On Wed, Jul 29, 2026 at 4:01 PM Jovan Dmitrovic <[email protected]> wrote: > > Function ivopts_estimate_reg_pressure is taxing candidate sets > by the number of candidates included in set. This makes for an > uneven playing field, making it very difficult for larger sets > to be chosen. > > In try_improve_iv_set to candidate set another candidate is added > only if the cost improves (therefore prefering fewer candidates > per set), but having reg pressure cost factor in the number of > candidates makes a disbalance when choosing the best option.
This is OK. Thanks, Richard. > gcc/ChangeLog: > > * tree-ssa-loop-ivopts.cc (ivopts_estimate_reg_pressure): > Remove n_cands bias from reg pressure cost calculation. > > Co-authored-by: Radosav Krunić <[email protected]> > Signed-off-by: Djordje Todorović <[email protected]> > Signed-off-by: Chao-Ying Fu <[email protected]> > Signed-off-by: Jovan Dmitrović <[email protected]> > Signed-off-by: Radosav Krunić <[email protected]> > --- > gcc/tree-ssa-loop-ivopts.cc | 4 +--- > 1 file changed, 1 insertion(+), 3 deletions(-) > > diff --git a/gcc/tree-ssa-loop-ivopts.cc b/gcc/tree-ssa-loop-ivopts.cc > index 3c0ce1794c2f..72f801a6fd89 100644 > --- a/gcc/tree-ssa-loop-ivopts.cc > +++ b/gcc/tree-ssa-loop-ivopts.cc > @@ -6111,9 +6111,7 @@ ivopts_estimate_reg_pressure (struct ivopts_data *data, > unsigned n_invs, > + target_spill_cost [speed] * (n_cands - available_regs) * 2 > + target_spill_cost [speed] * (regs_needed - n_cands); > > - /* Finally, add the number of candidates, so that we prefer eliminating > - induction variables if possible. */ > - return cost + n_cands; > + return cost; > } > > /* For each size of the induction variable set determine the penalty. */ > -- > 2.34.1
