36 lines
911 B
Rust
36 lines
911 B
Rust
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// SPDX-License-Identifier: Apache-2.0 OR MIT
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// Set the length of the vec when the `SetLenOnDrop` value goes out of scope.
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//
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// The idea is: The length field in SetLenOnDrop is a local variable
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// that the optimizer will see does not alias with any stores through the Vec's data
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// pointer. This is a workaround for alias analysis issue #32155
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pub(super) struct SetLenOnDrop<'a> {
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len: &'a mut usize,
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local_len: usize,
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}
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impl<'a> SetLenOnDrop<'a> {
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#[inline]
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pub(super) fn new(len: &'a mut usize) -> Self {
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SetLenOnDrop { local_len: *len, len }
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}
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#[inline]
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pub(super) fn increment_len(&mut self, increment: usize) {
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self.local_len += increment;
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}
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#[inline]
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pub(super) fn current_len(&self) -> usize {
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self.local_len
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}
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}
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impl Drop for SetLenOnDrop<'_> {
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#[inline]
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fn drop(&mut self) {
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*self.len = self.local_len;
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}
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}
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