diff options
| -rw-r--r-- | library/core/src/mem/mod.rs | 5 | ||||
| -rw-r--r-- | library/core/src/ptr/mod.rs | 22 |
2 files changed, 9 insertions, 18 deletions
diff --git a/library/core/src/mem/mod.rs b/library/core/src/mem/mod.rs index 2e1a667097c..b5eea08092e 100644 --- a/library/core/src/mem/mod.rs +++ b/library/core/src/mem/mod.rs @@ -730,10 +730,7 @@ pub const fn swap<T>(x: &mut T, y: &mut T) { // understanding `mem::replace`, `Option::take`, etc. - a better overall // solution might be to make `ptr::swap_nonoverlapping` into an intrinsic, which // a backend can choose to implement using the block optimization, or not. - // NOTE(scottmcm) MIRI is disabled here as reading in smaller units is a - // pessimization for it. Also, if the type contains any unaligned pointers, - // copying those over multiple reads is difficult to support. - #[cfg(not(any(target_arch = "spirv", miri)))] + #[cfg(not(any(target_arch = "spirv")))] { // For types that are larger multiples of their alignment, the simple way // tends to copy the whole thing to stack rather than doing it one part diff --git a/library/core/src/ptr/mod.rs b/library/core/src/ptr/mod.rs index 565c38d222a..5c4610472af 100644 --- a/library/core/src/ptr/mod.rs +++ b/library/core/src/ptr/mod.rs @@ -908,21 +908,15 @@ pub const unsafe fn swap_nonoverlapping<T>(x: *mut T, y: *mut T, count: usize) { ); } - // NOTE(scottmcm) Miri is disabled here as reading in smaller units is a - // pessimization for it. Also, if the type contains any unaligned pointers, - // copying those over multiple reads is difficult to support. - #[cfg(not(miri))] + // Split up the slice into small power-of-two-sized chunks that LLVM is able + // to vectorize (unless it's a special type with more-than-pointer alignment, + // because we don't want to pessimize things like slices of SIMD vectors.) + if mem::align_of::<T>() <= mem::size_of::<usize>() + && (!mem::size_of::<T>().is_power_of_two() + || mem::size_of::<T>() > mem::size_of::<usize>() * 2) { - // Split up the slice into small power-of-two-sized chunks that LLVM is able - // to vectorize (unless it's a special type with more-than-pointer alignment, - // because we don't want to pessimize things like slices of SIMD vectors.) - if mem::align_of::<T>() <= mem::size_of::<usize>() - && (!mem::size_of::<T>().is_power_of_two() - || mem::size_of::<T>() > mem::size_of::<usize>() * 2) - { - attempt_swap_as_chunks!(usize); - attempt_swap_as_chunks!(u8); - } + attempt_swap_as_chunks!(usize); + attempt_swap_as_chunks!(u8); } // SAFETY: Same preconditions as this function |