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Rollup merge of #72324 - Amanieu:atomic_minmax, r=dtolnay

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Stabilize AtomicN::fetch_min and AtomicN::fetch_max

Some architectures (ARMv8.1 LSE and RISC-V) have specific instructions for atomic min/max which the compiler can only generate through explicit instrinsics.
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Yuki Okushi 2020-05-29 15:06:57 +09:00 • committed by GitHub
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1 changed files with 2 additions and 10 deletions
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12
src/libcore/sync/atomic.rs
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@ -1878,7 +1878,6 @@ using [`Release`] makes the load part [`Relaxed`].
# Examples
```
#![feature(atomic_min_max)]
", $extra_feature, "use std::sync::atomic::{", stringify!($atomic_type), ", Ordering};
let foo = ", stringify!($atomic_type), "::new(23);
@ -1889,7 +1888,6 @@ assert_eq!(foo.load(Ordering::SeqCst), 42);
If you want to obtain the maximum value in one step, you can use the following:
```
#![feature(atomic_min_max)]
", $extra_feature, "use std::sync::atomic::{", stringify!($atomic_type), ", Ordering};
let foo = ", stringify!($atomic_type), "::new(23);
@ -1898,9 +1896,7 @@ let max_foo = foo.fetch_max(bar, Ordering::SeqCst).max(bar);
assert!(max_foo == 42);
```"),
#[inline]
#[unstable(feature = "atomic_min_max",
reason = "easier and faster min/max than writing manual CAS loop",
issue = "48655")]
#[stable(feature = "atomic_min_max", since = "1.45.0")]
#[$cfg_cas]
pub fn fetch_max(&self, val: $int_type, order: Ordering) -> $int_type {
// SAFETY: data races are prevented by atomic intrinsics.
@ -1929,7 +1925,6 @@ using [`Release`] makes the load part [`Relaxed`].
# Examples
```
#![feature(atomic_min_max)]
", $extra_feature, "use std::sync::atomic::{", stringify!($atomic_type), ", Ordering};
let foo = ", stringify!($atomic_type), "::new(23);
@ -1942,7 +1937,6 @@ assert_eq!(foo.load(Ordering::Relaxed), 22);
If you want to obtain the minimum value in one step, you can use the following:
```
#![feature(atomic_min_max)]
", $extra_feature, "use std::sync::atomic::{", stringify!($atomic_type), ", Ordering};
let foo = ", stringify!($atomic_type), "::new(23);
@ -1951,9 +1945,7 @@ let min_foo = foo.fetch_min(bar, Ordering::SeqCst).min(bar);
assert_eq!(min_foo, 12);
```"),
#[inline]
#[unstable(feature = "atomic_min_max",
reason = "easier and faster min/max than writing manual CAS loop",
issue = "48655")]
#[stable(feature = "atomic_min_max", since = "1.45.0")]
#[$cfg_cas]
pub fn fetch_min(&self, val: $int_type, order: Ordering) -> $int_type {
// SAFETY: data races are prevented by atomic intrinsics.