On Wed, Jun 24, 2026 at 4:28 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 (as it's simpler than 2/3 it should be re-ordered), it can be pushed independently. 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 | 6 ++---- > 1 file changed, 2 insertions(+), 4 deletions(-) > > diff --git a/gcc/tree-ssa-loop-ivopts.cc b/gcc/tree-ssa-loop-ivopts.cc > index 95c6dcf767ab..ef9274c4d6fb 100644 > --- a/gcc/tree-ssa-loop-ivopts.cc > +++ b/gcc/tree-ssa-loop-ivopts.cc > @@ -6113,10 +6113,8 @@ ivopts_estimate_reg_pressure (struct ivopts_data > *data, unsigned n_invs, > } > > /* Adjust cost of invariant register pressure in order to make > - the spilling of induction variables the most taxing. > - Finally, add the number of candidates, so that we prefer eliminating > - induction variables if possible. */ > - return adjust_setup_cost(data, cost) + iv_spill_cost + n_cands; > + the spilling of induction variables the most taxing. */ > + return adjust_setup_cost(data, cost) + iv_spill_cost; > } > > /* For each size of the induction variable set determine the penalty. */ > -- > 2.34.1
