[Bug tree-optimization/79981] Forwprop not working for __atomic_compare_exchange_n

[vogt at linux dot vnet.ibm.com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=79981

--- Comment #10 from Dominik Vogt <vogt at linux dot vnet.ibm.com> ---
Thanks for the fix; I'll regression test it soon, just need some time.