Hi! On Fri, Jun 04, 2021 at 09:40:58AM +0800, Xionghu Luo wrote: > >> Combine still fail to merge the two instructions: > >> > >> Trying 6 -> 7: > >> 6: r120:KF#0=r125:KF#0<-<0x40 > >> REG_DEAD r125:KF > >> 7: [sfp:DI+r123:DI]=r120:KF#0<-<0x40 > >> REG_DEAD r120:KF > >> Successfully matched this instruction: > >> (set (mem/c:V1TI (plus:DI (reg/f:DI 110 sfp) > >> (reg:DI 123)) [1 S16 A128]) > >> (subreg:V1TI (reg:KF 125) 0)) > >> rejecting combination of insns 6 and 7 > >> original costs 4 + 4 = 8 > >> replacement cost 12 > > > > So what instructions were these? Why did the store cost 4 but the new > > one costs 12?
The *vsx_le_perm_store_<mode> instruction has the *preferred* alternative with cost 12, while the other alternative has cost 8. Why is that? That looks like a bug. (set_attr "length" "12,8") > >> By hacking the vsx_le_perm_store_v1ti INSN_COST from 12 to 8, > > > > It should be the same cost as the other store! > > vsx_le_permute_v1ti's cost is defined to 4 in vsx.md: Yes. Why is alternative 0 of *vsx_le_perm_store_<mode> said to have a length of 3 insns? Segher
