Optimize empty case in Vec::retain · model-checking/verify-rust-std@5d51099 (original) (raw)

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Commit 5d51099

Optimize empty case in Vec::retain

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Lines changed: 6 additions & 0 deletions

Original file line number Diff line number Diff line change
@@ -1711,6 +1711,12 @@ impl<T, A: Allocator> Vec<T, A> {
1711 1711 F: FnMut(&mut T) -> bool,
1712 1712 {
1713 1713 let original_len = self.len();
1714 +
1715 +if original_len == 0 {
1716 +// Empty case: explicit return allows better optimization, vs letting compiler infer it
1717 +return;
1718 +}
1719 +
1714 1720 // Avoid double drop if the drop guard is not executed,
1715 1721 // since we may make some holes during the process.
1716 1722 unsafe { self.set_len(0) };