Fixes Miri error, Optimizes retain implementation, Adds benchmarks - #78
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fereidani wants to merge 3 commits into
Open
Fixes Miri error, Optimizes retain implementation, Adds benchmarks#78fereidani wants to merge 3 commits into
fereidani wants to merge 3 commits into
Conversation
Collaborator
|
Can you post benchmark results of before and after? Skeptic about the early "return for optimization" and some similar changes which feel drive-by? |
emilio
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Apr 8, 2026
Error in question:
---- src/lib.rs - ThinVec<T>::extract_if (line 1636) stdout ----
Test executable failed (exit status: 1).
stderr:
error: Undefined Behavior: trying to retag from <1422> for Unique permission at alloc211[0x10], but that tag does not exist in the borrow stack for this location
--> src/lib.rs:2999:25
|
2999 | let v = slice::from_raw_parts_mut(self.vec.as_mut_ptr(), self.old_len);
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ this error occurs as part of retag at alloc211[0x10..0x40]
|
= help: this indicates a potential bug in the program: it performed an invalid operation, but the Stacked Borrows rules it violated are still experimental
= help: see https://github.com/rust-lang/unsafe-code-guidelines/blob/master/wip/stacked-borrows.md for further information
help: <1422> would have been created here, but this is a zero-size retag ([0x10..0x10]) so the tag in question does not exist anywhere
--> src/lib.rs:2999:51
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2999 | let v = slice::from_raw_parts_mut(self.vec.as_mut_ptr(), self.old_len);
| ^^^^^^^^^^^^^^^^^^^^^
Cherry-picked from #78
Contributor
Author
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Hey, that's an LLVM trick, the Rust standard library uses it quite often too. This new algorithm is already in there; my PR got merged a few months ago to rust itself. |
Collaborator
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@fereidani could you link to that PR? Thanks. |
Contributor
Author
|
Sure: rust-lang/rust#149784 |
Contributor
Author
|
That's unsafe implementation of the same algorithm. |
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