[IR] Introduce `llvm.errno.tbaa` metadata for errno alias disambiguation

Add a new named module-level frontend-annotated metadata that
specifies the TBAA node for an integer access, for which, C/C++
`errno` accesses are guaranteed to use (under strict aliasing).
This should allow LLVM to prove the involved memory location/
accesses may not alias `errno`; thus, to perform optimizations
around errno-writing libcalls (store-to-load forwarding amongst
others).

Previous discussion: https://discourse.llvm.org/t/rfc-modelling-errno-memory-effects/82972.

0 files changed, 0 insertions, 0 deletions