Stabilize spin_loop_hint

Author: Stjepan Glavina

src/doc/unstable-book/src/library-features/hint-core-should-pause.md renamed to src/doc/unstable-book/src/library-features/spin-loop-hint.md

@@ -1,4 +1,4 @@
-# `hint_core_should_pause`
+# `spin_loop_hint`
 
 The tracking issue for this feature is: [#41196]
 
@@ -23,7 +23,7 @@ fn spin_loop(value: &AtomicBool) {
 These programs can be improved in performance like so:
 
 ```rust,no_run
-#![feature(hint_core_should_pause)]
+#![feature(spin_loop_hint)]
 use std::sync::atomic;
 use std::sync::atomic::{AtomicBool,Ordering};
 
@@ -32,10 +32,10 @@ fn spin_loop(value: &AtomicBool) {
         if value.load(Ordering::Acquire) {
              break;
         }
-        atomic::hint_core_should_pause();
+        atomic::spin_loop_hint();
     }
 }
 ```
 
-Further improvements could combine `hint_core_should_pause` with
+Further improvements could combine `spin_loop_hint` with
 exponential backoff or `std::thread::yield_now`.

src/libcore/sync/atomic.rs

@@ -103,9 +103,8 @@ use fmt;
 ///
 /// On some platforms this function may not do anything at all.
 #[inline]
-#[unstable(feature = "hint_core_should_pause", issue = "41196")]
-pub fn hint_core_should_pause()
-{
+#[stable(feature = "spin_loop_hint", since = "1.23.0")]
+pub fn spin_loop_hint() {
     #[cfg(any(target_arch = "x86", target_arch = "x86_64"))]
     unsafe {
         asm!("pause" ::: "memory" : "volatile");