diff options
Diffstat (limited to 'src/libcore/hint.rs')
| -rw-r--r-- | src/libcore/hint.rs | 15 |
1 files changed, 10 insertions, 5 deletions
diff --git a/src/libcore/hint.rs b/src/libcore/hint.rs index f4fb9ab1757..0d794de5fe8 100644 --- a/src/libcore/hint.rs +++ b/src/libcore/hint.rs @@ -2,8 +2,6 @@ //! Hints to compiler that affects how code should be emitted or optimized. -// ignore-tidy-undocumented-unsafe - use crate::intrinsics; /// Informs the compiler that this point in the code is not reachable, enabling @@ -43,7 +41,7 @@ use crate::intrinsics; /// /// assert_eq!(div_1(7, 0), 7); /// assert_eq!(div_1(9, 1), 4); -/// assert_eq!(div_1(11, std::u32::MAX), 0); +/// assert_eq!(div_1(11, u32::MAX), 0); /// ``` #[inline] #[stable(feature = "unreachable", since = "1.27.0")] @@ -68,11 +66,13 @@ pub fn spin_loop() { { #[cfg(target_arch = "x86")] { + // SAFETY: the `cfg` attr ensures that we only execute this on x86 targets. unsafe { crate::arch::x86::_mm_pause() }; } #[cfg(target_arch = "x86_64")] { + // SAFETY: the `cfg` attr ensures that we only execute this on x86_64 targets. unsafe { crate::arch::x86_64::_mm_pause() }; } } @@ -81,10 +81,13 @@ pub fn spin_loop() { { #[cfg(target_arch = "aarch64")] { + // SAFETY: the `cfg` attr ensures that we only execute this on aarch64 targets. unsafe { crate::arch::aarch64::__yield() }; } #[cfg(target_arch = "arm")] { + // SAFETY: the `cfg` attr ensures that we only execute this on arm targets + // with support for the v6 feature. unsafe { crate::arch::arm::__yield() }; } } @@ -112,8 +115,10 @@ pub fn black_box<T>(dummy: T) -> T { // this. LLVM's interpretation of inline assembly is that it's, well, a black // box. This isn't the greatest implementation since it probably deoptimizes // more than we want, but it's so far good enough. + + // SAFETY: the inline assembly is a no-op. unsafe { - asm!("" : : "r"(&dummy)); - return dummy; + llvm_asm!("" : : "r"(&dummy)); + dummy } } |