The advantage of performing superoptimization on IR level is that you have explicit data dependencies (due to SSA form). Thus you don't have unrelated instructi

The advantage of performing superoptimization on IR level is that you have explicit data dependencies (due to SSA form). Thus you don't have unrelated instructions in between. Figure 1 of the cited Optgen paper http://pp.info.uni-karlsruhe.de/uploads/publikationen/buchwald15cc.pdf http://pp.info.uni-karlsruhe.de/uploads/publikationen/buchwa... shows an example that can be optimized with IR-based superoptimization but not with a machine-specific one. In summary, no approache subsumes the other one. Thus, it is worthwhile to have them both.