[clang] [TBAA] Emit distinct TBAA tags for pointers with different depths,types. (PR #76612)

[Florian Hahn via cfe-commits]

https://github.com/fhahn commented:

> First of all I want to say that this is a really cool project, especially the type sanitizer part. Thanks for working on this!
> 
> > Just updated the tysan branches again. Unfortunately we aren't yet at a point where LLVM is `tysan` clean, there is a large number of reported violations when running the tblgen built with `tysan` even without this patch. I'd expect that a substantial amount of work is still needed to get to a state where we can build LLVM successfully with tysan.
> 
> Given that not even LLVM itself is clean (which has probably some of the densest population of compiler engineers), and you say that this will require a significant amount of work, would it maybe make sense to have this off-by-default for now and only enable it in a year or so by default? Especially if there are problems in any system libraries, like libc++, it would be rather unfortunate, since users can't do much about it.

Fair point especially as we are close to cutting a release branch and it should definitely be off by default there. I changed it to be disabled by default.

Not sure if we should wait a whole year, but we can figure out the details separately after the release branch has been cut

https://github.com/llvm/llvm-project/pull/76612