https://gcc.gnu.org/bugzilla/show_bug.cgi?id=117239
--- Comment #14 from Jeffrey A. Law <law at gcc dot gnu.org> --- Late to the party. The basic idea of the code being modified here is that there are cases where parts of the caller's stack are effectively "owned" by the callee. On the 32 bit PA ABI that was pretty explicit and it seems like we've stumbled across another case. The change looks sensible for both the trunk and release branches where I would expect it to be quite safe. After all it's just invalidating more stuff from cselib's hash table. But obviously your call if you're not comfortable with backporting it to a release branch.
