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Auto merge of #3021 - ttsugriy:bin-search, r=RalfJung

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Use Vec's binary search instead of hand-written one.
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bors 2023-08-09 20:10:37 +00:00
commit 43c869d1ec
1 changed files with 6 additions and 17 deletions
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23
src/tools/miri/src/concurrency/range_object_map.rs
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@ -42,30 +42,19 @@ impl<T> RangeObjectMap<T> {
/// in an existing allocation, then returns Err containing the position
/// where such allocation should be inserted
fn find_offset(&self, offset: Size) -> Result<Position, Position> {
// We do a binary search.
let mut left = 0usize; // inclusive
let mut right = self.v.len(); // exclusive
loop {
if left == right {
// No element contains the given offset. But the
// position is where such element should be placed at.
return Err(left);
}
let candidate = left.checked_add(right).unwrap() / 2;
let elem = &self.v[candidate];
self.v.binary_search_by(|elem| -> std::cmp::Ordering {
if offset < elem.range.start {
// We are too far right (offset is further left).
debug_assert!(candidate < right); // we are making progress
right = candidate;
// (`Greater` means that `elem` is greater than the desired target.)
std::cmp::Ordering::Greater
} else if offset >= elem.range.end() {
// We are too far left (offset is further right).
debug_assert!(candidate >= left); // we are making progress
left = candidate + 1;
std::cmp::Ordering::Less
} else {
// This is it!
return Ok(candidate);
std::cmp::Ordering::Equal
}
}
})
}
/// Determines whether a given access on `range` overlaps with