Separating the back folder between backend-agnostic and LLVM-specific code

5 files changed, 0 insertions, 1689 deletions

diff --git a/src/librustc_codegen_utils/Cargo.toml b/src/librustc_codegen_utils/Cargo.toml
index 4c57e978414..34a09f30b64 100644
--- a/src/librustc_codegen_utils/Cargo.toml
+++ b/src/librustc_codegen_utils/Cargo.toml
@@ -13,11 +13,9 @@ test = false
 flate2 = "1.0"
 log = "0.4"
 
-serialize = { path = "../libserialize" }
 syntax = { path = "../libsyntax" }
 syntax_pos = { path = "../libsyntax_pos" }
 rustc = { path = "../librustc" }
-rustc_allocator = { path = "../librustc_allocator" }
 rustc_target = { path = "../librustc_target" }
 rustc_data_structures = { path = "../librustc_data_structures" }
 rustc_metadata = { path = "../librustc_metadata" }
diff --git a/src/librustc_codegen_utils/command.rs b/src/librustc_codegen_utils/command.rs
deleted file mode 100644
index 9ebbdd7c3c9..00000000000
--- a/src/librustc_codegen_utils/command.rs
+++ /dev/null
@@ -1,175 +0,0 @@
-// Copyright 2017 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.
-
-//! A thin wrapper around `Command` in the standard library which allows us to
-//! read the arguments that are built up.
-
-use std::ffi::{OsStr, OsString};
-use std::fmt;
-use std::io;
-use std::mem;
-use std::process::{self, Output};
-
-use rustc_target::spec::LldFlavor;
-
-#[derive(Clone)]
-pub struct Command {
-    program: Program,
-    args: Vec<OsString>,
-    env: Vec<(OsString, OsString)>,
-}
-
-#[derive(Clone)]
-enum Program {
-    Normal(OsString),
-    CmdBatScript(OsString),
-    Lld(OsString, LldFlavor)
-}
-
-impl Command {
-    pub fn new<P: AsRef<OsStr>>(program: P) -> Command {
-        Command::_new(Program::Normal(program.as_ref().to_owned()))
-    }
-
-    pub fn bat_script<P: AsRef<OsStr>>(program: P) -> Command {
-        Command::_new(Program::CmdBatScript(program.as_ref().to_owned()))
-    }
-
-    pub fn lld<P: AsRef<OsStr>>(program: P, flavor: LldFlavor) -> Command {
-        Command::_new(Program::Lld(program.as_ref().to_owned(), flavor))
-    }
-
-    fn _new(program: Program) -> Command {
-        Command {
-            program,
-            args: Vec::new(),
-            env: Vec::new(),
-        }
-    }
-
-    pub fn arg<P: AsRef<OsStr>>(&mut self, arg: P) -> &mut Command {
-        self._arg(arg.as_ref());
-        self
-    }
-
-    pub fn args<I>(&mut self, args: I) -> &mut Command
-        where I: IntoIterator,
-              I::Item: AsRef<OsStr>,
-    {
-        for arg in args {
-            self._arg(arg.as_ref());
-        }
-        self
-    }
-
-    fn _arg(&mut self, arg: &OsStr) {
-        self.args.push(arg.to_owned());
-    }
-
-    pub fn env<K, V>(&mut self, key: K, value: V) -> &mut Command
-        where K: AsRef<OsStr>,
-              V: AsRef<OsStr>
-    {
-        self._env(key.as_ref(), value.as_ref());
-        self
-    }
-
-    fn _env(&mut self, key: &OsStr, value: &OsStr) {
-        self.env.push((key.to_owned(), value.to_owned()));
-    }
-
-    pub fn output(&mut self) -> io::Result<Output> {
-        self.command().output()
-    }
-
-    pub fn command(&self) -> process::Command {
-        let mut ret = match self.program {
-            Program::Normal(ref p) => process::Command::new(p),
-            Program::CmdBatScript(ref p) => {
-                let mut c = process::Command::new("cmd");
-                c.arg("/c").arg(p);
-                c
-            }
-            Program::Lld(ref p, flavor) => {
-                let mut c = process::Command::new(p);
-                c.arg("-flavor").arg(match flavor {
-                    LldFlavor::Wasm => "wasm",
-                    LldFlavor::Ld => "gnu",
-                    LldFlavor::Link => "link",
-                    LldFlavor::Ld64 => "darwin",
-                });
-                c
-            }
-        };
-        ret.args(&self.args);
-        ret.envs(self.env.clone());
-        return ret
-    }
-
-    // extensions
-
-    pub fn get_args(&self) -> &[OsString] {
-        &self.args
-    }
-
-    pub fn take_args(&mut self) -> Vec<OsString> {
-        mem::replace(&mut self.args, Vec::new())
-    }
-
-    /// Returns a `true` if we're pretty sure that this'll blow OS spawn limits,
-    /// or `false` if we should attempt to spawn and see what the OS says.
-    pub fn very_likely_to_exceed_some_spawn_limit(&self) -> bool {
-        // We mostly only care about Windows in this method, on Unix the limits
-        // can be gargantuan anyway so we're pretty unlikely to hit them
-        if cfg!(unix) {
-            return false
-        }
-
-        // Right now LLD doesn't support the `@` syntax of passing an argument
-        // through files, so regardless of the platform we try to go to the OS
-        // on this one.
-        if let Program::Lld(..) = self.program {
-            return false
-        }
-
-        // Ok so on Windows to spawn a process is 32,768 characters in its
-        // command line [1]. Unfortunately we don't actually have access to that
-        // as it's calculated just before spawning. Instead we perform a
-        // poor-man's guess as to how long our command line will be. We're
-        // assuming here that we don't have to escape every character...
-        //
-        // Turns out though that `cmd.exe` has even smaller limits, 8192
-        // characters [2]. Linkers can often be batch scripts (for example
-        // Emscripten, Gecko's current build system) which means that we're
-        // running through batch scripts. These linkers often just forward
-        // arguments elsewhere (and maybe tack on more), so if we blow 8192
-        // bytes we'll typically cause them to blow as well.
-        //
-        // Basically as a result just perform an inflated estimate of what our
-        // command line will look like and test if it's > 8192 (we actually
-        // test against 6k to artificially inflate our estimate). If all else
-        // fails we'll fall back to the normal unix logic of testing the OS
-        // error code if we fail to spawn and automatically re-spawning the
-        // linker with smaller arguments.
-        //
-        // [1]: https://msdn.microsoft.com/en-us/library/windows/desktop/ms682425(v=vs.85).aspx
-        // [2]: https://blogs.msdn.microsoft.com/oldnewthing/20031210-00/?p=41553
-
-        let estimated_command_line_len =
-            self.args.iter().map(|a| a.len()).sum::<usize>();
-        estimated_command_line_len > 1024 * 6
-    }
-}
-
-impl fmt::Debug for Command {
-    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
-        self.command().fmt(f)
-    }
-}
diff --git a/src/librustc_codegen_utils/lib.rs b/src/librustc_codegen_utils/lib.rs
index 8d85c6691c2..96b319481a7 100644
--- a/src/librustc_codegen_utils/lib.rs
+++ b/src/librustc_codegen_utils/lib.rs
@@ -31,10 +31,8 @@ extern crate flate2;
 #[macro_use]
 extern crate log;
 
-extern crate serialize;
 #[macro_use]
 extern crate rustc;
-extern crate rustc_allocator;
 extern crate rustc_target;
 extern crate rustc_metadata;
 extern crate rustc_mir;
@@ -43,16 +41,10 @@ extern crate syntax;
 extern crate syntax_pos;
 #[macro_use] extern crate rustc_data_structures;
 
-use std::path::PathBuf;
-
-use rustc::session::Session;
 use rustc::ty::TyCtxt;
 
-pub mod command;
 pub mod link;
-pub mod linker;
 pub mod codegen_backend;
-pub mod symbol_export;
 pub mod symbol_names;
 pub mod symbol_names_test;
 
@@ -70,27 +62,4 @@ pub fn check_for_rustc_errors_attr(tcx: TyCtxt) {
     }
 }
 
-pub fn find_library(name: &str, search_paths: &[PathBuf], sess: &Session)
-                    -> PathBuf {
-    // On Windows, static libraries sometimes show up as libfoo.a and other
-    // times show up as foo.lib
-    let oslibname = format!("{}{}{}",
-                            sess.target.target.options.staticlib_prefix,
-                            name,
-                            sess.target.target.options.staticlib_suffix);
-    let unixlibname = format!("lib{}.a", name);
-
-    for path in search_paths {
-        debug!("looking for {} inside {:?}", name, path);
-        let test = path.join(&oslibname);
-        if test.exists() { return test }
-        if oslibname != unixlibname {
-            let test = path.join(&unixlibname);
-            if test.exists() { return test }
-        }
-    }
-    sess.fatal(&format!("could not find native static library `{}`, \
-                         perhaps an -L flag is missing?", name));
-}
-
 __build_diagnostic_array! { librustc_codegen_utils, DIAGNOSTICS }
diff --git a/src/librustc_codegen_utils/linker.rs b/src/librustc_codegen_utils/linker.rs
deleted file mode 100644
index 219bf256638..00000000000
--- a/src/librustc_codegen_utils/linker.rs
+++ /dev/null
@@ -1,1077 +0,0 @@
-// 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 rustc_data_structures::fx::FxHashMap;
-use std::ffi::{OsStr, OsString};
-use std::fs::{self, File};
-use std::io::prelude::*;
-use std::io::{self, BufWriter};
-use std::path::{Path, PathBuf};
-
-use command::Command;
-use rustc::hir::def_id::{LOCAL_CRATE, CrateNum};
-use rustc::middle::dependency_format::Linkage;
-use rustc::session::Session;
-use rustc::session::config::{self, CrateType, OptLevel, DebugInfo,
-                             CrossLangLto};
-use rustc::ty::TyCtxt;
-use rustc_target::spec::{LinkerFlavor, LldFlavor};
-use serialize::{json, Encoder};
-
-/// For all the linkers we support, and information they might
-/// need out of the shared crate context before we get rid of it.
-pub struct LinkerInfo {
-    exports: FxHashMap<CrateType, Vec<String>>,
-}
-
-impl LinkerInfo {
-    pub fn new(tcx: TyCtxt) -> LinkerInfo {
-        LinkerInfo {
-            exports: tcx.sess.crate_types.borrow().iter().map(|&c| {
-                (c, exported_symbols(tcx, c))
-            }).collect(),
-        }
-    }
-
-    pub fn to_linker<'a>(
-        &'a self,
-        cmd: Command,
-        sess: &'a Session,
-        flavor: LinkerFlavor,
-        target_cpu: &'a str,
-    ) -> Box<dyn Linker+'a> {
-        match flavor {
-            LinkerFlavor::Lld(LldFlavor::Link) |
-            LinkerFlavor::Msvc => {
-                Box::new(MsvcLinker {
-                    cmd,
-                    sess,
-                    info: self
-                }) as Box<dyn Linker>
-            }
-            LinkerFlavor::Em =>  {
-                Box::new(EmLinker {
-                    cmd,
-                    sess,
-                    info: self
-                }) as Box<dyn Linker>
-            }
-            LinkerFlavor::Gcc =>  {
-                Box::new(GccLinker {
-                    cmd,
-                    sess,
-                    info: self,
-                    hinted_static: false,
-                    is_ld: false,
-                    target_cpu,
-                }) as Box<dyn Linker>
-            }
-
-            LinkerFlavor::Lld(LldFlavor::Ld) |
-            LinkerFlavor::Lld(LldFlavor::Ld64) |
-            LinkerFlavor::Ld => {
-                Box::new(GccLinker {
-                    cmd,
-                    sess,
-                    info: self,
-                    hinted_static: false,
-                    is_ld: true,
-                    target_cpu,
-                }) as Box<dyn Linker>
-            }
-
-            LinkerFlavor::Lld(LldFlavor::Wasm) => {
-                Box::new(WasmLd {
-                    cmd,
-                    sess,
-                    info: self
-                }) as Box<dyn Linker>
-            }
-        }
-    }
-}
-
-/// 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, keep_metadata: bool);
-    fn position_independent_executable(&mut self);
-    fn no_position_independent_executable(&mut self);
-    fn full_relro(&mut self);
-    fn partial_relro(&mut self);
-    fn no_relro(&mut self);
-    fn optimize(&mut self);
-    fn pgo_gen(&mut self);
-    fn debuginfo(&mut self);
-    fn no_default_libraries(&mut self);
-    fn build_dylib(&mut self, out_filename: &Path);
-    fn build_static_executable(&mut self);
-    fn args(&mut self, args: &[String]);
-    fn export_symbols(&mut self, tmpdir: &Path, crate_type: CrateType);
-    fn subsystem(&mut self, subsystem: &str);
-    fn group_start(&mut self);
-    fn group_end(&mut self);
-    fn cross_lang_lto(&mut self);
-    // Should have been finalize(self), but we don't support self-by-value on trait objects (yet?).
-    fn finalize(&mut self) -> Command;
-}
-
-pub struct GccLinker<'a> {
-    cmd: Command,
-    sess: &'a Session,
-    info: &'a LinkerInfo,
-    hinted_static: bool, // Keeps track of the current hinting mode.
-    // Link as ld
-    is_ld: bool,
-    target_cpu: &'a str,
-}
-
-impl<'a> GccLinker<'a> {
-    /// Argument that must be passed *directly* to the linker
-    ///
-    /// These arguments need to be prepended with '-Wl,' when a gcc-style linker is used
-    fn linker_arg<S>(&mut self, arg: S) -> &mut Self
-        where S: AsRef<OsStr>
-    {
-        if !self.is_ld {
-            let mut os = OsString::from("-Wl,");
-            os.push(arg.as_ref());
-            self.cmd.arg(os);
-        } else {
-            self.cmd.arg(arg);
-        }
-        self
-    }
-
-    fn takes_hints(&self) -> bool {
-        !self.sess.target.target.options.is_like_osx
-    }
-
-    // Some platforms take hints about whether a library is static or dynamic.
-    // For those that support this, we ensure we pass the option if the library
-    // was flagged "static" (most defaults are dynamic) to ensure that if
-    // libfoo.a and libfoo.so both exist that the right one is chosen.
-    fn hint_static(&mut self) {
-        if !self.takes_hints() { return }
-        if !self.hinted_static {
-            self.linker_arg("-Bstatic");
-            self.hinted_static = true;
-        }
-    }
-
-    fn hint_dynamic(&mut self) {
-        if !self.takes_hints() { return }
-        if self.hinted_static {
-            self.linker_arg("-Bdynamic");
-            self.hinted_static = false;
-        }
-    }
-
-    fn push_cross_lang_lto_args(&mut self, plugin_path: Option<&OsStr>) {
-        if let Some(plugin_path) = plugin_path {
-            let mut arg = OsString::from("-plugin=");
-            arg.push(plugin_path);
-            self.linker_arg(&arg);
-        }
-
-        let opt_level = match self.sess.opts.optimize {
-            config::OptLevel::No => "O0",
-            config::OptLevel::Less => "O1",
-            config::OptLevel::Default => "O2",
-            config::OptLevel::Aggressive => "O3",
-            config::OptLevel::Size => "Os",
-            config::OptLevel::SizeMin => "Oz",
-        };
-
-        self.linker_arg(&format!("-plugin-opt={}", opt_level));
-        let target_cpu = self.target_cpu;
-        self.linker_arg(&format!("-plugin-opt=mcpu={}", target_cpu));
-    }
-}
-
-impl<'a> Linker for GccLinker<'a> {
-    fn link_dylib(&mut self, lib: &str) { self.hint_dynamic(); self.cmd.arg(format!("-l{}", lib)); }
-    fn link_staticlib(&mut self, lib: &str) {
-        self.hint_static(); self.cmd.arg(format!("-l{}", lib));
-    }
-    fn link_rlib(&mut self, lib: &Path) { self.hint_static(); 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 no_position_independent_executable(&mut self) { self.cmd.arg("-no-pie"); }
-    fn full_relro(&mut self) { self.linker_arg("-zrelro"); self.linker_arg("-znow"); }
-    fn partial_relro(&mut self) { self.linker_arg("-zrelro"); }
-    fn no_relro(&mut self) { self.linker_arg("-znorelro"); }
-    fn build_static_executable(&mut self) { self.cmd.arg("-static"); }
-    fn args(&mut self, args: &[String]) { self.cmd.args(args); }
-
-    fn link_rust_dylib(&mut self, lib: &str, _path: &Path) {
-        self.hint_dynamic();
-        self.cmd.arg(format!("-l{}", lib));
-    }
-
-    fn link_framework(&mut self, framework: &str) {
-        self.hint_dynamic();
-        self.cmd.arg("-framework").arg(framework);
-    }
-
-    // Here we explicitly ask that the entire archive is included into the
-    // result artifact. For more details see #15460, but the gist is that
-    // the linker will strip away any unused objects in the archive if we
-    // don't otherwise explicitly reference them. This can occur for
-    // libraries which are just providing bindings, libraries with generic
-    // functions, etc.
-    fn link_whole_staticlib(&mut self, lib: &str, search_path: &[PathBuf]) {
-        self.hint_static();
-        let target = &self.sess.target.target;
-        if !target.options.is_like_osx {
-            self.linker_arg("--whole-archive").cmd.arg(format!("-l{}", lib));
-            self.linker_arg("--no-whole-archive");
-        } else {
-            // -force_load is the macOS equivalent of --whole-archive, but it
-            // involves passing the full path to the library to link.
-            self.linker_arg("-force_load");
-            let lib = ::find_library(lib, search_path, &self.sess);
-            self.linker_arg(&lib);
-        }
-    }
-
-    fn link_whole_rlib(&mut self, lib: &Path) {
-        self.hint_static();
-        if self.sess.target.target.options.is_like_osx {
-            self.linker_arg("-force_load");
-            self.linker_arg(&lib);
-        } else {
-            self.linker_arg("--whole-archive").cmd.arg(lib);
-            self.linker_arg("--no-whole-archive");
-        }
-    }
-
-    fn gc_sections(&mut self, keep_metadata: 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.linker_arg("-dead_strip");
-        } else if self.sess.target.target.options.is_like_solaris {
-            self.linker_arg("-zignore");
-
-        // 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 !keep_metadata {
-            self.linker_arg("--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.linker_arg("-O1");
-        }
-    }
-
-    fn pgo_gen(&mut self) {
-        if !self.sess.target.target.options.linker_is_gnu { return }
-
-        // If we're doing PGO generation stuff and on a GNU-like linker, use the
-        // "-u" flag to properly pull in the profiler runtime bits.
-        //
-        // This is because LLVM otherwise won't add the needed initialization
-        // for us on Linux (though the extra flag should be harmless if it
-        // does).
-        //
-        // See https://reviews.llvm.org/D14033 and https://reviews.llvm.org/D14030.
-        //
-        // Though it may be worth to try to revert those changes upstream, since
-        // the overhead of the initialization should be minor.
-        self.cmd.arg("-u");
-        self.cmd.arg("__llvm_profile_runtime");
-    }
-
-    fn debuginfo(&mut self) {
-        if let DebugInfo::None = self.sess.opts.debuginfo {
-            // If we are building without debuginfo enabled and we were called with
-            // `-Zstrip-debuginfo-if-disabled=yes`, tell the linker to strip any debuginfo
-            // found when linking to get rid of symbols from libstd.
-            if let Some(true) = self.sess.opts.debugging_opts.strip_debuginfo_if_disabled {
-                self.linker_arg("-S");
-            }
-        };
-    }
-
-    fn no_default_libraries(&mut self) {
-        if !self.is_ld {
-            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.arg("-dynamiclib");
-            self.linker_arg("-dylib");
-
-            // Note that the `osx_rpath_install_name` option here is a hack
-            // purely to support rustbuild right now, we should get a more
-            // principled solution at some point to force the compiler to pass
-            // the right `-Wl,-install_name` with an `@rpath` in it.
-            if self.sess.opts.cg.rpath || self.sess.opts.debugging_opts.osx_rpath_install_name {
-                self.linker_arg("-install_name");
-                let mut v = OsString::from("@rpath/");
-                v.push(out_filename.file_name().unwrap());
-                self.linker_arg(&v);
-            }
-        } else {
-            self.cmd.arg("-shared");
-        }
-    }
-
-    fn export_symbols(&mut self, tmpdir: &Path, crate_type: CrateType) {
-        // If we're compiling a dylib, then we let symbol visibility in object
-        // files to take care of whether they're exported or not.
-        //
-        // If we're compiling a cdylib, however, we manually create a list of
-        // exported symbols to ensure we don't expose any more. The object files
-        // have far more public symbols than we actually want to export, so we
-        // hide them all here.
-        if crate_type == CrateType::Dylib ||
-           crate_type == CrateType::ProcMacro {
-            return
-        }
-
-        let mut arg = OsString::new();
-        let path = tmpdir.join("list");
-
-        debug!("EXPORTED SYMBOLS:");
-
-        if self.sess.target.target.options.is_like_osx {
-            // Write a plain, newline-separated list of symbols
-            let res = (|| -> io::Result<()> {
-                let mut f = BufWriter::new(File::create(&path)?);
-                for sym in self.info.exports[&crate_type].iter() {
-                    debug!("  _{}", sym);
-                    writeln!(f, "_{}", sym)?;
-                }
-                Ok(())
-            })();
-            if let Err(e) = res {
-                self.sess.fatal(&format!("failed to write lib.def file: {}", e));
-            }
-        } else {
-            // Write an LD version script
-            let res = (|| -> io::Result<()> {
-                let mut f = BufWriter::new(File::create(&path)?);
-                writeln!(f, "{{\n  global:")?;
-                for sym in self.info.exports[&crate_type].iter() {
-                    debug!("    {};", sym);
-                    writeln!(f, "    {};", sym)?;
-                }
-                writeln!(f, "\n  local:\n    *;\n}};")?;
-                Ok(())
-            })();
-            if let Err(e) = res {
-                self.sess.fatal(&format!("failed to write version script: {}", e));
-            }
-        }
-
-        if self.sess.target.target.options.is_like_osx {
-            if !self.is_ld {
-                arg.push("-Wl,")
-            }
-            arg.push("-exported_symbols_list,");
-        } else if self.sess.target.target.options.is_like_solaris {
-            if !self.is_ld {
-                arg.push("-Wl,")
-            }
-            arg.push("-M,");
-        } else {
-            if !self.is_ld {
-                arg.push("-Wl,")
-            }
-            arg.push("--version-script=");
-        }
-
-        arg.push(&path);
-        self.cmd.arg(arg);
-    }
-
-    fn subsystem(&mut self, subsystem: &str) {
-        self.linker_arg("--subsystem");
-        self.linker_arg(&subsystem);
-    }
-
-    fn finalize(&mut self) -> Command {
-        self.hint_dynamic(); // Reset to default before returning the composed command line.
-
-        ::std::mem::replace(&mut self.cmd, Command::new(""))
-    }
-
-    fn group_start(&mut self) {
-        if !self.sess.target.target.options.is_like_osx {
-            self.linker_arg("--start-group");
-        }
-    }
-
-    fn group_end(&mut self) {
-        if !self.sess.target.target.options.is_like_osx {
-            self.linker_arg("--end-group");
-        }
-    }
-
-    fn cross_lang_lto(&mut self) {
-        match self.sess.opts.debugging_opts.cross_lang_lto {
-            CrossLangLto::Disabled => {
-                // Nothing to do
-            }
-            CrossLangLto::LinkerPluginAuto => {
-                self.push_cross_lang_lto_args(None);
-            }
-            CrossLangLto::LinkerPlugin(ref path) => {
-                self.push_cross_lang_lto_args(Some(path.as_os_str()));
-            }
-        }
-    }
-}
-
-pub struct MsvcLinker<'a> {
-    cmd: Command,
-    sess: &'a Session,
-    info: &'a LinkerInfo
-}
-
-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 build_static_executable(&mut self) {
-        // noop
-    }
-
-    fn gc_sections(&mut self, _keep_metadata: bool) {
-        // MSVC's ICF (Identical COMDAT Folding) link optimization is
-        // slow for Rust and thus we disable it by default when not in
-        // optimization build.
-        if self.sess.opts.optimize != config::OptLevel::No {
-            self.cmd.arg("/OPT:REF,ICF");
-        } else {
-            // It is necessary to specify NOICF here, because /OPT:REF
-            // implies ICF by default.
-            self.cmd.arg("/OPT:REF,NOICF");
-        }
-    }
-
-    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_position_independent_executable(&mut self) {
-        // noop
-    }
-
-    fn full_relro(&mut self) {
-        // noop
-    }
-
-    fn partial_relro(&mut self) {
-        // noop
-    }
-
-    fn no_relro(&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) {
-        bug!("frameworks are not supported on windows")
-    }
-    fn link_framework(&mut self, _framework: &str) {
-        bug!("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 pgo_gen(&mut self) {
-        // Nothing needed here.
-    }
-
-    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");
-
-        // This will cause the Microsoft linker to embed .natvis info into the PDB file
-        let sysroot = self.sess.sysroot();
-        let natvis_dir_path = sysroot.join("lib\\rustlib\\etc");
-        if let Ok(natvis_dir) = fs::read_dir(&natvis_dir_path) {
-            // LLVM 5.0.0's lld-link frontend doesn't yet recognize, and chokes
-            // on, the /NATVIS:... flags.  LLVM 6 (or earlier) should at worst ignore
-            // them, eventually mooting this workaround, per this landed patch:
-            // https://github.com/llvm-mirror/lld/commit/27b9c4285364d8d76bb43839daa100
-            if let Some(ref linker_path) = self.sess.opts.cg.linker {
-                if let Some(linker_name) = Path::new(&linker_path).file_stem() {
-                    if linker_name.to_str().unwrap().to_lowercase() == "lld-link" {
-                        self.sess.warn("not embedding natvis: lld-link may not support the flag");
-                        return;
-                    }
-                }
-            }
-            for entry in natvis_dir {
-                match entry {
-                    Ok(entry) => {
-                        let path = entry.path();
-                        if path.extension() == Some("natvis".as_ref()) {
-                            let mut arg = OsString::from("/NATVIS:");
-                            arg.push(path);
-                            self.cmd.arg(arg);
-                        }
-                    },
-                    Err(err) => {
-                        self.sess.warn(&format!("error enumerating natvis directory: {}", err));
-                    },
-                }
-            }
-        }
-    }
-
-    // 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 `codegen.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,
-                      tmpdir: &Path,
-                      crate_type: CrateType) {
-        let path = tmpdir.join("lib.def");
-        let res = (|| -> io::Result<()> {
-            let mut f = BufWriter::new(File::create(&path)?);
-
-            // Start off with the standard module name header and then go
-            // straight to exports.
-            writeln!(f, "LIBRARY")?;
-            writeln!(f, "EXPORTS")?;
-            for symbol in self.info.exports[&crate_type].iter() {
-                debug!("  _{}", symbol);
-                writeln!(f, "  {}", symbol)?;
-            }
-            Ok(())
-        })();
-        if let Err(e) = res {
-            self.sess.fatal(&format!("failed to write lib.def file: {}", e));
-        }
-        let mut arg = OsString::from("/DEF:");
-        arg.push(path);
-        self.cmd.arg(&arg);
-    }
-
-    fn subsystem(&mut self, subsystem: &str) {
-        // Note that previous passes of the compiler validated this subsystem,
-        // so we just blindly pass it to the linker.
-        self.cmd.arg(&format!("/SUBSYSTEM:{}", subsystem));
-
-        // Windows has two subsystems we're interested in right now, the console
-        // and windows subsystems. These both implicitly have different entry
-        // points (starting symbols). The console entry point starts with
-        // `mainCRTStartup` and the windows entry point starts with
-        // `WinMainCRTStartup`. These entry points, defined in system libraries,
-        // will then later probe for either `main` or `WinMain`, respectively to
-        // start the application.
-        //
-        // In Rust we just always generate a `main` function so we want control
-        // to always start there, so we force the entry point on the windows
-        // subsystem to be `mainCRTStartup` to get everything booted up
-        // correctly.
-        //
-        // For more information see RFC #1665
-        if subsystem == "windows" {
-            self.cmd.arg("/ENTRY:mainCRTStartup");
-        }
-    }
-
-    fn finalize(&mut self) -> Command {
-        ::std::mem::replace(&mut self.cmd, Command::new(""))
-    }
-
-    // MSVC doesn't need group indicators
-    fn group_start(&mut self) {}
-    fn group_end(&mut self) {}
-
-    fn cross_lang_lto(&mut self) {
-        // Do nothing
-    }
-}
-
-pub struct EmLinker<'a> {
-    cmd: Command,
-    sess: &'a Session,
-    info: &'a LinkerInfo
-}
-
-impl<'a> Linker for EmLinker<'a> {
-    fn include_path(&mut self, path: &Path) {
-        self.cmd.arg("-L").arg(path);
-    }
-
-    fn link_staticlib(&mut self, lib: &str) {
-        self.cmd.arg("-l").arg(lib);
-    }
-
-    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 link_dylib(&mut self, lib: &str) {
-        // Emscripten always links statically
-        self.link_staticlib(lib);
-    }
-
-    fn link_whole_staticlib(&mut self, lib: &str, _search_path: &[PathBuf]) {
-        // not supported?
-        self.link_staticlib(lib);
-    }
-
-    fn link_whole_rlib(&mut self, lib: &Path) {
-        // not supported?
-        self.link_rlib(lib);
-    }
-
-    fn link_rust_dylib(&mut self, lib: &str, _path: &Path) {
-        self.link_dylib(lib);
-    }
-
-    fn link_rlib(&mut self, lib: &Path) {
-        self.add_object(lib);
-    }
-
-    fn position_independent_executable(&mut self) {
-        // noop
-    }
-
-    fn no_position_independent_executable(&mut self) {
-        // noop
-    }
-
-    fn full_relro(&mut self) {
-        // noop
-    }
-
-    fn partial_relro(&mut self) {
-        // noop
-    }
-
-    fn no_relro(&mut self) {
-        // noop
-    }
-
-    fn args(&mut self, args: &[String]) {
-        self.cmd.args(args);
-    }
-
-    fn framework_path(&mut self, _path: &Path) {
-        bug!("frameworks are not supported on Emscripten")
-    }
-
-    fn link_framework(&mut self, _framework: &str) {
-        bug!("frameworks are not supported on Emscripten")
-    }
-
-    fn gc_sections(&mut self, _keep_metadata: bool) {
-        // noop
-    }
-
-    fn optimize(&mut self) {
-        // Emscripten performs own optimizations
-        self.cmd.arg(match self.sess.opts.optimize {
-            OptLevel::No => "-O0",
-            OptLevel::Less => "-O1",
-            OptLevel::Default => "-O2",
-            OptLevel::Aggressive => "-O3",
-            OptLevel::Size => "-Os",
-            OptLevel::SizeMin => "-Oz"
-        });
-        // Unusable until https://github.com/rust-lang/rust/issues/38454 is resolved
-        self.cmd.args(&["--memory-init-file", "0"]);
-    }
-
-    fn pgo_gen(&mut self) {
-        // noop, but maybe we need something like the gnu linker?
-    }
-
-    fn debuginfo(&mut self) {
-        // Preserve names or generate source maps depending on debug info
-        self.cmd.arg(match self.sess.opts.debuginfo {
-            DebugInfo::None => "-g0",
-            DebugInfo::Limited => "-g3",
-            DebugInfo::Full => "-g4"
-        });
-    }
-
-    fn no_default_libraries(&mut self) {
-        self.cmd.args(&["-s", "DEFAULT_LIBRARY_FUNCS_TO_INCLUDE=[]"]);
-    }
-
-    fn build_dylib(&mut self, _out_filename: &Path) {
-        bug!("building dynamic library is unsupported on Emscripten")
-    }
-
-    fn build_static_executable(&mut self) {
-        // noop
-    }
-
-    fn export_symbols(&mut self, _tmpdir: &Path, crate_type: CrateType) {
-        let symbols = &self.info.exports[&crate_type];
-
-        debug!("EXPORTED SYMBOLS:");
-
-        self.cmd.arg("-s");
-
-        let mut arg = OsString::from("EXPORTED_FUNCTIONS=");
-        let mut encoded = String::new();
-
-        {
-            let mut encoder = json::Encoder::new(&mut encoded);
-            let res = encoder.emit_seq(symbols.len(), |encoder| {
-                for (i, sym) in symbols.iter().enumerate() {
-                    encoder.emit_seq_elt(i, |encoder| {
-                        encoder.emit_str(&("_".to_owned() + sym))
-                    })?;
-                }
-                Ok(())
-            });
-            if let Err(e) = res {
-                self.sess.fatal(&format!("failed to encode exported symbols: {}", e));
-            }
-        }
-        debug!("{}", encoded);
-        arg.push(encoded);
-
-        self.cmd.arg(arg);
-    }
-
-    fn subsystem(&mut self, _subsystem: &str) {
-        // noop
-    }
-
-    fn finalize(&mut self) -> Command {
-        ::std::mem::replace(&mut self.cmd, Command::new(""))
-    }
-
-    // Appears not necessary on Emscripten
-    fn group_start(&mut self) {}
-    fn group_end(&mut self) {}
-
-    fn cross_lang_lto(&mut self) {
-        // Do nothing
-    }
-}
-
-fn exported_symbols(tcx: TyCtxt, crate_type: CrateType) -> Vec<String> {
-    let mut symbols = Vec::new();
-
-    let export_threshold =
-        ::symbol_export::crates_export_threshold(&[crate_type]);
-    for &(symbol, level) in tcx.exported_symbols(LOCAL_CRATE).iter() {
-        if level.is_below_threshold(export_threshold) {
-            symbols.push(symbol.symbol_name(tcx).to_string());
-        }
-    }
-
-    let formats = tcx.sess.dependency_formats.borrow();
-    let deps = formats[&crate_type].iter();
-
-    for (index, dep_format) in deps.enumerate() {
-        let cnum = CrateNum::new(index + 1);
-        // For each dependency that we are linking to statically ...
-        if *dep_format == Linkage::Static {
-            // ... we add its symbol list to our export list.
-            for &(symbol, level) in tcx.exported_symbols(cnum).iter() {
-                if level.is_below_threshold(export_threshold) {
-                    symbols.push(symbol.symbol_name(tcx).to_string());
-                }
-            }
-        }
-    }
-
-    symbols
-}
-
-pub struct WasmLd<'a> {
-    cmd: Command,
-    sess: &'a Session,
-    info: &'a LinkerInfo,
-}
-
-impl<'a> Linker for WasmLd<'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) {
-        panic!("frameworks not supported")
-    }
-
-    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) {
-    }
-
-    fn full_relro(&mut self) {
-    }
-
-    fn partial_relro(&mut self) {
-    }
-
-    fn no_relro(&mut self) {
-    }
-
-    fn build_static_executable(&mut self) {
-    }
-
-    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) {
-        panic!("frameworks not supported")
-    }
-
-    fn link_whole_staticlib(&mut self, lib: &str, _search_path: &[PathBuf]) {
-        self.cmd.arg("-l").arg(lib);
-    }
-
-    fn link_whole_rlib(&mut self, lib: &Path) {
-        self.cmd.arg(lib);
-    }
-
-    fn gc_sections(&mut self, _keep_metadata: bool) {
-        self.cmd.arg("--gc-sections");
-    }
-
-    fn optimize(&mut self) {
-        self.cmd.arg(match self.sess.opts.optimize {
-            OptLevel::No => "-O0",
-            OptLevel::Less => "-O1",
-            OptLevel::Default => "-O2",
-            OptLevel::Aggressive => "-O3",
-            // Currently LLD doesn't support `Os` and `Oz`, so pass through `O2`
-            // instead.
-            OptLevel::Size => "-O2",
-            OptLevel::SizeMin => "-O2"
-        });
-    }
-
-    fn pgo_gen(&mut self) {
-    }
-
-    fn debuginfo(&mut self) {
-    }
-
-    fn no_default_libraries(&mut self) {
-    }
-
-    fn build_dylib(&mut self, _out_filename: &Path) {
-    }
-
-    fn export_symbols(&mut self, _tmpdir: &Path, crate_type: CrateType) {
-        for sym in self.info.exports[&crate_type].iter() {
-            self.cmd.arg("--export").arg(&sym);
-        }
-    }
-
-    fn subsystem(&mut self, _subsystem: &str) {
-    }
-
-    fn no_position_independent_executable(&mut self) {
-    }
-
-    fn finalize(&mut self) -> Command {
-        // There have been reports in the wild (rustwasm/wasm-bindgen#119) of
-        // using threads causing weird hangs and bugs. Disable it entirely as
-        // this isn't yet the bottleneck of compilation at all anyway.
-        self.cmd.arg("--no-threads");
-
-        // By default LLD only gives us one page of stack (64k) which is a
-        // little small. Default to a larger stack closer to other PC platforms
-        // (1MB) and users can always inject their own link-args to override this.
-        self.cmd.arg("-z").arg("stack-size=1048576");
-
-        // By default LLD's memory layout is:
-        //
-        // 1. First, a blank page
-        // 2. Next, all static data
-        // 3. Finally, the main stack (which grows down)
-        //
-        // This has the unfortunate consequence that on stack overflows you
-        // corrupt static data and can cause some exceedingly weird bugs. To
-        // help detect this a little sooner we instead request that the stack is
-        // placed before static data.
-        //
-        // This means that we'll generate slightly larger binaries as references
-        // to static data will take more bytes in the ULEB128 encoding, but
-        // stack overflow will be guaranteed to trap as it underflows instead of
-        // corrupting static data.
-        self.cmd.arg("--stack-first");
-
-        // FIXME we probably shouldn't pass this but instead pass an explicit
-        // whitelist of symbols we'll allow to be undefined. Unfortunately
-        // though we can't handle symbols like `log10` that LLVM injects at a
-        // super late date without actually parsing object files. For now let's
-        // stick to this and hopefully fix it before stabilization happens.
-        self.cmd.arg("--allow-undefined");
-
-        // For now we just never have an entry symbol
-        self.cmd.arg("--no-entry");
-
-        // Make the default table accessible
-        self.cmd.arg("--export-table");
-
-        // Rust code should never have warnings, and warnings are often
-        // indicative of bugs, let's prevent them.
-        self.cmd.arg("--fatal-warnings");
-
-        ::std::mem::replace(&mut self.cmd, Command::new(""))
-    }
-
-    // Not needed for now with LLD
-    fn group_start(&mut self) {}
-    fn group_end(&mut self) {}
-
-    fn cross_lang_lto(&mut self) {
-        // Do nothing for now
-    }
-}
diff --git a/src/librustc_codegen_utils/symbol_export.rs b/src/librustc_codegen_utils/symbol_export.rs
deleted file mode 100644
index dff7e518630..00000000000
--- a/src/librustc_codegen_utils/symbol_export.rs
+++ /dev/null
@@ -1,404 +0,0 @@
-// Copyright 2016 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 rustc_data_structures::sync::Lrc;
-use std::sync::Arc;
-
-use rustc::ty::Instance;
-use rustc::hir;
-use rustc::hir::Node;
-use rustc::hir::CodegenFnAttrFlags;
-use rustc::hir::def_id::{CrateNum, DefId, LOCAL_CRATE, CRATE_DEF_INDEX};
-use rustc_data_structures::fingerprint::Fingerprint;
-use rustc::middle::exported_symbols::{SymbolExportLevel, ExportedSymbol, metadata_symbol_name};
-use rustc::session::config;
-use rustc::ty::{TyCtxt, SymbolName};
-use rustc::ty::query::Providers;
-use rustc::ty::subst::Substs;
-use rustc::util::nodemap::{FxHashMap, DefIdMap};
-use rustc_allocator::ALLOCATOR_METHODS;
-use rustc_data_structures::indexed_vec::IndexVec;
-use std::collections::hash_map::Entry::*;
-
-pub type ExportedSymbols = FxHashMap<
-    CrateNum,
-    Arc<Vec<(String, SymbolExportLevel)>>,
->;
-
-pub fn threshold(tcx: TyCtxt) -> SymbolExportLevel {
-    crates_export_threshold(&tcx.sess.crate_types.borrow())
-}
-
-fn crate_export_threshold(crate_type: config::CrateType) -> SymbolExportLevel {
-    match crate_type {
-        config::CrateType::Executable |
-        config::CrateType::Staticlib  |
-        config::CrateType::ProcMacro  |
-        config::CrateType::Cdylib     => SymbolExportLevel::C,
-        config::CrateType::Rlib       |
-        config::CrateType::Dylib      => SymbolExportLevel::Rust,
-    }
-}
-
-pub fn crates_export_threshold(crate_types: &[config::CrateType]) -> SymbolExportLevel {
-    if crate_types.iter().any(|&crate_type|
-        crate_export_threshold(crate_type) == SymbolExportLevel::Rust)
-    {
-        SymbolExportLevel::Rust
-    } else {
-        SymbolExportLevel::C
-    }
-}
-
-fn reachable_non_generics_provider<'a, 'tcx>(tcx: TyCtxt<'a, 'tcx, 'tcx>,
-                                             cnum: CrateNum)
-                                             -> Lrc<DefIdMap<SymbolExportLevel>>
-{
-    assert_eq!(cnum, LOCAL_CRATE);
-
-    if !tcx.sess.opts.output_types.should_codegen() {
-        return Lrc::new(DefIdMap())
-    }
-
-    // Check to see if this crate is a "special runtime crate". These
-    // crates, implementation details of the standard library, typically
-    // have a bunch of `pub extern` and `#[no_mangle]` functions as the
-    // ABI between them. We don't want their symbols to have a `C`
-    // export level, however, as they're just implementation details.
-    // Down below we'll hardwire all of the symbols to the `Rust` export
-    // level instead.
-    let special_runtime_crate = tcx.is_panic_runtime(LOCAL_CRATE) ||
-        tcx.is_compiler_builtins(LOCAL_CRATE);
-
-    let mut reachable_non_generics: DefIdMap<_> = tcx.reachable_set(LOCAL_CRATE).0
-        .iter()
-        .filter_map(|&node_id| {
-            // We want to ignore some FFI functions that are not exposed from
-            // this crate. Reachable FFI functions can be lumped into two
-            // categories:
-            //
-            // 1. Those that are included statically via a static library
-            // 2. Those included otherwise (e.g. dynamically or via a framework)
-            //
-            // Although our LLVM module is not literally emitting code for the
-            // statically included symbols, it's an export of our library which
-            // needs to be passed on to the linker and encoded in the metadata.
-            //
-            // As a result, if this id is an FFI item (foreign item) then we only
-            // let it through if it's included statically.
-            match tcx.hir.get(node_id) {
-                Node::ForeignItem(..) => {
-                    let def_id = tcx.hir.local_def_id(node_id);
-                    if tcx.is_statically_included_foreign_item(def_id) {
-                        Some(def_id)
-                    } else {
-                        None
-                    }
-                }
-
-                // Only consider nodes that actually have exported symbols.
-                Node::Item(&hir::Item {
-                    node: hir::ItemKind::Static(..),
-                    ..
-                }) |
-                Node::Item(&hir::Item {
-                    node: hir::ItemKind::Fn(..), ..
-                }) |
-                Node::ImplItem(&hir::ImplItem {
-                    node: hir::ImplItemKind::Method(..),
-                    ..
-                }) => {
-                    let def_id = tcx.hir.local_def_id(node_id);
-                    let generics = tcx.generics_of(def_id);
-                    if !generics.requires_monomorphization(tcx) &&
-                        // Functions marked with #[inline] are only ever codegened
-                        // with "internal" linkage and are never exported.
-                        !Instance::mono(tcx, def_id).def.requires_local(tcx) {
-                        Some(def_id)
-                    } else {
-                        None
-                    }
-                }
-
-                _ => None
-            }
-        })
-        .map(|def_id| {
-            let export_level = if special_runtime_crate {
-                let name = tcx.symbol_name(Instance::mono(tcx, def_id)).as_str();
-                // We can probably do better here by just ensuring that
-                // it has hidden visibility rather than public
-                // visibility, as this is primarily here to ensure it's
-                // not stripped during LTO.
-                //
-                // In general though we won't link right if these
-                // symbols are stripped, and LTO currently strips them.
-                if &*name == "rust_eh_personality" ||
-                   &*name == "rust_eh_register_frames" ||
-                   &*name == "rust_eh_unregister_frames" {
-                    SymbolExportLevel::C
-                } else {
-                    SymbolExportLevel::Rust
-                }
-            } else {
-                symbol_export_level(tcx, def_id)
-            };
-            debug!("EXPORTED SYMBOL (local): {} ({:?})",
-                   tcx.symbol_name(Instance::mono(tcx, def_id)),
-                   export_level);
-            (def_id, export_level)
-        })
-        .collect();
-
-    if let Some(id) = *tcx.sess.derive_registrar_fn.get() {
-        let def_id = tcx.hir.local_def_id(id);
-        reachable_non_generics.insert(def_id, SymbolExportLevel::C);
-    }
-
-    if let Some(id) = *tcx.sess.plugin_registrar_fn.get() {
-        let def_id = tcx.hir.local_def_id(id);
-        reachable_non_generics.insert(def_id, SymbolExportLevel::C);
-    }
-
-    Lrc::new(reachable_non_generics)
-}
-
-fn is_reachable_non_generic_provider_local<'a, 'tcx>(tcx: TyCtxt<'a, 'tcx, 'tcx>,
-                                                     def_id: DefId)
-                                                     -> bool {
-    let export_threshold = threshold(tcx);
-
-    if let Some(&level) = tcx.reachable_non_generics(def_id.krate).get(&def_id) {
-        level.is_below_threshold(export_threshold)
-    } else {
-        false
-    }
-}
-
-fn is_reachable_non_generic_provider_extern<'a, 'tcx>(tcx: TyCtxt<'a, 'tcx, 'tcx>,
-                                                      def_id: DefId)
-                                                      -> bool {
-    tcx.reachable_non_generics(def_id.krate).contains_key(&def_id)
-}
-
-fn exported_symbols_provider_local<'a, 'tcx>(tcx: TyCtxt<'a, 'tcx, 'tcx>,
-                                             cnum: CrateNum)
-                                             -> Arc<Vec<(ExportedSymbol<'tcx>,
-                                                         SymbolExportLevel)>>
-{
-    assert_eq!(cnum, LOCAL_CRATE);
-
-    if !tcx.sess.opts.output_types.should_codegen() {
-        return Arc::new(vec![])
-    }
-
-    let mut symbols: Vec<_> = tcx.reachable_non_generics(LOCAL_CRATE)
-                                 .iter()
-                                 .map(|(&def_id, &level)| {
-                                    (ExportedSymbol::NonGeneric(def_id), level)
-                                 })
-                                 .collect();
-
-    if tcx.sess.entry_fn.borrow().is_some() {
-        let exported_symbol = ExportedSymbol::NoDefId(SymbolName::new("main"));
-
-        symbols.push((exported_symbol, SymbolExportLevel::C));
-    }
-
-    if tcx.sess.allocator_kind.get().is_some() {
-        for method in ALLOCATOR_METHODS {
-            let symbol_name = format!("__rust_{}", method.name);
-            let exported_symbol = ExportedSymbol::NoDefId(SymbolName::new(&symbol_name));
-
-            symbols.push((exported_symbol, SymbolExportLevel::Rust));
-        }
-    }
-
-    if tcx.sess.opts.debugging_opts.pgo_gen.is_some() {
-        // These are weak symbols that point to the profile version and the
-        // profile name, which need to be treated as exported so LTO doesn't nix
-        // them.
-        const PROFILER_WEAK_SYMBOLS: [&'static str; 2] = [
-            "__llvm_profile_raw_version",
-            "__llvm_profile_filename",
-        ];
-        for sym in &PROFILER_WEAK_SYMBOLS {
-            let exported_symbol = ExportedSymbol::NoDefId(SymbolName::new(sym));
-            symbols.push((exported_symbol, SymbolExportLevel::C));
-        }
-    }
-
-    if tcx.sess.crate_types.borrow().contains(&config::CrateType::Dylib) {
-        let symbol_name = metadata_symbol_name(tcx);
-        let exported_symbol = ExportedSymbol::NoDefId(SymbolName::new(&symbol_name));
-
-        symbols.push((exported_symbol, SymbolExportLevel::Rust));
-    }
-
-    if tcx.sess.opts.share_generics() && tcx.local_crate_exports_generics() {
-        use rustc::mir::mono::{Linkage, Visibility, MonoItem};
-        use rustc::ty::InstanceDef;
-
-        // Normally, we require that shared monomorphizations are not hidden,
-        // because if we want to re-use a monomorphization from a Rust dylib, it
-        // needs to be exported.
-        // However, on platforms that don't allow for Rust dylibs, having
-        // external linkage is enough for monomorphization to be linked to.
-        let need_visibility = tcx.sess.target.target.options.dynamic_linking &&
-                              !tcx.sess.target.target.options.only_cdylib;
-
-        let (_, cgus) = tcx.collect_and_partition_mono_items(LOCAL_CRATE);
-
-        for (mono_item, &(linkage, visibility)) in cgus.iter()
-                                                       .flat_map(|cgu| cgu.items().iter()) {
-            if linkage != Linkage::External {
-                // We can only re-use things with external linkage, otherwise
-                // we'll get a linker error
-                continue
-            }
-
-            if need_visibility && visibility == Visibility::Hidden {
-                // If we potentially share things from Rust dylibs, they must
-                // not be hidden
-                continue
-            }
-
-            if let &MonoItem::Fn(Instance {
-                def: InstanceDef::Item(def_id),
-                substs,
-            }) = mono_item {
-                if substs.types().next().is_some() {
-                    symbols.push((ExportedSymbol::Generic(def_id, substs),
-                                  SymbolExportLevel::Rust));
-                }
-            }
-        }
-    }
-
-    // Sort so we get a stable incr. comp. hash.
-    symbols.sort_unstable_by(|&(ref symbol1, ..), &(ref symbol2, ..)| {
-        symbol1.compare_stable(tcx, symbol2)
-    });
-
-    Arc::new(symbols)
-}
-
-fn upstream_monomorphizations_provider<'a, 'tcx>(
-    tcx: TyCtxt<'a, 'tcx, 'tcx>,
-    cnum: CrateNum)
-    -> Lrc<DefIdMap<Lrc<FxHashMap<&'tcx Substs<'tcx>, CrateNum>>>>
-{
-    debug_assert!(cnum == LOCAL_CRATE);
-
-    let cnums = tcx.all_crate_nums(LOCAL_CRATE);
-
-    let mut instances: DefIdMap<FxHashMap<_, _>> = DefIdMap();
-
-    let cnum_stable_ids: IndexVec<CrateNum, Fingerprint> = {
-        let mut cnum_stable_ids = IndexVec::from_elem_n(Fingerprint::ZERO,
-                                                        cnums.len() + 1);
-
-        for &cnum in cnums.iter() {
-            cnum_stable_ids[cnum] = tcx.def_path_hash(DefId {
-                krate: cnum,
-                index: CRATE_DEF_INDEX,
-            }).0;
-        }
-
-        cnum_stable_ids
-    };
-
-    for &cnum in cnums.iter() {
-        for &(ref exported_symbol, _) in tcx.exported_symbols(cnum).iter() {
-            if let &ExportedSymbol::Generic(def_id, substs) = exported_symbol {
-                let substs_map = instances.entry(def_id).or_default();
-
-                match substs_map.entry(substs) {
-                    Occupied(mut e) => {
-                        // If there are multiple monomorphizations available,
-                        // we select one deterministically.
-                        let other_cnum = *e.get();
-                        if cnum_stable_ids[other_cnum] > cnum_stable_ids[cnum] {
-                            e.insert(cnum);
-                        }
-                    }
-                    Vacant(e) => {
-                        e.insert(cnum);
-                    }
-                }
-            }
-        }
-    }
-
-    Lrc::new(instances.into_iter()
-                      .map(|(key, value)| (key, Lrc::new(value)))
-                      .collect())
-}
-
-fn upstream_monomorphizations_for_provider<'a, 'tcx>(
-    tcx: TyCtxt<'a, 'tcx, 'tcx>,
-    def_id: DefId)
-    -> Option<Lrc<FxHashMap<&'tcx Substs<'tcx>, CrateNum>>>
-{
-    debug_assert!(!def_id.is_local());
-    tcx.upstream_monomorphizations(LOCAL_CRATE)
-       .get(&def_id)
-       .cloned()
-}
-
-fn is_unreachable_local_definition_provider(tcx: TyCtxt, def_id: DefId) -> bool {
-    if let Some(node_id) = tcx.hir.as_local_node_id(def_id) {
-        !tcx.reachable_set(LOCAL_CRATE).0.contains(&node_id)
-    } else {
-        bug!("is_unreachable_local_definition called with non-local DefId: {:?}",
-             def_id)
-    }
-}
-
-pub fn provide(providers: &mut Providers) {
-    providers.reachable_non_generics = reachable_non_generics_provider;
-    providers.is_reachable_non_generic = is_reachable_non_generic_provider_local;
-    providers.exported_symbols = exported_symbols_provider_local;
-    providers.upstream_monomorphizations = upstream_monomorphizations_provider;
-    providers.is_unreachable_local_definition = is_unreachable_local_definition_provider;
-}
-
-pub fn provide_extern(providers: &mut Providers) {
-    providers.is_reachable_non_generic = is_reachable_non_generic_provider_extern;
-    providers.upstream_monomorphizations_for = upstream_monomorphizations_for_provider;
-}
-
-fn symbol_export_level(tcx: TyCtxt, sym_def_id: DefId) -> SymbolExportLevel {
-    // We export anything that's not mangled at the "C" layer as it probably has
-    // to do with ABI concerns. We do not, however, apply such treatment to
-    // special symbols in the standard library for various plumbing between
-    // core/std/allocators/etc. For example symbols used to hook up allocation
-    // are not considered for export
-    let codegen_fn_attrs = tcx.codegen_fn_attrs(sym_def_id);
-    let is_extern = codegen_fn_attrs.contains_extern_indicator();
-    let std_internal =
-        codegen_fn_attrs.flags.contains(CodegenFnAttrFlags::RUSTC_STD_INTERNAL_SYMBOL);
-
-    if is_extern && !std_internal {
-        // Emscripten cannot export statics, so reduce their export level here
-        if tcx.sess.target.target.options.is_like_emscripten {
-            if let Some(Node::Item(&hir::Item {
-                node: hir::ItemKind::Static(..),
-                ..
-            })) = tcx.hir.get_if_local(sym_def_id) {
-                return SymbolExportLevel::Rust;
-            }
-        }
-
-        SymbolExportLevel::C
-    } else {
-        SymbolExportLevel::Rust
-    }
-}