[clang] [llvm] [sancov] Introduce optional callback for stack-depth tracking (PR #138323)

[Marco Elver via cfe-commits]

https://github.com/melver commented:

Generally LGTM - but let's also wait for others to comment.

Documentation of this feature is lacking (and afaik also wasn't added in https://reviews.llvm.org/D36839). Given this will be used in the kernel, some kind of official documentation might be good to have.

Btw, if you want a runtime test, it's possible to add one similar to the one in `compiler-rt/trunk/test/sanitizer_common/TestCases/sanitizer_coverage_stack_depth.cc`.

https://github.com/llvm/llvm-project/pull/138323