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Move almost all of cg_llvm/back/link.rs to cg_ssa

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bjorn3
2019-03-30 15:25:10 +01:00
parent de4ee55dc7
commit 93a3b414e3
8 changed files with 1115 additions and 1111 deletions
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Cargo.lock
+1
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@@ -2634,6 +2634,7 @@ dependencies = [
"serialize 0.0.0",
"syntax 0.0.0",
"syntax_pos 0.0.0",
"tempfile 3.0.5 (registry+https://github.com/rust-lang/crates.io-index)",
]
[[package]]
src/librustc_codegen_llvm/back/link.rs
+15 -1102
View File
@@ -1,1112 +1,25 @@
use super::archive::LlvmArchiveBuilder;
use super::rpath::RPathConfig;
use super::rpath;
use crate::back::wasm;
use rustc_codegen_ssa::{METADATA_FILENAME, RLIB_BYTECODE_EXTENSION};
use rustc_codegen_ssa::back::archive::ArchiveBuilder;
use rustc_codegen_ssa::back::linker::Linker;
use rustc_codegen_ssa::back::link::*;
use rustc_codegen_ssa::back::command::Command;
use rustc::session::config::{self, DebugInfo, OutputFilenames, OutputType, PrintRequest};
use rustc::session::config::{RUST_CGU_EXT, Sanitizer};
use rustc::session::filesearch;
use rustc::session::search_paths::PathKind;
use rustc::session::config::OutputFilenames;
use rustc::session::Session;
use rustc::middle::cstore::NativeLibraryKind;
use rustc::middle::dependency_format::Linkage;
use rustc_codegen_ssa::CodegenResults;
use rustc::util::common::{time, time_ext};
use rustc_fs_util::fix_windows_verbatim_for_gcc;
use rustc::hir::def_id::CrateNum;
use tempfile::{Builder as TempFileBuilder, TempDir};
use rustc_target::spec::{PanicStrategy, RelroLevel, LinkerFlavor};
use rustc_data_structures::fx::FxHashSet;
use std::ascii;
use std::char;
use std::env;
use std::fs;
use std::io;
use std::path::{Path, PathBuf};
use std::str;
use super::archive::LlvmArchiveBuilder;
use std::path::PathBuf;
pub use rustc_codegen_utils::link::*;
/// Performs the linkage portion of the compilation phase. This will generate all
/// of the requested outputs for this compilation session.
pub(crate) fn link_binary<'a>(sess: &'a Session,
codegen_results: &CodegenResults,
outputs: &OutputFilenames,
crate_name: &str) -> Vec<PathBuf> {
let target_cpu = crate::llvm_util::target_cpu(sess);
let mut out_filenames = Vec::new();
for &crate_type in sess.crate_types.borrow().iter() {
// Ignore executable crates if we have -Z no-codegen, as they will error.
let output_metadata = sess.opts.output_types.contains_key(&OutputType::Metadata);
if (sess.opts.debugging_opts.no_codegen || !sess.opts.output_types.should_codegen()) &&
!output_metadata &&
crate_type == config::CrateType::Executable {
continue;
}
if invalid_output_for_target(sess, crate_type) {
bug!("invalid output type `{:?}` for target os `{}`",
crate_type, sess.opts.target_triple);
}
let out_files = link_binary_output::<LlvmArchiveBuilder<'a>>(sess,
codegen_results,
crate_type,
outputs,
crate_name,
target_cpu);
out_filenames.extend(out_files);
}
// Remove the temporary object file and metadata if we aren't saving temps
if !sess.opts.cg.save_temps {
if sess.opts.output_types.should_codegen() && !preserve_objects_for_their_debuginfo(sess) {
for obj in codegen_results.modules.iter().filter_map(|m| m.object.as_ref()) {
remove(sess, obj);
}
}
for obj in codegen_results.modules.iter().filter_map(|m| m.bytecode_compressed.as_ref()) {
remove(sess, obj);
}
if let Some(ref obj) = codegen_results.metadata_module.object {
remove(sess, obj);
}
if let Some(ref allocator) = codegen_results.allocator_module {
if let Some(ref obj) = allocator.object {
remove(sess, obj);
}
if let Some(ref bc) = allocator.bytecode_compressed {
remove(sess, bc);
}
}
}
out_filenames
}
fn link_binary_output<'a, B: ArchiveBuilder<'a>>(sess: &'a Session,
codegen_results: &CodegenResults,
crate_type: config::CrateType,
outputs: &OutputFilenames,
crate_name: &str,
target_cpu: &str) -> Vec<PathBuf> {
for obj in codegen_results.modules.iter().filter_map(|m| m.object.as_ref()) {
check_file_is_writeable(obj, sess);
}
let mut out_filenames = vec![];
if outputs.outputs.contains_key(&OutputType::Metadata) {
let out_filename = filename_for_metadata(sess, crate_name, outputs);
// To avoid races with another rustc process scanning the output directory,
// we need to write the file somewhere else and atomically move it to its
// final destination, with a `fs::rename` call. In order for the rename to
// always succeed, the temporary file needs to be on the same filesystem,
// which is why we create it inside the output directory specifically.
let metadata_tmpdir = TempFileBuilder::new()
.prefix("rmeta")
.tempdir_in(out_filename.parent().unwrap())
.unwrap_or_else(|err| sess.fatal(&format!("couldn't create a temp dir: {}", err)));
let metadata = emit_metadata(sess, codegen_results, &metadata_tmpdir);
if let Err(e) = fs::rename(metadata, &out_filename) {
sess.fatal(&format!("failed to write {}: {}", out_filename.display(), e));
}
out_filenames.push(out_filename);
}
let tmpdir = TempFileBuilder::new().prefix("rustc").tempdir().unwrap_or_else(|err|
sess.fatal(&format!("couldn't create a temp dir: {}", err)));
if outputs.outputs.should_codegen() {
let out_filename = out_filename(sess, crate_type, outputs, crate_name);
match crate_type {
config::CrateType::Rlib => {
link_rlib::<B>(sess,
codegen_results,
RlibFlavor::Normal,
&out_filename,
&tmpdir).build();
}
config::CrateType::Staticlib => {
link_staticlib::<B>(sess, codegen_results, &out_filename, &tmpdir);
}
_ => {
link_natively::<B>(sess, crate_type, &out_filename, codegen_results, tmpdir.path(), target_cpu);
}
}
out_filenames.push(out_filename);
}
if sess.opts.cg.save_temps {
let _ = tmpdir.into_path();
}
out_filenames
}
/// We use a temp directory here to avoid races between concurrent rustc processes,
/// such as builds in the same directory using the same filename for metadata while
/// building an `.rlib` (stomping over one another), or writing an `.rmeta` into a
/// directory being searched for `extern crate` (observing an incomplete file).
/// The returned path is the temporary file containing the complete metadata.
fn emit_metadata<'a>(
pub(crate) fn link_binary<'a>(
sess: &'a Session,
codegen_results: &CodegenResults,
tmpdir: &TempDir
) -> PathBuf {
let out_filename = tmpdir.path().join(METADATA_FILENAME);
let result = fs::write(&out_filename, &codegen_results.metadata.raw_data);
if let Err(e) = result {
sess.fatal(&format!("failed to write {}: {}", out_filename.display(), e));
}
out_filename
}
// Create an 'rlib'
//
// An rlib in its current incarnation is essentially a renamed .a file. The
// rlib primarily contains the object file of the crate, but it also contains
// all of the object files from native libraries. This is done by unzipping
// native libraries and inserting all of the contents into this archive.
fn link_rlib<'a, B: ArchiveBuilder<'a>>(sess: &'a Session,
codegen_results: &CodegenResults,
flavor: RlibFlavor,
out_filename: &Path,
tmpdir: &TempDir) -> B {
info!("preparing rlib to {:?}", out_filename);
let mut ab = <B as ArchiveBuilder>::new(sess, out_filename, None);
for obj in codegen_results.modules.iter().filter_map(|m| m.object.as_ref()) {
ab.add_file(obj);
}
// Note that in this loop we are ignoring the value of `lib.cfg`. That is,
// we may not be configured to actually include a static library if we're
// adding it here. That's because later when we consume this rlib we'll
// decide whether we actually needed the static library or not.
//
// To do this "correctly" we'd need to keep track of which libraries added
// which object files to the archive. We don't do that here, however. The
// #[link(cfg(..))] feature is unstable, though, and only intended to get
// liblibc working. In that sense the check below just indicates that if
// there are any libraries we want to omit object files for at link time we
// just exclude all custom object files.
//
// Eventually if we want to stabilize or flesh out the #[link(cfg(..))]
// feature then we'll need to figure out how to record what objects were
// loaded from the libraries found here and then encode that into the
// metadata of the rlib we're generating somehow.
for lib in codegen_results.crate_info.used_libraries.iter() {
match lib.kind {
NativeLibraryKind::NativeStatic => {}
NativeLibraryKind::NativeStaticNobundle |
NativeLibraryKind::NativeFramework |
NativeLibraryKind::NativeUnknown => continue,
}
if let Some(name) = lib.name {
ab.add_native_library(&name.as_str());
}
}
// After adding all files to the archive, we need to update the
// symbol table of the archive.
ab.update_symbols();
// Note that it is important that we add all of our non-object "magical
// files" *after* all of the object files in the archive. The reason for
// this is as follows:
//
// * When performing LTO, this archive will be modified to remove
// objects from above. The reason for this is described below.
//
// * When the system linker looks at an archive, it will attempt to
// determine the architecture of the archive in order to see whether its
// linkable.
//
// The algorithm for this detection is: iterate over the files in the
// archive. Skip magical SYMDEF names. Interpret the first file as an
// object file. Read architecture from the object file.
//
// * As one can probably see, if "metadata" and "foo.bc" were placed
// before all of the objects, then the architecture of this archive would
// not be correctly inferred once 'foo.o' is removed.
//
// Basically, all this means is that this code should not move above the
// code above.
match flavor {
RlibFlavor::Normal => {
// Instead of putting the metadata in an object file section, rlibs
// contain the metadata in a separate file.
ab.add_file(&emit_metadata(sess, codegen_results, tmpdir));
// For LTO purposes, the bytecode of this library is also inserted
// into the archive.
for bytecode in codegen_results
.modules
.iter()
.filter_map(|m| m.bytecode_compressed.as_ref())
{
ab.add_file(bytecode);
}
// After adding all files to the archive, we need to update the
// symbol table of the archive. This currently dies on macOS (see
// #11162), and isn't necessary there anyway
if !sess.target.target.options.is_like_osx {
ab.update_symbols();
}
}
RlibFlavor::StaticlibBase => {
let obj = codegen_results.allocator_module
.as_ref()
.and_then(|m| m.object.as_ref());
if let Some(obj) = obj {
ab.add_file(obj);
}
}
}
ab
}
// Create a static archive
//
// This is essentially the same thing as an rlib, but it also involves adding
// all of the upstream crates' objects into the archive. This will slurp in
// all of the native libraries of upstream dependencies as well.
//
// Additionally, there's no way for us to link dynamic libraries, so we warn
// about all dynamic library dependencies that they're not linked in.
//
// There's no need to include metadata in a static archive, so ensure to not
// link in the metadata object file (and also don't prepare the archive with a
// metadata file).
fn link_staticlib<'a, B: ArchiveBuilder<'a>>(sess: &'a Session,
codegen_results: &CodegenResults,
out_filename: &Path,
tempdir: &TempDir) {
let mut ab = link_rlib::<B>(sess,
codegen_results,
RlibFlavor::StaticlibBase,
out_filename,
tempdir);
let mut all_native_libs = vec![];
let res = each_linked_rlib(sess, &codegen_results.crate_info, &mut |cnum, path| {
let name = &codegen_results.crate_info.crate_name[&cnum];
let native_libs = &codegen_results.crate_info.native_libraries[&cnum];
// Here when we include the rlib into our staticlib we need to make a
// decision whether to include the extra object files along the way.
// These extra object files come from statically included native
// libraries, but they may be cfg'd away with #[link(cfg(..))].
//
// This unstable feature, though, only needs liblibc to work. The only
// use case there is where musl is statically included in liblibc.rlib,
// so if we don't want the included version we just need to skip it. As
// a result the logic here is that if *any* linked library is cfg'd away
// we just skip all object files.
//
// Clearly this is not sufficient for a general purpose feature, and
// we'd want to read from the library's metadata to determine which
// object files come from where and selectively skip them.
let skip_object_files = native_libs.iter().any(|lib| {
lib.kind == NativeLibraryKind::NativeStatic && !relevant_lib(sess, lib)
});
ab.add_rlib(path,
&name.as_str(),
are_upstream_rust_objects_already_included(sess) &&
!ignored_for_lto(sess, &codegen_results.crate_info, cnum),
skip_object_files).unwrap();
all_native_libs.extend(codegen_results.crate_info.native_libraries[&cnum].iter().cloned());
});
if let Err(e) = res {
sess.fatal(&e);
}
ab.update_symbols();
ab.build();
if !all_native_libs.is_empty() {
if sess.opts.prints.contains(&PrintRequest::NativeStaticLibs) {
print_native_static_libs(sess, &all_native_libs);
}
}
}
// Create a dynamic library or executable
//
// This will invoke the system linker/cc to create the resulting file. This
// links to all upstream files as well.
fn link_natively<'a, B: ArchiveBuilder<'a>>(sess: &'a Session,
crate_type: config::CrateType,
out_filename: &Path,
codegen_results: &CodegenResults,
tmpdir: &Path,
target_cpu: &str) {
info!("preparing {:?} to {:?}", crate_type, out_filename);
let (linker, flavor) = linker_and_flavor(sess);
// The invocations of cc share some flags across platforms
let (pname, mut cmd) = get_linker(sess, &linker, flavor);
if let Some(args) = sess.target.target.options.pre_link_args.get(&flavor) {
cmd.args(args);
}
if let Some(args) = sess.target.target.options.pre_link_args_crt.get(&flavor) {
if sess.crt_static() {
cmd.args(args);
}
}
if let Some(ref args) = sess.opts.debugging_opts.pre_link_args {
cmd.args(args);
}
cmd.args(&sess.opts.debugging_opts.pre_link_arg);
if sess.target.target.options.is_like_fuchsia {
let prefix = match sess.opts.debugging_opts.sanitizer {
Some(Sanitizer::Address) => "asan/",
_ => "",
};
cmd.arg(format!("--dynamic-linker={}ld.so.1", prefix));
}
let pre_link_objects = if crate_type == config::CrateType::Executable {
&sess.target.target.options.pre_link_objects_exe
} else {
&sess.target.target.options.pre_link_objects_dll
};
for obj in pre_link_objects {
cmd.arg(get_file_path(sess, obj));
}
if crate_type == config::CrateType::Executable && sess.crt_static() {
for obj in &sess.target.target.options.pre_link_objects_exe_crt {
cmd.arg(get_file_path(sess, obj));
}
}
if sess.target.target.options.is_like_emscripten {
cmd.arg("-s");
cmd.arg(if sess.panic_strategy() == PanicStrategy::Abort {
"DISABLE_EXCEPTION_CATCHING=1"
} else {
"DISABLE_EXCEPTION_CATCHING=0"
});
}
{
let mut linker = codegen_results.linker_info.to_linker(cmd, &sess, flavor, target_cpu);
link_args::<B>(&mut *linker, flavor, sess, crate_type, tmpdir,
out_filename, codegen_results);
cmd = linker.finalize();
}
if let Some(args) = sess.target.target.options.late_link_args.get(&flavor) {
cmd.args(args);
}
for obj in &sess.target.target.options.post_link_objects {
cmd.arg(get_file_path(sess, obj));
}
if sess.crt_static() {
for obj in &sess.target.target.options.post_link_objects_crt {
cmd.arg(get_file_path(sess, obj));
}
}
if let Some(args) = sess.target.target.options.post_link_args.get(&flavor) {
cmd.args(args);
}
for &(ref k, ref v) in &sess.target.target.options.link_env {
cmd.env(k, v);
}
if sess.opts.debugging_opts.print_link_args {
println!("{:?}", &cmd);
}
// May have not found libraries in the right formats.
sess.abort_if_errors();
// Invoke the system linker
//
// Note that there's a terribly awful hack that really shouldn't be present
// in any compiler. Here an environment variable is supported to
// automatically retry the linker invocation if the linker looks like it
// segfaulted.
//
// Gee that seems odd, normally segfaults are things we want to know about!
// Unfortunately though in rust-lang/rust#38878 we're experiencing the
// linker segfaulting on Travis quite a bit which is causing quite a bit of
// pain to land PRs when they spuriously fail due to a segfault.
//
// The issue #38878 has some more debugging information on it as well, but
// this unfortunately looks like it's just a race condition in macOS's linker
// with some thread pool working in the background. It seems that no one
// currently knows a fix for this so in the meantime we're left with this...
info!("{:?}", &cmd);
let retry_on_segfault = env::var("RUSTC_RETRY_LINKER_ON_SEGFAULT").is_ok();
let mut prog;
let mut i = 0;
loop {
i += 1;
prog = time(sess, "running linker", || {
exec_linker(sess, &mut cmd, out_filename, tmpdir)
});
let output = match prog {
Ok(ref output) => output,
Err(_) => break,
};
if output.status.success() {
break
}
let mut out = output.stderr.clone();
out.extend(&output.stdout);
let out = String::from_utf8_lossy(&out);
// Check to see if the link failed with "unrecognized command line option:
// '-no-pie'" for gcc or "unknown argument: '-no-pie'" for clang. If so,
// reperform the link step without the -no-pie option. This is safe because
// if the linker doesn't support -no-pie then it should not default to
// linking executables as pie. Different versions of gcc seem to use
// different quotes in the error message so don't check for them.
if sess.target.target.options.linker_is_gnu &&
flavor != LinkerFlavor::Ld &&
(out.contains("unrecognized command line option") ||
out.contains("unknown argument")) &&
out.contains("-no-pie") &&
cmd.get_args().iter().any(|e| e.to_string_lossy() == "-no-pie") {
info!("linker output: {:?}", out);
warn!("Linker does not support -no-pie command line option. Retrying without.");
for arg in cmd.take_args() {
if arg.to_string_lossy() != "-no-pie" {
cmd.arg(arg);
}
}
info!("{:?}", &cmd);
continue;
}
if !retry_on_segfault || i > 3 {
break
}
let msg_segv = "clang: error: unable to execute command: Segmentation fault: 11";
let msg_bus = "clang: error: unable to execute command: Bus error: 10";
if !(out.contains(msg_segv) || out.contains(msg_bus)) {
break
}
warn!(
"looks like the linker segfaulted when we tried to call it, \
automatically retrying again. cmd = {:?}, out = {}.",
cmd,
out,
);
}
match prog {
Ok(prog) => {
fn escape_string(s: &[u8]) -> String {
str::from_utf8(s).map(|s| s.to_owned())
.unwrap_or_else(|_| {
let mut x = "Non-UTF-8 output: ".to_string();
x.extend(s.iter()
.flat_map(|&b| ascii::escape_default(b))
.map(char::from));
x
})
}
if !prog.status.success() {
let mut output = prog.stderr.clone();
output.extend_from_slice(&prog.stdout);
sess.struct_err(&format!("linking with `{}` failed: {}",
pname.display(),
prog.status))
.note(&format!("{:?}", &cmd))
.note(&escape_string(&output))
.emit();
sess.abort_if_errors();
}
info!("linker stderr:\n{}", escape_string(&prog.stderr));
info!("linker stdout:\n{}", escape_string(&prog.stdout));
},
Err(e) => {
let linker_not_found = e.kind() == io::ErrorKind::NotFound;
let mut linker_error = {
if linker_not_found {
sess.struct_err(&format!("linker `{}` not found", pname.display()))
} else {
sess.struct_err(&format!("could not exec the linker `{}`", pname.display()))
}
};
linker_error.note(&e.to_string());
if !linker_not_found {
linker_error.note(&format!("{:?}", &cmd));
}
linker_error.emit();
if sess.target.target.options.is_like_msvc && linker_not_found {
sess.note_without_error("the msvc targets depend on the msvc linker \
but `link.exe` was not found");
sess.note_without_error("please ensure that VS 2013, VS 2015 or VS 2017 \
was installed with the Visual C++ option");
}
sess.abort_if_errors();
}
}
// On macOS, debuggers need this utility to get run to do some munging of
// the symbols. Note, though, that if the object files are being preserved
// for their debug information there's no need for us to run dsymutil.
if sess.target.target.options.is_like_osx &&
sess.opts.debuginfo != DebugInfo::None &&
!preserve_objects_for_their_debuginfo(sess)
{
if let Err(e) = Command::new("dsymutil").arg(out_filename).output() {
sess.fatal(&format!("failed to run dsymutil: {}", e))
}
}
if sess.opts.target_triple.triple() == "wasm32-unknown-unknown" {
wasm::add_producer_section(
&out_filename,
&sess.edition().to_string(),
option_env!("CFG_VERSION").unwrap_or("unknown"),
);
}
}
fn link_args<'a, B: ArchiveBuilder<'a>>(cmd: &mut dyn Linker,
flavor: LinkerFlavor,
sess: &'a Session,
crate_type: config::CrateType,
tmpdir: &Path,
out_filename: &Path,
codegen_results: &CodegenResults) {
// Linker plugins should be specified early in the list of arguments
cmd.linker_plugin_lto();
// The default library location, we need this to find the runtime.
// The location of crates will be determined as needed.
let lib_path = sess.target_filesearch(PathKind::All).get_lib_path();
// target descriptor
let t = &sess.target.target;
cmd.include_path(&fix_windows_verbatim_for_gcc(&lib_path));
for obj in codegen_results.modules.iter().filter_map(|m| m.object.as_ref()) {
cmd.add_object(obj);
}
cmd.output_filename(out_filename);
if crate_type == config::CrateType::Executable &&
sess.target.target.options.is_like_windows {
if let Some(ref s) = codegen_results.windows_subsystem {
cmd.subsystem(s);
}
}
// If we're building a dynamic library then some platforms need to make sure
// that all symbols are exported correctly from the dynamic library.
if crate_type != config::CrateType::Executable ||
sess.target.target.options.is_like_emscripten {
cmd.export_symbols(tmpdir, crate_type);
}
// When linking a dynamic library, we put the metadata into a section of the
// executable. This metadata is in a separate object file from the main
// object file, so we link that in here.
if crate_type == config::CrateType::Dylib ||
crate_type == config::CrateType::ProcMacro {
if let Some(obj) = codegen_results.metadata_module.object.as_ref() {
cmd.add_object(obj);
}
}
let obj = codegen_results.allocator_module
.as_ref()
.and_then(|m| m.object.as_ref());
if let Some(obj) = obj {
cmd.add_object(obj);
}
// Try to strip as much out of the generated object by removing unused
// sections if possible. See more comments in linker.rs
if !sess.opts.cg.link_dead_code {
let keep_metadata = crate_type == config::CrateType::Dylib;
cmd.gc_sections(keep_metadata);
}
let used_link_args = &codegen_results.crate_info.link_args;
if crate_type == config::CrateType::Executable {
let mut position_independent_executable = false;
if t.options.position_independent_executables {
let empty_vec = Vec::new();
let args = sess.opts.cg.link_args.as_ref().unwrap_or(&empty_vec);
let more_args = &sess.opts.cg.link_arg;
let mut args = args.iter().chain(more_args.iter()).chain(used_link_args.iter());
if is_pic(sess) && !sess.crt_static() && !args.any(|x| *x == "-static") {
position_independent_executable = true;
}
}
if position_independent_executable {
cmd.position_independent_executable();
} else {
// recent versions of gcc can be configured to generate position
// independent executables by default. We have to pass -no-pie to
// explicitly turn that off. Not applicable to ld.
if sess.target.target.options.linker_is_gnu
&& flavor != LinkerFlavor::Ld {
cmd.no_position_independent_executable();
}
}
}
let relro_level = match sess.opts.debugging_opts.relro_level {
Some(level) => level,
None => t.options.relro_level,
};
match relro_level {
RelroLevel::Full => {
cmd.full_relro();
},
RelroLevel::Partial => {
cmd.partial_relro();
},
RelroLevel::Off => {
cmd.no_relro();
},
RelroLevel::None => {
},
}
// Pass optimization flags down to the linker.
cmd.optimize();
// Pass debuginfo flags down to the linker.
cmd.debuginfo();
// We want to, by default, prevent the compiler from accidentally leaking in
// any system libraries, so we may explicitly ask linkers to not link to any
// libraries by default. Note that this does not happen for windows because
// windows pulls in some large number of libraries and I couldn't quite
// figure out which subset we wanted.
//
// This is all naturally configurable via the standard methods as well.
if !sess.opts.cg.default_linker_libraries.unwrap_or(false) &&
t.options.no_default_libraries
{
cmd.no_default_libraries();
}
// Take careful note of the ordering of the arguments we pass to the linker
// here. Linkers will assume that things on the left depend on things to the
// right. Things on the right cannot depend on things on the left. This is
// all formally implemented in terms of resolving symbols (libs on the right
// resolve unknown symbols of libs on the left, but not vice versa).
//
// For this reason, we have organized the arguments we pass to the linker as
// such:
//
// 1. The local object that LLVM just generated
// 2. Local native libraries
// 3. Upstream rust libraries
// 4. Upstream native libraries
//
// The rationale behind this ordering is that those items lower down in the
// list can't depend on items higher up in the list. For example nothing can
// depend on what we just generated (e.g., that'd be a circular dependency).
// Upstream rust libraries are not allowed to depend on our local native
// libraries as that would violate the structure of the DAG, in that
// scenario they are required to link to them as well in a shared fashion.
//
// Note that upstream rust libraries may contain native dependencies as
// well, but they also can't depend on what we just started to add to the
// link line. And finally upstream native libraries can't depend on anything
// in this DAG so far because they're only dylibs and dylibs can only depend
// on other dylibs (e.g., other native deps).
add_local_native_libraries(cmd, sess, codegen_results);
add_upstream_rust_crates::<B>(cmd, sess, codegen_results, crate_type, tmpdir);
add_upstream_native_libraries(cmd, sess, codegen_results, crate_type);
// Tell the linker what we're doing.
if crate_type != config::CrateType::Executable {
cmd.build_dylib(out_filename);
}
if crate_type == config::CrateType::Executable && sess.crt_static() {
cmd.build_static_executable();
}
if sess.opts.debugging_opts.pgo_gen.enabled() {
cmd.pgo_gen();
}
// FIXME (#2397): At some point we want to rpath our guesses as to
// where extern libraries might live, based on the
// addl_lib_search_paths
if sess.opts.cg.rpath {
let target_triple = sess.opts.target_triple.triple();
let mut get_install_prefix_lib_path = || {
let install_prefix = option_env!("CFG_PREFIX").expect("CFG_PREFIX");
let tlib = filesearch::relative_target_lib_path(&sess.sysroot, target_triple);
let mut path = PathBuf::from(install_prefix);
path.push(&tlib);
path
};
let mut rpath_config = RPathConfig {
used_crates: &codegen_results.crate_info.used_crates_dynamic,
out_filename: out_filename.to_path_buf(),
has_rpath: sess.target.target.options.has_rpath,
is_like_osx: sess.target.target.options.is_like_osx,
linker_is_gnu: sess.target.target.options.linker_is_gnu,
get_install_prefix_lib_path: &mut get_install_prefix_lib_path,
};
cmd.args(&rpath::get_rpath_flags(&mut rpath_config));
}
// Finally add all the linker arguments provided on the command line along
// with any #[link_args] attributes found inside the crate
if let Some(ref args) = sess.opts.cg.link_args {
cmd.args(args);
}
cmd.args(&sess.opts.cg.link_arg);
cmd.args(&used_link_args);
}
// # 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)
fn add_upstream_rust_crates<'a, B: ArchiveBuilder<'a>>(cmd: &mut dyn Linker,
sess: &'a 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::<B>(cmd, sess, codegen_results, tmpdir, crate_type, cnum);
}
_ if codegen_results.crate_info.sanitizer_runtime == Some(cnum) => {
link_sanitizer_runtime::<B>(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::<B>(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::<B>(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<'a, B: ArchiveBuilder<'a>>(cmd: &mut dyn Linker,
sess: &'a 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 mut archive = <B as ArchiveBuilder>::new(sess, &dst, Some(cratepath));
archive.update_symbols();
for f in archive.src_files() {
if f.ends_with(RLIB_BYTECODE_EXTENSION) || f == METADATA_FILENAME {
archive.remove_file(&f);
}
}
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<'a, B: ArchiveBuilder<'a>>(cmd: &mut dyn Linker,
sess: &'a 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_ext(sess.time_extended(), Some(sess), &format!("altering {}.rlib", name), || {
let mut archive = <B as ArchiveBuilder>::new(sess, &dst, Some(cratepath));
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) {
// 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("")));
}
}
fn is_pic(sess: &Session) -> bool {
let reloc_model_arg = match sess.opts.cg.relocation_model {
Some(ref s) => &s[..],
None => &sess.target.target.options.relocation_model[..],
};
reloc_model_arg == "pic"
outputs: &OutputFilenames,
crate_name: &str,
) -> Vec<PathBuf> {
let target_cpu = crate::llvm_util::target_cpu(sess);
rustc_codegen_ssa::back::link::link_binary::<LlvmArchiveBuilder<'a>>(
sess,
codegen_results,
outputs,
crate_name,
target_cpu,
)
}
src/librustc_codegen_llvm/lib.rs
-4
View File
@@ -44,8 +44,6 @@
#[macro_use] extern crate syntax;
extern crate syntax_pos;
extern crate rustc_errors as errors;
extern crate serialize;
extern crate tempfile;
use rustc_codegen_ssa::traits::*;
use rustc_codegen_ssa::back::write::{CodegenContext, ModuleConfig, FatLTOInput};
@@ -78,8 +76,6 @@ mod back {
pub mod link;
pub mod lto;
pub mod write;
mod rpath;
pub mod wasm;
}
mod abi;
src/librustc_codegen_ssa/Cargo.toml
+1
View File
@@ -20,6 +20,7 @@ log = "0.4.5"
libc = "0.2.44"
jobserver = "0.1.11"
parking_lot = "0.7"
tempfile = "3.0.5"
serialize = { path = "../libserialize" }
syntax = { path = "../libsyntax" }
src/librustc_codegen_ssa/back/link.rs
+1096 -5
View File
@@ -1,24 +1,36 @@
/// For all the linkers we support, and information they might
/// need out of the shared crate context before we get rid of it.
use rustc::session::{Session, config};
use rustc::session::{Session, filesearch};
use rustc::session::config::{
self, RUST_CGU_EXT, DebugInfo, OutputFilenames, OutputType, PrintRequest, Sanitizer
};
use rustc::session::search_paths::PathKind;
use rustc::middle::dependency_format::Linkage;
use rustc::middle::cstore::{LibSource, NativeLibrary, NativeLibraryKind};
use rustc_target::spec::LinkerFlavor;
use rustc::util::common::{time, time_ext};
use rustc::hir::def_id::CrateNum;
use rustc_data_structures::fx::FxHashSet;
use rustc_fs_util::fix_windows_verbatim_for_gcc;
use rustc_target::spec::{PanicStrategy, RelroLevel, LinkerFlavor};
use crate::{METADATA_FILENAME, RLIB_BYTECODE_EXTENSION, CrateInfo, CodegenResults};
use super::archive::ArchiveBuilder;
use super::command::Command;
use crate::{CrateInfo, CodegenResults};
use crate::back::linker::Linker;
use super::linker::Linker;
use super::rpath::{self, RPathConfig};
use cc::windows_registry;
use tempfile::{Builder as TempFileBuilder, TempDir};
use std::ascii;
use std::char;
use std::fmt;
use std::fs;
use std::io;
use std::path::{Path, PathBuf};
use std::process::{Output, Stdio};
use std::str;
use std::env;
pub use rustc_codegen_utils::link::*;
@@ -31,6 +43,122 @@ pub fn remove(sess: &Session, path: &Path) {
}
}
/// Performs the linkage portion of the compilation phase. This will generate all
/// of the requested outputs for this compilation session.
pub fn link_binary<'a, B: ArchiveBuilder<'a>>(sess: &'a Session,
codegen_results: &CodegenResults,
outputs: &OutputFilenames,
crate_name: &str,
target_cpu: &str) -> Vec<PathBuf> {
let mut out_filenames = Vec::new();
for &crate_type in sess.crate_types.borrow().iter() {
// Ignore executable crates if we have -Z no-codegen, as they will error.
let output_metadata = sess.opts.output_types.contains_key(&OutputType::Metadata);
if (sess.opts.debugging_opts.no_codegen || !sess.opts.output_types.should_codegen()) &&
!output_metadata &&
crate_type == config::CrateType::Executable {
continue;
}
if invalid_output_for_target(sess, crate_type) {
bug!("invalid output type `{:?}` for target os `{}`",
crate_type, sess.opts.target_triple);
}
let out_files = link_binary_output::<B>(sess,
codegen_results,
crate_type,
outputs,
crate_name,
target_cpu);
out_filenames.extend(out_files);
}
// Remove the temporary object file and metadata if we aren't saving temps
if !sess.opts.cg.save_temps {
if sess.opts.output_types.should_codegen() && !preserve_objects_for_their_debuginfo(sess) {
for obj in codegen_results.modules.iter().filter_map(|m| m.object.as_ref()) {
remove(sess, obj);
}
}
for obj in codegen_results.modules.iter().filter_map(|m| m.bytecode_compressed.as_ref()) {
remove(sess, obj);
}
if let Some(ref obj) = codegen_results.metadata_module.object {
remove(sess, obj);
}
if let Some(ref allocator) = codegen_results.allocator_module {
if let Some(ref obj) = allocator.object {
remove(sess, obj);
}
if let Some(ref bc) = allocator.bytecode_compressed {
remove(sess, bc);
}
}
}
out_filenames
}
fn link_binary_output<'a, B: ArchiveBuilder<'a>>(sess: &'a Session,
codegen_results: &CodegenResults,
crate_type: config::CrateType,
outputs: &OutputFilenames,
crate_name: &str,
target_cpu: &str) -> Vec<PathBuf> {
for obj in codegen_results.modules.iter().filter_map(|m| m.object.as_ref()) {
check_file_is_writeable(obj, sess);
}
let mut out_filenames = vec![];
if outputs.outputs.contains_key(&OutputType::Metadata) {
let out_filename = filename_for_metadata(sess, crate_name, outputs);
// To avoid races with another rustc process scanning the output directory,
// we need to write the file somewhere else and atomically move it to its
// final destination, with a `fs::rename` call. In order for the rename to
// always succeed, the temporary file needs to be on the same filesystem,
// which is why we create it inside the output directory specifically.
let metadata_tmpdir = TempFileBuilder::new()
.prefix("rmeta")
.tempdir_in(out_filename.parent().unwrap())
.unwrap_or_else(|err| sess.fatal(&format!("couldn't create a temp dir: {}", err)));
let metadata = emit_metadata(sess, codegen_results, &metadata_tmpdir);
if let Err(e) = fs::rename(metadata, &out_filename) {
sess.fatal(&format!("failed to write {}: {}", out_filename.display(), e));
}
out_filenames.push(out_filename);
}
let tmpdir = TempFileBuilder::new().prefix("rustc").tempdir().unwrap_or_else(|err|
sess.fatal(&format!("couldn't create a temp dir: {}", err)));
if outputs.outputs.should_codegen() {
let out_filename = out_filename(sess, crate_type, outputs, crate_name);
match crate_type {
config::CrateType::Rlib => {
link_rlib::<B>(sess,
codegen_results,
RlibFlavor::Normal,
&out_filename,
&tmpdir).build();
}
config::CrateType::Staticlib => {
link_staticlib::<B>(sess, codegen_results, &out_filename, &tmpdir);
}
_ => {
link_natively::<B>(sess, crate_type, &out_filename, codegen_results, tmpdir.path(), target_cpu);
}
}
out_filenames.push(out_filename);
}
if sess.opts.cg.save_temps {
let _ = tmpdir.into_path();
}
out_filenames
}
// 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
@@ -123,6 +251,444 @@ pub fn each_linked_rlib(sess: &Session,
Ok(())
}
/// We use a temp directory here to avoid races between concurrent rustc processes,
/// such as builds in the same directory using the same filename for metadata while
/// building an `.rlib` (stomping over one another), or writing an `.rmeta` into a
/// directory being searched for `extern crate` (observing an incomplete file).
/// The returned path is the temporary file containing the complete metadata.
fn emit_metadata<'a>(
sess: &'a Session,
codegen_results: &CodegenResults,
tmpdir: &TempDir
) -> PathBuf {
let out_filename = tmpdir.path().join(METADATA_FILENAME);
let result = fs::write(&out_filename, &codegen_results.metadata.raw_data);
if let Err(e) = result {
sess.fatal(&format!("failed to write {}: {}", out_filename.display(), e));
}
out_filename
}
// Create an 'rlib'
//
// An rlib in its current incarnation is essentially a renamed .a file. The
// rlib primarily contains the object file of the crate, but it also contains
// all of the object files from native libraries. This is done by unzipping
// native libraries and inserting all of the contents into this archive.
fn link_rlib<'a, B: ArchiveBuilder<'a>>(sess: &'a Session,
codegen_results: &CodegenResults,
flavor: RlibFlavor,
out_filename: &Path,
tmpdir: &TempDir) -> B {
info!("preparing rlib to {:?}", out_filename);
let mut ab = <B as ArchiveBuilder>::new(sess, out_filename, None);
for obj in codegen_results.modules.iter().filter_map(|m| m.object.as_ref()) {
ab.add_file(obj);
}
// Note that in this loop we are ignoring the value of `lib.cfg`. That is,
// we may not be configured to actually include a static library if we're
// adding it here. That's because later when we consume this rlib we'll
// decide whether we actually needed the static library or not.
//
// To do this "correctly" we'd need to keep track of which libraries added
// which object files to the archive. We don't do that here, however. The
// #[link(cfg(..))] feature is unstable, though, and only intended to get
// liblibc working. In that sense the check below just indicates that if
// there are any libraries we want to omit object files for at link time we
// just exclude all custom object files.
//
// Eventually if we want to stabilize or flesh out the #[link(cfg(..))]
// feature then we'll need to figure out how to record what objects were
// loaded from the libraries found here and then encode that into the
// metadata of the rlib we're generating somehow.
for lib in codegen_results.crate_info.used_libraries.iter() {
match lib.kind {
NativeLibraryKind::NativeStatic => {}
NativeLibraryKind::NativeStaticNobundle |
NativeLibraryKind::NativeFramework |
NativeLibraryKind::NativeUnknown => continue,
}
if let Some(name) = lib.name {
ab.add_native_library(&name.as_str());
}
}
// After adding all files to the archive, we need to update the
// symbol table of the archive.
ab.update_symbols();
// Note that it is important that we add all of our non-object "magical
// files" *after* all of the object files in the archive. The reason for
// this is as follows:
//
// * When performing LTO, this archive will be modified to remove
// objects from above. The reason for this is described below.
//
// * When the system linker looks at an archive, it will attempt to
// determine the architecture of the archive in order to see whether its
// linkable.
//
// The algorithm for this detection is: iterate over the files in the
// archive. Skip magical SYMDEF names. Interpret the first file as an
// object file. Read architecture from the object file.
//
// * As one can probably see, if "metadata" and "foo.bc" were placed
// before all of the objects, then the architecture of this archive would
// not be correctly inferred once 'foo.o' is removed.
//
// Basically, all this means is that this code should not move above the
// code above.
match flavor {
RlibFlavor::Normal => {
// Instead of putting the metadata in an object file section, rlibs
// contain the metadata in a separate file.
ab.add_file(&emit_metadata(sess, codegen_results, tmpdir));
// For LTO purposes, the bytecode of this library is also inserted
// into the archive.
for bytecode in codegen_results
.modules
.iter()
.filter_map(|m| m.bytecode_compressed.as_ref())
{
ab.add_file(bytecode);
}
// After adding all files to the archive, we need to update the
// symbol table of the archive. This currently dies on macOS (see
// #11162), and isn't necessary there anyway
if !sess.target.target.options.is_like_osx {
ab.update_symbols();
}
}
RlibFlavor::StaticlibBase => {
let obj = codegen_results.allocator_module
.as_ref()
.and_then(|m| m.object.as_ref());
if let Some(obj) = obj {
ab.add_file(obj);
}
}
}
ab
}
// Create a static archive
//
// This is essentially the same thing as an rlib, but it also involves adding
// all of the upstream crates' objects into the archive. This will slurp in
// all of the native libraries of upstream dependencies as well.
//
// Additionally, there's no way for us to link dynamic libraries, so we warn
// about all dynamic library dependencies that they're not linked in.
//
// There's no need to include metadata in a static archive, so ensure to not
// link in the metadata object file (and also don't prepare the archive with a
// metadata file).
fn link_staticlib<'a, B: ArchiveBuilder<'a>>(sess: &'a Session,
codegen_results: &CodegenResults,
out_filename: &Path,
tempdir: &TempDir) {
let mut ab = link_rlib::<B>(sess,
codegen_results,
RlibFlavor::StaticlibBase,
out_filename,
tempdir);
let mut all_native_libs = vec![];
let res = each_linked_rlib(sess, &codegen_results.crate_info, &mut |cnum, path| {
let name = &codegen_results.crate_info.crate_name[&cnum];
let native_libs = &codegen_results.crate_info.native_libraries[&cnum];
// Here when we include the rlib into our staticlib we need to make a
// decision whether to include the extra object files along the way.
// These extra object files come from statically included native
// libraries, but they may be cfg'd away with #[link(cfg(..))].
//
// This unstable feature, though, only needs liblibc to work. The only
// use case there is where musl is statically included in liblibc.rlib,
// so if we don't want the included version we just need to skip it. As
// a result the logic here is that if *any* linked library is cfg'd away
// we just skip all object files.
//
// Clearly this is not sufficient for a general purpose feature, and
// we'd want to read from the library's metadata to determine which
// object files come from where and selectively skip them.
let skip_object_files = native_libs.iter().any(|lib| {
lib.kind == NativeLibraryKind::NativeStatic && !relevant_lib(sess, lib)
});
ab.add_rlib(path,
&name.as_str(),
are_upstream_rust_objects_already_included(sess) &&
!ignored_for_lto(sess, &codegen_results.crate_info, cnum),
skip_object_files).unwrap();
all_native_libs.extend(codegen_results.crate_info.native_libraries[&cnum].iter().cloned());
});
if let Err(e) = res {
sess.fatal(&e);
}
ab.update_symbols();
ab.build();
if !all_native_libs.is_empty() {
if sess.opts.prints.contains(&PrintRequest::NativeStaticLibs) {
print_native_static_libs(sess, &all_native_libs);
}
}
}
// Create a dynamic library or executable
//
// This will invoke the system linker/cc to create the resulting file. This
// links to all upstream files as well.
fn link_natively<'a, B: ArchiveBuilder<'a>>(sess: &'a Session,
crate_type: config::CrateType,
out_filename: &Path,
codegen_results: &CodegenResults,
tmpdir: &Path,
target_cpu: &str) {
info!("preparing {:?} to {:?}", crate_type, out_filename);
let (linker, flavor) = linker_and_flavor(sess);
// The invocations of cc share some flags across platforms
let (pname, mut cmd) = get_linker(sess, &linker, flavor);
if let Some(args) = sess.target.target.options.pre_link_args.get(&flavor) {
cmd.args(args);
}
if let Some(args) = sess.target.target.options.pre_link_args_crt.get(&flavor) {
if sess.crt_static() {
cmd.args(args);
}
}
if let Some(ref args) = sess.opts.debugging_opts.pre_link_args {
cmd.args(args);
}
cmd.args(&sess.opts.debugging_opts.pre_link_arg);
if sess.target.target.options.is_like_fuchsia {
let prefix = match sess.opts.debugging_opts.sanitizer {
Some(Sanitizer::Address) => "asan/",
_ => "",
};
cmd.arg(format!("--dynamic-linker={}ld.so.1", prefix));
}
let pre_link_objects = if crate_type == config::CrateType::Executable {
&sess.target.target.options.pre_link_objects_exe
} else {
&sess.target.target.options.pre_link_objects_dll
};
for obj in pre_link_objects {
cmd.arg(get_file_path(sess, obj));
}
if crate_type == config::CrateType::Executable && sess.crt_static() {
for obj in &sess.target.target.options.pre_link_objects_exe_crt {
cmd.arg(get_file_path(sess, obj));
}
}
if sess.target.target.options.is_like_emscripten {
cmd.arg("-s");
cmd.arg(if sess.panic_strategy() == PanicStrategy::Abort {
"DISABLE_EXCEPTION_CATCHING=1"
} else {
"DISABLE_EXCEPTION_CATCHING=0"
});
}
{
let mut linker = codegen_results.linker_info.to_linker(cmd, &sess, flavor, target_cpu);
link_args::<B>(&mut *linker, flavor, sess, crate_type, tmpdir,
out_filename, codegen_results);
cmd = linker.finalize();
}
if let Some(args) = sess.target.target.options.late_link_args.get(&flavor) {
cmd.args(args);
}
for obj in &sess.target.target.options.post_link_objects {
cmd.arg(get_file_path(sess, obj));
}
if sess.crt_static() {
for obj in &sess.target.target.options.post_link_objects_crt {
cmd.arg(get_file_path(sess, obj));
}
}
if let Some(args) = sess.target.target.options.post_link_args.get(&flavor) {
cmd.args(args);
}
for &(ref k, ref v) in &sess.target.target.options.link_env {
cmd.env(k, v);
}
if sess.opts.debugging_opts.print_link_args {
println!("{:?}", &cmd);
}
// May have not found libraries in the right formats.
sess.abort_if_errors();
// Invoke the system linker
//
// Note that there's a terribly awful hack that really shouldn't be present
// in any compiler. Here an environment variable is supported to
// automatically retry the linker invocation if the linker looks like it
// segfaulted.
//
// Gee that seems odd, normally segfaults are things we want to know about!
// Unfortunately though in rust-lang/rust#38878 we're experiencing the
// linker segfaulting on Travis quite a bit which is causing quite a bit of
// pain to land PRs when they spuriously fail due to a segfault.
//
// The issue #38878 has some more debugging information on it as well, but
// this unfortunately looks like it's just a race condition in macOS's linker
// with some thread pool working in the background. It seems that no one
// currently knows a fix for this so in the meantime we're left with this...
info!("{:?}", &cmd);
let retry_on_segfault = env::var("RUSTC_RETRY_LINKER_ON_SEGFAULT").is_ok();
let mut prog;
let mut i = 0;
loop {
i += 1;
prog = time(sess, "running linker", || {
exec_linker(sess, &mut cmd, out_filename, tmpdir)
});
let output = match prog {
Ok(ref output) => output,
Err(_) => break,
};
if output.status.success() {
break
}
let mut out = output.stderr.clone();
out.extend(&output.stdout);
let out = String::from_utf8_lossy(&out);
// Check to see if the link failed with "unrecognized command line option:
// '-no-pie'" for gcc or "unknown argument: '-no-pie'" for clang. If so,
// reperform the link step without the -no-pie option. This is safe because
// if the linker doesn't support -no-pie then it should not default to
// linking executables as pie. Different versions of gcc seem to use
// different quotes in the error message so don't check for them.
if sess.target.target.options.linker_is_gnu &&
flavor != LinkerFlavor::Ld &&
(out.contains("unrecognized command line option") ||
out.contains("unknown argument")) &&
out.contains("-no-pie") &&
cmd.get_args().iter().any(|e| e.to_string_lossy() == "-no-pie") {
info!("linker output: {:?}", out);
warn!("Linker does not support -no-pie command line option. Retrying without.");
for arg in cmd.take_args() {
if arg.to_string_lossy() != "-no-pie" {
cmd.arg(arg);
}
}
info!("{:?}", &cmd);
continue;
}
if !retry_on_segfault || i > 3 {
break
}
let msg_segv = "clang: error: unable to execute command: Segmentation fault: 11";
let msg_bus = "clang: error: unable to execute command: Bus error: 10";
if !(out.contains(msg_segv) || out.contains(msg_bus)) {
break
}
warn!(
"looks like the linker segfaulted when we tried to call it, \
automatically retrying again. cmd = {:?}, out = {}.",
cmd,
out,
);
}
match prog {
Ok(prog) => {
fn escape_string(s: &[u8]) -> String {
str::from_utf8(s).map(|s| s.to_owned())
.unwrap_or_else(|_| {
let mut x = "Non-UTF-8 output: ".to_string();
x.extend(s.iter()
.flat_map(|&b| ascii::escape_default(b))
.map(char::from));
x
})
}
if !prog.status.success() {
let mut output = prog.stderr.clone();
output.extend_from_slice(&prog.stdout);
sess.struct_err(&format!("linking with `{}` failed: {}",
pname.display(),
prog.status))
.note(&format!("{:?}", &cmd))
.note(&escape_string(&output))
.emit();
sess.abort_if_errors();
}
info!("linker stderr:\n{}", escape_string(&prog.stderr));
info!("linker stdout:\n{}", escape_string(&prog.stdout));
},
Err(e) => {
let linker_not_found = e.kind() == io::ErrorKind::NotFound;
let mut linker_error = {
if linker_not_found {
sess.struct_err(&format!("linker `{}` not found", pname.display()))
} else {
sess.struct_err(&format!("could not exec the linker `{}`", pname.display()))
}
};
linker_error.note(&e.to_string());
if !linker_not_found {
linker_error.note(&format!("{:?}", &cmd));
}
linker_error.emit();
if sess.target.target.options.is_like_msvc && linker_not_found {
sess.note_without_error("the msvc targets depend on the msvc linker \
but `link.exe` was not found");
sess.note_without_error("please ensure that VS 2013, VS 2015 or VS 2017 \
was installed with the Visual C++ option");
}
sess.abort_if_errors();
}
}
// On macOS, debuggers need this utility to get run to do some munging of
// the symbols. Note, though, that if the object files are being preserved
// for their debug information there's no need for us to run dsymutil.
if sess.target.target.options.is_like_osx &&
sess.opts.debuginfo != DebugInfo::None &&
!preserve_objects_for_their_debuginfo(sess)
{
if let Err(e) = Command::new("dsymutil").arg(out_filename).output() {
sess.fatal(&format!("failed to run dsymutil: {}", e))
}
}
if sess.opts.target_triple.triple() == "wasm32-unknown-unknown" {
super::wasm::add_producer_section(
&out_filename,
&sess.edition().to_string(),
option_env!("CFG_VERSION").unwrap_or("unknown"),
);
}
}
/// Returns a boolean indicating whether the specified crate should be ignored
/// during LTO.
///
@@ -258,7 +824,7 @@ pub fn archive_search_paths(sess: &Session) -> Vec<PathBuf> {
sess.target_filesearch(PathKind::Native).search_path_dirs()
}
pub enum RlibFlavor {
enum RlibFlavor {
Normal,
StaticlibBase,
}
@@ -451,6 +1017,209 @@ fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
}
}
fn link_args<'a, B: ArchiveBuilder<'a>>(cmd: &mut dyn Linker,
flavor: LinkerFlavor,
sess: &'a Session,
crate_type: config::CrateType,
tmpdir: &Path,
out_filename: &Path,
codegen_results: &CodegenResults) {
// Linker plugins should be specified early in the list of arguments
cmd.linker_plugin_lto();
// The default library location, we need this to find the runtime.
// The location of crates will be determined as needed.
let lib_path = sess.target_filesearch(PathKind::All).get_lib_path();
// target descriptor
let t = &sess.target.target;
cmd.include_path(&fix_windows_verbatim_for_gcc(&lib_path));
for obj in codegen_results.modules.iter().filter_map(|m| m.object.as_ref()) {
cmd.add_object(obj);
}
cmd.output_filename(out_filename);
if crate_type == config::CrateType::Executable &&
sess.target.target.options.is_like_windows {
if let Some(ref s) = codegen_results.windows_subsystem {
cmd.subsystem(s);
}
}
// If we're building a dynamic library then some platforms need to make sure
// that all symbols are exported correctly from the dynamic library.
if crate_type != config::CrateType::Executable ||
sess.target.target.options.is_like_emscripten {
cmd.export_symbols(tmpdir, crate_type);
}
// When linking a dynamic library, we put the metadata into a section of the
// executable. This metadata is in a separate object file from the main
// object file, so we link that in here.
if crate_type == config::CrateType::Dylib ||
crate_type == config::CrateType::ProcMacro {
if let Some(obj) = codegen_results.metadata_module.object.as_ref() {
cmd.add_object(obj);
}
}
let obj = codegen_results.allocator_module
.as_ref()
.and_then(|m| m.object.as_ref());
if let Some(obj) = obj {
cmd.add_object(obj);
}
// Try to strip as much out of the generated object by removing unused
// sections if possible. See more comments in linker.rs
if !sess.opts.cg.link_dead_code {
let keep_metadata = crate_type == config::CrateType::Dylib;
cmd.gc_sections(keep_metadata);
}
let used_link_args = &codegen_results.crate_info.link_args;
if crate_type == config::CrateType::Executable {
let mut position_independent_executable = false;
if t.options.position_independent_executables {
let empty_vec = Vec::new();
let args = sess.opts.cg.link_args.as_ref().unwrap_or(&empty_vec);
let more_args = &sess.opts.cg.link_arg;
let mut args = args.iter().chain(more_args.iter()).chain(used_link_args.iter());
if is_pic(sess) && !sess.crt_static() && !args.any(|x| *x == "-static") {
position_independent_executable = true;
}
}
if position_independent_executable {
cmd.position_independent_executable();
} else {
// recent versions of gcc can be configured to generate position
// independent executables by default. We have to pass -no-pie to
// explicitly turn that off. Not applicable to ld.
if sess.target.target.options.linker_is_gnu
&& flavor != LinkerFlavor::Ld {
cmd.no_position_independent_executable();
}
}
}
let relro_level = match sess.opts.debugging_opts.relro_level {
Some(level) => level,
None => t.options.relro_level,
};
match relro_level {
RelroLevel::Full => {
cmd.full_relro();
},
RelroLevel::Partial => {
cmd.partial_relro();
},
RelroLevel::Off => {
cmd.no_relro();
},
RelroLevel::None => {
},
}
// Pass optimization flags down to the linker.
cmd.optimize();
// Pass debuginfo flags down to the linker.
cmd.debuginfo();
// We want to, by default, prevent the compiler from accidentally leaking in
// any system libraries, so we may explicitly ask linkers to not link to any
// libraries by default. Note that this does not happen for windows because
// windows pulls in some large number of libraries and I couldn't quite
// figure out which subset we wanted.
//
// This is all naturally configurable via the standard methods as well.
if !sess.opts.cg.default_linker_libraries.unwrap_or(false) &&
t.options.no_default_libraries
{
cmd.no_default_libraries();
}
// Take careful note of the ordering of the arguments we pass to the linker
// here. Linkers will assume that things on the left depend on things to the
// right. Things on the right cannot depend on things on the left. This is
// all formally implemented in terms of resolving symbols (libs on the right
// resolve unknown symbols of libs on the left, but not vice versa).
//
// For this reason, we have organized the arguments we pass to the linker as
// such:
//
// 1. The local object that LLVM just generated
// 2. Local native libraries
// 3. Upstream rust libraries
// 4. Upstream native libraries
//
// The rationale behind this ordering is that those items lower down in the
// list can't depend on items higher up in the list. For example nothing can
// depend on what we just generated (e.g., that'd be a circular dependency).
// Upstream rust libraries are not allowed to depend on our local native
// libraries as that would violate the structure of the DAG, in that
// scenario they are required to link to them as well in a shared fashion.
//
// Note that upstream rust libraries may contain native dependencies as
// well, but they also can't depend on what we just started to add to the
// link line. And finally upstream native libraries can't depend on anything
// in this DAG so far because they're only dylibs and dylibs can only depend
// on other dylibs (e.g., other native deps).
add_local_native_libraries(cmd, sess, codegen_results);
add_upstream_rust_crates::<B>(cmd, sess, codegen_results, crate_type, tmpdir);
add_upstream_native_libraries(cmd, sess, codegen_results, crate_type);
// Tell the linker what we're doing.
if crate_type != config::CrateType::Executable {
cmd.build_dylib(out_filename);
}
if crate_type == config::CrateType::Executable && sess.crt_static() {
cmd.build_static_executable();
}
if sess.opts.debugging_opts.pgo_gen.enabled() {
cmd.pgo_gen();
}
// FIXME (#2397): At some point we want to rpath our guesses as to
// where extern libraries might live, based on the
// addl_lib_search_paths
if sess.opts.cg.rpath {
let target_triple = sess.opts.target_triple.triple();
let mut get_install_prefix_lib_path = || {
let install_prefix = option_env!("CFG_PREFIX").expect("CFG_PREFIX");
let tlib = filesearch::relative_target_lib_path(&sess.sysroot, target_triple);
let mut path = PathBuf::from(install_prefix);
path.push(&tlib);
path
};
let mut rpath_config = RPathConfig {
used_crates: &codegen_results.crate_info.used_crates_dynamic,
out_filename: out_filename.to_path_buf(),
has_rpath: sess.target.target.options.has_rpath,
is_like_osx: sess.target.target.options.is_like_osx,
linker_is_gnu: sess.target.target.options.linker_is_gnu,
get_install_prefix_lib_path: &mut get_install_prefix_lib_path,
};
cmd.args(&rpath::get_rpath_flags(&mut rpath_config));
}
// Finally add all the linker arguments provided on the command line along
// with any #[link_args] attributes found inside the crate
if let Some(ref args) = sess.opts.cg.link_args {
cmd.args(args);
}
cmd.args(&sess.opts.cg.link_arg);
cmd.args(&used_link_args);
}
// # Native library linking
//
// User-supplied library search paths (-L on the command line). These are
@@ -493,6 +1262,319 @@ pub fn add_local_native_libraries(cmd: &mut dyn Linker,
}
}
// # 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)
fn add_upstream_rust_crates<'a, B: ArchiveBuilder<'a>>(cmd: &mut dyn Linker,
sess: &'a 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::<B>(cmd, sess, codegen_results, tmpdir, crate_type, cnum);
}
_ if codegen_results.crate_info.sanitizer_runtime == Some(cnum) => {
link_sanitizer_runtime::<B>(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::<B>(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::<B>(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<'a, B: ArchiveBuilder<'a>>(cmd: &mut dyn Linker,
sess: &'a 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 mut archive = <B as ArchiveBuilder>::new(sess, &dst, Some(cratepath));
archive.update_symbols();
for f in archive.src_files() {
if f.ends_with(RLIB_BYTECODE_EXTENSION) || f == METADATA_FILENAME {
archive.remove_file(&f);
}
}
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<'a, B: ArchiveBuilder<'a>>(cmd: &mut dyn Linker,
sess: &'a 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_ext(sess.time_extended(), Some(sess), &format!("altering {}.rlib", name), || {
let mut archive = <B as ArchiveBuilder>::new(sess, &dst, Some(cratepath));
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) {
// 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("")));
}
}
// 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:
@@ -577,3 +1659,12 @@ pub fn are_upstream_rust_objects_already_included(sess: &Session) -> bool {
config::Lto::ThinLocal => false,
}
}
fn is_pic(sess: &Session) -> bool {
let reloc_model_arg = match sess.opts.cg.relocation_model {
Some(ref s) => &s[..],
None => &sess.target.target.options.relocation_model[..],
};
reloc_model_arg == "pic"
}
src/librustc_codegen_ssa/back/mod.rs
+2
View File
@@ -5,3 +5,5 @@
pub mod command;
pub mod symbol_export;
pub mod archive;
pub mod rpath;
pub mod wasm;
src/librustc_codegen_llvm/back/rpath.rs → src/librustc_codegen_ssa/back/rpath.rs
View File
src/librustc_codegen_llvm/back/wasm.rs → src/librustc_codegen_ssa/back/wasm.rs
View File