"Kewen.Lin" <li...@linux.ibm.com> writes: > on 2020/1/20 下午9:14, Segher Boessenkool wrote: >> Hi! >> >> On Mon, Jan 20, 2020 at 10:42:12AM +0000, Richard Sandiford wrote: >>> "Kewen.Lin" <li...@linux.ibm.com> writes: >>>> gcc/ChangeLog >>>> >>>> 2020-01-16 Kewen Lin <li...@gcc.gnu.org> >>>> >>>> * config/rs6000/rs6000.c (TARGET_STRIDE_DFORM_VALID_P): New macro. >>>> (rs6000_stride_dform_valid_p): New function. >>>> * doc/tm.texi: Regenerate. >>>> * doc/tm.texi.in (TARGET_STRIDE_DFORM_VALID_P): New hook. >>>> * target.def (stride_dform_valid_p): New hook. >>> >>> It looks like we should able to derive this information from the normal >>> legitimate_address_p hook. >> >> Yes, probably. >> >>> Also, "D-form" vs. "X-form" is AFAIK a PowerPC-specific classification. >>> It would be good to use a more generic term in target-independent code. >> >> Yeah. X-form is [reg+reg] addressing; D-form is [reg+imm] addressing. >> We can do simple [reg] addressing in either form as well. Whether D-form >> can be used for some access depends on many factors (ISA version, mode of >> the datum, alignment, and how big the offset is of course). But the usual >> legitimate_address_p hook should do fine. The ivopts code already has an >> addr_offset_valid_p function, maybe that could be adjusted for this? >> >> >> Segher >> > > Hi Segher and Richard S., > > Sorry for late response. Thanks for your comments on legitimate_address_p > hook > and function addr_offset_valid_p. I updated the IVOPTs part with > addr_offset_valid_p, although rs6000_legitimate_offset_address_p doesn't check > strictly all the time (like worst_case is false), it works well with SPEC2017. > Based on it, the hook is simplified as attached patch.
Thanks for the update. I think it would be better to add a --param rather than a bool hook though. Targets can then change the default (if necessary) using SET_OPTION_IF_UNSET. The user can override the default if they want to. It might also be better to start with an opt-out rather than an opt-in (i.e. with the default param value being true rather than false). With a default-off option, it's much harder to tell whether something has been deliberately turned off or whether no-one's thought about it either way. We can always flip the default later if it turns out that nothing other than rs6000 benefits. Richard
