Vladimir Makarov <vmaka...@redhat.com> writes: > The following patch fixes > > https://gcc.gnu.org/bugzilla/show_bug.cgi?id=88282 > > The patch was successfully bootstrapped and tested on > x86/x86-64/ppc64/aarch64. > > Committed as rev. 266784. > > Index: ChangeLog > =================================================================== > --- ChangeLog (revision 266783) > +++ ChangeLog (working copy) > @@ -1,3 +1,9 @@ > +2018-12-04 Vladimir Makarov <vmaka...@redhat.com> > + > + PR target/88282 > + * ira-costs.c (exec): Try bigger class to use smaller register > + move cost. > + > 2018-12-04 Michael Ploujnikov <michael.ploujni...@oracle.com> > > PR ipa/88297 > Index: ira-costs.c > =================================================================== > --- ira-costs.c (revision 266678) > +++ ira-costs.c (working copy) > @@ -1314,28 +1314,50 @@ record_operand_costs (rtx_insn *insn, en > machine_mode mode = GET_MODE (SET_SRC (set)); > cost_classes_t cost_classes_ptr = regno_cost_classes[regno]; > enum reg_class *cost_classes = cost_classes_ptr->classes; > - reg_class_t rclass, hard_reg_class, pref_class; > + reg_class_t rclass, hard_reg_class, pref_class, bigger_hard_reg_class; > int cost, k; > + move_table *move_costs; > bool dead_p = find_regno_note (insn, REG_DEAD, REGNO (src)); > > ira_init_register_move_cost_if_necessary (mode); > + move_costs = ira_register_move_cost[mode]; > hard_reg_class = REGNO_REG_CLASS (other_regno); > + bigger_hard_reg_class = ira_pressure_class_translate[hard_reg_class]; > + if (bigger_hard_reg_class == NO_REGS > + && (other_regno == STACK_POINTER_REGNUM > +#ifdef STATIC_CHAIN_REGNUM > + || other_regno == STATIC_CHAIN_REGNUM > +#endif > + || other_regno == FRAME_POINTER_REGNUM > + || other_regno == HARD_FRAME_POINTER_REGNUM)) > + bigger_hard_reg_class = GENERAL_REGS; > /* Target code may return any cost for mode which does not > fit the the hard reg class (e.g. DImode for AREG on > i386). Check this and use a bigger class to get the > right cost. */ > if (! ira_hard_reg_in_set_p (other_regno, mode, > reg_class_contents[hard_reg_class])) > - hard_reg_class = ira_pressure_class_translate[hard_reg_class]; > + hard_reg_class = bigger_hard_reg_class; > i = regno == (int) REGNO (src) ? 1 : 0; > for (k = cost_classes_ptr->num - 1; k >= 0; k--) > { > rclass = cost_classes[k]; > - cost = ((i == 0 > - ? ira_register_move_cost[mode][hard_reg_class][rclass] > - : ira_register_move_cost[mode][rclass][hard_reg_class]) > - * frequency); > - op_costs[i]->cost[k] = cost; > + cost = (i == 0 > + ? move_costs[hard_reg_class][rclass] > + : move_costs[rclass][hard_reg_class]); > + /* Target code might define wrong big costs for smaller > + reg classes or reg classes containing only fixed hard > + regs. Try a bigger class. */ > + if (bigger_hard_reg_class != hard_reg_class) > + { > + int cost2 = (i == 0 > + ? move_costs[bigger_hard_reg_class][rclass] > + : move_costs[rclass][bigger_hard_reg_class]); > + if (cost2 < cost) > + cost = cost2; > + } > + > + op_costs[i]->cost[k] = cost * frequency; > /* If we have assigned a class to this allocno in our > first pass, add a cost to this alternative > corresponding to what we would add if this allocno
This seems like a hack to me. I don't see any reason why FRAME_POINTER_REGNUM etc. have to be in GENERAL_REGS, so picking that seems arbitrary. And is there a reason not to include ARG_POINTER_REGNUM or PIC_OFFSET_TABLE_REGNUM? It sounds from the comments in the PR that the backend isn't defining its costs correctly. If so, what specifically does it get wrong? I think it would be better to fix the backends than accumulate more workarounds like this. Thanks, Richard
