Auto merge of rust-lang#77611 - oli-obk:atomic_miri_leakage, r=nagisa

Directly use raw pointers in `AtomicPtr` store/load

I was unable to find any reason for this limitation in the latest source of LLVM or in the documentation [here](http://llvm.org/docs/Atomics.html#libcalls-atomic).

fixes rust-lang/miri#1574

Author: bors

core/src/sync/atomic.rs

@@ -966,8 +966,16 @@ impl<T> AtomicPtr<T> {
     #[inline]
     #[stable(feature = "rust1", since = "1.0.0")]
     pub fn load(&self, order: Ordering) -> *mut T {
+        #[cfg(not(bootstrap))]
         // SAFETY: data races are prevented by atomic intrinsics.
-        unsafe { atomic_load(self.p.get() as *mut usize, order) as *mut T }
+        unsafe {
+            atomic_load(self.p.get(), order)
+        }
+        #[cfg(bootstrap)]
+        // SAFETY: data races are prevented by atomic intrinsics.
+        unsafe {
+            atomic_load(self.p.get() as *mut usize, order) as *mut T
+        }
     }
 
     /// Stores a value into the pointer.
@@ -994,6 +1002,12 @@ impl<T> AtomicPtr<T> {
     #[inline]
     #[stable(feature = "rust1", since = "1.0.0")]
     pub fn store(&self, ptr: *mut T, order: Ordering) {
+        #[cfg(not(bootstrap))]
+        // SAFETY: data races are prevented by atomic intrinsics.
+        unsafe {
+            atomic_store(self.p.get(), ptr, order);
+        }
+        #[cfg(bootstrap)]
         // SAFETY: data races are prevented by atomic intrinsics.
         unsafe {
             atomic_store(self.p.get() as *mut usize, ptr as usize, order);
@@ -1105,6 +1119,7 @@ impl<T> AtomicPtr<T> {
         success: Ordering,
         failure: Ordering,
     ) -> Result<*mut T, *mut T> {
+        #[cfg(bootstrap)]
         // SAFETY: data races are prevented by atomic intrinsics.
         unsafe {
             let res = atomic_compare_exchange(
@@ -1119,6 +1134,11 @@ impl<T> AtomicPtr<T> {
                 Err(x) => Err(x as *mut T),
             }
         }
+        #[cfg(not(bootstrap))]
+        // SAFETY: data races are prevented by atomic intrinsics.
+        unsafe {
+            atomic_compare_exchange(self.p.get(), current, new, success, failure)
+        }
     }
 
     /// Stores a value into the pointer if the current value is the same as the `current` value.
@@ -1165,6 +1185,7 @@ impl<T> AtomicPtr<T> {
         success: Ordering,
         failure: Ordering,
     ) -> Result<*mut T, *mut T> {
+        #[cfg(bootstrap)]
         // SAFETY: data races are prevented by atomic intrinsics.
         unsafe {
             let res = atomic_compare_exchange_weak(
@@ -1179,6 +1200,14 @@ impl<T> AtomicPtr<T> {
                 Err(x) => Err(x as *mut T),
             }
         }
+        #[cfg(not(bootstrap))]
+        // SAFETY: This intrinsic is unsafe because it operates on a raw pointer
+        // but we know for sure that the pointer is valid (we just got it from
+        // an `UnsafeCell` that we have by reference) and the atomic operation
+        // itself allows us to safely mutate the `UnsafeCell` contents.
+        unsafe {
+            atomic_compare_exchange_weak(self.p.get(), current, new, success, failure)
+        }
     }
 
     /// Fetches the value, and applies a function to it that returns an optional

std/src/sys/windows/thread_local_key.rs

@@ -110,16 +110,6 @@ struct Node {
     next: *mut Node,
 }
 
-#[cfg(miri)]
-extern "Rust" {
-    /// Miri-provided extern function to mark the block `ptr` points to as a "root"
-    /// for some static memory. This memory and everything reachable by it is not
-    /// considered leaking even if it still exists when the program terminates.
-    ///
-    /// `ptr` has to point to the beginning of an allocated block.
-    fn miri_static_root(ptr: *const u8);
-}
-
 unsafe fn register_dtor(key: Key, dtor: Dtor) {
     let mut node = Box::new(Node { key, dtor, next: ptr::null_mut() });
 
@@ -128,9 +118,6 @@ unsafe fn register_dtor(key: Key, dtor: Dtor) {
         node.next = head;
         match DTORS.compare_exchange(head, &mut *node, SeqCst, SeqCst) {
             Ok(_) => {
-                #[cfg(miri)]
-                miri_static_root(&*node as *const _ as *const u8);
-
                 mem::forget(node);
                 return;
             }