1 use super::symbol_export;
2 use super::command::Command;
5 use rustc_data_structures::fx::FxHashMap;
6 use std::ffi::{OsStr, OsString};
7 use std::fs::{self, File};
8 use std::io::prelude::*;
9 use std::io::{self, BufWriter};
10 use std::path::{Path, PathBuf};
12 use rustc::hir::def_id::{LOCAL_CRATE, CrateNum};
13 use rustc::middle::dependency_format::Linkage;
14 use rustc::session::Session;
15 use rustc::session::config::{self, CrateType, OptLevel, DebugInfo,
16 LinkerPluginLto, Lto};
17 use rustc::ty::TyCtxt;
18 use rustc_target::spec::{LinkerFlavor, LldFlavor};
19 use serialize::{json, Encoder};
21 /// For all the linkers we support, and information they might
22 /// need out of the shared crate context before we get rid of it.
23 pub struct LinkerInfo {
24 exports: FxHashMap<CrateType, Vec<String>>,
28 pub fn new(tcx: TyCtxt<'_, '_, '_>) -> LinkerInfo {
30 exports: tcx.sess.crate_types.borrow().iter().map(|&c| {
31 (c, exported_symbols(tcx, c))
42 ) -> Box<dyn Linker+'a> {
44 LinkerFlavor::Lld(LldFlavor::Link) |
45 LinkerFlavor::Msvc => {
59 LinkerFlavor::Gcc => {
70 LinkerFlavor::Lld(LldFlavor::Ld) |
71 LinkerFlavor::Lld(LldFlavor::Ld64) |
83 LinkerFlavor::Lld(LldFlavor::Wasm) => {
84 Box::new(WasmLd::new(cmd, sess, self)) as Box<dyn Linker>
87 LinkerFlavor::PtxLinker => {
88 Box::new(PtxLinker { cmd, sess }) as Box<dyn Linker>
94 /// Linker abstraction used by `back::link` to build up the command to invoke a
97 /// This trait is the total list of requirements needed by `back::link` and
98 /// represents the meaning of each option being passed down. This trait is then
99 /// used to dispatch on whether a GNU-like linker (generally `ld.exe`) or an
100 /// MSVC linker (e.g., `link.exe`) is being used.
102 fn link_dylib(&mut self, lib: &str);
103 fn link_rust_dylib(&mut self, lib: &str, path: &Path);
104 fn link_framework(&mut self, framework: &str);
105 fn link_staticlib(&mut self, lib: &str);
106 fn link_rlib(&mut self, lib: &Path);
107 fn link_whole_rlib(&mut self, lib: &Path);
108 fn link_whole_staticlib(&mut self, lib: &str, search_path: &[PathBuf]);
109 fn include_path(&mut self, path: &Path);
110 fn framework_path(&mut self, path: &Path);
111 fn output_filename(&mut self, path: &Path);
112 fn add_object(&mut self, path: &Path);
113 fn gc_sections(&mut self, keep_metadata: bool);
114 fn position_independent_executable(&mut self);
115 fn no_position_independent_executable(&mut self);
116 fn full_relro(&mut self);
117 fn partial_relro(&mut self);
118 fn no_relro(&mut self);
119 fn optimize(&mut self);
120 fn pgo_gen(&mut self);
121 fn debuginfo(&mut self);
122 fn no_default_libraries(&mut self);
123 fn build_dylib(&mut self, out_filename: &Path);
124 fn build_static_executable(&mut self);
125 fn args(&mut self, args: &[String]);
126 fn export_symbols(&mut self, tmpdir: &Path, crate_type: CrateType);
127 fn subsystem(&mut self, subsystem: &str);
128 fn group_start(&mut self);
129 fn group_end(&mut self);
130 fn linker_plugin_lto(&mut self);
131 // Should have been finalize(self), but we don't support self-by-value on trait objects (yet?).
132 fn finalize(&mut self) -> Command;
135 pub struct GccLinker<'a> {
138 info: &'a LinkerInfo,
139 hinted_static: bool, // Keeps track of the current hinting mode.
145 impl<'a> GccLinker<'a> {
146 /// Argument that must be passed *directly* to the linker
148 /// These arguments need to be prepended with `-Wl`, when a GCC-style linker is used.
149 fn linker_arg<S>(&mut self, arg: S) -> &mut Self
150 where S: AsRef<OsStr>
153 let mut os = OsString::from("-Wl,");
154 os.push(arg.as_ref());
162 fn takes_hints(&self) -> bool {
163 // Really this function only returns true if the underlying linker
164 // configured for a compiler is binutils `ld.bfd` and `ld.gold`. We
165 // don't really have a foolproof way to detect that, so rule out some
166 // platforms where currently this is guaranteed to *not* be the case:
168 // * On OSX they have their own linker, not binutils'
169 // * For WebAssembly the only functional linker is LLD, which doesn't
170 // support hint flags
171 !self.sess.target.target.options.is_like_osx &&
172 self.sess.target.target.arch != "wasm32"
175 // Some platforms take hints about whether a library is static or dynamic.
176 // For those that support this, we ensure we pass the option if the library
177 // was flagged "static" (most defaults are dynamic) to ensure that if
178 // libfoo.a and libfoo.so both exist that the right one is chosen.
179 fn hint_static(&mut self) {
180 if !self.takes_hints() { return }
181 if !self.hinted_static {
182 self.linker_arg("-Bstatic");
183 self.hinted_static = true;
187 fn hint_dynamic(&mut self) {
188 if !self.takes_hints() { return }
189 if self.hinted_static {
190 self.linker_arg("-Bdynamic");
191 self.hinted_static = false;
195 fn push_linker_plugin_lto_args(&mut self, plugin_path: Option<&OsStr>) {
196 if let Some(plugin_path) = plugin_path {
197 let mut arg = OsString::from("-plugin=");
198 arg.push(plugin_path);
199 self.linker_arg(&arg);
202 let opt_level = match self.sess.opts.optimize {
203 config::OptLevel::No => "O0",
204 config::OptLevel::Less => "O1",
205 config::OptLevel::Default => "O2",
206 config::OptLevel::Aggressive => "O3",
207 config::OptLevel::Size => "Os",
208 config::OptLevel::SizeMin => "Oz",
211 self.linker_arg(&format!("-plugin-opt={}", opt_level));
212 let target_cpu = self.target_cpu;
213 self.linker_arg(&format!("-plugin-opt=mcpu={}", target_cpu));
217 impl<'a> Linker for GccLinker<'a> {
218 fn link_dylib(&mut self, lib: &str) { self.hint_dynamic(); self.cmd.arg(format!("-l{}", lib)); }
219 fn link_staticlib(&mut self, lib: &str) {
220 self.hint_static(); self.cmd.arg(format!("-l{}", lib));
222 fn link_rlib(&mut self, lib: &Path) { self.hint_static(); self.cmd.arg(lib); }
223 fn include_path(&mut self, path: &Path) { self.cmd.arg("-L").arg(path); }
224 fn framework_path(&mut self, path: &Path) { self.cmd.arg("-F").arg(path); }
225 fn output_filename(&mut self, path: &Path) { self.cmd.arg("-o").arg(path); }
226 fn add_object(&mut self, path: &Path) { self.cmd.arg(path); }
227 fn position_independent_executable(&mut self) { self.cmd.arg("-pie"); }
228 fn no_position_independent_executable(&mut self) { self.cmd.arg("-no-pie"); }
229 fn full_relro(&mut self) { self.linker_arg("-zrelro"); self.linker_arg("-znow"); }
230 fn partial_relro(&mut self) { self.linker_arg("-zrelro"); }
231 fn no_relro(&mut self) { self.linker_arg("-znorelro"); }
232 fn build_static_executable(&mut self) { self.cmd.arg("-static"); }
233 fn args(&mut self, args: &[String]) { self.cmd.args(args); }
235 fn link_rust_dylib(&mut self, lib: &str, _path: &Path) {
237 self.cmd.arg(format!("-l{}", lib));
240 fn link_framework(&mut self, framework: &str) {
242 self.cmd.arg("-framework").arg(framework);
245 // Here we explicitly ask that the entire archive is included into the
246 // result artifact. For more details see #15460, but the gist is that
247 // the linker will strip away any unused objects in the archive if we
248 // don't otherwise explicitly reference them. This can occur for
249 // libraries which are just providing bindings, libraries with generic
251 fn link_whole_staticlib(&mut self, lib: &str, search_path: &[PathBuf]) {
253 let target = &self.sess.target.target;
254 if !target.options.is_like_osx {
255 self.linker_arg("--whole-archive").cmd.arg(format!("-l{}", lib));
256 self.linker_arg("--no-whole-archive");
258 // -force_load is the macOS equivalent of --whole-archive, but it
259 // involves passing the full path to the library to link.
260 self.linker_arg("-force_load");
261 let lib = archive::find_library(lib, search_path, &self.sess);
262 self.linker_arg(&lib);
266 fn link_whole_rlib(&mut self, lib: &Path) {
268 if self.sess.target.target.options.is_like_osx {
269 self.linker_arg("-force_load");
270 self.linker_arg(&lib);
272 self.linker_arg("--whole-archive").cmd.arg(lib);
273 self.linker_arg("--no-whole-archive");
277 fn gc_sections(&mut self, keep_metadata: bool) {
278 // The dead_strip option to the linker specifies that functions and data
279 // unreachable by the entry point will be removed. This is quite useful
280 // with Rust's compilation model of compiling libraries at a time into
281 // one object file. For example, this brings hello world from 1.7MB to
284 // Note that this is done for both executables and dynamic libraries. We
285 // won't get much benefit from dylibs because LLVM will have already
286 // stripped away as much as it could. This has not been seen to impact
287 // link times negatively.
289 // -dead_strip can't be part of the pre_link_args because it's also used
290 // for partial linking when using multiple codegen units (-r). So we
292 if self.sess.target.target.options.is_like_osx {
293 self.linker_arg("-dead_strip");
294 } else if self.sess.target.target.options.is_like_solaris {
295 self.linker_arg("-zignore");
297 // If we're building a dylib, we don't use --gc-sections because LLVM
298 // has already done the best it can do, and we also don't want to
299 // eliminate the metadata. If we're building an executable, however,
300 // --gc-sections drops the size of hello world from 1.8MB to 597K, a 67%
302 } else if !keep_metadata {
303 self.linker_arg("--gc-sections");
307 fn optimize(&mut self) {
308 if !self.sess.target.target.options.linker_is_gnu { return }
310 // GNU-style linkers support optimization with -O. GNU ld doesn't
311 // need a numeric argument, but other linkers do.
312 if self.sess.opts.optimize == config::OptLevel::Default ||
313 self.sess.opts.optimize == config::OptLevel::Aggressive {
314 self.linker_arg("-O1");
318 fn pgo_gen(&mut self) {
319 if !self.sess.target.target.options.linker_is_gnu { return }
321 // If we're doing PGO generation stuff and on a GNU-like linker, use the
322 // "-u" flag to properly pull in the profiler runtime bits.
324 // This is because LLVM otherwise won't add the needed initialization
325 // for us on Linux (though the extra flag should be harmless if it
328 // See https://reviews.llvm.org/D14033 and https://reviews.llvm.org/D14030.
330 // Though it may be worth to try to revert those changes upstream, since
331 // the overhead of the initialization should be minor.
333 self.cmd.arg("__llvm_profile_runtime");
336 fn debuginfo(&mut self) {
337 if let DebugInfo::None = self.sess.opts.debuginfo {
338 // If we are building without debuginfo enabled and we were called with
339 // `-Zstrip-debuginfo-if-disabled=yes`, tell the linker to strip any debuginfo
340 // found when linking to get rid of symbols from libstd.
341 if let Some(true) = self.sess.opts.debugging_opts.strip_debuginfo_if_disabled {
342 self.linker_arg("-S");
347 fn no_default_libraries(&mut self) {
349 self.cmd.arg("-nodefaultlibs");
353 fn build_dylib(&mut self, out_filename: &Path) {
354 // On mac we need to tell the linker to let this library be rpathed
355 if self.sess.target.target.options.is_like_osx {
356 self.cmd.arg("-dynamiclib");
357 self.linker_arg("-dylib");
359 // Note that the `osx_rpath_install_name` option here is a hack
360 // purely to support rustbuild right now, we should get a more
361 // principled solution at some point to force the compiler to pass
362 // the right `-Wl,-install_name` with an `@rpath` in it.
363 if self.sess.opts.cg.rpath || self.sess.opts.debugging_opts.osx_rpath_install_name {
364 self.linker_arg("-install_name");
365 let mut v = OsString::from("@rpath/");
366 v.push(out_filename.file_name().unwrap());
370 self.cmd.arg("-shared");
374 fn export_symbols(&mut self, tmpdir: &Path, crate_type: CrateType) {
375 // If we're compiling a dylib, then we let symbol visibility in object
376 // files to take care of whether they're exported or not.
378 // If we're compiling a cdylib, however, we manually create a list of
379 // exported symbols to ensure we don't expose any more. The object files
380 // have far more public symbols than we actually want to export, so we
381 // hide them all here.
382 if crate_type == CrateType::Dylib ||
383 crate_type == CrateType::ProcMacro {
387 // Symbol visibility takes care of this for the WebAssembly.
388 // Additionally the only known linker, LLD, doesn't support the script
389 // arguments just yet
390 if self.sess.target.target.arch == "wasm32" {
394 let mut arg = OsString::new();
395 let path = tmpdir.join("list");
397 debug!("EXPORTED SYMBOLS:");
399 if self.sess.target.target.options.is_like_osx {
400 // Write a plain, newline-separated list of symbols
401 let res: io::Result<()> = try {
402 let mut f = BufWriter::new(File::create(&path)?);
403 for sym in self.info.exports[&crate_type].iter() {
405 writeln!(f, "_{}", sym)?;
408 if let Err(e) = res {
409 self.sess.fatal(&format!("failed to write lib.def file: {}", e));
412 // Write an LD version script
413 let res: io::Result<()> = try {
414 let mut f = BufWriter::new(File::create(&path)?);
415 writeln!(f, "{{\n global:")?;
416 for sym in self.info.exports[&crate_type].iter() {
418 writeln!(f, " {};", sym)?;
420 writeln!(f, "\n local:\n *;\n}};")?;
422 if let Err(e) = res {
423 self.sess.fatal(&format!("failed to write version script: {}", e));
427 if self.sess.target.target.options.is_like_osx {
431 arg.push("-exported_symbols_list,");
432 } else if self.sess.target.target.options.is_like_solaris {
441 arg.push("--version-script=");
448 fn subsystem(&mut self, subsystem: &str) {
449 self.linker_arg("--subsystem");
450 self.linker_arg(&subsystem);
453 fn finalize(&mut self) -> Command {
454 self.hint_dynamic(); // Reset to default before returning the composed command line.
456 ::std::mem::replace(&mut self.cmd, Command::new(""))
459 fn group_start(&mut self) {
460 if self.takes_hints() {
461 self.linker_arg("--start-group");
465 fn group_end(&mut self) {
466 if self.takes_hints() {
467 self.linker_arg("--end-group");
471 fn linker_plugin_lto(&mut self) {
472 match self.sess.opts.cg.linker_plugin_lto {
473 LinkerPluginLto::Disabled => {
476 LinkerPluginLto::LinkerPluginAuto => {
477 self.push_linker_plugin_lto_args(None);
479 LinkerPluginLto::LinkerPlugin(ref path) => {
480 self.push_linker_plugin_lto_args(Some(path.as_os_str()));
486 pub struct MsvcLinker<'a> {
492 impl<'a> Linker for MsvcLinker<'a> {
493 fn link_rlib(&mut self, lib: &Path) { self.cmd.arg(lib); }
494 fn add_object(&mut self, path: &Path) { self.cmd.arg(path); }
495 fn args(&mut self, args: &[String]) { self.cmd.args(args); }
497 fn build_dylib(&mut self, out_filename: &Path) {
498 self.cmd.arg("/DLL");
499 let mut arg: OsString = "/IMPLIB:".into();
500 arg.push(out_filename.with_extension("dll.lib"));
504 fn build_static_executable(&mut self) {
508 fn gc_sections(&mut self, _keep_metadata: bool) {
509 // MSVC's ICF (Identical COMDAT Folding) link optimization is
510 // slow for Rust and thus we disable it by default when not in
511 // optimization build.
512 if self.sess.opts.optimize != config::OptLevel::No {
513 self.cmd.arg("/OPT:REF,ICF");
515 // It is necessary to specify NOICF here, because /OPT:REF
516 // implies ICF by default.
517 self.cmd.arg("/OPT:REF,NOICF");
521 fn link_dylib(&mut self, lib: &str) {
522 self.cmd.arg(&format!("{}.lib", lib));
525 fn link_rust_dylib(&mut self, lib: &str, path: &Path) {
526 // When producing a dll, the MSVC linker may not actually emit a
527 // `foo.lib` file if the dll doesn't actually export any symbols, so we
528 // check to see if the file is there and just omit linking to it if it's
530 let name = format!("{}.dll.lib", lib);
531 if fs::metadata(&path.join(&name)).is_ok() {
536 fn link_staticlib(&mut self, lib: &str) {
537 self.cmd.arg(&format!("{}.lib", lib));
540 fn position_independent_executable(&mut self) {
544 fn no_position_independent_executable(&mut self) {
548 fn full_relro(&mut self) {
552 fn partial_relro(&mut self) {
556 fn no_relro(&mut self) {
560 fn no_default_libraries(&mut self) {
561 // Currently we don't pass the /NODEFAULTLIB flag to the linker on MSVC
562 // as there's been trouble in the past of linking the C++ standard
563 // library required by LLVM. This likely needs to happen one day, but
564 // in general Windows is also a more controlled environment than
565 // Unix, so it's not necessarily as critical that this be implemented.
567 // Note that there are also some licensing worries about statically
568 // linking some libraries which require a specific agreement, so it may
569 // not ever be possible for us to pass this flag.
572 fn include_path(&mut self, path: &Path) {
573 let mut arg = OsString::from("/LIBPATH:");
578 fn output_filename(&mut self, path: &Path) {
579 let mut arg = OsString::from("/OUT:");
584 fn framework_path(&mut self, _path: &Path) {
585 bug!("frameworks are not supported on windows")
587 fn link_framework(&mut self, _framework: &str) {
588 bug!("frameworks are not supported on windows")
591 fn link_whole_staticlib(&mut self, lib: &str, _search_path: &[PathBuf]) {
593 self.link_staticlib(lib);
595 fn link_whole_rlib(&mut self, path: &Path) {
597 self.link_rlib(path);
599 fn optimize(&mut self) {
600 // Needs more investigation of `/OPT` arguments
603 fn pgo_gen(&mut self) {
604 // Nothing needed here.
607 fn debuginfo(&mut self) {
608 // This will cause the Microsoft linker to generate a PDB file
609 // from the CodeView line tables in the object files.
610 self.cmd.arg("/DEBUG");
612 // This will cause the Microsoft linker to embed .natvis info into the PDB file
613 let natvis_dir_path = self.sess.sysroot.join("lib\\rustlib\\etc");
614 if let Ok(natvis_dir) = fs::read_dir(&natvis_dir_path) {
615 for entry in natvis_dir {
618 let path = entry.path();
619 if path.extension() == Some("natvis".as_ref()) {
620 let mut arg = OsString::from("/NATVIS:");
626 self.sess.warn(&format!("error enumerating natvis directory: {}", err));
633 // Currently the compiler doesn't use `dllexport` (an LLVM attribute) to
634 // export symbols from a dynamic library. When building a dynamic library,
635 // however, we're going to want some symbols exported, so this function
636 // generates a DEF file which lists all the symbols.
638 // The linker will read this `*.def` file and export all the symbols from
639 // the dynamic library. Note that this is not as simple as just exporting
640 // all the symbols in the current crate (as specified by `codegen.reachable`)
641 // but rather we also need to possibly export the symbols of upstream
642 // crates. Upstream rlibs may be linked statically to this dynamic library,
643 // in which case they may continue to transitively be used and hence need
644 // their symbols exported.
645 fn export_symbols(&mut self,
647 crate_type: CrateType) {
648 let path = tmpdir.join("lib.def");
649 let res: io::Result<()> = try {
650 let mut f = BufWriter::new(File::create(&path)?);
652 // Start off with the standard module name header and then go
653 // straight to exports.
654 writeln!(f, "LIBRARY")?;
655 writeln!(f, "EXPORTS")?;
656 for symbol in self.info.exports[&crate_type].iter() {
657 debug!(" _{}", symbol);
658 writeln!(f, " {}", symbol)?;
661 if let Err(e) = res {
662 self.sess.fatal(&format!("failed to write lib.def file: {}", e));
664 let mut arg = OsString::from("/DEF:");
669 fn subsystem(&mut self, subsystem: &str) {
670 // Note that previous passes of the compiler validated this subsystem,
671 // so we just blindly pass it to the linker.
672 self.cmd.arg(&format!("/SUBSYSTEM:{}", subsystem));
674 // Windows has two subsystems we're interested in right now, the console
675 // and windows subsystems. These both implicitly have different entry
676 // points (starting symbols). The console entry point starts with
677 // `mainCRTStartup` and the windows entry point starts with
678 // `WinMainCRTStartup`. These entry points, defined in system libraries,
679 // will then later probe for either `main` or `WinMain`, respectively to
680 // start the application.
682 // In Rust we just always generate a `main` function so we want control
683 // to always start there, so we force the entry point on the windows
684 // subsystem to be `mainCRTStartup` to get everything booted up
687 // For more information see RFC #1665
688 if subsystem == "windows" {
689 self.cmd.arg("/ENTRY:mainCRTStartup");
693 fn finalize(&mut self) -> Command {
694 ::std::mem::replace(&mut self.cmd, Command::new(""))
697 // MSVC doesn't need group indicators
698 fn group_start(&mut self) {}
699 fn group_end(&mut self) {}
701 fn linker_plugin_lto(&mut self) {
706 pub struct EmLinker<'a> {
712 impl<'a> Linker for EmLinker<'a> {
713 fn include_path(&mut self, path: &Path) {
714 self.cmd.arg("-L").arg(path);
717 fn link_staticlib(&mut self, lib: &str) {
718 self.cmd.arg("-l").arg(lib);
721 fn output_filename(&mut self, path: &Path) {
722 self.cmd.arg("-o").arg(path);
725 fn add_object(&mut self, path: &Path) {
729 fn link_dylib(&mut self, lib: &str) {
730 // Emscripten always links statically
731 self.link_staticlib(lib);
734 fn link_whole_staticlib(&mut self, lib: &str, _search_path: &[PathBuf]) {
736 self.link_staticlib(lib);
739 fn link_whole_rlib(&mut self, lib: &Path) {
744 fn link_rust_dylib(&mut self, lib: &str, _path: &Path) {
745 self.link_dylib(lib);
748 fn link_rlib(&mut self, lib: &Path) {
749 self.add_object(lib);
752 fn position_independent_executable(&mut self) {
756 fn no_position_independent_executable(&mut self) {
760 fn full_relro(&mut self) {
764 fn partial_relro(&mut self) {
768 fn no_relro(&mut self) {
772 fn args(&mut self, args: &[String]) {
776 fn framework_path(&mut self, _path: &Path) {
777 bug!("frameworks are not supported on Emscripten")
780 fn link_framework(&mut self, _framework: &str) {
781 bug!("frameworks are not supported on Emscripten")
784 fn gc_sections(&mut self, _keep_metadata: bool) {
788 fn optimize(&mut self) {
789 // Emscripten performs own optimizations
790 self.cmd.arg(match self.sess.opts.optimize {
791 OptLevel::No => "-O0",
792 OptLevel::Less => "-O1",
793 OptLevel::Default => "-O2",
794 OptLevel::Aggressive => "-O3",
795 OptLevel::Size => "-Os",
796 OptLevel::SizeMin => "-Oz"
798 // Unusable until https://github.com/rust-lang/rust/issues/38454 is resolved
799 self.cmd.args(&["--memory-init-file", "0"]);
802 fn pgo_gen(&mut self) {
803 // noop, but maybe we need something like the gnu linker?
806 fn debuginfo(&mut self) {
807 // Preserve names or generate source maps depending on debug info
808 self.cmd.arg(match self.sess.opts.debuginfo {
809 DebugInfo::None => "-g0",
810 DebugInfo::Limited => "-g3",
811 DebugInfo::Full => "-g4"
815 fn no_default_libraries(&mut self) {
816 self.cmd.args(&["-s", "DEFAULT_LIBRARY_FUNCS_TO_INCLUDE=[]"]);
819 fn build_dylib(&mut self, _out_filename: &Path) {
820 bug!("building dynamic library is unsupported on Emscripten")
823 fn build_static_executable(&mut self) {
827 fn export_symbols(&mut self, _tmpdir: &Path, crate_type: CrateType) {
828 let symbols = &self.info.exports[&crate_type];
830 debug!("EXPORTED SYMBOLS:");
834 let mut arg = OsString::from("EXPORTED_FUNCTIONS=");
835 let mut encoded = String::new();
838 let mut encoder = json::Encoder::new(&mut encoded);
839 let res = encoder.emit_seq(symbols.len(), |encoder| {
840 for (i, sym) in symbols.iter().enumerate() {
841 encoder.emit_seq_elt(i, |encoder| {
842 encoder.emit_str(&("_".to_owned() + sym))
847 if let Err(e) = res {
848 self.sess.fatal(&format!("failed to encode exported symbols: {}", e));
851 debug!("{}", encoded);
857 fn subsystem(&mut self, _subsystem: &str) {
861 fn finalize(&mut self) -> Command {
862 ::std::mem::replace(&mut self.cmd, Command::new(""))
865 // Appears not necessary on Emscripten
866 fn group_start(&mut self) {}
867 fn group_end(&mut self) {}
869 fn linker_plugin_lto(&mut self) {
874 pub struct WasmLd<'a> {
877 info: &'a LinkerInfo,
880 impl<'a> WasmLd<'a> {
881 fn new(cmd: Command, sess: &'a Session, info: &'a LinkerInfo) -> WasmLd<'a> {
882 WasmLd { cmd, sess, info }
886 impl<'a> Linker for WasmLd<'a> {
887 fn link_dylib(&mut self, lib: &str) {
888 self.cmd.arg("-l").arg(lib);
891 fn link_staticlib(&mut self, lib: &str) {
892 self.cmd.arg("-l").arg(lib);
895 fn link_rlib(&mut self, lib: &Path) {
899 fn include_path(&mut self, path: &Path) {
900 self.cmd.arg("-L").arg(path);
903 fn framework_path(&mut self, _path: &Path) {
904 panic!("frameworks not supported")
907 fn output_filename(&mut self, path: &Path) {
908 self.cmd.arg("-o").arg(path);
911 fn add_object(&mut self, path: &Path) {
915 fn position_independent_executable(&mut self) {
918 fn full_relro(&mut self) {
921 fn partial_relro(&mut self) {
924 fn no_relro(&mut self) {
927 fn build_static_executable(&mut self) {
930 fn args(&mut self, args: &[String]) {
934 fn link_rust_dylib(&mut self, lib: &str, _path: &Path) {
935 self.cmd.arg("-l").arg(lib);
938 fn link_framework(&mut self, _framework: &str) {
939 panic!("frameworks not supported")
942 fn link_whole_staticlib(&mut self, lib: &str, _search_path: &[PathBuf]) {
943 self.cmd.arg("-l").arg(lib);
946 fn link_whole_rlib(&mut self, lib: &Path) {
950 fn gc_sections(&mut self, _keep_metadata: bool) {
951 self.cmd.arg("--gc-sections");
954 fn optimize(&mut self) {
955 self.cmd.arg(match self.sess.opts.optimize {
956 OptLevel::No => "-O0",
957 OptLevel::Less => "-O1",
958 OptLevel::Default => "-O2",
959 OptLevel::Aggressive => "-O3",
960 // Currently LLD doesn't support `Os` and `Oz`, so pass through `O2`
962 OptLevel::Size => "-O2",
963 OptLevel::SizeMin => "-O2"
967 fn pgo_gen(&mut self) {
970 fn debuginfo(&mut self) {
973 fn no_default_libraries(&mut self) {
976 fn build_dylib(&mut self, _out_filename: &Path) {
977 self.cmd.arg("--no-entry");
980 fn export_symbols(&mut self, _tmpdir: &Path, crate_type: CrateType) {
981 for sym in self.info.exports[&crate_type].iter() {
982 self.cmd.arg("--export").arg(&sym);
986 fn subsystem(&mut self, _subsystem: &str) {
989 fn no_position_independent_executable(&mut self) {
992 fn finalize(&mut self) -> Command {
993 ::std::mem::replace(&mut self.cmd, Command::new(""))
996 // Not needed for now with LLD
997 fn group_start(&mut self) {}
998 fn group_end(&mut self) {}
1000 fn linker_plugin_lto(&mut self) {
1001 // Do nothing for now
1005 fn exported_symbols(tcx: TyCtxt<'_, '_, '_>, crate_type: CrateType) -> Vec<String> {
1006 if let Some(ref exports) = tcx.sess.target.target.options.override_export_symbols {
1007 return exports.clone()
1010 let mut symbols = Vec::new();
1012 let export_threshold = symbol_export::crates_export_threshold(&[crate_type]);
1013 for &(symbol, level) in tcx.exported_symbols(LOCAL_CRATE).iter() {
1014 if level.is_below_threshold(export_threshold) {
1015 symbols.push(symbol.symbol_name(tcx).to_string());
1019 let formats = tcx.sess.dependency_formats.borrow();
1020 let deps = formats[&crate_type].iter();
1022 for (index, dep_format) in deps.enumerate() {
1023 let cnum = CrateNum::new(index + 1);
1024 // For each dependency that we are linking to statically ...
1025 if *dep_format == Linkage::Static {
1026 // ... we add its symbol list to our export list.
1027 for &(symbol, level) in tcx.exported_symbols(cnum).iter() {
1028 if level.is_below_threshold(export_threshold) {
1029 symbols.push(symbol.symbol_name(tcx).to_string());
1038 /// Much simplified and explicit CLI for the NVPTX linker. The linker operates
1039 /// with bitcode and uses LLVM backend to generate a PTX assembly.
1040 pub struct PtxLinker<'a> {
1045 impl<'a> Linker for PtxLinker<'a> {
1046 fn link_rlib(&mut self, path: &Path) {
1047 self.cmd.arg("--rlib").arg(path);
1050 fn link_whole_rlib(&mut self, path: &Path) {
1051 self.cmd.arg("--rlib").arg(path);
1054 fn include_path(&mut self, path: &Path) {
1055 self.cmd.arg("-L").arg(path);
1058 fn debuginfo(&mut self) {
1059 self.cmd.arg("--debug");
1062 fn add_object(&mut self, path: &Path) {
1063 self.cmd.arg("--bitcode").arg(path);
1066 fn args(&mut self, args: &[String]) {
1067 self.cmd.args(args);
1070 fn optimize(&mut self) {
1071 match self.sess.lto() {
1072 Lto::Thin | Lto::Fat | Lto::ThinLocal => {
1073 self.cmd.arg("-Olto");
1080 fn output_filename(&mut self, path: &Path) {
1081 self.cmd.arg("-o").arg(path);
1084 fn finalize(&mut self) -> Command {
1085 // Provide the linker with fallback to internal `target-cpu`.
1086 self.cmd.arg("--fallback-arch").arg(match self.sess.opts.cg.target_cpu {
1088 None => &self.sess.target.target.options.cpu
1091 ::std::mem::replace(&mut self.cmd, Command::new(""))
1094 fn link_dylib(&mut self, _lib: &str) {
1095 panic!("external dylibs not supported")
1098 fn link_rust_dylib(&mut self, _lib: &str, _path: &Path) {
1099 panic!("external dylibs not supported")
1102 fn link_staticlib(&mut self, _lib: &str) {
1103 panic!("staticlibs not supported")
1106 fn link_whole_staticlib(&mut self, _lib: &str, _search_path: &[PathBuf]) {
1107 panic!("staticlibs not supported")
1110 fn framework_path(&mut self, _path: &Path) {
1111 panic!("frameworks not supported")
1114 fn link_framework(&mut self, _framework: &str) {
1115 panic!("frameworks not supported")
1118 fn position_independent_executable(&mut self) {
1121 fn full_relro(&mut self) {
1124 fn partial_relro(&mut self) {
1127 fn no_relro(&mut self) {
1130 fn build_static_executable(&mut self) {
1133 fn gc_sections(&mut self, _keep_metadata: bool) {
1136 fn pgo_gen(&mut self) {
1139 fn no_default_libraries(&mut self) {
1142 fn build_dylib(&mut self, _out_filename: &Path) {
1145 fn export_symbols(&mut self, _tmpdir: &Path, _crate_type: CrateType) {
1148 fn subsystem(&mut self, _subsystem: &str) {
1151 fn no_position_independent_executable(&mut self) {
1154 fn group_start(&mut self) {
1157 fn group_end(&mut self) {
1160 fn linker_plugin_lto(&mut self) {