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Move spin_loop_hint to core::hint module

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This commit is contained in:
Clar Fon 2018-12-19 16:43:29 -05:00
parent e2f221c759
commit 24ca530526
3 changed files with 27 additions and 9 deletions
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23
src/libcore/hint.rs
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@ -49,3 +49,26 @@ use intrinsics;
pub unsafe fn unreachable_unchecked() -> ! {
intrinsics::unreachable()
}
/// Save power or switch hyperthreads in a busy-wait spin-loop.
///
/// This function is deliberately more primitive than
/// [`std::thread::yield_now`](../../std/thread/fn.yield_now.html) and
/// does not directly yield to the system's scheduler.
/// In some cases it might be useful to use a combination of both functions.
/// Careful benchmarking is advised.
///
/// On some platforms this function may not do anything at all.
#[inline]
#[unstable(feature = "renamed_spin_loop", issue = "55002")]
pub fn spin_loop() {
#[cfg(any(target_arch = "x86", target_arch = "x86_64"))]
unsafe {
asm!("pause" ::: "memory" : "volatile");
}
#[cfg(target_arch = "aarch64")]
unsafe {
asm!("yield" ::: "memory" : "volatile");
}
}