[libcxx-commits] [libcxx] [llvm] [libcxx] Remove ASan container overflow checks for SSO strings (PR #194208)

[Nikita Belenkiy via libcxx-commits]

kitsnet wrote:

> > I am touching short string annotations in #191023 at the moment. It may fix some of the problems.
> 
> speculative loads in compiler is the main issue.

Well, the memory barrier handling in string is quite messy. We do have it for  __get_short/long_size/pointer(), but we don't have it for direct __rep_ copying. We could fix that too, but it has no obvious test failures in CI.

My concern was that we don't properly handle annotations when we do direct __rep_ copying. The compiler ignores it when it byte-copies the union with default assignment operator, but triggers short __data_ array check if the assignment operator for the union is user-defined.

https://github.com/llvm/llvm-project/pull/194208