> I think what Jha was questioning was whether catching up to ARM is feasible if your main weapon is macro-op fusion. I don't think so, there are indeed unreal

> I think what Jha was questioning was whether catching up to ARM is feasible if your main weapon is macro-op fusion. I don't think so, there are indeed unrealistic macro-op fusion patterns that can reasonably be described as "unfeasible" or "unrealistic". But macro-op fusion patterns suggested in the RISC-V spec, papers about macro-op fusion on RISC-V, and the SiFive patent on macro-op fusion are realistic and feasible. > Bruce Hoult's comment from a few months ago suggests that it wasn't really being tried at SiFive Commits from SiFive people's in GCC [1] suggest that short-forward-branch macro-op fusion patterns are recognized by SiFive hardware. I don't know if they recognize other macro-op fusion patterns. But SiFive has a bunch of stuff to improve before diving into macro-op fusion. [1]: https://patchwork.ozlabs.org/project/gcc/patch/20190430234741.8120-1-jimw@sifive.com/ https://patchwork.ozlabs.org/project/gcc/patch/2019043023474...