> -----Original Message-----
> From: Jiang, Haochen <haochen.ji...@intel.com>
> Sent: Wednesday, March 19, 2025 3:38 PM
> To: gcc-patches@gcc.gnu.org
> Cc: Liu, Hongtao <hongtao....@intel.com>; ubiz...@gmail.com
> Subject: [PATCH 00/27] Use avx10.x as the only option for AVX10 with 512 bit
> vector support while remove avx10.x-256/512 option and 256 bit rounding
> support
>
> Hi all,
>
> It is a little late for this change but I hope this will be a welcoming
> change since
> it will greatly simplify the compiler options and reduce confusion for AVX10
> option combination with AVX512.
>
> AVX10 whitepaper just got a major change and it will impact how we design
> the compiler option, which will actually simplify everything.
I like the decision.
Ok for the series.
But I'd like to leave a little time for others to comment. so please COMMIT
this series in next week if there's no objection.
>
> Ref: https://cdrdv2.intel.com/v1/dl/getContent/784343
>
> In this new whitepaper, all the platforms will support 512 bit vector width
> (previously, E-core is up to 256 bit, leading to hybrid clients and Atom
> Server
> 256 bit only). Also, 256 bit rounding is not that useful because we currently
> have rounding feature directly on E-core now and no need to use 256-bit
> rounding as somehow a workaround. HW will remove that support.
>
> Thus, there is no need to add avx10.x-256/512 into compiler options. A
> simple avx10.x supporting all vector length is all we need. The change also
> makes -mno-evex512 not that useful. It is introduced with avx10.1-256 for
> compiling 256 bit only binary on legacy platforms to have a partial trial for
> avx10.x-256. What we also need to do is to remove 256 bit rounding.
>
> For new features added in GCC 15 (i.e., option avx10.2-256/512 and 256 bit
> rounding), we will just simply remove them. Since avx10.2 has been directed
> to 512 bit previously. No need to change that option. We will keep the
> testcase
> and intrin file structure for now since it is late in GCC 15 release cycle
> and do
> clean up in GCC 16.
>
> For features added in GCC 14 (i.e., option avx10.1-256/512 and no-evex512),
> we will raise a deprecate warning in GCC 15 and finally remove them in GCC
> 16. Also, we will need to add avx10.1 back (it was removed just less than one
> month ago) and direct it to 512 bit with a warning in GCC 15 since it was
> aliased to 256 bit previously. The deprecate and re-alias warning would also
> like to be backported to GCC 14 and landed into GCC 14.3.
>
> The change will also lead to AVX10 and AVX512 option combination design
> simplification. Since we do not need to consider vector width enabled
> anymore, it is much more natural to just treat avx10.1 to an alias of all
> avx512xxx in SPR. Thus, "-mavx10.1 -mno-avx512fp16" should enable all
> AVX512 features while disabling AVX512FP16. And "-mavx512f -mno-
> avx10.1"
> should disable all AVX512 features. Both of the two combinations currently
> will ignore "-mno-". In GCC 15, we will raise a warning to mention that we are
> going to change that behavior in GCC 16.
>
> Upcoming would be the patches we want to landed in GCC 15. The first two
> patches are removing 256 bit roundings added with AVX10.2 new
> instructions.
> Then the following 22 are simple revert patch for the legacy instruction
> 256 bit ymm rounding addition. The last three patch is for avx10.x option
> change.
>
> Thx,
> Haochen
>
