Hi. Honza asked me to explain the change more verbosely. The patch simplify enhances verbose dump of IVOPTS so that # of iterations is printed. Apart from that it also prints invariant expression that are used during the algorithm which considers a set of candidates which is improved.
Main motivation for doing this was that sometimes the optimization considers a constant integer as invariant expression (Bin Cheng is working on removal of these) and that both IVs and IE are considered by the cost model to occupy a register. Which is not ideal and it sometimes tend to introduce more IVs that one would expect. === New format ===: Improved to: cost: 27 (complexity 2) cand_cost: 11 cand_group_cost: 10 (complexity 2) candidates: 3, 5 group:0 --> iv_cand:5, cost=(2,0) group:1 --> iv_cand:5, cost=(4,1) group:2 --> iv_cand:5, cost=(4,1) group:3 --> iv_cand:3, cost=(0,0) group:4 --> iv_cand:3, cost=(0,0) invariants 1, 6 used invariant expressions: inv_expr:3: ((sizetype) _976 - (sizetype) _922) * 4 inv_expr:6: ((sizetype) _1335 - (sizetype) _922) * 4 Original cost 27 (complexity 2) Final cost 27 (complexity 2) Selected IV set for loop 96 at original.f90:820, 5 avg niters, 2 expressions, 2 IVs: === Before ===: Improved to: cost: 27 (complexity 2) cand_cost: 11 cand_group_cost: 10 (complexity 2) candidates: 3, 5 group:0 --> iv_cand:5, cost=(2,0) group:1 --> iv_cand:5, cost=(4,1) group:2 --> iv_cand:5, cost=(4,1) group:3 --> iv_cand:3, cost=(0,0) group:4 --> iv_cand:3, cost=(0,0) invariants 1, 6 Original cost 27 (complexity 2) Final cost 27 (complexity 2) Selected IV set for loop 96 at original.f90:820, 2 IVs: Martin
