std: Move elf TLS to sys::fast_thread_local

2 files changed, 3 insertions, 162 deletions

diff --git a/src/libstd/thread/local.rs b/src/libstd/thread/local.rs
index 54d3f793045..f74dd592495 100644
--- a/src/libstd/thread/local.rs
+++ b/src/libstd/thread/local.rs
@@ -166,8 +166,8 @@ macro_rules! __thread_local_inner {
         {
             #[thread_local]
             #[cfg(target_thread_local)]
-            static __KEY: $crate::thread::__ElfLocalKeyInner<$t> =
-                $crate::thread::__ElfLocalKeyInner::new();
+            static __KEY: $crate::thread::__FastLocalKeyInner<$t> =
+                $crate::thread::__FastLocalKeyInner::new();
 
             #[cfg(not(target_thread_local))]
             static __KEY: $crate::thread::__OsLocalKeyInner<$t> =
@@ -310,165 +310,6 @@ impl<T: 'static> LocalKey<T> {
     }
 }
 
-#[cfg(target_thread_local)]
-#[doc(hidden)]
-pub mod elf {
-    use cell::{Cell, UnsafeCell};
-    use intrinsics;
-    use ptr;
-
-    pub struct Key<T> {
-        inner: UnsafeCell<Option<T>>,
-
-        // Metadata to keep track of the state of the destructor. Remember that
-        // these variables are thread-local, not global.
-        dtor_registered: Cell<bool>,
-        dtor_running: Cell<bool>,
-    }
-
-    unsafe impl<T> ::marker::Sync for Key<T> { }
-
-    impl<T> Key<T> {
-        pub const fn new() -> Key<T> {
-            Key {
-                inner: UnsafeCell::new(None),
-                dtor_registered: Cell::new(false),
-                dtor_running: Cell::new(false)
-            }
-        }
-
-        pub fn get(&'static self) -> Option<&'static UnsafeCell<Option<T>>> {
-            unsafe {
-                if intrinsics::needs_drop::<T>() && self.dtor_running.get() {
-                    return None
-                }
-                self.register_dtor();
-            }
-            Some(&self.inner)
-        }
-
-        unsafe fn register_dtor(&self) {
-            if !intrinsics::needs_drop::<T>() || self.dtor_registered.get() {
-                return
-            }
-
-            register_dtor(self as *const _ as *mut u8,
-                          destroy_value::<T>);
-            self.dtor_registered.set(true);
-        }
-    }
-
-    #[cfg(any(target_os = "linux", target_os = "fuchsia"))]
-    unsafe fn register_dtor_fallback(t: *mut u8, dtor: unsafe extern fn(*mut u8)) {
-        // The fallback implementation uses a vanilla OS-based TLS key to track
-        // the list of destructors that need to be run for this thread. The key
-        // then has its own destructor which runs all the other destructors.
-        //
-        // The destructor for DTORS is a little special in that it has a `while`
-        // loop to continuously drain the list of registered destructors. It
-        // *should* be the case that this loop always terminates because we
-        // provide the guarantee that a TLS key cannot be set after it is
-        // flagged for destruction.
-        use sys_common::thread_local as os;
-
-        static DTORS: os::StaticKey = os::StaticKey::new(Some(run_dtors));
-        type List = Vec<(*mut u8, unsafe extern fn(*mut u8))>;
-        if DTORS.get().is_null() {
-            let v: Box<List> = box Vec::new();
-            DTORS.set(Box::into_raw(v) as *mut u8);
-        }
-        let list: &mut List = &mut *(DTORS.get() as *mut List);
-        list.push((t, dtor));
-
-        unsafe extern fn run_dtors(mut ptr: *mut u8) {
-            while !ptr.is_null() {
-                let list: Box<List> = Box::from_raw(ptr as *mut List);
-                for &(ptr, dtor) in list.iter() {
-                    dtor(ptr);
-                }
-                ptr = DTORS.get();
-                DTORS.set(ptr::null_mut());
-            }
-        }
-    }
-
-    // Since what appears to be glibc 2.18 this symbol has been shipped which
-    // GCC and clang both use to invoke destructors in thread_local globals, so
-    // let's do the same!
-    //
-    // Note, however, that we run on lots older linuxes, as well as cross
-    // compiling from a newer linux to an older linux, so we also have a
-    // fallback implementation to use as well.
-    //
-    // Due to rust-lang/rust#18804, make sure this is not generic!
-    #[cfg(target_os = "linux")]
-    unsafe fn register_dtor(t: *mut u8, dtor: unsafe extern fn(*mut u8)) {
-        use mem;
-        use libc;
-
-        extern {
-            #[linkage = "extern_weak"]
-            static __dso_handle: *mut u8;
-            #[linkage = "extern_weak"]
-            static __cxa_thread_atexit_impl: *const libc::c_void;
-        }
-        if !__cxa_thread_atexit_impl.is_null() {
-            type F = unsafe extern fn(dtor: unsafe extern fn(*mut u8),
-                                      arg: *mut u8,
-                                      dso_handle: *mut u8) -> libc::c_int;
-            mem::transmute::<*const libc::c_void, F>(__cxa_thread_atexit_impl)
-            (dtor, t, &__dso_handle as *const _ as *mut _);
-            return
-        }
-        register_dtor_fallback(t, dtor);
-    }
-
-    // OSX's analog of the above linux function is this _tlv_atexit function.
-    // The disassembly of thread_local globals in C++ (at least produced by
-    // clang) will have this show up in the output.
-    #[cfg(target_os = "macos")]
-    unsafe fn register_dtor(t: *mut u8, dtor: unsafe extern fn(*mut u8)) {
-        extern {
-            fn _tlv_atexit(dtor: unsafe extern fn(*mut u8),
-                           arg: *mut u8);
-        }
-        _tlv_atexit(dtor, t);
-    }
-
-    // Just use the thread_local fallback implementation, at least until there's
-    // a more direct implementation.
-    #[cfg(target_os = "fuchsia")]
-    unsafe fn register_dtor(t: *mut u8, dtor: unsafe extern fn(*mut u8)) {
-        register_dtor_fallback(t, dtor);
-    }
-
-    pub unsafe extern fn destroy_value<T>(ptr: *mut u8) {
-        let ptr = ptr as *mut Key<T>;
-        // Right before we run the user destructor be sure to flag the
-        // destructor as running for this thread so calls to `get` will return
-        // `None`.
-        (*ptr).dtor_running.set(true);
-
-        // The OSX implementation of TLS apparently had an odd aspect to it
-        // where the pointer we have may be overwritten while this destructor
-        // is running. Specifically if a TLS destructor re-accesses TLS it may
-        // trigger a re-initialization of all TLS variables, paving over at
-        // least some destroyed ones with initial values.
-        //
-        // This means that if we drop a TLS value in place on OSX that we could
-        // revert the value to its original state halfway through the
-        // destructor, which would be bad!
-        //
-        // Hence, we use `ptr::read` on OSX (to move to a "safe" location)
-        // instead of drop_in_place.
-        if cfg!(target_os = "macos") {
-            ptr::read((*ptr).inner.get());
-        } else {
-            ptr::drop_in_place((*ptr).inner.get());
-        }
-    }
-}
-
 #[doc(hidden)]
 pub mod os {
     use cell::{Cell, UnsafeCell};
diff --git a/src/libstd/thread/mod.rs b/src/libstd/thread/mod.rs
index 150482e4af4..4c3980b3c7b 100644
--- a/src/libstd/thread/mod.rs
+++ b/src/libstd/thread/mod.rs
@@ -183,7 +183,7 @@ pub use self::local::{LocalKey, LocalKeyState};
 
 #[unstable(feature = "libstd_thread_internals", issue = "0")]
 #[cfg(target_thread_local)]
-#[doc(hidden)] pub use self::local::elf::Key as __ElfLocalKeyInner;
+#[doc(hidden)] pub use sys::fast_thread_local::Key as __FastLocalKeyInner;
 #[unstable(feature = "libstd_thread_internals", issue = "0")]
 #[doc(hidden)] pub use self::local::os::Key as __OsLocalKeyInner;