https://gcc.gnu.org/bugzilla/show_bug.cgi?id=68122
--- Comment #9 from torvald at gcc dot gnu.org --- Marek, just skipping handling of internal functions is not correct I think. In the worst case, it should treat them as txn-unsafe, unless they are considered txn-pure. Do we have some idea of how many built-ins would be affected? For example I believe it wouldn't be critical if TM wouldn't be compatible with UBSan for now, but if there are builtins for code that would be intuitively txn-safe, supporting them would be good. Regarding UBSan specifically, I believe many of the checks could be handled in a straight-forward way: All values returned by transactional memory accesses will form a consistent snapshot, always. So, for example, an addition-with-check call that takes values as arguments should be tm_pure because it will check values that could have happened in some execution, even if the transaction has to be rolled back later on.
