Hi! On Mon, Mar 30, 2020 at 12:18:59PM +0800, luoxhu wrote: > >>>If df_regs_ever_live_p(31) is false there is no hard frame pointer > >>>anywhere in the program. How can it be used then? > >> > >>There is a piece of code emit move instruction to r31 even > >>df_regs_ever_live_p(31) is false > >>in pro_and_epilogue. > > > >Can you point out where (in rs6000-logue.c ot similar)? We should fix > >*that*.
> >frame_pointer_needed is often true when the backend can figure out we do > >not actually need it. > >(so just that "if" clause changes), it'll all be fine. Could you test > >that please? > > Tried with below patch, it still fails at same place, I guess this is not > enough. > The instruction in 100dc034 change r31 from 0x105fdd70 to 0x7fffffffbbf0 > and didn't > restore it before return. So where was *that* insn generated, then? Segher
