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remove no-longer-needed work-arounds from the standard library

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This commit is contained in:
Ralf Jung 2022-11-06 14:20:09 +01:00
parent eb4bdb00a4
commit 6b7f6b98c7
2 changed files with 9 additions and 18 deletions
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5
library/core/src/mem/mod.rs
View File

@ -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

22
library/core/src/ptr/mod.rs
View File

@ -908,21 +908,15 @@ macro_rules! attempt_swap_as_chunks {
);
}
// 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