Replace deprecated compare_and_swap with compare_exchange

Author: taiki-e

src/lib.rs

@@ -392,7 +392,10 @@ impl Event {
             let new = Arc::into_raw(new) as *mut Inner;
 
             // Attempt to replace the null-pointer with the new state pointer.
-            inner = self.inner.compare_and_swap(inner, new, Ordering::AcqRel);
+            inner = self
+                .inner
+                .compare_exchange(inner, new, Ordering::AcqRel, Ordering::Acquire)
+                .unwrap_or_else(|x| x);
 
             // Check if the old pointer value was indeed null.
             if inner.is_null() {
@@ -970,7 +973,7 @@ fn full_fence() {
         // a `SeqCst` fence.
         //
         // 1. `atomic::fence(SeqCst)`, which compiles into a `mfence` instruction.
-        // 2. `_.compare_and_swap(_, _, SeqCst)`, which compiles into a `lock cmpxchg` instruction.
+        // 2. `_.compare_exchange(_, _, SeqCst, SeqCst)`, which compiles into a `lock cmpxchg` instruction.
         //
         // Both instructions have the effect of a full barrier, but empirical benchmarks have shown
         // that the second one is sometimes a bit faster.
@@ -979,7 +982,7 @@ fn full_fence() {
         // temporary atomic variable and compare-and-exchanging its value. No sane compiler to
         // x86 platforms is going to optimize this away.
         let a = AtomicUsize::new(0);
-        a.compare_and_swap(0, 1, Ordering::SeqCst);
+        let _ = a.compare_exchange(0, 1, Ordering::SeqCst, Ordering::SeqCst);
     } else {
         atomic::fence(Ordering::SeqCst);
     }