/src/librustc_trans/back/linker.rs
Rust | 368 lines | 238 code | 43 blank | 87 comment | 27 complexity | 1f154a2070e9176eb884749687cfc451 MD5 | raw file
- // Copyright 2015 The Rust Project Developers. See the COPYRIGHT
- // file at the top-level directory of this distribution and at
- // http://rust-lang.org/COPYRIGHT.
- //
- // Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
- // http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
- // <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
- // option. This file may not be copied, modified, or distributed
- // except according to those terms.
- use std::ffi::OsString;
- use std::fs::{self, File};
- use std::io::{self, BufWriter};
- use std::io::prelude::*;
- use std::path::{Path, PathBuf};
- use std::process::Command;
- use back::archive;
- use middle::cstore::CrateStore;
- use middle::dependency_format::Linkage;
- use session::Session;
- use session::config::CrateTypeDylib;
- use session::config;
- use syntax::ast;
- use trans::CrateTranslation;
- /// Linker abstraction used by back::link to build up the command to invoke a
- /// linker.
- ///
- /// This trait is the total list of requirements needed by `back::link` and
- /// represents the meaning of each option being passed down. This trait is then
- /// used to dispatch on whether a GNU-like linker (generally `ld.exe`) or an
- /// MSVC linker (e.g. `link.exe`) is being used.
- pub trait Linker {
- fn link_dylib(&mut self, lib: &str);
- fn link_rust_dylib(&mut self, lib: &str, path: &Path);
- fn link_framework(&mut self, framework: &str);
- fn link_staticlib(&mut self, lib: &str);
- fn link_rlib(&mut self, lib: &Path);
- fn link_whole_rlib(&mut self, lib: &Path);
- fn link_whole_staticlib(&mut self, lib: &str, search_path: &[PathBuf]);
- fn include_path(&mut self, path: &Path);
- fn framework_path(&mut self, path: &Path);
- fn output_filename(&mut self, path: &Path);
- fn add_object(&mut self, path: &Path);
- fn gc_sections(&mut self, is_dylib: bool);
- fn position_independent_executable(&mut self);
- fn optimize(&mut self);
- fn debuginfo(&mut self);
- fn no_default_libraries(&mut self);
- fn build_dylib(&mut self, out_filename: &Path);
- fn args(&mut self, args: &[String]);
- fn hint_static(&mut self);
- fn hint_dynamic(&mut self);
- fn whole_archives(&mut self);
- fn no_whole_archives(&mut self);
- fn export_symbols(&mut self, sess: &Session, trans: &CrateTranslation,
- tmpdir: &Path);
- }
- pub struct GnuLinker<'a> {
- pub cmd: &'a mut Command,
- pub sess: &'a Session,
- }
- impl<'a> GnuLinker<'a> {
- fn takes_hints(&self) -> bool {
- !self.sess.target.target.options.is_like_osx
- }
- }
- impl<'a> Linker for GnuLinker<'a> {
- fn link_dylib(&mut self, lib: &str) { self.cmd.arg("-l").arg(lib); }
- fn link_staticlib(&mut self, lib: &str) { self.cmd.arg("-l").arg(lib); }
- fn link_rlib(&mut self, lib: &Path) { self.cmd.arg(lib); }
- fn include_path(&mut self, path: &Path) { self.cmd.arg("-L").arg(path); }
- fn framework_path(&mut self, path: &Path) { self.cmd.arg("-F").arg(path); }
- fn output_filename(&mut self, path: &Path) { self.cmd.arg("-o").arg(path); }
- fn add_object(&mut self, path: &Path) { self.cmd.arg(path); }
- fn position_independent_executable(&mut self) { self.cmd.arg("-pie"); }
- fn args(&mut self, args: &[String]) { self.cmd.args(args); }
- fn link_rust_dylib(&mut self, lib: &str, _path: &Path) {
- self.cmd.arg("-l").arg(lib);
- }
- fn link_framework(&mut self, framework: &str) {
- self.cmd.arg("-framework").arg(framework);
- }
- fn link_whole_staticlib(&mut self, lib: &str, search_path: &[PathBuf]) {
- let target = &self.sess.target.target;
- if !target.options.is_like_osx {
- self.cmd.arg("-Wl,--whole-archive")
- .arg("-l").arg(lib)
- .arg("-Wl,--no-whole-archive");
- } else {
- // -force_load is the OSX equivalent of --whole-archive, but it
- // involves passing the full path to the library to link.
- let mut v = OsString::from("-Wl,-force_load,");
- v.push(&archive::find_library(lib, search_path, &self.sess));
- self.cmd.arg(&v);
- }
- }
- fn link_whole_rlib(&mut self, lib: &Path) {
- if self.sess.target.target.options.is_like_osx {
- let mut v = OsString::from("-Wl,-force_load,");
- v.push(lib);
- self.cmd.arg(&v);
- } else {
- self.cmd.arg("-Wl,--whole-archive").arg(lib)
- .arg("-Wl,--no-whole-archive");
- }
- }
- fn gc_sections(&mut self, is_dylib: bool) {
- // The dead_strip option to the linker specifies that functions and data
- // unreachable by the entry point will be removed. This is quite useful
- // with Rust's compilation model of compiling libraries at a time into
- // one object file. For example, this brings hello world from 1.7MB to
- // 458K.
- //
- // Note that this is done for both executables and dynamic libraries. We
- // won't get much benefit from dylibs because LLVM will have already
- // stripped away as much as it could. This has not been seen to impact
- // link times negatively.
- //
- // -dead_strip can't be part of the pre_link_args because it's also used
- // for partial linking when using multiple codegen units (-r). So we
- // insert it here.
- if self.sess.target.target.options.is_like_osx {
- self.cmd.arg("-Wl,-dead_strip");
- // If we're building a dylib, we don't use --gc-sections because LLVM
- // has already done the best it can do, and we also don't want to
- // eliminate the metadata. If we're building an executable, however,
- // --gc-sections drops the size of hello world from 1.8MB to 597K, a 67%
- // reduction.
- } else if !is_dylib {
- self.cmd.arg("-Wl,--gc-sections");
- }
- }
- fn optimize(&mut self) {
- if !self.sess.target.target.options.linker_is_gnu { return }
- // GNU-style linkers support optimization with -O. GNU ld doesn't
- // need a numeric argument, but other linkers do.
- if self.sess.opts.optimize == config::OptLevel::Default ||
- self.sess.opts.optimize == config::OptLevel::Aggressive {
- self.cmd.arg("-Wl,-O1");
- }
- }
- fn debuginfo(&mut self) {
- // Don't do anything special here for GNU-style linkers.
- }
- fn no_default_libraries(&mut self) {
- self.cmd.arg("-nodefaultlibs");
- }
- fn build_dylib(&mut self, out_filename: &Path) {
- // On mac we need to tell the linker to let this library be rpathed
- if self.sess.target.target.options.is_like_osx {
- self.cmd.args(&["-dynamiclib", "-Wl,-dylib"]);
- if self.sess.opts.cg.rpath {
- let mut v = OsString::from("-Wl,-install_name,@rpath/");
- v.push(out_filename.file_name().unwrap());
- self.cmd.arg(&v);
- }
- } else {
- self.cmd.arg("-shared");
- }
- }
- fn whole_archives(&mut self) {
- if !self.takes_hints() { return }
- self.cmd.arg("-Wl,--whole-archive");
- }
- fn no_whole_archives(&mut self) {
- if !self.takes_hints() { return }
- self.cmd.arg("-Wl,--no-whole-archive");
- }
- fn hint_static(&mut self) {
- if !self.takes_hints() { return }
- self.cmd.arg("-Wl,-Bstatic");
- }
- fn hint_dynamic(&mut self) {
- if !self.takes_hints() { return }
- self.cmd.arg("-Wl,-Bdynamic");
- }
- fn export_symbols(&mut self, _: &Session, _: &CrateTranslation, _: &Path) {
- // noop, visibility in object files takes care of this
- }
- }
- pub struct MsvcLinker<'a> {
- pub cmd: &'a mut Command,
- pub sess: &'a Session,
- }
- impl<'a> Linker for MsvcLinker<'a> {
- fn link_rlib(&mut self, lib: &Path) { self.cmd.arg(lib); }
- fn add_object(&mut self, path: &Path) { self.cmd.arg(path); }
- fn args(&mut self, args: &[String]) { self.cmd.args(args); }
- fn build_dylib(&mut self, out_filename: &Path) {
- self.cmd.arg("/DLL");
- let mut arg: OsString = "/IMPLIB:".into();
- arg.push(out_filename.with_extension("dll.lib"));
- self.cmd.arg(arg);
- }
- fn gc_sections(&mut self, _is_dylib: bool) { self.cmd.arg("/OPT:REF,ICF"); }
- fn link_dylib(&mut self, lib: &str) {
- self.cmd.arg(&format!("{}.lib", lib));
- }
- fn link_rust_dylib(&mut self, lib: &str, path: &Path) {
- // When producing a dll, the MSVC linker may not actually emit a
- // `foo.lib` file if the dll doesn't actually export any symbols, so we
- // check to see if the file is there and just omit linking to it if it's
- // not present.
- let name = format!("{}.dll.lib", lib);
- if fs::metadata(&path.join(&name)).is_ok() {
- self.cmd.arg(name);
- }
- }
- fn link_staticlib(&mut self, lib: &str) {
- self.cmd.arg(&format!("{}.lib", lib));
- }
- fn position_independent_executable(&mut self) {
- // noop
- }
- fn no_default_libraries(&mut self) {
- // Currently we don't pass the /NODEFAULTLIB flag to the linker on MSVC
- // as there's been trouble in the past of linking the C++ standard
- // library required by LLVM. This likely needs to happen one day, but
- // in general Windows is also a more controlled environment than
- // Unix, so it's not necessarily as critical that this be implemented.
- //
- // Note that there are also some licensing worries about statically
- // linking some libraries which require a specific agreement, so it may
- // not ever be possible for us to pass this flag.
- }
- fn include_path(&mut self, path: &Path) {
- let mut arg = OsString::from("/LIBPATH:");
- arg.push(path);
- self.cmd.arg(&arg);
- }
- fn output_filename(&mut self, path: &Path) {
- let mut arg = OsString::from("/OUT:");
- arg.push(path);
- self.cmd.arg(&arg);
- }
- fn framework_path(&mut self, _path: &Path) {
- panic!("frameworks are not supported on windows")
- }
- fn link_framework(&mut self, _framework: &str) {
- panic!("frameworks are not supported on windows")
- }
- fn link_whole_staticlib(&mut self, lib: &str, _search_path: &[PathBuf]) {
- // not supported?
- self.link_staticlib(lib);
- }
- fn link_whole_rlib(&mut self, path: &Path) {
- // not supported?
- self.link_rlib(path);
- }
- fn optimize(&mut self) {
- // Needs more investigation of `/OPT` arguments
- }
- fn debuginfo(&mut self) {
- // This will cause the Microsoft linker to generate a PDB file
- // from the CodeView line tables in the object files.
- self.cmd.arg("/DEBUG");
- }
- fn whole_archives(&mut self) {
- // hints not supported?
- }
- fn no_whole_archives(&mut self) {
- // hints not supported?
- }
- // On windows static libraries are of the form `foo.lib` and dynamic
- // libraries are not linked against directly, but rather through their
- // import libraries also called `foo.lib`. As a result there's no
- // possibility for a native library to appear both dynamically and
- // statically in the same folder so we don't have to worry about hints like
- // we do on Unix platforms.
- fn hint_static(&mut self) {}
- fn hint_dynamic(&mut self) {}
- // Currently the compiler doesn't use `dllexport` (an LLVM attribute) to
- // export symbols from a dynamic library. When building a dynamic library,
- // however, we're going to want some symbols exported, so this function
- // generates a DEF file which lists all the symbols.
- //
- // The linker will read this `*.def` file and export all the symbols from
- // the dynamic library. Note that this is not as simple as just exporting
- // all the symbols in the current crate (as specified by `trans.reachable`)
- // but rather we also need to possibly export the symbols of upstream
- // crates. Upstream rlibs may be linked statically to this dynamic library,
- // in which case they may continue to transitively be used and hence need
- // their symbols exported.
- fn export_symbols(&mut self, sess: &Session, trans: &CrateTranslation,
- tmpdir: &Path) {
- let path = tmpdir.join("lib.def");
- let res = (|| -> io::Result<()> {
- let mut f = BufWriter::new(try!(File::create(&path)));
- // Start off with the standard module name header and then go
- // straight to exports.
- try!(writeln!(f, "LIBRARY"));
- try!(writeln!(f, "EXPORTS"));
- // Write out all our local symbols
- for sym in trans.reachable.iter() {
- try!(writeln!(f, " {}", sym));
- }
- // Take a look at how all upstream crates are linked into this
- // dynamic library. For all statically linked libraries we take all
- // their reachable symbols and emit them as well.
- let cstore = &sess.cstore;
- let formats = sess.dependency_formats.borrow();
- let symbols = formats[&CrateTypeDylib].iter();
- let symbols = symbols.enumerate().filter_map(|(i, f)| {
- if *f == Linkage::Static {
- Some((i + 1) as ast::CrateNum)
- } else {
- None
- }
- }).flat_map(|cnum| {
- cstore.reachable_ids(cnum)
- }).map(|did| {
- cstore.item_symbol(did)
- });
- for symbol in symbols {
- try!(writeln!(f, " {}", symbol));
- }
- Ok(())
- })();
- if let Err(e) = res {
- sess.fatal(&format!("failed to write lib.def file: {}", e));
- }
- let mut arg = OsString::from("/DEF:");
- arg.push(path);
- self.cmd.arg(&arg);
- }
- }