2 use super::command
::Command
;
3 use super::symbol_export
;
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
::middle
::dependency_format
::Linkage
;
13 use rustc
::session
::config
::{self, CrateType, DebugInfo, LinkerPluginLto, Lto, OptLevel}
;
14 use rustc
::session
::Session
;
15 use rustc
::ty
::TyCtxt
;
16 use rustc_hir
::def_id
::{CrateNum, LOCAL_CRATE}
;
17 use rustc_serialize
::{json, Encoder}
;
18 use rustc_span
::symbol
::Symbol
;
19 use rustc_target
::spec
::{LinkerFlavor, LldFlavor}
;
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 #[derive(RustcEncodable, RustcDecodable)]
24 pub struct LinkerInfo
{
25 exports
: FxHashMap
<CrateType
, Vec
<String
>>,
29 pub fn new(tcx
: TyCtxt
<'_
>) -> LinkerInfo
{
36 .map(|&c
| (c
, exported_symbols(tcx
, c
)))
47 ) -> Box
<dyn Linker
+ 'a
> {
49 LinkerFlavor
::Lld(LldFlavor
::Link
) | LinkerFlavor
::Msvc
=> {
50 Box
::new(MsvcLinker { cmd, sess, info: self }
) as Box
<dyn Linker
>
52 LinkerFlavor
::Em
=> Box
::new(EmLinker { cmd, sess, info: self }
) as Box
<dyn Linker
>,
53 LinkerFlavor
::Gcc
=> Box
::new(GccLinker
{
60 }) as Box
<dyn Linker
>,
62 LinkerFlavor
::Lld(LldFlavor
::Ld
)
63 | LinkerFlavor
::Lld(LldFlavor
::Ld64
)
64 | LinkerFlavor
::Ld
=> Box
::new(GccLinker
{
71 }) as Box
<dyn Linker
>,
73 LinkerFlavor
::Lld(LldFlavor
::Wasm
) => {
74 Box
::new(WasmLd
::new(cmd
, sess
, self)) as Box
<dyn Linker
>
77 LinkerFlavor
::PtxLinker
=> Box
::new(PtxLinker { cmd, sess }
) as Box
<dyn Linker
>,
82 /// Linker abstraction used by `back::link` to build up the command to invoke a
85 /// This trait is the total list of requirements needed by `back::link` and
86 /// represents the meaning of each option being passed down. This trait is then
87 /// used to dispatch on whether a GNU-like linker (generally `ld.exe`) or an
88 /// MSVC linker (e.g., `link.exe`) is being used.
90 fn link_dylib(&mut self, lib
: Symbol
);
91 fn link_rust_dylib(&mut self, lib
: Symbol
, path
: &Path
);
92 fn link_framework(&mut self, framework
: Symbol
);
93 fn link_staticlib(&mut self, lib
: Symbol
);
94 fn link_rlib(&mut self, lib
: &Path
);
95 fn link_whole_rlib(&mut self, lib
: &Path
);
96 fn link_whole_staticlib(&mut self, lib
: Symbol
, search_path
: &[PathBuf
]);
97 fn include_path(&mut self, path
: &Path
);
98 fn framework_path(&mut self, path
: &Path
);
99 fn output_filename(&mut self, path
: &Path
);
100 fn add_object(&mut self, path
: &Path
);
101 fn gc_sections(&mut self, keep_metadata
: bool
);
102 fn position_independent_executable(&mut self);
103 fn no_position_independent_executable(&mut self);
104 fn full_relro(&mut self);
105 fn partial_relro(&mut self);
106 fn no_relro(&mut self);
107 fn optimize(&mut self);
108 fn pgo_gen(&mut self);
109 fn debuginfo(&mut self);
110 fn no_default_libraries(&mut self);
111 fn build_dylib(&mut self, out_filename
: &Path
);
112 fn build_static_executable(&mut self);
113 fn args(&mut self, args
: &[String
]);
114 fn export_symbols(&mut self, tmpdir
: &Path
, crate_type
: CrateType
);
115 fn subsystem(&mut self, subsystem
: &str);
116 fn group_start(&mut self);
117 fn group_end(&mut self);
118 fn linker_plugin_lto(&mut self);
119 // Should have been finalize(self), but we don't support self-by-value on trait objects (yet?).
120 fn finalize(&mut self) -> Command
;
123 pub struct GccLinker
<'a
> {
126 info
: &'a LinkerInfo
,
127 hinted_static
: bool
, // Keeps track of the current hinting mode.
133 impl<'a
> GccLinker
<'a
> {
134 /// Argument that must be passed *directly* to the linker
136 /// These arguments need to be prepended with `-Wl`, when a GCC-style linker is used.
137 fn linker_arg
<S
>(&mut self, arg
: S
) -> &mut Self
142 let mut os
= OsString
::from("-Wl,");
143 os
.push(arg
.as_ref());
151 fn takes_hints(&self) -> bool
{
152 // Really this function only returns true if the underlying linker
153 // configured for a compiler is binutils `ld.bfd` and `ld.gold`. We
154 // don't really have a foolproof way to detect that, so rule out some
155 // platforms where currently this is guaranteed to *not* be the case:
157 // * On OSX they have their own linker, not binutils'
158 // * For WebAssembly the only functional linker is LLD, which doesn't
159 // support hint flags
160 !self.sess
.target
.target
.options
.is_like_osx
&& self.sess
.target
.target
.arch
!= "wasm32"
163 // Some platforms take hints about whether a library is static or dynamic.
164 // For those that support this, we ensure we pass the option if the library
165 // was flagged "static" (most defaults are dynamic) to ensure that if
166 // libfoo.a and libfoo.so both exist that the right one is chosen.
167 fn hint_static(&mut self) {
168 if !self.takes_hints() {
171 if !self.hinted_static
{
172 self.linker_arg("-Bstatic");
173 self.hinted_static
= true;
177 fn hint_dynamic(&mut self) {
178 if !self.takes_hints() {
181 if self.hinted_static
{
182 self.linker_arg("-Bdynamic");
183 self.hinted_static
= false;
187 fn push_linker_plugin_lto_args(&mut self, plugin_path
: Option
<&OsStr
>) {
188 if let Some(plugin_path
) = plugin_path
{
189 let mut arg
= OsString
::from("-plugin=");
190 arg
.push(plugin_path
);
191 self.linker_arg(&arg
);
194 let opt_level
= match self.sess
.opts
.optimize
{
195 config
::OptLevel
::No
=> "O0",
196 config
::OptLevel
::Less
=> "O1",
197 config
::OptLevel
::Default
=> "O2",
198 config
::OptLevel
::Aggressive
=> "O3",
199 config
::OptLevel
::Size
=> "Os",
200 config
::OptLevel
::SizeMin
=> "Oz",
203 self.linker_arg(&format
!("-plugin-opt={}", opt_level
));
204 let target_cpu
= self.target_cpu
;
205 self.linker_arg(&format
!("-plugin-opt=mcpu={}", target_cpu
));
209 impl<'a
> Linker
for GccLinker
<'a
> {
210 fn link_dylib(&mut self, lib
: Symbol
) {
212 self.cmd
.arg(format
!("-l{}", lib
));
214 fn link_staticlib(&mut self, lib
: Symbol
) {
216 self.cmd
.arg(format
!("-l{}", lib
));
218 fn link_rlib(&mut self, lib
: &Path
) {
222 fn include_path(&mut self, path
: &Path
) {
223 self.cmd
.arg("-L").arg(path
);
225 fn framework_path(&mut self, path
: &Path
) {
226 self.cmd
.arg("-F").arg(path
);
228 fn output_filename(&mut self, path
: &Path
) {
229 self.cmd
.arg("-o").arg(path
);
231 fn add_object(&mut self, path
: &Path
) {
234 fn position_independent_executable(&mut self) {
235 self.cmd
.arg("-pie");
237 fn no_position_independent_executable(&mut self) {
238 self.cmd
.arg("-no-pie");
240 fn full_relro(&mut self) {
241 self.linker_arg("-zrelro");
242 self.linker_arg("-znow");
244 fn partial_relro(&mut self) {
245 self.linker_arg("-zrelro");
247 fn no_relro(&mut self) {
248 self.linker_arg("-znorelro");
250 fn build_static_executable(&mut self) {
251 self.cmd
.arg("-static");
253 fn args(&mut self, args
: &[String
]) {
257 fn link_rust_dylib(&mut self, lib
: Symbol
, _path
: &Path
) {
259 self.cmd
.arg(format
!("-l{}", lib
));
262 fn link_framework(&mut self, framework
: Symbol
) {
264 self.cmd
.arg("-framework").sym_arg(framework
);
267 // Here we explicitly ask that the entire archive is included into the
268 // result artifact. For more details see #15460, but the gist is that
269 // the linker will strip away any unused objects in the archive if we
270 // don't otherwise explicitly reference them. This can occur for
271 // libraries which are just providing bindings, libraries with generic
273 fn link_whole_staticlib(&mut self, lib
: Symbol
, search_path
: &[PathBuf
]) {
275 let target
= &self.sess
.target
.target
;
276 if !target
.options
.is_like_osx
{
277 self.linker_arg("--whole-archive").cmd
.arg(format
!("-l{}", lib
));
278 self.linker_arg("--no-whole-archive");
280 // -force_load is the macOS equivalent of --whole-archive, but it
281 // involves passing the full path to the library to link.
282 self.linker_arg("-force_load");
283 let lib
= archive
::find_library(lib
, search_path
, &self.sess
);
284 self.linker_arg(&lib
);
288 fn link_whole_rlib(&mut self, lib
: &Path
) {
290 if self.sess
.target
.target
.options
.is_like_osx
{
291 self.linker_arg("-force_load");
292 self.linker_arg(&lib
);
294 self.linker_arg("--whole-archive").cmd
.arg(lib
);
295 self.linker_arg("--no-whole-archive");
299 fn gc_sections(&mut self, keep_metadata
: bool
) {
300 // The dead_strip option to the linker specifies that functions and data
301 // unreachable by the entry point will be removed. This is quite useful
302 // with Rust's compilation model of compiling libraries at a time into
303 // one object file. For example, this brings hello world from 1.7MB to
306 // Note that this is done for both executables and dynamic libraries. We
307 // won't get much benefit from dylibs because LLVM will have already
308 // stripped away as much as it could. This has not been seen to impact
309 // link times negatively.
311 // -dead_strip can't be part of the pre_link_args because it's also used
312 // for partial linking when using multiple codegen units (-r). So we
314 if self.sess
.target
.target
.options
.is_like_osx
{
315 self.linker_arg("-dead_strip");
316 } else if self.sess
.target
.target
.options
.is_like_solaris
{
317 self.linker_arg("-zignore");
319 // If we're building a dylib, we don't use --gc-sections because LLVM
320 // has already done the best it can do, and we also don't want to
321 // eliminate the metadata. If we're building an executable, however,
322 // --gc-sections drops the size of hello world from 1.8MB to 597K, a 67%
324 } else if !keep_metadata
{
325 self.linker_arg("--gc-sections");
329 fn optimize(&mut self) {
330 if !self.sess
.target
.target
.options
.linker_is_gnu
{
334 // GNU-style linkers support optimization with -O. GNU ld doesn't
335 // need a numeric argument, but other linkers do.
336 if self.sess
.opts
.optimize
== config
::OptLevel
::Default
337 || self.sess
.opts
.optimize
== config
::OptLevel
::Aggressive
339 self.linker_arg("-O1");
343 fn pgo_gen(&mut self) {
344 if !self.sess
.target
.target
.options
.linker_is_gnu
{
348 // If we're doing PGO generation stuff and on a GNU-like linker, use the
349 // "-u" flag to properly pull in the profiler runtime bits.
351 // This is because LLVM otherwise won't add the needed initialization
352 // for us on Linux (though the extra flag should be harmless if it
355 // See https://reviews.llvm.org/D14033 and https://reviews.llvm.org/D14030.
357 // Though it may be worth to try to revert those changes upstream, since
358 // the overhead of the initialization should be minor.
360 self.cmd
.arg("__llvm_profile_runtime");
363 fn debuginfo(&mut self) {
364 if let DebugInfo
::None
= self.sess
.opts
.debuginfo
{
365 // If we are building without debuginfo enabled and we were called with
366 // `-Zstrip-debuginfo-if-disabled=yes`, tell the linker to strip any debuginfo
367 // found when linking to get rid of symbols from libstd.
368 if let Some(true) = self.sess
.opts
.debugging_opts
.strip_debuginfo_if_disabled
{
369 self.linker_arg("-S");
374 fn no_default_libraries(&mut self) {
376 self.cmd
.arg("-nodefaultlibs");
380 fn build_dylib(&mut self, out_filename
: &Path
) {
381 // On mac we need to tell the linker to let this library be rpathed
382 if self.sess
.target
.target
.options
.is_like_osx
{
383 self.cmd
.arg("-dynamiclib");
384 self.linker_arg("-dylib");
386 // Note that the `osx_rpath_install_name` option here is a hack
387 // purely to support rustbuild right now, we should get a more
388 // principled solution at some point to force the compiler to pass
389 // the right `-Wl,-install_name` with an `@rpath` in it.
390 if self.sess
.opts
.cg
.rpath
|| self.sess
.opts
.debugging_opts
.osx_rpath_install_name
{
391 self.linker_arg("-install_name");
392 let mut v
= OsString
::from("@rpath/");
393 v
.push(out_filename
.file_name().unwrap());
397 self.cmd
.arg("-shared");
398 if self.sess
.target
.target
.options
.is_like_windows
{
399 // The output filename already contains `dll_suffix` so
400 // the resulting import library will have a name in the
401 // form of libfoo.dll.a
403 out_filename
.file_name().and_then(|file
| file
.to_str()).map(|file
| {
406 self.sess
.target
.target
.options
.staticlib_prefix
,
408 self.sess
.target
.target
.options
.staticlib_suffix
411 if let Some(implib_name
) = implib_name
{
412 let implib
= out_filename
.parent().map(|dir
| dir
.join(&implib_name
));
413 if let Some(implib
) = implib
{
414 self.linker_arg(&format
!("--out-implib,{}", (*implib
).to_str().unwrap()));
421 fn export_symbols(&mut self, tmpdir
: &Path
, crate_type
: CrateType
) {
422 // Symbol visibility in object files typically takes care of this.
423 if crate_type
== CrateType
::Executable
424 && self.sess
.target
.target
.options
.override_export_symbols
.is_none()
429 // We manually create a list of exported symbols to ensure we don't expose any more.
430 // The object files have far more public symbols than we actually want to export,
431 // so we hide them all here.
433 if !self.sess
.target
.target
.options
.limit_rdylib_exports
{
437 if crate_type
== CrateType
::ProcMacro
{
441 let mut arg
= OsString
::new();
442 let path
= tmpdir
.join("list");
444 debug
!("EXPORTED SYMBOLS:");
446 if self.sess
.target
.target
.options
.is_like_osx
{
447 // Write a plain, newline-separated list of symbols
448 let res
: io
::Result
<()> = try
{
449 let mut f
= BufWriter
::new(File
::create(&path
)?
);
450 for sym
in self.info
.exports
[&crate_type
].iter() {
452 writeln
!(f
, "_{}", sym
)?
;
455 if let Err(e
) = res
{
456 self.sess
.fatal(&format
!("failed to write lib.def file: {}", e
));
459 // Write an LD version script
460 let res
: io
::Result
<()> = try
{
461 let mut f
= BufWriter
::new(File
::create(&path
)?
);
463 if !self.info
.exports
[&crate_type
].is_empty() {
464 writeln
!(f
, " global:")?
;
465 for sym
in self.info
.exports
[&crate_type
].iter() {
467 writeln
!(f
, " {};", sym
)?
;
470 writeln
!(f
, "\n local:\n *;\n}};")?
;
472 if let Err(e
) = res
{
473 self.sess
.fatal(&format
!("failed to write version script: {}", e
));
477 if self.sess
.target
.target
.options
.is_like_osx
{
481 arg
.push("-exported_symbols_list,");
482 } else if self.sess
.target
.target
.options
.is_like_solaris
{
491 arg
.push("--version-script=");
498 fn subsystem(&mut self, subsystem
: &str) {
499 self.linker_arg("--subsystem");
500 self.linker_arg(&subsystem
);
503 fn finalize(&mut self) -> Command
{
504 self.hint_dynamic(); // Reset to default before returning the composed command line.
506 ::std
::mem
::replace(&mut self.cmd
, Command
::new(""))
509 fn group_start(&mut self) {
510 if self.takes_hints() {
511 self.linker_arg("--start-group");
515 fn group_end(&mut self) {
516 if self.takes_hints() {
517 self.linker_arg("--end-group");
521 fn linker_plugin_lto(&mut self) {
522 match self.sess
.opts
.cg
.linker_plugin_lto
{
523 LinkerPluginLto
::Disabled
=> {
526 LinkerPluginLto
::LinkerPluginAuto
=> {
527 self.push_linker_plugin_lto_args(None
);
529 LinkerPluginLto
::LinkerPlugin(ref path
) => {
530 self.push_linker_plugin_lto_args(Some(path
.as_os_str()));
536 pub struct MsvcLinker
<'a
> {
539 info
: &'a LinkerInfo
,
542 impl<'a
> Linker
for MsvcLinker
<'a
> {
543 fn link_rlib(&mut self, lib
: &Path
) {
546 fn add_object(&mut self, path
: &Path
) {
549 fn args(&mut self, args
: &[String
]) {
553 fn build_dylib(&mut self, out_filename
: &Path
) {
554 self.cmd
.arg("/DLL");
555 let mut arg
: OsString
= "/IMPLIB:".into();
556 arg
.push(out_filename
.with_extension("dll.lib"));
560 fn build_static_executable(&mut self) {
564 fn gc_sections(&mut self, _keep_metadata
: bool
) {
565 // MSVC's ICF (Identical COMDAT Folding) link optimization is
566 // slow for Rust and thus we disable it by default when not in
567 // optimization build.
568 if self.sess
.opts
.optimize
!= config
::OptLevel
::No
{
569 self.cmd
.arg("/OPT:REF,ICF");
571 // It is necessary to specify NOICF here, because /OPT:REF
572 // implies ICF by default.
573 self.cmd
.arg("/OPT:REF,NOICF");
577 fn link_dylib(&mut self, lib
: Symbol
) {
578 self.cmd
.arg(&format
!("{}.lib", lib
));
581 fn link_rust_dylib(&mut self, lib
: Symbol
, path
: &Path
) {
582 // When producing a dll, the MSVC linker may not actually emit a
583 // `foo.lib` file if the dll doesn't actually export any symbols, so we
584 // check to see if the file is there and just omit linking to it if it's
586 let name
= format
!("{}.dll.lib", lib
);
587 if fs
::metadata(&path
.join(&name
)).is_ok() {
592 fn link_staticlib(&mut self, lib
: Symbol
) {
593 self.cmd
.arg(&format
!("{}.lib", lib
));
596 fn position_independent_executable(&mut self) {
600 fn no_position_independent_executable(&mut self) {
604 fn full_relro(&mut self) {
608 fn partial_relro(&mut self) {
612 fn no_relro(&mut self) {
616 fn no_default_libraries(&mut self) {
617 // Currently we don't pass the /NODEFAULTLIB flag to the linker on MSVC
618 // as there's been trouble in the past of linking the C++ standard
619 // library required by LLVM. This likely needs to happen one day, but
620 // in general Windows is also a more controlled environment than
621 // Unix, so it's not necessarily as critical that this be implemented.
623 // Note that there are also some licensing worries about statically
624 // linking some libraries which require a specific agreement, so it may
625 // not ever be possible for us to pass this flag.
628 fn include_path(&mut self, path
: &Path
) {
629 let mut arg
= OsString
::from("/LIBPATH:");
634 fn output_filename(&mut self, path
: &Path
) {
635 let mut arg
= OsString
::from("/OUT:");
640 fn framework_path(&mut self, _path
: &Path
) {
641 bug
!("frameworks are not supported on windows")
643 fn link_framework(&mut self, _framework
: Symbol
) {
644 bug
!("frameworks are not supported on windows")
647 fn link_whole_staticlib(&mut self, lib
: Symbol
, _search_path
: &[PathBuf
]) {
649 self.link_staticlib(lib
);
651 fn link_whole_rlib(&mut self, path
: &Path
) {
653 self.link_rlib(path
);
655 fn optimize(&mut self) {
656 // Needs more investigation of `/OPT` arguments
659 fn pgo_gen(&mut self) {
660 // Nothing needed here.
663 fn debuginfo(&mut self) {
664 // This will cause the Microsoft linker to generate a PDB file
665 // from the CodeView line tables in the object files.
666 self.cmd
.arg("/DEBUG");
668 // This will cause the Microsoft linker to embed .natvis info into the PDB file
669 let natvis_dir_path
= self.sess
.sysroot
.join("lib\\rustlib\\etc");
670 if let Ok(natvis_dir
) = fs
::read_dir(&natvis_dir_path
) {
671 for entry
in natvis_dir
{
674 let path
= entry
.path();
675 if path
.extension() == Some("natvis".as_ref()) {
676 let mut arg
= OsString
::from("/NATVIS:");
682 self.sess
.warn(&format
!("error enumerating natvis directory: {}", err
));
689 // Currently the compiler doesn't use `dllexport` (an LLVM attribute) to
690 // export symbols from a dynamic library. When building a dynamic library,
691 // however, we're going to want some symbols exported, so this function
692 // generates a DEF file which lists all the symbols.
694 // The linker will read this `*.def` file and export all the symbols from
695 // the dynamic library. Note that this is not as simple as just exporting
696 // all the symbols in the current crate (as specified by `codegen.reachable`)
697 // but rather we also need to possibly export the symbols of upstream
698 // crates. Upstream rlibs may be linked statically to this dynamic library,
699 // in which case they may continue to transitively be used and hence need
700 // their symbols exported.
701 fn export_symbols(&mut self, tmpdir
: &Path
, crate_type
: CrateType
) {
702 // Symbol visibility takes care of this typically
703 if crate_type
== CrateType
::Executable
{
707 let path
= tmpdir
.join("lib.def");
708 let res
: io
::Result
<()> = try
{
709 let mut f
= BufWriter
::new(File
::create(&path
)?
);
711 // Start off with the standard module name header and then go
712 // straight to exports.
713 writeln
!(f
, "LIBRARY")?
;
714 writeln
!(f
, "EXPORTS")?
;
715 for symbol
in self.info
.exports
[&crate_type
].iter() {
716 debug
!(" _{}", symbol
);
717 writeln
!(f
, " {}", symbol
)?
;
720 if let Err(e
) = res
{
721 self.sess
.fatal(&format
!("failed to write lib.def file: {}", e
));
723 let mut arg
= OsString
::from("/DEF:");
728 fn subsystem(&mut self, subsystem
: &str) {
729 // Note that previous passes of the compiler validated this subsystem,
730 // so we just blindly pass it to the linker.
731 self.cmd
.arg(&format
!("/SUBSYSTEM:{}", subsystem
));
733 // Windows has two subsystems we're interested in right now, the console
734 // and windows subsystems. These both implicitly have different entry
735 // points (starting symbols). The console entry point starts with
736 // `mainCRTStartup` and the windows entry point starts with
737 // `WinMainCRTStartup`. These entry points, defined in system libraries,
738 // will then later probe for either `main` or `WinMain`, respectively to
739 // start the application.
741 // In Rust we just always generate a `main` function so we want control
742 // to always start there, so we force the entry point on the windows
743 // subsystem to be `mainCRTStartup` to get everything booted up
746 // For more information see RFC #1665
747 if subsystem
== "windows" {
748 self.cmd
.arg("/ENTRY:mainCRTStartup");
752 fn finalize(&mut self) -> Command
{
753 ::std
::mem
::replace(&mut self.cmd
, Command
::new(""))
756 // MSVC doesn't need group indicators
757 fn group_start(&mut self) {}
758 fn group_end(&mut self) {}
760 fn linker_plugin_lto(&mut self) {
765 pub struct EmLinker
<'a
> {
768 info
: &'a LinkerInfo
,
771 impl<'a
> Linker
for EmLinker
<'a
> {
772 fn include_path(&mut self, path
: &Path
) {
773 self.cmd
.arg("-L").arg(path
);
776 fn link_staticlib(&mut self, lib
: Symbol
) {
777 self.cmd
.arg("-l").sym_arg(lib
);
780 fn output_filename(&mut self, path
: &Path
) {
781 self.cmd
.arg("-o").arg(path
);
784 fn add_object(&mut self, path
: &Path
) {
788 fn link_dylib(&mut self, lib
: Symbol
) {
789 // Emscripten always links statically
790 self.link_staticlib(lib
);
793 fn link_whole_staticlib(&mut self, lib
: Symbol
, _search_path
: &[PathBuf
]) {
795 self.link_staticlib(lib
);
798 fn link_whole_rlib(&mut self, lib
: &Path
) {
803 fn link_rust_dylib(&mut self, lib
: Symbol
, _path
: &Path
) {
804 self.link_dylib(lib
);
807 fn link_rlib(&mut self, lib
: &Path
) {
808 self.add_object(lib
);
811 fn position_independent_executable(&mut self) {
815 fn no_position_independent_executable(&mut self) {
819 fn full_relro(&mut self) {
823 fn partial_relro(&mut self) {
827 fn no_relro(&mut self) {
831 fn args(&mut self, args
: &[String
]) {
835 fn framework_path(&mut self, _path
: &Path
) {
836 bug
!("frameworks are not supported on Emscripten")
839 fn link_framework(&mut self, _framework
: Symbol
) {
840 bug
!("frameworks are not supported on Emscripten")
843 fn gc_sections(&mut self, _keep_metadata
: bool
) {
847 fn optimize(&mut self) {
848 // Emscripten performs own optimizations
849 self.cmd
.arg(match self.sess
.opts
.optimize
{
850 OptLevel
::No
=> "-O0",
851 OptLevel
::Less
=> "-O1",
852 OptLevel
::Default
=> "-O2",
853 OptLevel
::Aggressive
=> "-O3",
854 OptLevel
::Size
=> "-Os",
855 OptLevel
::SizeMin
=> "-Oz",
857 // Unusable until https://github.com/rust-lang/rust/issues/38454 is resolved
858 self.cmd
.args(&["--memory-init-file", "0"]);
861 fn pgo_gen(&mut self) {
862 // noop, but maybe we need something like the gnu linker?
865 fn debuginfo(&mut self) {
866 // Preserve names or generate source maps depending on debug info
867 self.cmd
.arg(match self.sess
.opts
.debuginfo
{
868 DebugInfo
::None
=> "-g0",
869 DebugInfo
::Limited
=> "-g3",
870 DebugInfo
::Full
=> "-g4",
874 fn no_default_libraries(&mut self) {
875 self.cmd
.args(&["-s", "DEFAULT_LIBRARY_FUNCS_TO_INCLUDE=[]"]);
878 fn build_dylib(&mut self, _out_filename
: &Path
) {
879 bug
!("building dynamic library is unsupported on Emscripten")
882 fn build_static_executable(&mut self) {
886 fn export_symbols(&mut self, _tmpdir
: &Path
, crate_type
: CrateType
) {
887 let symbols
= &self.info
.exports
[&crate_type
];
889 debug
!("EXPORTED SYMBOLS:");
893 let mut arg
= OsString
::from("EXPORTED_FUNCTIONS=");
894 let mut encoded
= String
::new();
897 let mut encoder
= json
::Encoder
::new(&mut encoded
);
898 let res
= encoder
.emit_seq(symbols
.len(), |encoder
| {
899 for (i
, sym
) in symbols
.iter().enumerate() {
900 encoder
.emit_seq_elt(i
, |encoder
| encoder
.emit_str(&("_".to_owned() + sym
)))?
;
904 if let Err(e
) = res
{
905 self.sess
.fatal(&format
!("failed to encode exported symbols: {}", e
));
908 debug
!("{}", encoded
);
914 fn subsystem(&mut self, _subsystem
: &str) {
918 fn finalize(&mut self) -> Command
{
919 ::std
::mem
::replace(&mut self.cmd
, Command
::new(""))
922 // Appears not necessary on Emscripten
923 fn group_start(&mut self) {}
924 fn group_end(&mut self) {}
926 fn linker_plugin_lto(&mut self) {
931 pub struct WasmLd
<'a
> {
934 info
: &'a LinkerInfo
,
937 impl<'a
> WasmLd
<'a
> {
938 fn new(mut cmd
: Command
, sess
: &'a Session
, info
: &'a LinkerInfo
) -> WasmLd
<'a
> {
939 // If the atomics feature is enabled for wasm then we need a whole bunch
942 // * `--shared-memory` - the link won't even succeed without this, flags
943 // the one linear memory as `shared`
945 // * `--max-memory=1G` - when specifying a shared memory this must also
946 // be specified. We conservatively choose 1GB but users should be able
947 // to override this with `-C link-arg`.
949 // * `--import-memory` - it doesn't make much sense for memory to be
950 // exported in a threaded module because typically you're
951 // sharing memory and instantiating the module multiple times. As a
952 // result if it were exported then we'd just have no sharing.
954 // * `--passive-segments` - all memory segments should be passive to
955 // prevent each module instantiation from reinitializing memory.
957 // * `--export=__wasm_init_memory` - when using `--passive-segments` the
958 // linker will synthesize this function, and so we need to make sure
959 // that our usage of `--export` below won't accidentally cause this
960 // function to get deleted.
962 // * `--export=*tls*` - when `#[thread_local]` symbols are used these
963 // symbols are how the TLS segments are initialized and configured.
964 let atomics
= sess
.opts
.cg
.target_feature
.contains("+atomics")
965 || sess
.target
.target
.options
.features
.contains("+atomics");
967 cmd
.arg("--shared-memory");
968 cmd
.arg("--max-memory=1073741824");
969 cmd
.arg("--import-memory");
970 cmd
.arg("--passive-segments");
971 cmd
.arg("--export=__wasm_init_memory");
972 cmd
.arg("--export=__wasm_init_tls");
973 cmd
.arg("--export=__tls_size");
974 cmd
.arg("--export=__tls_align");
975 cmd
.arg("--export=__tls_base");
977 WasmLd { cmd, sess, info }
981 impl<'a
> Linker
for WasmLd
<'a
> {
982 fn link_dylib(&mut self, lib
: Symbol
) {
983 self.cmd
.arg("-l").sym_arg(lib
);
986 fn link_staticlib(&mut self, lib
: Symbol
) {
987 self.cmd
.arg("-l").sym_arg(lib
);
990 fn link_rlib(&mut self, lib
: &Path
) {
994 fn include_path(&mut self, path
: &Path
) {
995 self.cmd
.arg("-L").arg(path
);
998 fn framework_path(&mut self, _path
: &Path
) {
999 panic
!("frameworks not supported")
1002 fn output_filename(&mut self, path
: &Path
) {
1003 self.cmd
.arg("-o").arg(path
);
1006 fn add_object(&mut self, path
: &Path
) {
1010 fn position_independent_executable(&mut self) {}
1012 fn full_relro(&mut self) {}
1014 fn partial_relro(&mut self) {}
1016 fn no_relro(&mut self) {}
1018 fn build_static_executable(&mut self) {}
1020 fn args(&mut self, args
: &[String
]) {
1021 self.cmd
.args(args
);
1024 fn link_rust_dylib(&mut self, lib
: Symbol
, _path
: &Path
) {
1025 self.cmd
.arg("-l").sym_arg(lib
);
1028 fn link_framework(&mut self, _framework
: Symbol
) {
1029 panic
!("frameworks not supported")
1032 fn link_whole_staticlib(&mut self, lib
: Symbol
, _search_path
: &[PathBuf
]) {
1033 self.cmd
.arg("-l").sym_arg(lib
);
1036 fn link_whole_rlib(&mut self, lib
: &Path
) {
1040 fn gc_sections(&mut self, _keep_metadata
: bool
) {
1041 self.cmd
.arg("--gc-sections");
1044 fn optimize(&mut self) {
1045 self.cmd
.arg(match self.sess
.opts
.optimize
{
1046 OptLevel
::No
=> "-O0",
1047 OptLevel
::Less
=> "-O1",
1048 OptLevel
::Default
=> "-O2",
1049 OptLevel
::Aggressive
=> "-O3",
1050 // Currently LLD doesn't support `Os` and `Oz`, so pass through `O2`
1052 OptLevel
::Size
=> "-O2",
1053 OptLevel
::SizeMin
=> "-O2",
1057 fn pgo_gen(&mut self) {}
1059 fn debuginfo(&mut self) {}
1061 fn no_default_libraries(&mut self) {}
1063 fn build_dylib(&mut self, _out_filename
: &Path
) {
1064 self.cmd
.arg("--no-entry");
1067 fn export_symbols(&mut self, _tmpdir
: &Path
, crate_type
: CrateType
) {
1068 for sym
in self.info
.exports
[&crate_type
].iter() {
1069 self.cmd
.arg("--export").arg(&sym
);
1072 // LLD will hide these otherwise-internal symbols since our `--export`
1073 // list above is a whitelist of what to export. Various bits and pieces
1074 // of tooling use this, so be sure these symbols make their way out of
1075 // the linker as well.
1076 self.cmd
.arg("--export=__heap_base");
1077 self.cmd
.arg("--export=__data_end");
1080 fn subsystem(&mut self, _subsystem
: &str) {}
1082 fn no_position_independent_executable(&mut self) {}
1084 fn finalize(&mut self) -> Command
{
1085 ::std
::mem
::replace(&mut self.cmd
, Command
::new(""))
1088 // Not needed for now with LLD
1089 fn group_start(&mut self) {}
1090 fn group_end(&mut self) {}
1092 fn linker_plugin_lto(&mut self) {
1093 // Do nothing for now
1097 fn exported_symbols(tcx
: TyCtxt
<'_
>, crate_type
: CrateType
) -> Vec
<String
> {
1098 if let Some(ref exports
) = tcx
.sess
.target
.target
.options
.override_export_symbols
{
1099 return exports
.clone();
1102 let mut symbols
= Vec
::new();
1104 let export_threshold
= symbol_export
::crates_export_threshold(&[crate_type
]);
1105 for &(symbol
, level
) in tcx
.exported_symbols(LOCAL_CRATE
).iter() {
1106 if level
.is_below_threshold(export_threshold
) {
1107 symbols
.push(symbol_export
::symbol_name_for_instance_in_crate(
1115 let formats
= tcx
.dependency_formats(LOCAL_CRATE
);
1118 .filter_map(|(t
, list
)| if *t
== crate_type { Some(list) }
else { None }
)
1122 for (index
, dep_format
) in deps
.iter().enumerate() {
1123 let cnum
= CrateNum
::new(index
+ 1);
1124 // For each dependency that we are linking to statically ...
1125 if *dep_format
== Linkage
::Static
{
1126 // ... we add its symbol list to our export list.
1127 for &(symbol
, level
) in tcx
.exported_symbols(cnum
).iter() {
1128 if !level
.is_below_threshold(export_threshold
) {
1132 symbols
.push(symbol_export
::symbol_name_for_instance_in_crate(tcx
, symbol
, cnum
));
1140 /// Much simplified and explicit CLI for the NVPTX linker. The linker operates
1141 /// with bitcode and uses LLVM backend to generate a PTX assembly.
1142 pub struct PtxLinker
<'a
> {
1147 impl<'a
> Linker
for PtxLinker
<'a
> {
1148 fn link_rlib(&mut self, path
: &Path
) {
1149 self.cmd
.arg("--rlib").arg(path
);
1152 fn link_whole_rlib(&mut self, path
: &Path
) {
1153 self.cmd
.arg("--rlib").arg(path
);
1156 fn include_path(&mut self, path
: &Path
) {
1157 self.cmd
.arg("-L").arg(path
);
1160 fn debuginfo(&mut self) {
1161 self.cmd
.arg("--debug");
1164 fn add_object(&mut self, path
: &Path
) {
1165 self.cmd
.arg("--bitcode").arg(path
);
1168 fn args(&mut self, args
: &[String
]) {
1169 self.cmd
.args(args
);
1172 fn optimize(&mut self) {
1173 match self.sess
.lto() {
1174 Lto
::Thin
| Lto
::Fat
| Lto
::ThinLocal
=> {
1175 self.cmd
.arg("-Olto");
1182 fn output_filename(&mut self, path
: &Path
) {
1183 self.cmd
.arg("-o").arg(path
);
1186 fn finalize(&mut self) -> Command
{
1187 // Provide the linker with fallback to internal `target-cpu`.
1188 self.cmd
.arg("--fallback-arch").arg(match self.sess
.opts
.cg
.target_cpu
{
1190 None
=> &self.sess
.target
.target
.options
.cpu
,
1193 ::std
::mem
::replace(&mut self.cmd
, Command
::new(""))
1196 fn link_dylib(&mut self, _lib
: Symbol
) {
1197 panic
!("external dylibs not supported")
1200 fn link_rust_dylib(&mut self, _lib
: Symbol
, _path
: &Path
) {
1201 panic
!("external dylibs not supported")
1204 fn link_staticlib(&mut self, _lib
: Symbol
) {
1205 panic
!("staticlibs not supported")
1208 fn link_whole_staticlib(&mut self, _lib
: Symbol
, _search_path
: &[PathBuf
]) {
1209 panic
!("staticlibs not supported")
1212 fn framework_path(&mut self, _path
: &Path
) {
1213 panic
!("frameworks not supported")
1216 fn link_framework(&mut self, _framework
: Symbol
) {
1217 panic
!("frameworks not supported")
1220 fn position_independent_executable(&mut self) {}
1222 fn full_relro(&mut self) {}
1224 fn partial_relro(&mut self) {}
1226 fn no_relro(&mut self) {}
1228 fn build_static_executable(&mut self) {}
1230 fn gc_sections(&mut self, _keep_metadata
: bool
) {}
1232 fn pgo_gen(&mut self) {}
1234 fn no_default_libraries(&mut self) {}
1236 fn build_dylib(&mut self, _out_filename
: &Path
) {}
1238 fn export_symbols(&mut self, _tmpdir
: &Path
, _crate_type
: CrateType
) {}
1240 fn subsystem(&mut self, _subsystem
: &str) {}
1242 fn no_position_independent_executable(&mut self) {}
1244 fn group_start(&mut self) {}
1246 fn group_end(&mut self) {}
1248 fn linker_plugin_lto(&mut self) {}