cstr == ptr::null() {
62 let err = CString::new(cstr, false);
63 let err = str::from_utf8_lossy(err.as_bytes());
64 sess.fatal(msg + ": " + err.as_slice());
69 pub fn WriteOutputFile(
71 target: lib::llvm::TargetMachineRef,
72 pm: lib::llvm::PassManagerRef,
75 file_type: lib::llvm::FileType) {
77 output.with_c_str(|output| {
78 let result = llvm::LLVMRustWriteOutputFile(
79 target, pm, m, output, file_type);
81 llvm_err(sess, ~"could not write output");
90 use back::link::{WriteOutputFile, OutputType};
91 use back::link::{OutputTypeAssembly, OutputTypeBitcode};
92 use back::link::{OutputTypeExe, OutputTypeLlvmAssembly};
93 use back::link::{OutputTypeObject};
94 use driver::driver::{CrateTranslation, OutputFilenames};
95 use driver::session::{NoDebugInfo, Session};
98 use lib::llvm::{ModuleRef, TargetMachineRef, PassManagerRef};
100 use util::common::time;
103 use std::c_str::ToCStr;
104 use std::io::Process;
105 use std::libc::{c_uint, c_int};
108 // On android, we by default compile for armv7 processors. This enables
109 // things like double word CAS instructions (rather than emulating them)
110 // which are *far* more efficient. This is obviously undesirable in some
111 // cases, so if any sort of target feature is specified we don't append v7
112 // to the feature list.
113 fn target_feature<'a>(sess: &'a Session) -> &'a str {
114 match sess.targ_cfg.os {
116 if "" == sess.opts.cg.target_feature {
119 sess.opts.cg.target_feature.as_slice()
122 _ => sess.opts.cg.target_feature.as_slice()
126 pub fn run_passes(sess: &Session,
127 trans: &CrateTranslation,
128 output_types: &[OutputType],
129 output: &OutputFilenames) {
130 let llmod = trans.module;
131 let llcx = trans.context;
133 configure_llvm(sess);
135 if sess.opts.cg.save_temps {
136 output.with_extension("no-opt.bc").with_c_str(|buf| {
137 llvm::LLVMWriteBitcodeToFile(llmod, buf);
141 let opt_level = match sess.opts.optimize {
142 session::No => lib::llvm::CodeGenLevelNone,
143 session::Less => lib::llvm::CodeGenLevelLess,
144 session::Default => lib::llvm::CodeGenLevelDefault,
145 session::Aggressive => lib::llvm::CodeGenLevelAggressive,
147 let use_softfp = sess.opts.cg.soft_float;
149 // FIXME: #11906: Omitting frame pointers breaks retrieving the value of a parameter.
150 // FIXME: #11954: mac64 unwinding may not work with fp elim
151 let no_fp_elim = (sess.opts.debuginfo != NoDebugInfo) ||
152 (sess.targ_cfg.os == abi::OsMacos &&
153 sess.targ_cfg.arch == abi::X86_64);
155 let tm = sess.targ_cfg.target_strs.target_triple.with_c_str(|t| {
156 sess.opts.cg.target_cpu.with_c_str(|cpu| {
157 target_feature(sess).with_c_str(|features| {
158 llvm::LLVMRustCreateTargetMachine(
160 lib::llvm::CodeModelDefault,
171 // Create the two optimizing pass managers. These mirror what clang
172 // does, and are by populated by LLVM's default PassManagerBuilder.
173 // Each manager has a different set of passes, but they also share
174 // some common passes.
175 let fpm = llvm::LLVMCreateFunctionPassManagerForModule(llmod);
176 let mpm = llvm::LLVMCreatePassManager();
178 // If we're verifying or linting, add them to the function pass
180 let addpass = |pass: &str| {
181 pass.with_c_str(|s| llvm::LLVMRustAddPass(fpm, s))
183 if !sess.no_verify() { assert!(addpass("verify")); }
185 if !sess.opts.cg.no_prepopulate_passes {
186 llvm::LLVMRustAddAnalysisPasses(tm, fpm, llmod);
187 llvm::LLVMRustAddAnalysisPasses(tm, mpm, llmod);
188 populate_llvm_passes(fpm, mpm, llmod, opt_level);
191 for pass in sess.opts.cg.passes.iter() {
192 pass.with_c_str(|s| {
193 if !llvm::LLVMRustAddPass(mpm, s) {
194 sess.warn(format!("unknown pass {}, ignoring", *pass));
199 // Finally, run the actual optimization passes
200 time(sess.time_passes(), "llvm function passes", (), |()|
201 llvm::LLVMRustRunFunctionPassManager(fpm, llmod));
202 time(sess.time_passes(), "llvm module passes", (), |()|
203 llvm::LLVMRunPassManager(mpm, llmod));
205 // Deallocate managers that we're now done with
206 llvm::LLVMDisposePassManager(fpm);
207 llvm::LLVMDisposePassManager(mpm);
209 // Emit the bytecode if we're either saving our temporaries or
210 // emitting an rlib. Whenever an rlib is created, the bytecode is
211 // inserted into the archive in order to allow LTO against it.
212 if sess.opts.cg.save_temps ||
213 (sess.crate_types.borrow().contains(&session::CrateTypeRlib) &&
214 sess.opts.output_types.contains(&OutputTypeExe)) {
215 output.temp_path(OutputTypeBitcode).with_c_str(|buf| {
216 llvm::LLVMWriteBitcodeToFile(llmod, buf);
221 time(sess.time_passes(), "all lto passes", (), |()|
222 lto::run(sess, llmod, tm, trans.reachable.as_slice()));
224 if sess.opts.cg.save_temps {
225 output.with_extension("lto.bc").with_c_str(|buf| {
226 llvm::LLVMWriteBitcodeToFile(llmod, buf);
231 // A codegen-specific pass manager is used to generate object
232 // files for an LLVM module.
234 // Apparently each of these pass managers is a one-shot kind of
235 // thing, so we create a new one for each type of output. The
236 // pass manager passed to the closure should be ensured to not
237 // escape the closure itself, and the manager should only be
239 fn with_codegen(tm: TargetMachineRef, llmod: ModuleRef,
240 f: |PassManagerRef|) {
242 let cpm = llvm::LLVMCreatePassManager();
243 llvm::LLVMRustAddAnalysisPasses(tm, cpm, llmod);
244 llvm::LLVMRustAddLibraryInfo(cpm, llmod);
246 llvm::LLVMDisposePassManager(cpm);
250 let mut object_file = None;
251 let mut needs_metadata = false;
252 for output_type in output_types.iter() {
253 let path = output.path(*output_type);
255 OutputTypeBitcode => {
256 path.with_c_str(|buf| {
257 llvm::LLVMWriteBitcodeToFile(llmod, buf);
260 OutputTypeLlvmAssembly => {
261 path.with_c_str(|output| {
262 with_codegen(tm, llmod, |cpm| {
263 llvm::LLVMRustPrintModule(cpm, llmod, output);
267 OutputTypeAssembly => {
268 // If we're not using the LLVM assembler, this function
269 // could be invoked specially with output_type_assembly,
270 // so in this case we still want the metadata object
272 let ty = OutputTypeAssembly;
273 let path = if sess.opts.output_types.contains(&ty) {
276 needs_metadata = true;
277 output.temp_path(OutputTypeAssembly)
279 with_codegen(tm, llmod, |cpm| {
280 WriteOutputFile(sess, tm, cpm, llmod, &path,
281 lib::llvm::AssemblyFile);
284 OutputTypeObject => {
285 object_file = Some(path);
288 object_file = Some(output.temp_path(OutputTypeObject));
289 needs_metadata = true;
294 time(sess.time_passes(), "codegen passes", (), |()| {
297 with_codegen(tm, llmod, |cpm| {
298 WriteOutputFile(sess, tm, cpm, llmod, path,
299 lib::llvm::ObjectFile);
305 with_codegen(tm, trans.metadata_module, |cpm| {
306 let out = output.temp_path(OutputTypeObject)
307 .with_extension("metadata.o");
308 WriteOutputFile(sess, tm, cpm,
309 trans.metadata_module, &out,
310 lib::llvm::ObjectFile);
315 llvm::LLVMRustDisposeTargetMachine(tm);
316 llvm::LLVMDisposeModule(trans.metadata_module);
317 llvm::LLVMDisposeModule(llmod);
318 llvm::LLVMContextDispose(llcx);
319 if sess.time_llvm_passes() { llvm::LLVMRustPrintPassTimings(); }
323 pub fn run_assembler(sess: &Session, outputs: &OutputFilenames) {
324 let cc = super::get_cc_prog(sess);
325 let assembly = outputs.temp_path(OutputTypeAssembly);
326 let object = outputs.path(OutputTypeObject);
328 // FIXME (#9639): This needs to handle non-utf8 paths
331 ~"-o", object.as_str().unwrap().to_owned(),
332 assembly.as_str().unwrap().to_owned()];
334 debug!("{} '{}'", cc, args.connect("' '"));
335 match Process::output(cc, args) {
337 if !prog.status.success() {
338 sess.err(format!("linking with `{}` failed: {}", cc, prog.status));
339 sess.note(format!("{} arguments: '{}'", cc, args.connect("' '")));
340 sess.note(str::from_utf8_owned(prog.error + prog.output).unwrap());
341 sess.abort_if_errors();
345 sess.err(format!("could not exec the linker `{}`: {}", cc, e));
346 sess.abort_if_errors();
351 unsafe fn configure_llvm(sess: &Session) {
352 use sync::one::{Once, ONCE_INIT};
353 static mut INIT: Once = ONCE_INIT;
355 // Copy what clang does by turning on loop vectorization at O2 and
356 // slp vectorization at O3
357 let vectorize_loop = !sess.opts.cg.no_vectorize_loops &&
358 (sess.opts.optimize == session::Default ||
359 sess.opts.optimize == session::Aggressive);
360 let vectorize_slp = !sess.opts.cg.no_vectorize_slp &&
361 sess.opts.optimize == session::Aggressive;
363 let mut llvm_c_strs = Vec::new();
364 let mut llvm_args = Vec::new();
366 let add = |arg: &str| {
367 let s = arg.to_c_str();
368 llvm_args.push(s.with_ref(|p| p));
371 add("rustc"); // fake program name
372 if vectorize_loop { add("-vectorize-loops"); }
373 if vectorize_slp { add("-vectorize-slp"); }
374 if sess.time_llvm_passes() { add("-time-passes"); }
375 if sess.print_llvm_passes() { add("-debug-pass=Structure"); }
377 for arg in sess.opts.cg.llvm_args.iter() {
383 llvm::LLVMInitializePasses();
385 // Only initialize the platforms supported by Rust here, because
386 // using --llvm-root will have multiple platforms that rustllvm
387 // doesn't actually link to and it's pointless to put target info
388 // into the registry that Rust cannot generate machine code for.
389 llvm::LLVMInitializeX86TargetInfo();
390 llvm::LLVMInitializeX86Target();
391 llvm::LLVMInitializeX86TargetMC();
392 llvm::LLVMInitializeX86AsmPrinter();
393 llvm::LLVMInitializeX86AsmParser();
395 llvm::LLVMInitializeARMTargetInfo();
396 llvm::LLVMInitializeARMTarget();
397 llvm::LLVMInitializeARMTargetMC();
398 llvm::LLVMInitializeARMAsmPrinter();
399 llvm::LLVMInitializeARMAsmParser();
401 llvm::LLVMInitializeMipsTargetInfo();
402 llvm::LLVMInitializeMipsTarget();
403 llvm::LLVMInitializeMipsTargetMC();
404 llvm::LLVMInitializeMipsAsmPrinter();
405 llvm::LLVMInitializeMipsAsmParser();
407 llvm::LLVMRustSetLLVMOptions(llvm_args.len() as c_int,
412 unsafe fn populate_llvm_passes(fpm: lib::llvm::PassManagerRef,
413 mpm: lib::llvm::PassManagerRef,
415 opt: lib::llvm::CodeGenOptLevel) {
416 // Create the PassManagerBuilder for LLVM. We configure it with
417 // reasonable defaults and prepare it to actually populate the pass
419 let builder = llvm::LLVMPassManagerBuilderCreate();
421 lib::llvm::CodeGenLevelNone => {
422 // Don't add lifetime intrinsics at O0
423 llvm::LLVMRustAddAlwaysInlinePass(builder, false);
425 lib::llvm::CodeGenLevelLess => {
426 llvm::LLVMRustAddAlwaysInlinePass(builder, true);
428 // numeric values copied from clang
429 lib::llvm::CodeGenLevelDefault => {
430 llvm::LLVMPassManagerBuilderUseInlinerWithThreshold(builder,
433 lib::llvm::CodeGenLevelAggressive => {
434 llvm::LLVMPassManagerBuilderUseInlinerWithThreshold(builder,
438 llvm::LLVMPassManagerBuilderSetOptLevel(builder, opt as c_uint);
439 llvm::LLVMRustAddBuilderLibraryInfo(builder, llmod);
441 // Use the builder to populate the function/module pass managers.
442 llvm::LLVMPassManagerBuilderPopulateFunctionPassManager(builder, fpm);
443 llvm::LLVMPassManagerBuilderPopulateModulePassManager(builder, mpm);
444 llvm::LLVMPassManagerBuilderDispose(builder);
450 * Name mangling and its relationship to metadata. This is complex. Read
453 * The semantic model of Rust linkage is, broadly, that "there's no global
454 * namespace" between crates. Our aim is to preserve the illusion of this
455 * model despite the fact that it's not *quite* possible to implement on
456 * modern linkers. We initially didn't use system linkers at all, but have
457 * been convinced of their utility.
459 * There are a few issues to handle:
461 * - Linkers operate on a flat namespace, so we have to flatten names.
462 * We do this using the C++ namespace-mangling technique. Foo::bar
465 * - Symbols with the same name but different types need to get different
466 * linkage-names. We do this by hashing a string-encoding of the type into
467 * a fixed-size (currently 16-byte hex) cryptographic hash function (CHF:
468 * we use SHA256) to "prevent collisions". This is not airtight but 16 hex
469 * digits on uniform probability means you're going to need 2**32 same-name
470 * symbols in the same process before you're even hitting birthday-paradox
471 * collision probability.
473 * - Symbols in different crates but with same names "within" the crate need
474 * to get different linkage-names.
476 * - The hash shown in the filename needs to be predictable and stable for
477 * build tooling integration. It also needs to be using a hash function
478 * which is easy to use from Python, make, etc.
480 * So here is what we do:
482 * - Consider the package id; every crate has one (specified with crate_id
483 * attribute). If a package id isn't provided explicitly, we infer a
484 * versionless one from the output name. The version will end up being 0.0
485 * in this case. CNAME and CVERS are taken from this package id. For
486 * example, github.com/mozilla/CNAME#CVERS.
488 * - Define CMH as SHA256(crateid).
490 * - Define CMH8 as the first 8 characters of CMH.
492 * - Compile our crate to lib CNAME-CMH8-CVERS.so
494 * - Define STH(sym) as SHA256(CMH, type_str(sym))
496 * - Suffix a mangled sym with ::STH@CVERS, so that it is unique in the
497 * name, non-name metadata, and type sense, and versioned in the way
498 * system linkers understand.
501 pub fn find_crate_id(attrs: &[ast::Attribute], out_filestem: &str) -> CrateId {
502 match attr::find_crateid(attrs) {
503 None => from_str(out_filestem).unwrap(),
508 pub fn crate_id_hash(crate_id: &CrateId) -> ~str {
509 // This calculates CMH as defined above. Note that we don't use the path of
510 // the crate id in the hash because lookups are only done by (name/vers),
512 let mut s = Sha256::new();
513 s.input_str(crate_id.short_name_with_version());
514 truncated_hash_result(&mut s).slice_to(8).to_owned()
517 pub fn build_link_meta(krate: &ast::Crate, out_filestem: &str) -> LinkMeta {
519 crateid: find_crate_id(krate.attrs.as_slice(), out_filestem),
520 crate_hash: Svh::calculate(krate),
526 fn truncated_hash_result(symbol_hasher: &mut Sha256) -> ~str {
527 let output = symbol_hasher.result_bytes();
528 // 64 bits should be enough to avoid collisions.
529 output.slice_to(8).to_hex()
533 // This calculates STH for a symbol, as defined above
534 fn symbol_hash(tcx: &ty::ctxt, symbol_hasher: &mut Sha256,
535 t: ty::t, link_meta: &LinkMeta) -> ~str {
536 // NB: do *not* use abbrevs here as we want the symbol names
537 // to be independent of one another in the crate.
539 symbol_hasher.reset();
540 symbol_hasher.input_str(link_meta.crateid.name);
541 symbol_hasher.input_str("-");
542 symbol_hasher.input_str(link_meta.crate_hash.as_str());
543 symbol_hasher.input_str("-");
544 symbol_hasher.input_str(encoder::encoded_ty(tcx, t));
545 let mut hash = truncated_hash_result(symbol_hasher);
546 // Prefix with 'h' so that it never blends into adjacent digits
547 hash.unshift_char('h');
551 fn get_symbol_hash(ccx: &CrateContext, t: ty::t) -> ~str {
552 match ccx.type_hashcodes.borrow().find(&t) {
553 Some(h) => return h.to_str(),
557 let mut symbol_hasher = ccx.symbol_hasher.borrow_mut();
558 let hash = symbol_hash(ccx.tcx(), &mut *symbol_hasher, t, &ccx.link_meta);
559 ccx.type_hashcodes.borrow_mut().insert(t, hash.clone());
564 // Name sanitation. LLVM will happily accept identifiers with weird names, but
566 // gas accepts the following characters in symbols: a-z, A-Z, 0-9, ., _, $
567 pub fn sanitize(s: &str) -> ~str {
568 let mut result = ~"";
571 // Escape these with $ sequences
572 '@' => result.push_str("$SP$"),
573 '~' => result.push_str("$UP$"),
574 '*' => result.push_str("$RP$"),
575 '&' => result.push_str("$BP$"),
576 '<' => result.push_str("$LT$"),
577 '>' => result.push_str("$GT$"),
578 '(' => result.push_str("$LP$"),
579 ')' => result.push_str("$RP$"),
580 ',' => result.push_str("$C$"),
582 // '.' doesn't occur in types and functions, so reuse it
584 '-' | ':' => result.push_char('.'),
586 // These are legal symbols
590 | '_' | '.' | '$' => result.push_char(c),
594 char::escape_unicode(c, |c| tstr.push_char(c));
595 result.push_char('$');
596 result.push_str(tstr.slice_from(1));
601 // Underscore-qualify anything that didn't start as an ident.
602 if result.len() > 0u &&
603 result[0] != '_' as u8 &&
604 ! char::is_XID_start(result[0] as char) {
605 return ~"_" + result;
611 pub fn mangle<PI: Iterator<PathElem>>(mut path: PI,
613 vers: Option<&str>) -> ~str {
614 // Follow C++ namespace-mangling style, see
615 // http://en.wikipedia.org/wiki/Name_mangling for more info.
617 // It turns out that on OSX you can actually have arbitrary symbols in
618 // function names (at least when given to LLVM), but this is not possible
619 // when using unix's linker. Perhaps one day when we just use a linker from LLVM
620 // we won't need to do this name mangling. The problem with name mangling is
621 // that it seriously limits the available characters. For example we can't
622 // have things like &T or ~[T] in symbol names when one would theoretically
623 // want them for things like impls of traits on that type.
625 // To be able to work on all platforms and get *some* reasonable output, we
626 // use C++ name-mangling.
628 let mut n = ~"_ZN"; // _Z == Begin name-sequence, N == nested
630 fn push(n: &mut ~str, s: &str) {
631 let sani = sanitize(s);
632 n.push_str(format!("{}{}", sani.len(), sani));
635 // First, connect each component with <len, name> pairs.
637 push(&mut n, token::get_name(e.name()).get().as_slice())
641 Some(s) => push(&mut n, s),
645 Some(s) => push(&mut n, s),
649 n.push_char('E'); // End name-sequence.
653 pub fn exported_name(path: PathElems, hash: &str, vers: &str) -> ~str {
654 // The version will get mangled to have a leading '_', but it makes more
655 // sense to lead with a 'v' b/c this is a version...
656 let vers = if vers.len() > 0 && !char::is_XID_start(vers.char_at(0)) {
662 mangle(path, Some(hash), Some(vers.as_slice()))
665 pub fn mangle_exported_name(ccx: &CrateContext, path: PathElems,
666 t: ty::t, id: ast::NodeId) -> ~str {
667 let mut hash = get_symbol_hash(ccx, t);
669 // Paths can be completely identical for different nodes,
670 // e.g. `fn foo() { { fn a() {} } { fn a() {} } }`, so we
671 // generate unique characters from the node id. For now
672 // hopefully 3 characters is enough to avoid collisions.
673 static EXTRA_CHARS: &'static str =
674 "abcdefghijklmnopqrstuvwxyz\
675 ABCDEFGHIJKLMNOPQRSTUVWXYZ\
678 let extra1 = id % EXTRA_CHARS.len();
679 let id = id / EXTRA_CHARS.len();
680 let extra2 = id % EXTRA_CHARS.len();
681 let id = id / EXTRA_CHARS.len();
682 let extra3 = id % EXTRA_CHARS.len();
683 hash.push_char(EXTRA_CHARS[extra1] as char);
684 hash.push_char(EXTRA_CHARS[extra2] as char);
685 hash.push_char(EXTRA_CHARS[extra3] as char);
687 exported_name(path, hash, ccx.link_meta.crateid.version_or_default())
690 pub fn mangle_internal_name_by_type_and_seq(ccx: &CrateContext,
692 name: &str) -> ~str {
693 let s = ppaux::ty_to_str(ccx.tcx(), t);
694 let path = [PathName(token::intern(s)),
696 let hash = get_symbol_hash(ccx, t);
697 mangle(ast_map::Values(path.iter()), Some(hash.as_slice()), None)
700 pub fn mangle_internal_name_by_path_and_seq(path: PathElems, flav: &str) -> ~str {
701 mangle(path.chain(Some(gensym_name(flav)).move_iter()), None, None)
704 pub fn output_lib_filename(id: &CrateId) -> ~str {
705 format!("{}-{}-{}", id.name, crate_id_hash(id), id.version_or_default())
708 pub fn get_cc_prog(sess: &Session) -> ~str {
709 match sess.opts.cg.linker {
710 Some(ref linker) => return linker.to_owned(),
714 // In the future, FreeBSD will use clang as default compiler.
715 // It would be flexible to use cc (system's default C compiler)
716 // instead of hard-coded gcc.
717 // For win32, there is no cc command, so we add a condition to make it use gcc.
718 match sess.targ_cfg.os {
719 abi::OsWin32 => return ~"gcc",
723 get_system_tool(sess, "cc")
726 pub fn get_ar_prog(sess: &Session) -> ~str {
727 match sess.opts.cg.ar {
728 Some(ref ar) => return ar.to_owned(),
732 get_system_tool(sess, "ar")
735 fn get_system_tool(sess: &Session, tool: &str) -> ~str {
736 match sess.targ_cfg.os {
737 abi::OsAndroid => match sess.opts.cg.android_cross_path {
739 let tool_str = match tool {
743 format!("{}/bin/arm-linux-androideabi-{}", *path, tool_str)
746 sess.fatal(format!("need Android NDK path for the '{}' tool \
747 (-C android-cross-path)", tool))
750 _ => tool.to_owned(),
754 fn remove(sess: &Session, path: &Path) {
755 match fs::unlink(path) {
758 sess.err(format!("failed to remove {}: {}", path.display(), e));
763 /// Perform the linkage portion of the compilation phase. This will generate all
764 /// of the requested outputs for this compilation session.
765 pub fn link_binary(sess: &Session,
766 trans: &CrateTranslation,
767 outputs: &OutputFilenames,
768 id: &CrateId) -> Vec<Path> {
769 let mut out_filenames = Vec::new();
770 for &crate_type in sess.crate_types.borrow().iter() {
771 let out_file = link_binary_output(sess, trans, crate_type, outputs, id);
772 out_filenames.push(out_file);
775 // Remove the temporary object file and metadata if we aren't saving temps
776 if !sess.opts.cg.save_temps {
777 let obj_filename = outputs.temp_path(OutputTypeObject);
778 if !sess.opts.output_types.contains(&OutputTypeObject) {
779 remove(sess, &obj_filename);
781 remove(sess, &obj_filename.with_extension("metadata.o"));
787 fn is_writeable(p: &Path) -> bool {
790 Ok(m) => m.perm & io::UserWrite == io::UserWrite
794 pub fn filename_for_input(sess: &Session, crate_type: session::CrateType,
795 id: &CrateId, out_filename: &Path) -> Path {
796 let libname = output_lib_filename(id);
798 session::CrateTypeRlib => {
799 out_filename.with_filename(format!("lib{}.rlib", libname))
801 session::CrateTypeDylib => {
802 let (prefix, suffix) = match sess.targ_cfg.os {
803 abi::OsWin32 => (win32::DLL_PREFIX, win32::DLL_SUFFIX),
804 abi::OsMacos => (macos::DLL_PREFIX, macos::DLL_SUFFIX),
805 abi::OsLinux => (linux::DLL_PREFIX, linux::DLL_SUFFIX),
806 abi::OsAndroid => (android::DLL_PREFIX, android::DLL_SUFFIX),
807 abi::OsFreebsd => (freebsd::DLL_PREFIX, freebsd::DLL_SUFFIX),
809 out_filename.with_filename(format!("{}{}{}", prefix, libname, suffix))
811 session::CrateTypeStaticlib => {
812 out_filename.with_filename(format!("lib{}.a", libname))
814 session::CrateTypeExecutable => out_filename.clone(),
818 fn link_binary_output(sess: &Session,
819 trans: &CrateTranslation,
820 crate_type: session::CrateType,
821 outputs: &OutputFilenames,
822 id: &CrateId) -> Path {
823 let obj_filename = outputs.temp_path(OutputTypeObject);
824 let out_filename = match outputs.single_output_file {
825 Some(ref file) => file.clone(),
827 let out_filename = outputs.path(OutputTypeExe);
828 filename_for_input(sess, crate_type, id, &out_filename)
832 // Make sure the output and obj_filename are both writeable.
833 // Mac, FreeBSD, and Windows system linkers check this already --
834 // however, the Linux linker will happily overwrite a read-only file.
835 // We should be consistent.
836 let obj_is_writeable = is_writeable(&obj_filename);
837 let out_is_writeable = is_writeable(&out_filename);
838 if !out_is_writeable {
839 sess.fatal(format!("output file {} is not writeable -- check its permissions.",
840 out_filename.display()));
842 else if !obj_is_writeable {
843 sess.fatal(format!("object file {} is not writeable -- check its permissions.",
844 obj_filename.display()));
848 session::CrateTypeRlib => {
849 link_rlib(sess, Some(trans), &obj_filename, &out_filename);
851 session::CrateTypeStaticlib => {
852 link_staticlib(sess, &obj_filename, &out_filename);
854 session::CrateTypeExecutable => {
855 link_natively(sess, false, &obj_filename, &out_filename);
857 session::CrateTypeDylib => {
858 link_natively(sess, true, &obj_filename, &out_filename);
867 // An rlib in its current incarnation is essentially a renamed .a file. The
868 // rlib primarily contains the object file of the crate, but it also contains
869 // all of the object files from native libraries. This is done by unzipping
870 // native libraries and inserting all of the contents into this archive.
871 fn link_rlib<'a>(sess: &'a Session,
872 trans: Option<&CrateTranslation>, // None == no metadata/bytecode
874 out_filename: &Path) -> Archive<'a> {
875 let mut a = Archive::create(sess, out_filename, obj_filename);
877 for &(ref l, kind) in sess.cstore.get_used_libraries().borrow().iter() {
879 cstore::NativeStatic => {
880 a.add_native_library(l.as_slice()).unwrap();
882 cstore::NativeFramework | cstore::NativeUnknown => {}
886 // Note that it is important that we add all of our non-object "magical
887 // files" *after* all of the object files in the archive. The reason for
888 // this is as follows:
890 // * When performing LTO, this archive will be modified to remove
891 // obj_filename from above. The reason for this is described below.
893 // * When the system linker looks at an archive, it will attempt to
894 // determine the architecture of the archive in order to see whether its
897 // The algorithm for this detection is: iterate over the files in the
898 // archive. Skip magical SYMDEF names. Interpret the first file as an
899 // object file. Read architecture from the object file.
901 // * As one can probably see, if "metadata" and "foo.bc" were placed
902 // before all of the objects, then the architecture of this archive would
903 // not be correctly inferred once 'foo.o' is removed.
905 // Basically, all this means is that this code should not move above the
909 // Instead of putting the metadata in an object file section, rlibs
910 // contain the metadata in a separate file. We use a temp directory
911 // here so concurrent builds in the same directory don't try to use
912 // the same filename for metadata (stomping over one another)
913 let tmpdir = TempDir::new("rustc").expect("needs a temp dir");
914 let metadata = tmpdir.path().join(METADATA_FILENAME);
915 match fs::File::create(&metadata).write(trans.metadata
919 sess.err(format!("failed to write {}: {}",
920 metadata.display(), e));
921 sess.abort_if_errors();
924 a.add_file(&metadata, false);
925 remove(sess, &metadata);
927 // For LTO purposes, the bytecode of this library is also inserted
929 let bc = obj_filename.with_extension("bc");
930 let bc_deflated = obj_filename.with_extension("bc.deflate");
931 match fs::File::open(&bc).read_to_end().and_then(|data| {
932 fs::File::create(&bc_deflated).write(flate::deflate_bytes(data).as_slice())
936 sess.err(format!("failed to compress bytecode: {}", e));
937 sess.abort_if_errors()
940 a.add_file(&bc_deflated, false);
941 remove(sess, &bc_deflated);
942 if !sess.opts.cg.save_temps &&
943 !sess.opts.output_types.contains(&OutputTypeBitcode) {
947 // After adding all files to the archive, we need to update the
948 // symbol table of the archive. This currently dies on OSX (see
949 // #11162), and isn't necessary there anyway
950 match sess.targ_cfg.os {
952 _ => { a.update_symbols(); }
961 // Create a static archive
963 // This is essentially the same thing as an rlib, but it also involves adding
964 // all of the upstream crates' objects into the archive. This will slurp in
965 // all of the native libraries of upstream dependencies as well.
967 // Additionally, there's no way for us to link dynamic libraries, so we warn
968 // about all dynamic library dependencies that they're not linked in.
970 // There's no need to include metadata in a static archive, so ensure to not
971 // link in the metadata object file (and also don't prepare the archive with a
973 fn link_staticlib(sess: &Session, obj_filename: &Path, out_filename: &Path) {
974 let mut a = link_rlib(sess, None, obj_filename, out_filename);
975 a.add_native_library("morestack").unwrap();
976 a.add_native_library("compiler-rt").unwrap();
978 let crates = sess.cstore.get_used_crates(cstore::RequireStatic);
979 for &(cnum, ref path) in crates.iter() {
980 let name = sess.cstore.get_crate_data(cnum).name.clone();
981 let p = match *path {
982 Some(ref p) => p.clone(), None => {
983 sess.err(format!("could not find rlib for: `{}`", name));
987 a.add_rlib(&p, name, sess.lto()).unwrap();
988 let native_libs = csearch::get_native_libraries(&sess.cstore, cnum);
989 for &(kind, ref lib) in native_libs.iter() {
990 let name = match kind {
991 cstore::NativeStatic => "static library",
992 cstore::NativeUnknown => "library",
993 cstore::NativeFramework => "framework",
995 sess.warn(format!("unlinked native {}: {}", name, *lib));
1000 // Create a dynamic library or executable
1002 // This will invoke the system linker/cc to create the resulting file. This
1003 // links to all upstream files as well.
1004 fn link_natively(sess: &Session, dylib: bool, obj_filename: &Path,
1005 out_filename: &Path) {
1006 let tmpdir = TempDir::new("rustc").expect("needs a temp dir");
1007 // The invocations of cc share some flags across platforms
1008 let cc_prog = get_cc_prog(sess);
1009 let mut cc_args = sess.targ_cfg.target_strs.cc_args.clone();
1010 cc_args.push_all_move(link_args(sess, dylib, tmpdir.path(),
1011 obj_filename, out_filename));
1012 if (sess.opts.debugging_opts & session::PRINT_LINK_ARGS) != 0 {
1013 println!("{} link args: '{}'", cc_prog, cc_args.connect("' '"));
1016 // May have not found libraries in the right formats.
1017 sess.abort_if_errors();
1019 // Invoke the system linker
1020 debug!("{} {}", cc_prog, cc_args.connect(" "));
1021 let prog = time(sess.time_passes(), "running linker", (), |()|
1022 Process::output(cc_prog, cc_args.as_slice()));
1025 if !prog.status.success() {
1026 sess.err(format!("linking with `{}` failed: {}", cc_prog, prog.status));
1027 sess.note(format!("{} arguments: '{}'", cc_prog, cc_args.connect("' '")));
1028 sess.note(str::from_utf8_owned(prog.error + prog.output).unwrap());
1029 sess.abort_if_errors();
1033 sess.err(format!("could not exec the linker `{}`: {}", cc_prog, e));
1034 sess.abort_if_errors();
1039 // On OSX, debuggers need this utility to get run to do some munging of
1041 if sess.targ_cfg.os == abi::OsMacos && (sess.opts.debuginfo != NoDebugInfo) {
1042 // FIXME (#9639): This needs to handle non-utf8 paths
1043 match Process::status("dsymutil",
1044 [out_filename.as_str().unwrap().to_owned()]) {
1047 sess.err(format!("failed to run dsymutil: {}", e));
1048 sess.abort_if_errors();
1054 fn link_args(sess: &Session,
1057 obj_filename: &Path,
1058 out_filename: &Path) -> Vec<~str> {
1060 // The default library location, we need this to find the runtime.
1061 // The location of crates will be determined as needed.
1062 // FIXME (#9639): This needs to handle non-utf8 paths
1063 let lib_path = sess.filesearch().get_target_lib_path();
1064 let stage: ~str = ~"-L" + lib_path.as_str().unwrap();
1066 let mut args = vec!(stage);
1068 // FIXME (#9639): This needs to handle non-utf8 paths
1070 ~"-o", out_filename.as_str().unwrap().to_owned(),
1071 obj_filename.as_str().unwrap().to_owned()]);
1073 // Stack growth requires statically linking a __morestack function. Note
1074 // that this is listed *before* all other libraries, even though it may be
1075 // used to resolve symbols in other libraries. The only case that this
1076 // wouldn't be pulled in by the object file is if the object file had no
1079 // If we're building an executable, there must be at least one function (the
1080 // main function), and if we're building a dylib then we don't need it for
1081 // later libraries because they're all dylibs (not rlibs).
1083 // I'm honestly not entirely sure why this needs to come first. Apparently
1084 // the --as-needed flag above sometimes strips out libstd from the command
1085 // line, but inserting this farther to the left makes the
1086 // "rust_stack_exhausted" symbol an outstanding undefined symbol, which
1087 // flags libstd as a required library (or whatever provides the symbol).
1088 args.push(~"-lmorestack");
1090 // When linking a dynamic library, we put the metadata into a section of the
1091 // executable. This metadata is in a separate object file from the main
1092 // object file, so we link that in here.
1094 let metadata = obj_filename.with_extension("metadata.o");
1095 args.push(metadata.as_str().unwrap().to_owned());
1098 // We want to prevent the compiler from accidentally leaking in any system
1099 // libraries, so we explicitly ask gcc to not link to any libraries by
1100 // default. Note that this does not happen for windows because windows pulls
1101 // in some large number of libraries and I couldn't quite figure out which
1102 // subset we wanted.
1104 // FIXME(#11937) we should invoke the system linker directly
1105 if sess.targ_cfg.os != abi::OsWin32 {
1106 args.push(~"-nodefaultlibs");
1109 if sess.targ_cfg.os == abi::OsLinux {
1110 // GNU-style linkers will use this to omit linking to libraries which
1111 // don't actually fulfill any relocations, but only for libraries which
1112 // follow this flag. Thus, use it before specifying libraries to link to.
1113 args.push(~"-Wl,--as-needed");
1115 // GNU-style linkers support optimization with -O. --gc-sections
1116 // removes metadata and potentially other useful things, so don't
1117 // include it. GNU ld doesn't need a numeric argument, but other linkers
1119 if sess.opts.optimize == session::Default ||
1120 sess.opts.optimize == session::Aggressive {
1121 args.push(~"-Wl,-O1");
1125 if sess.targ_cfg.os == abi::OsWin32 {
1126 // Make sure that we link to the dynamic libgcc, otherwise cross-module
1127 // DWARF stack unwinding will not work.
1128 // This behavior may be overridden by --link-args "-static-libgcc"
1129 args.push(~"-shared-libgcc");
1132 if sess.targ_cfg.os == abi::OsAndroid {
1133 // Many of the symbols defined in compiler-rt are also defined in libgcc.
1134 // Android linker doesn't like that by default.
1135 args.push(~"-Wl,--allow-multiple-definition");
1138 // Take careful note of the ordering of the arguments we pass to the linker
1139 // here. Linkers will assume that things on the left depend on things to the
1140 // right. Things on the right cannot depend on things on the left. This is
1141 // all formally implemented in terms of resolving symbols (libs on the right
1142 // resolve unknown symbols of libs on the left, but not vice versa).
1144 // For this reason, we have organized the arguments we pass to the linker as
1147 // 1. The local object that LLVM just generated
1148 // 2. Upstream rust libraries
1149 // 3. Local native libraries
1150 // 4. Upstream native libraries
1152 // This is generally fairly natural, but some may expect 2 and 3 to be
1153 // swapped. The reason that all native libraries are put last is that it's
1154 // not recommended for a native library to depend on a symbol from a rust
1155 // crate. If this is the case then a staticlib crate is recommended, solving
1158 // Additionally, it is occasionally the case that upstream rust libraries
1159 // depend on a local native library. In the case of libraries such as
1160 // lua/glfw/etc the name of the library isn't the same across all platforms,
1161 // so only the consumer crate of a library knows the actual name. This means
1162 // that downstream crates will provide the #[link] attribute which upstream
1163 // crates will depend on. Hence local native libraries are after out
1164 // upstream rust crates.
1166 // In theory this means that a symbol in an upstream native library will be
1167 // shadowed by a local native library when it wouldn't have been before, but
1168 // this kind of behavior is pretty platform specific and generally not
1169 // recommended anyway, so I don't think we're shooting ourself in the foot
1171 add_upstream_rust_crates(&mut args, sess, dylib, tmpdir);
1172 add_local_native_libraries(&mut args, sess);
1173 add_upstream_native_libraries(&mut args, sess);
1175 // # Telling the linker what we're doing
1178 // On mac we need to tell the linker to let this library be rpathed
1179 if sess.targ_cfg.os == abi::OsMacos {
1180 args.push(~"-dynamiclib");
1181 args.push(~"-Wl,-dylib");
1182 // FIXME (#9639): This needs to handle non-utf8 paths
1183 if !sess.opts.cg.no_rpath {
1184 args.push(~"-Wl,-install_name,@rpath/" +
1185 out_filename.filename_str().unwrap());
1188 args.push(~"-shared")
1192 if sess.targ_cfg.os == abi::OsFreebsd {
1193 args.push_all([~"-L/usr/local/lib",
1194 ~"-L/usr/local/lib/gcc46",
1195 ~"-L/usr/local/lib/gcc44"]);
1198 // FIXME (#2397): At some point we want to rpath our guesses as to
1199 // where extern libraries might live, based on the
1200 // addl_lib_search_paths
1201 if !sess.opts.cg.no_rpath {
1202 args.push_all(rpath::get_rpath_flags(sess, out_filename).as_slice());
1205 // compiler-rt contains implementations of low-level LLVM helpers. This is
1206 // used to resolve symbols from the object file we just created, as well as
1207 // any system static libraries that may be expecting gcc instead. Most
1208 // symbols in libgcc also appear in compiler-rt.
1210 // This is the end of the command line, so this library is used to resolve
1211 // *all* undefined symbols in all other libraries, and this is intentional.
1212 args.push(~"-lcompiler-rt");
1214 // Finally add all the linker arguments provided on the command line along
1215 // with any #[link_args] attributes found inside the crate
1216 args.push_all(sess.opts.cg.link_args.as_slice());
1217 for arg in sess.cstore.get_used_link_args().borrow().iter() {
1218 args.push(arg.clone());
1223 // # Native library linking
1225 // User-supplied library search paths (-L on the command line). These are
1226 // the same paths used to find Rust crates, so some of them may have been
1227 // added already by the previous crate linking code. This only allows them
1228 // to be found at compile time so it is still entirely up to outside
1229 // forces to make sure that library can be found at runtime.
1231 // Also note that the native libraries linked here are only the ones located
1232 // in the current crate. Upstream crates with native library dependencies
1233 // may have their native library pulled in above.
1234 fn add_local_native_libraries(args: &mut Vec<~str>, sess: &Session) {
1235 for path in sess.opts.addl_lib_search_paths.borrow().iter() {
1236 // FIXME (#9639): This needs to handle non-utf8 paths
1237 args.push("-L" + path.as_str().unwrap().to_owned());
1240 let rustpath = filesearch::rust_path();
1241 for path in rustpath.iter() {
1242 // FIXME (#9639): This needs to handle non-utf8 paths
1243 args.push("-L" + path.as_str().unwrap().to_owned());
1246 for &(ref l, kind) in sess.cstore.get_used_libraries().borrow().iter() {
1248 cstore::NativeUnknown | cstore::NativeStatic => {
1249 args.push("-l" + *l);
1251 cstore::NativeFramework => {
1252 args.push(~"-framework");
1253 args.push(l.to_owned());
1259 // # Rust Crate linking
1261 // Rust crates are not considered at all when creating an rlib output. All
1262 // dependencies will be linked when producing the final output (instead of
1263 // the intermediate rlib version)
1264 fn add_upstream_rust_crates(args: &mut Vec<~str>, sess: &Session,
1265 dylib: bool, tmpdir: &Path) {
1267 // As a limitation of the current implementation, we require that everything
1268 // must be static or everything must be dynamic. The reasons for this are a
1269 // little subtle, but as with staticlibs and rlibs, the goal is to prevent
1270 // duplicate copies of the same library showing up. For example, a static
1271 // immediate dependency might show up as an upstream dynamic dependency and
1272 // we currently have no way of knowing that. We know that all dynamic
1273 // libraries require dynamic dependencies (see above), so it's satisfactory
1274 // to include either all static libraries or all dynamic libraries.
1276 // With this limitation, we expose a compiler default linkage type and an
1277 // option to reverse that preference. The current behavior looks like:
1279 // * If a dylib is being created, upstream dependencies must be dylibs
1280 // * If nothing else is specified, static linking is preferred
1281 // * If the -C prefer-dynamic flag is given, dynamic linking is preferred
1282 // * If one form of linking fails, the second is also attempted
1283 // * If both forms fail, then we emit an error message
1285 let dynamic = get_deps(&sess.cstore, cstore::RequireDynamic);
1286 let statik = get_deps(&sess.cstore, cstore::RequireStatic);
1287 match (dynamic, statik, sess.opts.cg.prefer_dynamic, dylib) {
1288 (_, Some(deps), false, false) => {
1289 add_static_crates(args, sess, tmpdir, deps)
1292 (None, Some(deps), true, false) => {
1293 // If you opted in to dynamic linking and we decided to emit a
1294 // static output, you should probably be notified of such an event!
1295 sess.warn("dynamic linking was preferred, but dependencies \
1296 could not all be found in an dylib format.");
1297 sess.warn("linking statically instead, using rlibs");
1298 add_static_crates(args, sess, tmpdir, deps)
1301 (Some(deps), _, _, _) => add_dynamic_crates(args, sess, deps),
1303 (None, _, _, true) => {
1304 sess.err("dylib output requested, but some depenencies could not \
1305 be found in the dylib format");
1306 let deps = sess.cstore.get_used_crates(cstore::RequireDynamic);
1307 for (cnum, path) in deps.move_iter() {
1308 if path.is_some() { continue }
1309 let name = sess.cstore.get_crate_data(cnum).name.clone();
1310 sess.note(format!("dylib not found: {}", name));
1314 (None, None, pref, false) => {
1315 let (pref, name) = if pref {
1316 sess.err("dynamic linking is preferred, but dependencies were \
1317 not found in either dylib or rlib format");
1318 (cstore::RequireDynamic, "dylib")
1320 sess.err("dependencies were not all found in either dylib or \
1322 (cstore::RequireStatic, "rlib")
1324 sess.note(format!("dependencies not found in the `{}` format",
1326 for (cnum, path) in sess.cstore.get_used_crates(pref).move_iter() {
1327 if path.is_some() { continue }
1328 let name = sess.cstore.get_crate_data(cnum).name.clone();
1334 // Converts a library file-stem into a cc -l argument
1335 fn unlib(config: &session::Config, stem: &str) -> ~str {
1336 if stem.starts_with("lib") && config.os != abi::OsWin32 {
1337 stem.slice(3, stem.len()).to_owned()
1343 // Attempts to find all dependencies with a certain linkage preference,
1344 // returning `None` if not all libraries could be found with that
1346 fn get_deps(cstore: &cstore::CStore, preference: cstore::LinkagePreference)
1347 -> Option<Vec<(ast::CrateNum, Path)> >
1349 let crates = cstore.get_used_crates(preference);
1350 if crates.iter().all(|&(_, ref p)| p.is_some()) {
1351 Some(crates.move_iter().map(|(a, b)| (a, b.unwrap())).collect())
1357 // Adds the static "rlib" versions of all crates to the command line.
1358 fn add_static_crates(args: &mut Vec<~str>, sess: &Session, tmpdir: &Path,
1359 crates: Vec<(ast::CrateNum, Path)>) {
1360 for (cnum, cratepath) in crates.move_iter() {
1361 // When performing LTO on an executable output, all of the
1362 // bytecode from the upstream libraries has already been
1363 // included in our object file output. We need to modify all of
1364 // the upstream archives to remove their corresponding object
1365 // file to make sure we don't pull the same code in twice.
1367 // We must continue to link to the upstream archives to be sure
1368 // to pull in native static dependencies. As the final caveat,
1369 // on linux it is apparently illegal to link to a blank archive,
1370 // so if an archive no longer has any object files in it after
1371 // we remove `lib.o`, then don't link against it at all.
1373 // If we're not doing LTO, then our job is simply to just link
1374 // against the archive.
1376 let name = sess.cstore.get_crate_data(cnum).name.clone();
1377 time(sess.time_passes(), format!("altering {}.rlib", name),
1379 let dst = tmpdir.join(cratepath.filename().unwrap());
1380 match fs::copy(&cratepath, &dst) {
1383 sess.err(format!("failed to copy {} to {}: {}",
1384 cratepath.display(),
1387 sess.abort_if_errors();
1390 let dst_str = dst.as_str().unwrap().to_owned();
1391 let mut archive = Archive::open(sess, dst);
1392 archive.remove_file(format!("{}.o", name));
1393 let files = archive.files();
1394 if files.iter().any(|s| s.ends_with(".o")) {
1399 args.push(cratepath.as_str().unwrap().to_owned());
1404 // Same thing as above, but for dynamic crates instead of static crates.
1405 fn add_dynamic_crates(args: &mut Vec<~str>, sess: &Session,
1406 crates: Vec<(ast::CrateNum, Path)> ) {
1407 // If we're performing LTO, then it should have been previously required
1408 // that all upstream rust dependencies were available in an rlib format.
1409 assert!(!sess.lto());
1411 for (_, cratepath) in crates.move_iter() {
1412 // Just need to tell the linker about where the library lives and
1414 let dir = cratepath.dirname_str().unwrap();
1415 if !dir.is_empty() { args.push("-L" + dir); }
1416 let libarg = unlib(&sess.targ_cfg, cratepath.filestem_str().unwrap());
1417 args.push("-l" + libarg);
1422 // Link in all of our upstream crates' native dependencies. Remember that
1423 // all of these upstream native depenencies are all non-static
1424 // dependencies. We've got two cases then:
1426 // 1. The upstream crate is an rlib. In this case we *must* link in the
1427 // native dependency because the rlib is just an archive.
1429 // 2. The upstream crate is a dylib. In order to use the dylib, we have to
1430 // have the dependency present on the system somewhere. Thus, we don't
1431 // gain a whole lot from not linking in the dynamic dependency to this
1434 // The use case for this is a little subtle. In theory the native
1435 // dependencies of a crate a purely an implementation detail of the crate
1436 // itself, but the problem arises with generic and inlined functions. If a
1437 // generic function calls a native function, then the generic function must
1438 // be instantiated in the target crate, meaning that the native symbol must
1439 // also be resolved in the target crate.
1440 fn add_upstream_native_libraries(args: &mut Vec<~str>, sess: &Session) {
1441 let cstore = &sess.cstore;
1442 cstore.iter_crate_data(|cnum, _| {
1443 let libs = csearch::get_native_libraries(cstore, cnum);
1444 for &(kind, ref lib) in libs.iter() {
1446 cstore::NativeUnknown => args.push("-l" + *lib),
1447 cstore::NativeFramework => {
1448 args.push(~"-framework");
1449 args.push(lib.to_owned());
1451 cstore::NativeStatic => {
1452 sess.bug("statics shouldn't be propagated");