rust/src/link_copied.rs

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//! All functions here are copied from https://github.com/rust-lang/rust/blob/942864a000efd74b73e36bda5606b2cdb55ecf39/src/librustc_codegen_llvm/back/link.rs
use std::env;
use std::fmt;
use std::fs;
use std::io;
use std::iter;
use std::path::{Path, PathBuf};
use std::process::{Output, Stdio};
use cc::windows_registry;
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use log::info;
use rustc::middle::cstore::{NativeLibrary, NativeLibraryKind};
use rustc::middle::dependency_format::Linkage;
use rustc::session::config::{self, OutputType, RUST_CGU_EXT};
use rustc::session::search_paths::PathKind;
use rustc::session::Session;
use rustc::util::common::time;
use rustc_codegen_utils::command::Command;
use rustc_codegen_utils::linker::*;
use rustc_data_structures::fx::FxHashSet;
use rustc_fs_util::fix_windows_verbatim_for_gcc;
use rustc_target::spec::LinkerFlavor;
use syntax::attr;
use crate::prelude::*;
use crate::archive::{ArchiveBuilder, ArchiveConfig};
use crate::metadata::METADATA_FILENAME;
// cg_clif doesn't have bytecode, so this is just a dummy
const RLIB_BYTECODE_EXTENSION: &str = ".cg_clif_bytecode_dummy";
fn archive_search_paths(sess: &Session) -> Vec<PathBuf> {
let mut search = Vec::new();
sess.target_filesearch(PathKind::Native).for_each_lib_search_path(|path, _| {
search.push(path.to_path_buf());
});
return search;
}
fn archive_config<'a>(sess: &'a Session,
output: &Path,
input: Option<&Path>) -> ArchiveConfig<'a> {
ArchiveConfig {
sess,
dst: output.to_path_buf(),
src: input.map(|p| p.to_path_buf()),
lib_search_paths: archive_search_paths(sess),
}
}
// The third parameter is for env vars, used on windows to set up the
// path for MSVC to find its DLLs, and gcc to find its bundled
// toolchain
pub fn get_linker(sess: &Session, linker: &Path, flavor: LinkerFlavor) -> (PathBuf, Command) {
let msvc_tool = windows_registry::find_tool(&sess.opts.target_triple.triple(), "link.exe");
// If our linker looks like a batch script on Windows then to execute this
// we'll need to spawn `cmd` explicitly. This is primarily done to handle
// emscripten where the linker is `emcc.bat` and needs to be spawned as
// `cmd /c emcc.bat ...`.
//
// This worked historically but is needed manually since #42436 (regression
// was tagged as #42791) and some more info can be found on #44443 for
// emscripten itself.
let mut cmd = match linker.to_str() {
Some(linker) if cfg!(windows) && linker.ends_with(".bat") => Command::bat_script(linker),
_ => match flavor {
LinkerFlavor::Lld(f) => Command::lld(linker, f),
LinkerFlavor::Msvc
if sess.opts.cg.linker.is_none() && sess.target.target.options.linker.is_none() =>
{
Command::new(msvc_tool.as_ref().map(|t| t.path()).unwrap_or(linker))
},
_ => Command::new(linker),
}
};
// The compiler's sysroot often has some bundled tools, so add it to the
// PATH for the child.
let mut new_path = sess.host_filesearch(PathKind::All)
.get_tools_search_paths();
let mut msvc_changed_path = false;
if sess.target.target.options.is_like_msvc {
if let Some(ref tool) = msvc_tool {
cmd.args(tool.args());
for &(ref k, ref v) in tool.env() {
if k == "PATH" {
new_path.extend(env::split_paths(v));
msvc_changed_path = true;
} else {
cmd.env(k, v);
}
}
}
}
if !msvc_changed_path {
if let Some(path) = env::var_os("PATH") {
new_path.extend(env::split_paths(&path));
}
}
cmd.env("PATH", env::join_paths(new_path).unwrap());
(linker.to_path_buf(), cmd)
}
pub fn linker_and_flavor(sess: &Session) -> (PathBuf, LinkerFlavor) {
fn infer_from(
sess: &Session,
linker: Option<PathBuf>,
flavor: Option<LinkerFlavor>,
) -> Option<(PathBuf, LinkerFlavor)> {
match (linker, flavor) {
(Some(linker), Some(flavor)) => Some((linker, flavor)),
// only the linker flavor is known; use the default linker for the selected flavor
(None, Some(flavor)) => Some((PathBuf::from(match flavor {
LinkerFlavor::Em => if cfg!(windows) { "emcc.bat" } else { "emcc" },
LinkerFlavor::Gcc => "cc",
LinkerFlavor::Ld => "ld",
LinkerFlavor::Msvc => "link.exe",
LinkerFlavor::Lld(_) => "lld",
}), flavor)),
(Some(linker), None) => {
let stem = linker.file_stem().and_then(|stem| stem.to_str()).unwrap_or_else(|| {
sess.fatal("couldn't extract file stem from specified linker");
}).to_owned();
let flavor = if stem == "emcc" {
LinkerFlavor::Em
} else if stem == "gcc" || stem.ends_with("-gcc") {
LinkerFlavor::Gcc
} else if stem == "ld" || stem == "ld.lld" || stem.ends_with("-ld") {
LinkerFlavor::Ld
} else if stem == "link" || stem == "lld-link" {
LinkerFlavor::Msvc
} else if stem == "lld" || stem == "rust-lld" {
LinkerFlavor::Lld(sess.target.target.options.lld_flavor)
} else {
// fall back to the value in the target spec
sess.target.target.linker_flavor
};
Some((linker, flavor))
},
(None, None) => None,
}
}
// linker and linker flavor specified via command line have precedence over what the target
// specification specifies
if let Some(ret) = infer_from(
sess,
sess.opts.cg.linker.clone(),
sess.opts.debugging_opts.linker_flavor,
) {
return ret;
}
if let Some(ret) = infer_from(
sess,
sess.target.target.options.linker.clone().map(PathBuf::from),
Some(sess.target.target.linker_flavor),
) {
return ret;
}
bug!("Not enough information provided to determine how to invoke the linker");
}
pub fn exec_linker(sess: &Session, cmd: &mut Command, out_filename: &Path, tmpdir: &Path)
-> io::Result<Output>
{
// When attempting to spawn the linker we run a risk of blowing out the
// size limits for spawning a new process with respect to the arguments
// we pass on the command line.
//
// Here we attempt to handle errors from the OS saying "your list of
// arguments is too big" by reinvoking the linker again with an `@`-file
// that contains all the arguments. The theory is that this is then
// accepted on all linkers and the linker will read all its options out of
// there instead of looking at the command line.
if !cmd.very_likely_to_exceed_some_spawn_limit() {
match cmd.command().stdout(Stdio::piped()).stderr(Stdio::piped()).spawn() {
Ok(child) => {
let output = child.wait_with_output();
flush_linked_file(&output, out_filename)?;
return output;
}
Err(ref e) if command_line_too_big(e) => {
info!("command line to linker was too big: {}", e);
}
Err(e) => return Err(e)
}
}
info!("falling back to passing arguments to linker via an @-file");
let mut cmd2 = cmd.clone();
let mut args = String::new();
for arg in cmd2.take_args() {
args.push_str(&Escape {
arg: arg.to_str().unwrap(),
is_like_msvc: sess.target.target.options.is_like_msvc,
}.to_string());
args.push_str("\n");
}
let file = tmpdir.join("linker-arguments");
let bytes = if sess.target.target.options.is_like_msvc {
let mut out = Vec::with_capacity((1 + args.len()) * 2);
// start the stream with a UTF-16 BOM
for c in iter::once(0xFEFF).chain(args.encode_utf16()) {
// encode in little endian
out.push(c as u8);
out.push((c >> 8) as u8);
}
out
} else {
args.into_bytes()
};
fs::write(&file, &bytes)?;
cmd2.arg(format!("@{}", file.display()));
info!("invoking linker {:?}", cmd2);
let output = cmd2.output();
flush_linked_file(&output, out_filename)?;
return output;
#[cfg(unix)]
fn flush_linked_file(_: &io::Result<Output>, _: &Path) -> io::Result<()> {
Ok(())
}
#[cfg(windows)]
fn flush_linked_file(command_output: &io::Result<Output>, out_filename: &Path)
-> io::Result<()>
{
// On Windows, under high I/O load, output buffers are sometimes not flushed,
// even long after process exit, causing nasty, non-reproducible output bugs.
//
// File::sync_all() calls FlushFileBuffers() down the line, which solves the problem.
//
// А full writeup of the original Chrome bug can be found at
// randomascii.wordpress.com/2018/02/25/compiler-bug-linker-bug-windows-kernel-bug/amp
if let &Ok(ref out) = command_output {
if out.status.success() {
if let Ok(of) = fs::OpenOptions::new().write(true).open(out_filename) {
of.sync_all()?;
}
}
}
Ok(())
}
#[cfg(unix)]
fn command_line_too_big(err: &io::Error) -> bool {
err.raw_os_error() == Some(::libc::E2BIG)
}
#[cfg(windows)]
fn command_line_too_big(err: &io::Error) -> bool {
const ERROR_FILENAME_EXCED_RANGE: i32 = 206;
err.raw_os_error() == Some(ERROR_FILENAME_EXCED_RANGE)
}
struct Escape<'a> {
arg: &'a str,
is_like_msvc: bool,
}
impl<'a> fmt::Display for Escape<'a> {
fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
if self.is_like_msvc {
// This is "documented" at
// https://msdn.microsoft.com/en-us/library/4xdcbak7.aspx
//
// Unfortunately there's not a great specification of the
// syntax I could find online (at least) but some local
// testing showed that this seemed sufficient-ish to catch
// at least a few edge cases.
write!(f, "\"")?;
for c in self.arg.chars() {
match c {
'"' => write!(f, "\\{}", c)?,
c => write!(f, "{}", c)?,
}
}
write!(f, "\"")?;
} else {
// This is documented at https://linux.die.net/man/1/ld, namely:
//
// > Options in file are separated by whitespace. A whitespace
// > character may be included in an option by surrounding the
// > entire option in either single or double quotes. Any
// > character (including a backslash) may be included by
// > prefixing the character to be included with a backslash.
//
// We put an argument on each line, so all we need to do is
// ensure the line is interpreted as one whole argument.
for c in self.arg.chars() {
match c {
'\\' |
' ' => write!(f, "\\{}", c)?,
c => write!(f, "{}", c)?,
}
}
}
Ok(())
}
}
}
// # Rust Crate linking
//
// Rust crates are not considered at all when creating an rlib output. All
// dependencies will be linked when producing the final output (instead of
// the intermediate rlib version)
pub fn add_upstream_rust_crates(cmd: &mut dyn Linker,
sess: &Session,
codegen_results: &CodegenResults,
crate_type: config::CrateType,
tmpdir: &Path) {
// All of the heavy lifting has previously been accomplished by the
// dependency_format module of the compiler. This is just crawling the
// output of that module, adding crates as necessary.
//
// Linking to a rlib involves just passing it to the linker (the linker
// will slurp up the object files inside), and linking to a dynamic library
// involves just passing the right -l flag.
let formats = sess.dependency_formats.borrow();
let data = formats.get(&crate_type).unwrap();
// Invoke get_used_crates to ensure that we get a topological sorting of
// crates.
let deps = &codegen_results.crate_info.used_crates_dynamic;
// There's a few internal crates in the standard library (aka libcore and
// libstd) which actually have a circular dependence upon one another. This
// currently arises through "weak lang items" where libcore requires things
// like `rust_begin_unwind` but libstd ends up defining it. To get this
// circular dependence to work correctly in all situations we'll need to be
// sure to correctly apply the `--start-group` and `--end-group` options to
// GNU linkers, otherwise if we don't use any other symbol from the standard
// library it'll get discarded and the whole application won't link.
//
// In this loop we're calculating the `group_end`, after which crate to
// pass `--end-group` and `group_start`, before which crate to pass
// `--start-group`. We currently do this by passing `--end-group` after
// the first crate (when iterating backwards) that requires a lang item
// defined somewhere else. Once that's set then when we've defined all the
// necessary lang items we'll pass `--start-group`.
//
// Note that this isn't amazing logic for now but it should do the trick
// for the current implementation of the standard library.
let mut group_end = None;
let mut group_start = None;
let mut end_with = FxHashSet::default();
let info = &codegen_results.crate_info;
for &(cnum, _) in deps.iter().rev() {
if let Some(missing) = info.missing_lang_items.get(&cnum) {
end_with.extend(missing.iter().cloned());
if end_with.len() > 0 && group_end.is_none() {
group_end = Some(cnum);
}
}
end_with.retain(|item| info.lang_item_to_crate.get(item) != Some(&cnum));
if end_with.len() == 0 && group_end.is_some() {
group_start = Some(cnum);
break
}
}
// If we didn't end up filling in all lang items from upstream crates then
// we'll be filling it in with our crate. This probably means we're the
// standard library itself, so skip this for now.
if group_end.is_some() && group_start.is_none() {
group_end = None;
}
let mut compiler_builtins = None;
for &(cnum, _) in deps.iter() {
if group_start == Some(cnum) {
cmd.group_start();
}
// We may not pass all crates through to the linker. Some crates may
// appear statically in an existing dylib, meaning we'll pick up all the
// symbols from the dylib.
let src = &codegen_results.crate_info.used_crate_source[&cnum];
match data[cnum.as_usize() - 1] {
_ if codegen_results.crate_info.profiler_runtime == Some(cnum) => {
add_static_crate(cmd, sess, codegen_results, tmpdir, crate_type, cnum);
}
_ if codegen_results.crate_info.sanitizer_runtime == Some(cnum) => {
link_sanitizer_runtime(cmd, sess, codegen_results, tmpdir, cnum);
}
// compiler-builtins are always placed last to ensure that they're
// linked correctly.
_ if codegen_results.crate_info.compiler_builtins == Some(cnum) => {
assert!(compiler_builtins.is_none());
compiler_builtins = Some(cnum);
}
Linkage::NotLinked |
Linkage::IncludedFromDylib => {}
Linkage::Static => {
add_static_crate(cmd, sess, codegen_results, tmpdir, crate_type, cnum);
}
Linkage::Dynamic => {
add_dynamic_crate(cmd, sess, &src.dylib.as_ref().unwrap().0)
}
}
if group_end == Some(cnum) {
cmd.group_end();
}
}
// compiler-builtins are always placed last to ensure that they're
// linked correctly.
// We must always link the `compiler_builtins` crate statically. Even if it
// was already "included" in a dylib (e.g. `libstd` when `-C prefer-dynamic`
// is used)
if let Some(cnum) = compiler_builtins {
add_static_crate(cmd, sess, codegen_results, tmpdir, crate_type, cnum);
}
// Converts a library file-stem into a cc -l argument
fn unlib<'a>(config: &config::Config, stem: &'a str) -> &'a str {
if stem.starts_with("lib") && !config.target.options.is_like_windows {
&stem[3..]
} else {
stem
}
}
// We must link the sanitizer runtime using -Wl,--whole-archive but since
// it's packed in a .rlib, it contains stuff that are not objects that will
// make the linker error. So we must remove those bits from the .rlib before
// linking it.
fn link_sanitizer_runtime(cmd: &mut dyn Linker,
sess: &Session,
codegen_results: &CodegenResults,
tmpdir: &Path,
cnum: CrateNum) {
let src = &codegen_results.crate_info.used_crate_source[&cnum];
let cratepath = &src.rlib.as_ref().unwrap().0;
if sess.target.target.options.is_like_osx {
// On Apple platforms, the sanitizer is always built as a dylib, and
// LLVM will link to `@rpath/*.dylib`, so we need to specify an
// rpath to the library as well (the rpath should be absolute, see
// PR #41352 for details).
//
// FIXME: Remove this logic into librustc_*san once Cargo supports it
let rpath = cratepath.parent().unwrap();
let rpath = rpath.to_str().expect("non-utf8 component in path");
cmd.args(&["-Wl,-rpath".into(), "-Xlinker".into(), rpath.into()]);
}
let dst = tmpdir.join(cratepath.file_name().unwrap());
let cfg = archive_config(sess, &dst, Some(cratepath));
let mut archive = ArchiveBuilder::new(cfg);
archive.update_symbols();
for f in archive.src_files() {
if f.ends_with(RLIB_BYTECODE_EXTENSION) || f == METADATA_FILENAME {
archive.remove_file(&f);
continue
}
}
archive.build();
cmd.link_whole_rlib(&dst);
}
// Adds the static "rlib" versions of all crates to the command line.
// There's a bit of magic which happens here specifically related to LTO and
// dynamic libraries. Specifically:
//
// * For LTO, we remove upstream object files.
// * For dylibs we remove metadata and bytecode from upstream rlibs
//
// When performing LTO, almost(*) all of the bytecode from the upstream
// libraries has already been included in our object file output. As a
// result we need to remove the object files in the upstream libraries so
// the linker doesn't try to include them twice (or whine about duplicate
// symbols). We must continue to include the rest of the rlib, however, as
// it may contain static native libraries which must be linked in.
//
// (*) Crates marked with `#![no_builtins]` don't participate in LTO and
// their bytecode wasn't included. The object files in those libraries must
// still be passed to the linker.
//
// When making a dynamic library, linkers by default don't include any
// object files in an archive if they're not necessary to resolve the link.
// We basically want to convert the archive (rlib) to a dylib, though, so we
// *do* want everything included in the output, regardless of whether the
// linker thinks it's needed or not. As a result we must use the
// --whole-archive option (or the platform equivalent). When using this
// option the linker will fail if there are non-objects in the archive (such
// as our own metadata and/or bytecode). All in all, for rlibs to be
// entirely included in dylibs, we need to remove all non-object files.
//
// Note, however, that if we're not doing LTO or we're not producing a dylib
// (aka we're making an executable), we can just pass the rlib blindly to
// the linker (fast) because it's fine if it's not actually included as
// we're at the end of the dependency chain.
fn add_static_crate(cmd: &mut dyn Linker,
sess: &Session,
codegen_results: &CodegenResults,
tmpdir: &Path,
crate_type: config::CrateType,
cnum: CrateNum) {
let src = &codegen_results.crate_info.used_crate_source[&cnum];
let cratepath = &src.rlib.as_ref().unwrap().0;
// See the comment above in `link_staticlib` and `link_rlib` for why if
// there's a static library that's not relevant we skip all object
// files.
let native_libs = &codegen_results.crate_info.native_libraries[&cnum];
let skip_native = native_libs.iter().any(|lib| {
lib.kind == NativeLibraryKind::NativeStatic && !relevant_lib(sess, lib)
});
if (!are_upstream_rust_objects_already_included(sess) ||
ignored_for_lto(sess, &codegen_results.crate_info, cnum)) &&
crate_type != config::CrateType::Dylib &&
!skip_native {
cmd.link_rlib(&fix_windows_verbatim_for_gcc(cratepath));
return
}
let dst = tmpdir.join(cratepath.file_name().unwrap());
let name = cratepath.file_name().unwrap().to_str().unwrap();
let name = &name[3..name.len() - 5]; // chop off lib/.rlib
time(sess, &format!("altering {}.rlib", name), || {
let cfg = archive_config(sess, &dst, Some(cratepath));
let mut archive = ArchiveBuilder::new(cfg);
archive.update_symbols();
let mut any_objects = false;
for f in archive.src_files() {
if f.ends_with(RLIB_BYTECODE_EXTENSION) || f == METADATA_FILENAME {
archive.remove_file(&f);
continue
}
let canonical = f.replace("-", "_");
let canonical_name = name.replace("-", "_");
// Look for `.rcgu.o` at the end of the filename to conclude
// that this is a Rust-related object file.
fn looks_like_rust(s: &str) -> bool {
let path = Path::new(s);
let ext = path.extension().and_then(|s| s.to_str());
if ext != Some(OutputType::Object.extension()) {
return false
}
let ext2 = path.file_stem()
.and_then(|s| Path::new(s).extension())
.and_then(|s| s.to_str());
ext2 == Some(RUST_CGU_EXT)
}
let is_rust_object =
canonical.starts_with(&canonical_name) &&
looks_like_rust(&f);
// If we've been requested to skip all native object files
// (those not generated by the rust compiler) then we can skip
// this file. See above for why we may want to do this.
let skip_because_cfg_say_so = skip_native && !is_rust_object;
// If we're performing LTO and this is a rust-generated object
// file, then we don't need the object file as it's part of the
// LTO module. Note that `#![no_builtins]` is excluded from LTO,
// though, so we let that object file slide.
let skip_because_lto = are_upstream_rust_objects_already_included(sess) &&
is_rust_object &&
(sess.target.target.options.no_builtins ||
!codegen_results.crate_info.is_no_builtins.contains(&cnum));
if skip_because_cfg_say_so || skip_because_lto {
archive.remove_file(&f);
} else {
any_objects = true;
}
}
if !any_objects {
return
}
archive.build();
// If we're creating a dylib, then we need to include the
// whole of each object in our archive into that artifact. This is
// because a `dylib` can be reused as an intermediate artifact.
//
// Note, though, that we don't want to include the whole of a
// compiler-builtins crate (e.g. compiler-rt) because it'll get
// repeatedly linked anyway.
if crate_type == config::CrateType::Dylib &&
codegen_results.crate_info.compiler_builtins != Some(cnum) {
cmd.link_whole_rlib(&fix_windows_verbatim_for_gcc(&dst));
} else {
cmd.link_rlib(&fix_windows_verbatim_for_gcc(&dst));
}
});
}
// Same thing as above, but for dynamic crates instead of static crates.
fn add_dynamic_crate(cmd: &mut dyn Linker, sess: &Session, cratepath: &Path) {
// If we're performing LTO, then it should have been previously required
// that all upstream rust dependencies were available in an rlib format.
assert!(!are_upstream_rust_objects_already_included(sess));
// Just need to tell the linker about where the library lives and
// what its name is
let parent = cratepath.parent();
if let Some(dir) = parent {
cmd.include_path(&fix_windows_verbatim_for_gcc(dir));
}
let filestem = cratepath.file_stem().unwrap().to_str().unwrap();
cmd.link_rust_dylib(&unlib(&sess.target, filestem),
parent.unwrap_or(Path::new("")));
}
}
// # Native library linking
//
// User-supplied library search paths (-L on the command line). These are
// the same paths used to find Rust crates, so some of them may have been
// added already by the previous crate linking code. This only allows them
// to be found at compile time so it is still entirely up to outside
// forces to make sure that library can be found at runtime.
//
// Also note that the native libraries linked here are only the ones located
// in the current crate. Upstream crates with native library dependencies
// may have their native library pulled in above.
pub fn add_local_native_libraries(cmd: &mut dyn Linker,
sess: &Session,
codegen_results: &CodegenResults) {
sess.target_filesearch(PathKind::All).for_each_lib_search_path(|path, k| {
match k {
PathKind::Framework => { cmd.framework_path(path); }
_ => { cmd.include_path(&fix_windows_verbatim_for_gcc(path)); }
}
});
let relevant_libs = codegen_results.crate_info.used_libraries.iter().filter(|l| {
relevant_lib(sess, l)
});
let search_path = archive_search_paths(sess);
for lib in relevant_libs {
let name = match lib.name {
Some(ref l) => l,
None => continue,
};
match lib.kind {
NativeLibraryKind::NativeUnknown => cmd.link_dylib(&name.as_str()),
NativeLibraryKind::NativeFramework => cmd.link_framework(&name.as_str()),
NativeLibraryKind::NativeStaticNobundle => cmd.link_staticlib(&name.as_str()),
NativeLibraryKind::NativeStatic => cmd.link_whole_staticlib(&name.as_str(),
&search_path)
}
}
}
// Link in all of our upstream crates' native dependencies. Remember that
// all of these upstream native dependencies are all non-static
// dependencies. We've got two cases then:
//
// 1. The upstream crate is an rlib. In this case we *must* link in the
// native dependency because the rlib is just an archive.
//
// 2. The upstream crate is a dylib. In order to use the dylib, we have to
// have the dependency present on the system somewhere. Thus, we don't
// gain a whole lot from not linking in the dynamic dependency to this
// crate as well.
//
// The use case for this is a little subtle. In theory the native
// dependencies of a crate are purely an implementation detail of the crate
// itself, but the problem arises with generic and inlined functions. If a
// generic function calls a native function, then the generic function must
// be instantiated in the target crate, meaning that the native symbol must
// also be resolved in the target crate.
pub fn add_upstream_native_libraries(cmd: &mut dyn Linker,
sess: &Session,
codegen_results: &CodegenResults,
crate_type: config::CrateType) {
// Be sure to use a topological sorting of crates because there may be
// interdependencies between native libraries. When passing -nodefaultlibs,
// for example, almost all native libraries depend on libc, so we have to
// make sure that's all the way at the right (liblibc is near the base of
// the dependency chain).
//
// This passes RequireStatic, but the actual requirement doesn't matter,
// we're just getting an ordering of crate numbers, we're not worried about
// the paths.
let formats = sess.dependency_formats.borrow();
let data = formats.get(&crate_type).unwrap();
let crates = &codegen_results.crate_info.used_crates_static;
for &(cnum, _) in crates {
for lib in codegen_results.crate_info.native_libraries[&cnum].iter() {
let name = match lib.name {
Some(ref l) => l,
None => continue,
};
if !relevant_lib(sess, &lib) {
continue
}
match lib.kind {
NativeLibraryKind::NativeUnknown => cmd.link_dylib(&name.as_str()),
NativeLibraryKind::NativeFramework => cmd.link_framework(&name.as_str()),
NativeLibraryKind::NativeStaticNobundle => {
// Link "static-nobundle" native libs only if the crate they originate from
// is being linked statically to the current crate. If it's linked dynamically
// or is an rlib already included via some other dylib crate, the symbols from
// native libs will have already been included in that dylib.
if data[cnum.as_usize() - 1] == Linkage::Static {
cmd.link_staticlib(&name.as_str())
}
},
// ignore statically included native libraries here as we've
// already included them when we included the rust library
// previously
NativeLibraryKind::NativeStatic => {}
}
}
}
}
/// Returns a boolean indicating whether the specified crate should be ignored
/// during LTO.
///
/// Crates ignored during LTO are not lumped together in the "massive object
/// file" that we create and are linked in their normal rlib states. See
/// comments below for what crates do not participate in LTO.
///
/// It's unusual for a crate to not participate in LTO. Typically only
/// compiler-specific and unstable crates have a reason to not participate in
/// LTO.
fn ignored_for_lto(sess: &Session, info: &CrateInfo, cnum: CrateNum) -> bool {
// If our target enables builtin function lowering in LLVM then the
// crates providing these functions don't participate in LTO (e.g.
// no_builtins or compiler builtins crates).
!sess.target.target.options.no_builtins &&
(info.is_no_builtins.contains(&cnum) || info.compiler_builtins == Some(cnum))
}
fn relevant_lib(sess: &Session, lib: &NativeLibrary) -> bool {
match lib.cfg {
Some(ref cfg) => attr::cfg_matches(cfg, &sess.parse_sess, None),
None => true,
}
}
fn are_upstream_rust_objects_already_included(sess: &Session) -> bool {
match sess.lto() {
Lto::Fat => true,
Lto::Thin => {
// If we defer LTO to the linker, we haven't run LTO ourselves, so
// any upstream object files have not been copied yet.
!sess.opts.debugging_opts.cross_lang_lto.enabled()
}
Lto::No |
Lto::ThinLocal => false,
}
}