https://gcc.gnu.org/bugzilla/show_bug.cgi?id=127205
--- Comment #6 from Richard Biener <rguenth at gcc dot gnu.org> --- For the pair-fusion case it seems to me that IVOPTs should model that somehow (like it attempts to model autoinc). The author of the series claimed that the number of IVs (aka n_cands) is already taken into account elsewhere. The series definitely removed double-accounting in the register pressure cost estimate function. The main goal (which is achieved IMO) is to make the costing less GIGO, it now makes "sense", even though we of course still add and compare apples and oranges. If selecting more IVs results in cheaper use + update cost then that is good. Are you sure the costs are accurate on arm? (besides the missed pair fusion modeling?)
