[Bug rtl-optimization/116066] ext-dce + uncommitted LoongArch patch breaks libcpp

[law at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=116066

--- Comment #2 from Jeffrey A. Law <law at gcc dot gnu.org> ---
Xi, can you give the latest trunk a fresh try.  There's a nonzero chance the
patch I just installed for 116039 fixes your problem.    There's not enough RTL
shown to be sure though.