On Tue, Aug 22, 2023 at 4:36 PM Hongtao Liu <crazy...@gmail.com> wrote:
>
> On Tue, Aug 22, 2023 at 9:54 PM Jakub Jelinek <ja...@redhat.com> wrote:
> >
> > On Tue, Aug 22, 2023 at 09:35:44PM +0800, Hongtao Liu wrote:
> > > Ok, then we can't avoid TARGET_AVX10_1 in those existing 256/128-bit
> > > evex instruction patterns.
> >
> > Why?
> > Internally for md etc. purposes, we should have the current
> > TARGET_AVX512* etc. ISA flags, plus one new one, whatever we call it
> > (TARGET_EVEX512 even if it is not completely descriptive because of kandq
> > etc., or some other name) which says if 512-bit vector modes can be used,
> > if g modifier can be used, if the 64-bit mask operations can be used etc.
> > Plus, if AVX10.1 contains any instructions not covered in the preexisting
> > TARGET_AVX512* sets, TARGET_AVX10_1 which covers that delta, otherwise
> > keep -mavx10.1 just as an command line option which enables/disables
> Let's assume there's no detla now, AVX10.1-512 is equal to
> AVX512{F,VL,BW,DQ,CD,BF16,FP16,VBMI,VBMI2,VNNI,IFMA,BITALG, VPOPCNTDQ}
> > other stuff.
> > The current common/config/i386/i386-common.cc OPTION_MASK_ISA*SET* would be
> > like now, except that the current AVX512* sets imply also EVEX512/whatever
> > it will be called, that option itself enables nothing (or TARGET_AVX512F),
> > and unsetting it doesn't disable all the TARGET_AVX512*.
> > -mavx10.1 would enable the AVX512* sets without EVEX512/whatever.
> So for -mavx512bw -mavx10.1-256, -mavx512bw will set EVEX512, but
> -mavx10.1-256 doesn't clear EVEX512 but just enable all AVX512* sets?.As I said earlier -mavx10.1-256 (and -mavx10.1-512) should not exist. So instead we'd have -mavx512bw -mavx10.1 where -mavx512bw enables evex512 and -mavx10.1 will enable the 10.1 ISAs _not affecting_ whether evex512 is set or not. We then have the -mevex512 flag (or whatever name we agree to) to enable (or disable) 512bit support. If you insist on having -mavx10.1-256 that should alias to -mavx10.1 + -mno-evex512, but Jakub disagrees here, so I'd rather not have it at all. We could have -mavx10.1-512 aliasing to -mavx10.1 + -mevex512 (Jakub would agree here). Richard.
