Hi! On Wed, Sep 02, 2020 at 11:16:00AM +0800, Kewen.Lin wrote: > on 2020/9/1 上午3:41, Segher Boessenkool wrote: > > On Tue, Aug 25, 2020 at 08:46:55PM +0800, Kewen.Lin wrote: > >> 1) Currently address_cost hook on rs6000 always return zero, but at least > >> from Power7, pre_inc/pre_dec kind instructions are cracked, it means we > >> have to take the address update into account (scalar normal operation). > > > > From Power4 on already (not sure about Power6, but does anyone care?) > > Thanks for the information, it looks this issue exists for a long time.
Well, *is* it an issue? The addressing doesn't get more expensive... For example, an ldu 3,16(4) is cracked to an ld 3,16(4) and an addi 4,4,16 (the addi is not on the critical path of the load). So it seems to me this shouldn't increase the addressing cost at all? (The instruction of course is really two insns in one.) Segher
