[Bug target/123604] [15/16 regression] Regression: GCC 15 does not use adds while GCC 14 does since r15-2890

[rearnsha at gcc dot gnu.org via Gcc-bugs]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=123604

--- Comment #13 from Richard Earnshaw <rearnsha at gcc dot gnu.org> ---
Interestingly, aarch64 can create merged arith/compare insns during the cmpelim
pass.  Arm lacks TARGET_FLAGS_REGNUM to enable that pass, but even adding that
does not cause the merged insns to be created.

Investigating...