sadd32, sadd64, uadd32, uadd64, ssub32, ssub64, usub32, usub64, smul32, smul64, umul32, umul64
I don't think it's a fusion problem; even if you did fuse these sequences, they'd still be bad, since they'd be writing lots of extra registers.
And worth noting that these are just the ones where you usually have good sequences on other cpus, but even then (like signed mul) they’re not perfect. Lots of room for improvement. It’s just that risc-v didn’t seize the opportunity.
sadd32, sadd64, uadd32, uadd64, ssub32, ssub64, usub32, usub64, smul32, smul64, umul32, umul64