https://gcc.gnu.org/bugzilla/show_bug.cgi?id=62631
--- Comment #29 from amker at gcc dot gnu.org --- (In reply to amker from comment #28) > On hppa 32, the two iv uses are: > use 0 > address > in statement *p_1 = 0; > > at position *p_1 > type int * > base p_7 > step 4 > base object (void *) p_7 > related candidates > use 1 > compare > in statement if (i_11 <= 99) > > at position > type unsigned int > base i_4(D) + 1 > step 1 > is a biv > related candidates > And the BIV/GIV candidates are: > candidate 3 (important) > original biv > type int * > base p_7 > step 4 > base object (void *) p_7 > candidate 4 (important) > ... > candidate 5 (important) > original biv > type unsigned int > base i_4(D) > step 1 > > The costs table are: > > Candidate costs: > cand cost > 0 5 > 1 5 > 2 5 > 3 4 > 4 5 > 5 4 > 6 5 > 7 5 > Use 0: > cand cost compl. depends on > 0 1 2 1 > 1 1 0 > 2 1 1 1 > 3 1 0 > 4 3 2 inv_expr:0 > 5 3 2 inv_expr:0 > 6 1 1 > 7 19 3 inv_expr:1 > > Use 1: > cand cost compl. depends on > 0 4 0 inv_expr:2 > 3 3 0 inv_expr:3 > 4 0 0 > 5 0 0 > 7 4 1 > > It seems cand3 and cand5 have same level cost, but GCC chooses candidate 5 Ah, candidate 5 is considered cheaper according to the cost table. > as below: > Initial set of candidates: > cost: 9 (complexity 2) > cand_cost: 4 > cand_use_cost: 3 (complexity 2) > candidates: 5 > use:0 --> iv_cand:5, cost=(3,2) > use:1 --> iv_cand:5, cost=(0,0) > > While on other targets, cand 3 is selected.
