On Sat, Sep 7, 2024 at 8:22 PM H.J. Lu <hjl.to...@gmail.com> wrote:
>
>
> On Sat, Sep 7, 2024, 11:07 AM Georg-Johann Lay <a...@gjlay.de> wrote:
>>
>> Am 07.09.24 um 19:51 schrieb H.J. Lu:
>> > On Sat, Sep 7, 2024 at 10:49 AM Georg-Johann Lay <a...@gjlay.de> wrote:
>> >> Am 07.09.24 um 18:35 schrieb Jeff Law:
>> >>> On 9/6/24 3:40 AM, Georg-Johann Lay wrote:
>> >>>> The reason for PR116326 is that LRA and reload require different
>> >>>> ELIMINABLE_REGS for a multi-register frame pointer. As ELIMINABLE_REGS
>> >>>> is used to initialize static const objects, it is not possible to make
>> >>>> ELIMINABLE_REGS to depend on options or patch it in some target hook.
>> >>>>
>> >>>> It was also concluded that it is not desirable to adjust reload so that
>> >>>> it behaves like LRA, but a hack like #define IN_RELOAD1_CC at the top
>> >>>> of reload1.cc would be fine, see
>> >>>>
>> >>>> https://gcc.gnu.org/bugzilla/show_bug.cgi?id=116326#c8
>> >>>>
>> >>>> This is an according patch that defines IN_RELOAD1_CC and uses it in
>> >>>> avr.h to define ELIMINABLE_REGS.
>> >>>>
>> >>>> This is only required for trunk.
>> >>>>
>> >>>> PR116326 occurred for some test case in avr-torture.exp, so I didn't
>> >>>> duplicate the test case.
>> >>>>
>> >>>> As it appears, this patch also fixes:
>> >>>>
>> >>>> https://gcc.gnu.org/PR116324
>> >>>> https://gcc.gnu.org/PR116325
>> >>>> https://gcc.gnu.org/PR116550
>> >>>>
>> >>>> Johann
>> >>>>
>> >>>> --
>> >>>>
>> >>>> AVR: target/116326 - Adjust ELIMINABLE_REGS to reload resp. LRA.
>> >>>>
>> >>>> PR target/116326
>> >>>> gcc/
>> >>>> * reload1.cc (IN_RELOAD1_CC): Define prior to all includes.
>> >>>> * config/avr/avr.h (ELIMINABLE_REGS): Depend on IN_RELOAD1_CC.
>> >>> I'm going to have to NAK this. It's too hackish, even with reload going
>> >>> away....
>> >>>
>> >>> Jeff
>> >>
>> >> So what is your proposal?
>> >>
>> >> I'd agree with Richard that we don't want to change reload
>> >> implementations such that they agree on ELIMINABLE_REGS.
>> >>
>> >> A different way would be to change reload1.cc such that it includes
>> >> reload.h prior to tm.h, i.e. prior to backend.h. This would make the
>> >> hack avr realm entirely, but it won't be trivially no-op.
>> >>
>> >> Johann
>> >
>> > Why not add RELOAD_ELIMINABLE_REGS and default it
>> > to ELIMINABLE_REGS?
>>
>> I can't find RELOAD_ELIMINABLE_REGS anywhere.
>> So are you proposing a new hook macro?
>
>
> A new macro.
Sounds good to me btw. - the other alternative is to avoid having
-m{,no-}lra and default to LRA now (not sure if that's feasible).
Richard.
>>
>> Johann
>>
