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refactor: manual location setting #672

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Merged
alejandro-vaz merged 3 commits into from
Sep 24, 2026
Merged

refactor: manual location setting #672

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2654258
refactor: manual location setting
alejandro-vaz Sep 24, 2026
f7c5252
Merge branch 'v2' into manual-location
alejandro-vaz Sep 24, 2026
50557be
fix: rename len to length
alejandro-vaz Sep 24, 2026
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30 changes: 5 additions & 25 deletions src/lib.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -415,26 +415,6 @@ impl<T: Clone, const N: usize> SmallVec<T, N> {
impl<T, const N: usize, A: Allocator> SmallVec<T, N, A> {
const IS_ZST: bool = size_of::<T>() == 0;

/// Sets the tag to be on the heap
///
/// # Safety
///
/// The active union member must be the self.raw.heap
#[inline]
unsafe fn set_on_heap(&mut self) {
self.length = TaggedLen::new(self.len(), true);
}

/// Sets the tag to be inline
///
/// # Safety
///
/// The active union member must be the self.raw.inline
#[inline]
unsafe fn set_inline(&mut self) {
self.length = TaggedLen::new(self.len(), false);
}

/// Sets the length of a vector.
///
/// This will explicitly set the size of the vector, without actually
Expand Down Expand Up @@ -723,7 +703,7 @@ impl<T, const N: usize, A: Allocator> SmallVec<T, N, A> {
if result.is_ok() {
// SAFETY: the allocation succeeded, so self.raw.heap is now
// active
unsafe { self.set_on_heap() };
self.length.set_location::<true>();
}
result
} else {
Expand All @@ -743,7 +723,7 @@ impl<T, const N: usize, A: Allocator> SmallVec<T, N, A> {
align: align_of::<T>(),
allocator: &self.allocator
});
self.set_inline();
self.length.set_location::<false>();
}
}
Ok(())
Expand Down Expand Up @@ -800,7 +780,7 @@ impl<T, const N: usize, A: Allocator> SmallVec<T, N, A> {
unsafe {
let (ptr, capacity) = self.raw.heap;
copy_nonoverlapping(ptr.as_ptr(), self.raw.as_mut_ptr_inline(), length);
self.set_inline();
self.length.set_location::<false>();
self.allocator.deallocate(
ptr.cast(),
Layout::from_size_align_unchecked(capacity * size_of::<T>(), align_of::<T>())
Expand Down Expand Up @@ -833,7 +813,7 @@ impl<T, const N: usize, A: Allocator> SmallVec<T, N, A> {
unsafe {
let (ptr, capacity) = self.raw.heap;
copy_nonoverlapping(ptr.as_ptr(), self.raw.as_mut_ptr_inline(), length);
self.set_inline();
self.length.set_location::<false>();
self.allocator.deallocate(
ptr.cast(),
Layout::from_size_align_unchecked(
Expand Down Expand Up @@ -1411,7 +1391,7 @@ impl<T, const N: usize, A: Allocator> SmallVec<T, N, A> {
}?;

// SAFETY: the allocation succeeded, so self.raw.heap is now active
unsafe { this.set_on_heap() };
this.length.set_location::<true>();
}
Ok(this)
}
Expand Down
7 changes: 7 additions & 0 deletions src/taggedlen.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -55,6 +55,13 @@ impl<T> TaggedLen<T> {
(self.0 >> Self::SHIFT, (self.0 & Self::TAG) != 0)
}

#[inline(always)]
pub const fn set_location<const ON: bool>(&mut self) {
if Self::TAG != 0 {
self.0 = (self.0 & !Self::TAG) | ON as usize;
}
}

/// # Safety
///
/// current length+n must be smaller than MAX_LEN on 64-bit target
Expand Down
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