[libcxx-commits] [PATCH] D144155: [ASan] Unpoisoning vectors memory before deallocation

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AdvenamTacet added a comment.

The point of `__annotate_delete` is to return memory in the same state as it was just after allocation. And yes, `clear()` is poisoning memory of all present objects in a vector (at the end, whole buffer is poisoned as container overflow).

1. Therefore, there is no point to unpoison memory before a call to `clear`.
2. I don't think clear() is called there because of ASan, as from ASan point of view, container does not have to be empty.
3. The goal is to deallocate unpoisoned memory and there is no easy way to turn off poisoning inside a single call to the `clear` function (at least I don't know it).

If complexity is the main concern, I can add  additional `if` before every `__annotate_delete()` call, and don't call them with standard allocator, as in that implementation, it's not necessary. But it depends on memory deallocator implementation.
Also, that memory will be probably poisoned by deallocator soon after, but sometimes deallocator may access memory and then it cannot be poisoned <https://github.com/llvm/llvm-project/issues/60384>.


Repository:
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https://reviews.llvm.org/D144155