rustc: Enable #[thread_local] for Windows

src/librustc_back/target/x86_64_pc_windows_msvc.rs

@@ -15,6 +15,7 @@ pub fn target() -> TargetResult {
     let mut base = super::windows_msvc_base::opts();
     base.cpu = "x86-64".to_string();
     base.max_atomic_width = Some(64);
+    base.has_elf_tls = true;
 
     Ok(Target {
         llvm_target: "x86_64-pc-windows-msvc".to_string(),

src/libstd/sys/unix/fast_thread_local.rs

@@ -11,92 +11,6 @@
 #![cfg(target_thread_local)]
 #![unstable(feature = "thread_local_internals", issue = "0")]
 
-use cell::{Cell, UnsafeCell};
-use fmt;
-use mem;
-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>,
-}
-
-impl<T> fmt::Debug for Key<T> {
-    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
-        f.pad("Key { .. }")
-    }
-}
-
-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 mem::needs_drop::<T>() && self.dtor_running.get() {
-                return None
-            }
-            self.register_dtor();
-        }
-        Some(&self.inner)
-    }
-
-    unsafe fn register_dtor(&self) {
-        if !mem::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!
@@ -107,9 +21,10 @@ unsafe fn register_dtor_fallback(t: *mut u8, dtor: unsafe extern fn(*mut u8)) {
 //
 // 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;
+pub unsafe fn register_dtor(t: *mut u8, dtor: unsafe extern fn(*mut u8)) {
     use libc;
+    use mem;
+    use sys_common::thread_local::register_dtor_fallback;
 
     extern {
         #[linkage = "extern_weak"]
@@ -132,7 +47,7 @@ unsafe fn register_dtor(t: *mut u8, dtor: unsafe extern fn(*mut u8)) {
 // 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)) {
+pub 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);
@@ -143,17 +58,9 @@ unsafe fn register_dtor(t: *mut u8, dtor: unsafe extern fn(*mut u8)) {
 // 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);
+pub use sys_common::thread_local::register_dtor_fallback as register_dtor;
 
+pub fn requires_move_before_drop() -> bool {
     // The macOS 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
@@ -166,9 +73,5 @@ pub unsafe extern fn destroy_value<T>(ptr: *mut u8) {
     //
     // Hence, we use `ptr::read` on macOS (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());
-    }
+    cfg!(target_os = "macos")
 }

src/libstd/sys/windows/fast_thread_local.rs

@@ -0,0 +1,18 @@
+// Copyright 2014-2015 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.
+
+#![unstable(feature = "thread_local_internals", issue = "0")]
+#![cfg(target_thread_local)]
+
+pub use sys_common::thread_local::register_dtor_fallback as register_dtor;
+
+pub fn requires_move_before_drop() -> bool {
+    false
+}

src/libstd/sys/windows/mod.rs

@@ -26,6 +26,7 @@ pub mod condvar;
 pub mod dynamic_lib;
 pub mod env;
 pub mod ext;
+pub mod fast_thread_local;
 pub mod fs;
 pub mod handle;
 pub mod memchr;

src/libstd/sys_common/thread_local.rs

@@ -58,8 +58,8 @@
 #![unstable(feature = "thread_local_internals", issue = "0")]
 #![allow(dead_code)] // sys isn't exported yet
 
+use ptr;
 use sync::atomic::{self, AtomicUsize, Ordering};
-
 use sys::thread_local as imp;
 use sys_common::mutex::Mutex;
 
@@ -238,6 +238,39 @@ impl Drop for Key {
     }
 }
 
+pub 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.
+
+    static DTORS: StaticKey = 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());
+        }
+    }
+}
+
 #[cfg(test)]
 mod tests {
     use super::{Key, StaticKey};

src/libstd/thread/local.rs

@@ -333,6 +333,82 @@ impl<T: 'static> LocalKey<T> {
     }
 }
 
+#[doc(hidden)]
+#[cfg(target_thread_local)]
+pub mod fast {
+    use cell::{Cell, UnsafeCell};
+    use fmt;
+    use mem;
+    use ptr;
+    use sys::fast_thread_local::{register_dtor, requires_move_before_drop};
+
+    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>,
+    }
+
+    impl<T> fmt::Debug for Key<T> {
+        fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+            f.pad("Key { .. }")
+        }
+    }
+
+    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 mem::needs_drop::<T>() && self.dtor_running.get() {
+                    return None
+                }
+                self.register_dtor();
+            }
+            Some(&self.inner)
+        }
+
+        unsafe fn register_dtor(&self) {
+            if !mem::needs_drop::<T>() || self.dtor_registered.get() {
+                return
+            }
+
+            register_dtor(self as *const _ as *mut u8,
+                          destroy_value::<T>);
+            self.dtor_registered.set(true);
+        }
+    }
+
+    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);
+
+        // Some implementations may require us to move the value before we drop
+        // it as it could get re-initialized in-place during destruction.
+        //
+        // Hence, we use `ptr::read` on those platforms (to move to a "safe"
+        // location) instead of drop_in_place.
+        if requires_move_before_drop() {
+            ptr::read((*ptr).inner.get());
+        } else {
+            ptr::drop_in_place((*ptr).inner.get());
+        }
+    }
+}
+
 #[doc(hidden)]
 pub mod os {
     use cell::{Cell, UnsafeCell};
@@ -378,8 +454,8 @@ pub mod os {
                     return Some(&(*ptr).value);
                 }
 
-                // If the lookup returned null, we haven't initialized our own local
-                // copy, so do that now.
+                // If the lookup returned null, we haven't initialized our own
+                // local copy, so do that now.
                 let ptr: Box<Value<T>> = box Value {
                     key: self,
                     value: UnsafeCell::new(None),
@@ -391,7 +467,7 @@ pub mod os {
         }
     }
 
-    pub unsafe extern fn destroy_value<T: 'static>(ptr: *mut u8) {
+    unsafe extern fn destroy_value<T: 'static>(ptr: *mut u8) {
         // The OS TLS ensures that this key contains a NULL value when this
         // destructor starts to run. We set it back to a sentinel value of 1 to
         // ensure that any future calls to `get` for this thread will return

src/libstd/thread/mod.rs

@@ -172,7 +172,7 @@ pub use self::local::{LocalKey, LocalKeyState};
 
 #[unstable(feature = "libstd_thread_internals", issue = "0")]
 #[cfg(target_thread_local)]
-#[doc(hidden)] pub use sys::fast_thread_local::Key as __FastLocalKeyInner;
+#[doc(hidden)] pub use self::local::fast::Key as __FastLocalKeyInner;
 #[unstable(feature = "libstd_thread_internals", issue = "0")]
 #[doc(hidden)] pub use self::local::os::Key as __OsLocalKeyInner;