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Remove size_of == 1 case from fill specialization.
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m-ou-se committed Aug 9, 2021
1 parent eaf6f46 commit 3838301
Showing 1 changed file with 2 additions and 14 deletions.
16 changes: 2 additions & 14 deletions library/core/src/slice/specialize.rs
Original file line number Diff line number Diff line change
@@ -1,6 +1,3 @@
use crate::mem::{size_of, transmute_copy};
use crate::ptr::write_bytes;

pub(super) trait SpecFill<T> {
fn spec_fill(&mut self, value: T);
}
Expand All @@ -19,17 +16,8 @@ impl<T: Clone> SpecFill<T> for [T] {

impl<T: Copy> SpecFill<T> for [T] {
fn spec_fill(&mut self, value: T) {
if size_of::<T>() == 1 {
// SAFETY: The size_of check above ensures that values are 1 byte wide, as required
// for the transmute and write_bytes
unsafe {
let value: u8 = transmute_copy(&value);
write_bytes(self.as_mut_ptr(), value, self.len());
}
} else {
for item in self.iter_mut() {
*item = value;
}
for item in self.iter_mut() {
*item = value;
}
}
}

2 comments on commit 3838301

@raggi
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@raggi raggi commented on 3838301 Oct 8, 2021

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Does this still optimize to a memset? If so, do you have a pointer to the place that occurs?

@m-ou-se
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Yes. LLVM does that.

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