https://gcc.gnu.org/bugzilla/show_bug.cgi?id=122593
--- Comment #1 from Jeffrey A. Law <law at gcc dot gnu.org> ---
It's a bit more complex on rv64 with the provided testcase due to the
extensions. We end up with something like:
(set (reg:DI 146)
(sign_extend:DI (plus:SI (subreg:SI (smax:DI (sign_extend:DI (neg:SI
(subreg:SI (reg/v:DI 138 [ b ]) 0)))
(reg:DI 148 [ a ])) 0)
(subreg:SI (reg/v:DI 138 [ b ]) 0))))
But it still a 3 insn sequence, so we can emit the addw+max style sequence to
get the desired code. When the inputs are the same size as the target word,
then it'll have the struture Andrew noted in the original report.
