[PATCH v2 0/2] RISC-V: add gcc support for Scalar Cryptography v1.0.0-rc6

[Kito Cheng]

I would prefer to accept those patchset even with no builtin function
or intrinsic function yet,
this not only add the support of -march option, but also introduce the
predefined macros like __riscv_zk*,
which could be used in *.S file to check if those instructions are
available or not.


On Wed, Nov 24, 2021 at 11:23 AM Palmer Dabbelt <palmer@rivosinc.com> wrote:
>
> [Changing to Jim's new address]
>
> On Mon, 22 Nov 2021 00:19:08 PST (-0800), siyu@isrc.iscas.ac.cn wrote:
> > From: SiYu Wu <siyu@isrc.iscas.ac.cn>
> >
> > This patch add gcc backend support for RISC-V Scalar Cryptography
> > Extension (k-ext), including machine description, builtins defines and
> > testcases for each k-ext's subset.
> >
> > A note about Zbkx: The Zbkx should be implemented in bitmanip's Zbp, but
> > since zbp is not included in the bitmanip spec v1.0, and crypto's v1.0
> > release will earlier than bitmanip's next release, so for now we
> > implementing it here.
> >
> > Version logs:
> >
> > v2: As Kito mentions, now this patch only includes the arch string related
> > stuff, the builtins and md changes is not included, waiting for the builtin
> > and intrinsic added to the spec. Also removed the unnecessary patches and add
> > Changelogs.
>
> I don't think there's anything wrong with what's here, but IMO we should
> hold off on merging until GCC does something with these extensions.
>
> IIUC all this enables is passing "-march=*Zk*" instead of
> "-Wa,-march=*Zk*", and while that is useful I'm worried it'll just make
> more of a headache for users who lose a simple way to detect the
> intrinsics.  IMO forcing users to pass -Wa properly encodes the "GCC
> doesn't support these, but binutils does" scenario pretty sanely, and
> users doing things at this level of complexity should be used to that
> already because it happens somewhat frequently.
>
> I'm not sure if I'm missing some use case this for this, though.
>
> > SiYu Wu (2):
> >   RISC-V: Add option defines for Scalar Cryptography
> >   RISC-V: Add implied defines of Zk, Zkn and Zks
> >
> >  gcc/common/config/riscv/riscv-common.c | 38 +++++++++++++++++++++++++-
> >  gcc/config/riscv/arch-canonicalize     | 16 ++++++++++-
> >  gcc/config/riscv/riscv-opts.h          | 22 +++++++++++++++
> >  gcc/config/riscv/riscv.opt             |  3 ++
> >  4 files changed, 77 insertions(+), 2 deletions(-)