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| author | bors <bors@rust-lang.org> | 2017-09-20 06:29:42 +0000 |
|---|---|---|
| committer | bors <bors@rust-lang.org> | 2017-09-20 06:29:42 +0000 |
| commit | 94a82adbb491b5fd0585370d4fcc7b36798e70d5 (patch) | |
| tree | de14b4b931e0cea4245b79eb557ab7cce878c959 /src/liballoc | |
| parent | 54996837a399421f8d691c6901eea5ab20a30f46 (diff) | |
| parent | 10384ab18a386e6f7b58c714def62e405182d968 (diff) | |
| download | rust-94a82adbb491b5fd0585370d4fcc7b36798e70d5.tar.gz rust-94a82adbb491b5fd0585370d4fcc7b36798e70d5.zip | |
Auto merge of #44355 - Xaeroxe:optimize_drain_filter, r=alexcrichton
Optimize drain_filter This PR cuts out two copies from each iteration of `drain_filter` by exchanging the swap operation for a copy_nonoverlapping function call instead. Since the data being swapped is not needed anymore we can just overwrite it instead.
Diffstat (limited to 'src/liballoc')
| -rw-r--r-- | src/liballoc/vec.rs | 8 |
1 files changed, 7 insertions, 1 deletions
diff --git a/src/liballoc/vec.rs b/src/liballoc/vec.rs index 75d54b82076..7dd8895c1ae 100644 --- a/src/liballoc/vec.rs +++ b/src/liballoc/vec.rs @@ -2694,7 +2694,13 @@ impl<'a, T, F> Iterator for DrainFilter<'a, T, F> self.del += 1; return Some(ptr::read(&v[i])); } else if self.del > 0 { - v.swap(i - self.del, i); + let del = self.del; + let src: *const T = &v[i]; + let dst: *mut T = &mut v[i - del]; + // This is safe because self.vec has length 0 + // thus its elements will not have Drop::drop + // called on them in the event of a panic. + ptr::copy_nonoverlapping(src, dst, 1); } } None |