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Shrink some slice iterator MIR
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scottmcm committed Jun 18, 2024
1 parent 3f8d51d commit d5584dd
Showing 1 changed file with 4 additions and 2 deletions.
6 changes: 4 additions & 2 deletions library/core/src/slice/iter/macros.rs
Original file line number Diff line number Diff line change
Expand Up @@ -103,7 +103,8 @@ macro_rules! iterator {
// so this new pointer is inside `self` and thus guaranteed to be non-null.
unsafe {
if_zst!(mut self,
len => *len = len.unchecked_sub(offset),
// Using the intrinsic directly avoids emitting a UbCheck
len => *len = crate::intrinsics::unchecked_sub(*len, offset),
_end => self.ptr = self.ptr.add(offset),
);
}
Expand All @@ -119,7 +120,8 @@ macro_rules! iterator {
// SAFETY: By our precondition, `offset` can be at most the
// current length, so the subtraction can never overflow.
len => unsafe {
*len = len.unchecked_sub(offset);
// Using the intrinsic directly avoids emitting a UbCheck
*len = crate::intrinsics::unchecked_sub(*len, offset);
self.ptr
},
// SAFETY: the caller guarantees that `offset` doesn't exceed `self.len()`,
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