> -----Original Message----- > From: ZiNgA BuRgA <zingabu...@hotmail.com> > Sent: Monday, August 21, 2023 5:27 PM > To: Richard Biener <richard.guent...@gmail.com>; Hongtao Liu > <crazy...@gmail.com> > Cc: Jiang, Haochen <haochen.ji...@intel.com>; gcc-patches@gcc.gnu.org > Subject: Re: Intel AVX10.1 Compiler Design and Support > > Another way (not saying this is better, just throwing out ideas) is to > break AVX10.1 into all the AVX-512 subsets. > So you'd have something like -mavx10.1-256-vl, -mavx10.1-512-vbmi etc. > > * -mavx10.1-256 would effectively be an alias for all the 128+256-bit > subsets, and set the __AVX10_1__ define > * -mavx512vbmi would effectively be an alias for `-mavx10.1-128-vbmi > -mavx10.1-256-vbmi -mavx10.1-512-vbmi` and set the __AVX512VBMI__ define > (`-mavx10.1-512-vl` might not make much sense unless it implies AVX512F?) > * -mno-avx512vbmi would similarly be an alias for > `-mno-avx10.1-128-vbmi -mno-avx10.1-256-vbmi -mno-avx10.1-512-vbmi`; > with this, `-mavx10.1-256 -mno-avx512vbmi` would make sense, even if > unusual (enable all AVX10.1 but disable all VBMI) > * -mavx10.2-256 would act as a single feature, cementing in AVX10.2 > like the current AVX10.1 proposal, and AVX-512 subsets can't be turned off
I am considering a proposal quite similar to this if we want to change the design so that it is flexible. But there are a few proposals on the table. The problem for this proposal is that if it is a over-design to make each AVX512 feature to split since in most scenarios we just need to keep the vector width as the same. Thx, Haochen > > > On 21/08/2023 5:36 pm, Richard Biener wrote: > > On Mon, Aug 21, 2023 at 3:20 AM Hongtao Liu via Gcc-patches > > <gcc-patches@gcc.gnu.org> wrote: > > > > Yes. Note we cannot really re-purpose -mprefer-vector-width=256 since that > > would also make uses of 512bit intrinsics ill-formed. So we'd need a new > > flag that would restrict AVX512VL to 256bit, possibly using a common > > internal > > flag for this and the -mavx10.1-256 vector size effect. > > > > Maybe -mdisable-vector-width-512 or -mavx512vl-for-avx10.1-256 or > > -mavx512vl-256? Writing these the last looks most sensible to me? > > Note it should combine with -mavx512vl to -mavx512vl-256 to make > > -march=native -mavx512vl-256 work (I think we should also allow the > > flag together with -mavx10.1*?) > > > > mavx512vl-256 > > Target ... > > Disable the 512bit vector ISA subset of AVX512 or AVX10, enable > > the 256bit vector ISA subset of AVX512. > > > > Richard. >
