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Auto merge of #33553 - alexcrichton:cdylibs, r=brson
rustc: Add a new crate type, cdylib This commit is an implementation of [RFC 1510] which adds a new crate type, `cdylib`, to the compiler. This new crate type differs from the existing `dylib` crate type in a few key ways: * No metadata is present in the final artifact * Symbol visibility rules are the same as executables, that is only reachable `extern` functions are visible symbols * LTO is allowed * All libraries are always linked statically This commit is relatively simple by just plubming the compiler with another crate type which takes different branches here and there. The only major change is an implementation of the `Linker::export_symbols` function on Unix which now actually does something. This helps restrict the public symbols from a cdylib on Unix. With this PR a "hello world" `cdylib` is 7.2K while the same `dylib` is 2.4MB, which is some nice size savings! [RFC 1510]: rust-lang/rfcs#1510 Closes #33132
2 parents cde0fa5 + 0d2c26c commit d27bdaf

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-94
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+283
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‎src/librustc/middle/dependency_format.rs

+4-3
Original file line numberDiff line numberDiff line change
@@ -115,9 +115,10 @@ fn calculate_type(sess: &session::Session,
115115
// got long ago), so don't bother with anything.
116116
config::CrateTypeRlib => return Vec::new(),
117117

118-
// Staticlibs must have all static dependencies. If any fail to be
119-
// found, we generate some nice pretty errors.
120-
config::CrateTypeStaticlib => {
118+
// Staticlibs and cdylibs must have all static dependencies. If any fail
119+
// to be found, we generate some nice pretty errors.
120+
config::CrateTypeStaticlib |
121+
config::CrateTypeCdylib => {
121122
match attempt_static(sess) {
122123
Some(v) => return v,
123124
None => {}

‎src/librustc/middle/reachable.rs

+1-1
Original file line numberDiff line numberDiff line change
@@ -145,7 +145,7 @@ impl<'a, 'tcx> ReachableContext<'a, 'tcx> {
145145
// Creates a new reachability computation context.
146146
fn new(tcx: TyCtxt<'a, 'tcx, 'tcx>) -> ReachableContext<'a, 'tcx> {
147147
let any_library = tcx.sess.crate_types.borrow().iter().any(|ty| {
148-
*ty != config::CrateTypeExecutable
148+
*ty == config::CrateTypeRlib || *ty == config::CrateTypeDylib
149149
});
150150
ReachableContext {
151151
tcx: tcx,

‎src/librustc/middle/weak_lang_items.rs

+1
Original file line numberDiff line numberDiff line change
@@ -70,6 +70,7 @@ fn verify(sess: &Session, items: &lang_items::LanguageItems) {
7070
let needs_check = sess.crate_types.borrow().iter().any(|kind| {
7171
match *kind {
7272
config::CrateTypeDylib |
73+
config::CrateTypeCdylib |
7374
config::CrateTypeExecutable |
7475
config::CrateTypeStaticlib => true,
7576
config::CrateTypeRlib => false,

‎src/librustc/session/config.rs

+4-1
Original file line numberDiff line numberDiff line change
@@ -300,6 +300,7 @@ pub enum CrateType {
300300
CrateTypeDylib,
301301
CrateTypeRlib,
302302
CrateTypeStaticlib,
303+
CrateTypeCdylib,
303304
}
304305

305306
#[derive(Clone)]
@@ -1326,6 +1327,7 @@ pub fn parse_crate_types_from_list(list_list: Vec<String>) -> Result<Vec<CrateTy
13261327
"rlib" => CrateTypeRlib,
13271328
"staticlib" => CrateTypeStaticlib,
13281329
"dylib" => CrateTypeDylib,
1330+
"cdylib" => CrateTypeCdylib,
13291331
"bin" => CrateTypeExecutable,
13301332
_ => {
13311333
return Err(format!("unknown crate type: `{}`",
@@ -1413,7 +1415,8 @@ impl fmt::Display for CrateType {
14131415
CrateTypeExecutable => "bin".fmt(f),
14141416
CrateTypeDylib => "dylib".fmt(f),
14151417
CrateTypeRlib => "rlib".fmt(f),
1416-
CrateTypeStaticlib => "staticlib".fmt(f)
1418+
CrateTypeStaticlib => "staticlib".fmt(f),
1419+
CrateTypeCdylib => "cdylib".fmt(f),
14171420
}
14181421
}
14191422
}

‎src/librustc_driver/driver.rs

+3
Original file line numberDiff line numberDiff line change
@@ -1174,6 +1174,9 @@ pub fn collect_crate_types(session: &Session, attrs: &[ast::Attribute]) -> Vec<c
11741174
Some(ref n) if *n == "dylib" => {
11751175
Some(config::CrateTypeDylib)
11761176
}
1177+
Some(ref n) if *n == "cdylib" => {
1178+
Some(config::CrateTypeCdylib)
1179+
}
11771180
Some(ref n) if *n == "lib" => {
11781181
Some(config::default_lib_output())
11791182
}

‎src/librustc_metadata/creader.rs

+1
Original file line numberDiff line numberDiff line change
@@ -744,6 +744,7 @@ impl<'a> CrateReader<'a> {
744744
match *ct {
745745
config::CrateTypeExecutable => need_exe_alloc = true,
746746
config::CrateTypeDylib |
747+
config::CrateTypeCdylib |
747748
config::CrateTypeStaticlib => need_lib_alloc = true,
748749
config::CrateTypeRlib => {}
749750
}

‎src/librustc_trans/back/link.rs

+42-38
Original file line numberDiff line numberDiff line change
@@ -231,6 +231,7 @@ pub fn invalid_output_for_target(sess: &Session,
231231
crate_type: config::CrateType) -> bool {
232232
match (sess.target.target.options.dynamic_linking,
233233
sess.target.target.options.executables, crate_type) {
234+
(false, _, config::CrateTypeCdylib) |
234235
(false, _, config::CrateTypeDylib) => true,
235236
(_, false, config::CrateTypeExecutable) => true,
236237
_ => false
@@ -253,6 +254,7 @@ pub fn filename_for_input(sess: &Session,
253254
config::CrateTypeRlib => {
254255
outputs.out_directory.join(&format!("lib{}.rlib", libname))
255256
}
257+
config::CrateTypeCdylib |
256258
config::CrateTypeDylib => {
257259
let (prefix, suffix) = (&sess.target.target.options.dll_prefix,
258260
&sess.target.target.options.dll_suffix);
@@ -281,9 +283,10 @@ pub fn each_linked_rlib(sess: &Session,
281283
f: &mut FnMut(ast::CrateNum, &Path)) {
282284
let crates = sess.cstore.used_crates(LinkagePreference::RequireStatic).into_iter();
283285
let fmts = sess.dependency_formats.borrow();
284-
let fmts = fmts.get(&config::CrateTypeExecutable).or_else(|| {
285-
fmts.get(&config::CrateTypeStaticlib)
286-
}).unwrap_or_else(|| {
286+
let fmts = fmts.get(&config::CrateTypeExecutable)
287+
.or_else(|| fmts.get(&config::CrateTypeStaticlib))
288+
.or_else(|| fmts.get(&config::CrateTypeCdylib));
289+
let fmts = fmts.unwrap_or_else(|| {
287290
bug!("could not find formats for rlibs")
288291
});
289292
for (cnum, path) in crates {
@@ -338,13 +341,9 @@ fn link_binary_output(sess: &Session,
338341
config::CrateTypeStaticlib => {
339342
link_staticlib(sess, &objects, &out_filename, tmpdir.path());
340343
}
341-
config::CrateTypeExecutable => {
342-
link_natively(sess, false, &objects, &out_filename, trans, outputs,
343-
tmpdir.path());
344-
}
345-
config::CrateTypeDylib => {
346-
link_natively(sess, true, &objects, &out_filename, trans, outputs,
347-
tmpdir.path());
344+
_ => {
345+
link_natively(sess, crate_type, &objects, &out_filename, trans,
346+
outputs, tmpdir.path());
348347
}
349348
}
350349

@@ -612,13 +611,14 @@ fn link_staticlib(sess: &Session, objects: &[PathBuf], out_filename: &Path,
612611
//
613612
// This will invoke the system linker/cc to create the resulting file. This
614613
// links to all upstream files as well.
615-
fn link_natively(sess: &Session, dylib: bool,
616-
objects: &[PathBuf], out_filename: &Path,
614+
fn link_natively(sess: &Session,
615+
crate_type: config::CrateType,
616+
objects: &[PathBuf],
617+
out_filename: &Path,
617618
trans: &CrateTranslation,
618619
outputs: &OutputFilenames,
619620
tmpdir: &Path) {
620-
info!("preparing dylib? ({}) from {:?} to {:?}", dylib, objects,
621-
out_filename);
621+
info!("preparing {:?} from {:?} to {:?}", crate_type, objects, out_filename);
622622

623623
// The invocations of cc share some flags across platforms
624624
let (pname, mut cmd) = get_linker(sess);
@@ -627,10 +627,10 @@ fn link_natively(sess: &Session, dylib: bool,
627627
let root = sess.target_filesearch(PathKind::Native).get_lib_path();
628628
cmd.args(&sess.target.target.options.pre_link_args);
629629

630-
let pre_link_objects = if dylib {
631-
&sess.target.target.options.pre_link_objects_dll
632-
} else {
630+
let pre_link_objects = if crate_type == config::CrateTypeExecutable {
633631
&sess.target.target.options.pre_link_objects_exe
632+
} else {
633+
&sess.target.target.options.pre_link_objects_dll
634634
};
635635
for obj in pre_link_objects {
636636
cmd.arg(root.join(obj));
@@ -642,7 +642,7 @@ fn link_natively(sess: &Session, dylib: bool,
642642
} else {
643643
Box::new(GnuLinker { cmd: &mut cmd, sess: &sess }) as Box<Linker>
644644
};
645-
link_args(&mut *linker, sess, dylib, tmpdir,
645+
link_args(&mut *linker, sess, crate_type, tmpdir,
646646
objects, out_filename, trans, outputs);
647647
if !sess.target.target.options.no_compiler_rt {
648648
linker.link_staticlib("compiler-rt");
@@ -708,7 +708,7 @@ fn link_natively(sess: &Session, dylib: bool,
708708

709709
fn link_args(cmd: &mut Linker,
710710
sess: &Session,
711-
dylib: bool,
711+
crate_type: config::CrateType,
712712
tmpdir: &Path,
713713
objects: &[PathBuf],
714714
out_filename: &Path,
@@ -730,26 +730,28 @@ fn link_args(cmd: &mut Linker,
730730

731731
// If we're building a dynamic library then some platforms need to make sure
732732
// that all symbols are exported correctly from the dynamic library.
733-
if dylib {
734-
cmd.export_symbols(sess, trans, tmpdir);
733+
if crate_type != config::CrateTypeExecutable {
734+
cmd.export_symbols(sess, trans, tmpdir, crate_type);
735735
}
736736

737737
// When linking a dynamic library, we put the metadata into a section of the
738738
// executable. This metadata is in a separate object file from the main
739739
// object file, so we link that in here.
740-
if dylib {
740+
if crate_type == config::CrateTypeDylib {
741741
cmd.add_object(&outputs.with_extension("metadata.o"));
742742
}
743743

744744
// Try to strip as much out of the generated object by removing unused
745745
// sections if possible. See more comments in linker.rs
746746
if !sess.opts.cg.link_dead_code {
747-
cmd.gc_sections(dylib);
747+
let keep_metadata = crate_type == config::CrateTypeDylib;
748+
cmd.gc_sections(keep_metadata);
748749
}
749750

750751
let used_link_args = sess.cstore.used_link_args();
751752

752-
if !dylib && t.options.position_independent_executables {
753+
if crate_type == config::CrateTypeExecutable &&
754+
t.options.position_independent_executables {
753755
let empty_vec = Vec::new();
754756
let empty_str = String::new();
755757
let args = sess.opts.cg.link_args.as_ref().unwrap_or(&empty_vec);
@@ -804,12 +806,12 @@ fn link_args(cmd: &mut Linker,
804806
// in this DAG so far because they're only dylibs and dylibs can only depend
805807
// on other dylibs (e.g. other native deps).
806808
add_local_native_libraries(cmd, sess);
807-
add_upstream_rust_crates(cmd, sess, dylib, tmpdir);
809+
add_upstream_rust_crates(cmd, sess, crate_type, tmpdir);
808810
add_upstream_native_libraries(cmd, sess);
809811

810812
// # Telling the linker what we're doing
811813

812-
if dylib {
814+
if crate_type != config::CrateTypeExecutable {
813815
cmd.build_dylib(out_filename);
814816
}
815817

@@ -907,8 +909,10 @@ fn add_local_native_libraries(cmd: &mut Linker, sess: &Session) {
907909
// Rust crates are not considered at all when creating an rlib output. All
908910
// dependencies will be linked when producing the final output (instead of
909911
// the intermediate rlib version)
910-
fn add_upstream_rust_crates(cmd: &mut Linker, sess: &Session,
911-
dylib: bool, tmpdir: &Path) {
912+
fn add_upstream_rust_crates(cmd: &mut Linker,
913+
sess: &Session,
914+
crate_type: config::CrateType,
915+
tmpdir: &Path) {
912916
// All of the heavy lifting has previously been accomplished by the
913917
// dependency_format module of the compiler. This is just crawling the
914918
// output of that module, adding crates as necessary.
@@ -918,11 +922,7 @@ fn add_upstream_rust_crates(cmd: &mut Linker, sess: &Session,
918922
// involves just passing the right -l flag.
919923

920924
let formats = sess.dependency_formats.borrow();
921-
let data = if dylib {
922-
formats.get(&config::CrateTypeDylib).unwrap()
923-
} else {
924-
formats.get(&config::CrateTypeExecutable).unwrap()
925-
};
925+
let data = formats.get(&crate_type).unwrap();
926926

927927
// Invoke get_used_crates to ensure that we get a topological sorting of
928928
// crates.
@@ -937,7 +937,8 @@ fn add_upstream_rust_crates(cmd: &mut Linker, sess: &Session,
937937
Linkage::NotLinked |
938938
Linkage::IncludedFromDylib => {}
939939
Linkage::Static => {
940-
add_static_crate(cmd, sess, tmpdir, dylib, &src.rlib.unwrap().0)
940+
add_static_crate(cmd, sess, tmpdir, crate_type,
941+
&src.rlib.unwrap().0)
941942
}
942943
Linkage::Dynamic => {
943944
add_dynamic_crate(cmd, sess, &src.dylib.unwrap().0)
@@ -982,9 +983,12 @@ fn add_upstream_rust_crates(cmd: &mut Linker, sess: &Session,
982983
// (aka we're making an executable), we can just pass the rlib blindly to
983984
// the linker (fast) because it's fine if it's not actually included as
984985
// we're at the end of the dependency chain.
985-
fn add_static_crate(cmd: &mut Linker, sess: &Session, tmpdir: &Path,
986-
dylib: bool, cratepath: &Path) {
987-
if !sess.lto() && !dylib {
986+
fn add_static_crate(cmd: &mut Linker,
987+
sess: &Session,
988+
tmpdir: &Path,
989+
crate_type: config::CrateType,
990+
cratepath: &Path) {
991+
if !sess.lto() && crate_type != config::CrateTypeDylib {
988992
cmd.link_rlib(&fix_windows_verbatim_for_gcc(cratepath));
989993
return
990994
}
@@ -1020,7 +1024,7 @@ fn add_upstream_rust_crates(cmd: &mut Linker, sess: &Session,
10201024

10211025
if any_objects {
10221026
archive.build();
1023-
if dylib {
1027+
if crate_type == config::CrateTypeDylib {
10241028
cmd.link_whole_rlib(&fix_windows_verbatim_for_gcc(&dst));
10251029
} else {
10261030
cmd.link_rlib(&fix_windows_verbatim_for_gcc(&dst));

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