[PATCH 00/13] Add support for the T-Head vendor extensions
Christoph Müllner
christoph.muellner@vrull.eu
Sun Sep 18 06:51:05 GMT 2022
On Fri, Sep 16, 2022 at 11:58 AM Palmer Dabbelt <palmer@dabbelt.com> wrote:
> On Fri, 16 Sep 2022 02:36:32 PDT (-0700), nelson@rivosinc.com wrote:
> > Hi Christoph,
> >
> >
> > On Tue, Sep 6, 2022 at 8:22 PM Christoph Muellner
> > <christoph.muellner@vrull.eu> wrote:
> >>
> >> From: Christoph Müllner <christoph.muellner@vrull.eu>
> >>
> >> This series introduces support for the T-Head vendor extensions,
> >> which are implemented e.g. in the XuanTie C906 and XuanTie C910
> >> processors:
> >> * XTheadBa
> >> * XTheadBb
> >> * XTheadBs
> >> * XTheadCmo
> >> * XTheadCondMov
> >> * XTheadFMemIdx
> >> * XTheadMac
> >> * XTheadMemIdx
> >> * XTheadMemPair
> >> * XTheadSync
> >>
> >> The xthead* extensions are documented here:
> >>
> https://github.com/T-head-Semi/thead-extension-spec/releases/download/2.0.0/xthead-2022-09-05-2.0.0.pdf
> >>
> >> The "th." instruction prefix prevents future conflicts with standard
> >> extensions and has been documentented in a PR for the RISC-V toolchain
> >> conventions:
> >> https://github.com/riscv-non-isa/riscv-toolchain-conventions/pull/19
> >>
> >> The goal of this patchset is to provide access to these instruction
> >> so that compilers/users can optimize SW accordingly.
> >>
> >> Note, that the T-Head vendor extensions do not contain all
> >> vendor-specific
> >> functionality of the T-Head SoCs (e.g. no vendor-specific CSRs are
> >> included).
> >> Instead the extensions cover coherent functionality, that is exposed to
> >> S and U mode.
> >>
> >> To enable the extensions above, the following two methods are possible:
> >> * add the extension to the arch string (e.g.
> >> * -march=rv64gc_xtheadcmo_xtheadsync)
> >> * implicitly select the extensions via CPU selection (e.g.
> >> * -mcpu=thead-c910)
> >>
> >> The patchset attempts to minimize code changes in generic/infrastructure
> >> code. All patches in this series come with tests to avoid future
> regressions.
> >>
> >> Christoph Müllner (13):
> >> RISC-V: Add generic support for vendor extensions
> >> RISC-V: Add T-Head CMO vendor extension
> >> RISC-V: Add T-Head SYNC vendor extension
> >> RISC-V: Add support for arbitrary immediate encoding formats
> >> RISC-V: Add T-Head Bitmanip vendor extension
> >> RISC-V: Add T-Head CondMov vendor extension
> >> RISC-V: Add T-Head MAC vendor extension
> >> RISC-V: Add T-Head FMemIdx vendor extension
> >> RISC-V: Add T-Head MemIdx vendor extension
> >> RISC-V: Add support for literal instruction arguments
> >> RISC-V: Add T-Head MemPair vendor extension
> >
> > There are three minor issues,
> >
> > 1. Probably need to add new extension support in
> > riscv_multi_subset_supports_ext, although it is just used for
> > reporting better error messages.
> > 2. The operand L seems only to be used for t-head for now, so it
> > should be still a vendor operand, named with the X prefix probably
> > better.
> > 3. I remember Lifang mentioned before that we should add these vendor
> > stuff based on the vendor infra in the integration branch, and that's
> > what I asked him to rebase his patches to there before, since the
> > previous policy cannot accept vendor stuff on master branch. But now
> > I think most of us agree to accept t-head extensions on mainline
> > directly, so I figured these things cannot be blocked by the vendor
> > infra and cannot be committed. That doesn't mean we don't need the
> > vendor infra, that means we can support the vendor infra later if me
> > or someone have time to move them back to mainline.
> >
> > Therefore, these patches look good to me for now, thank you very much
> > for spending so much time to implement these. But personally, I think
> > we should get the approval from the T-Head guys at least. Btw, If
> > these implementations are referred to and based on the integration
> > branch, then I think it would be better to keep at least the
> > co-authors there in the commit message here; if these patches are
> > re-write without referring to the implementation from the integration
> > branch, then I need to apologize to them, because I asked them to
> > rewrite their patches over there, and cannot be committed to mainline
> > at that time...
> >
> >> riscv: gas: Add command line option '-mcpu=' to specify the CPU
> >> riscv: Add T-Head entries for the -mcpu= flag
> >
> > Not sure if it is necessary to add -mcpu in assembler, since the
> > compiler should recognize -mcpu, and will expand it to the correct
> > extensions to assembler. If there are no objections for a period of
> > time, then please go ahead and commit these.
>
> I'd also learn towards keeping -mcpu out of the assembler, it's just
> going to result in subtly different behavior between GCC and GAS which
> will cause subtle headaches in the future. All -mcpu does is set -march
> and -mtune, so if we just continue keeping it in GCC then we have a
> single source of truth. GCC will already need to understand -march for
> everything that GAS needs to know anyway, so it's not like it's adding
> complexity.
>
> Is there something broken in GCC where -mcpu isn't setting the right
> -march for GAS and thus we're not getting the right extensions enabled?
> If that's the case I'd argue we're better off just fixing the bug over
> there.
>
No, nothing is broken.
The main use case was direct invocations of the assembler,
but I'm fine with dropping the patch.
Thanks,
Christoph
>
> >
> > Thank you very much
> > Nelson
> >
> >> bfd/elfxx-riscv.c | 39 ++-
> >> gas/config/tc-riscv.c | 127 +++++++
> >> gas/doc/c-riscv.texi | 70 ++++
> >> gas/testsuite/gas/riscv/mcpu-fail-unknown.d | 3 +
> >> gas/testsuite/gas/riscv/mcpu-fail-unknown.l | 2 +
> >> gas/testsuite/gas/riscv/mcpu-ok-c906.d | 6 +
> >> gas/testsuite/gas/riscv/mcpu-ok-c910.d | 6 +
> >> gas/testsuite/gas/riscv/x-thead-ba-fail.d | 3 +
> >> gas/testsuite/gas/riscv/x-thead-ba-fail.l | 3 +
> >> gas/testsuite/gas/riscv/x-thead-ba-fail.s | 3 +
> >> gas/testsuite/gas/riscv/x-thead-ba.d | 13 +
> >> gas/testsuite/gas/riscv/x-thead-ba.s | 6 +
> >> gas/testsuite/gas/riscv/x-thead-bb-fail.d | 3 +
> >> gas/testsuite/gas/riscv/x-thead-bb-fail.l | 7 +
> >> gas/testsuite/gas/riscv/x-thead-bb-fail.s | 7 +
> >> gas/testsuite/gas/riscv/x-thead-bb.d | 30 ++
> >> gas/testsuite/gas/riscv/x-thead-bb.s | 22 ++
> >> gas/testsuite/gas/riscv/x-thead-bs-fail.d | 3 +
> >> gas/testsuite/gas/riscv/x-thead-bs-fail.l | 3 +
> >> gas/testsuite/gas/riscv/x-thead-bs-fail.s | 3 +
> >> gas/testsuite/gas/riscv/x-thead-bs.d | 14 +
> >> gas/testsuite/gas/riscv/x-thead-bs.s | 6 +
> >> gas/testsuite/gas/riscv/x-thead-cmo-fail.d | 3 +
> >> gas/testsuite/gas/riscv/x-thead-cmo-fail.l | 22 ++
> >> gas/testsuite/gas/riscv/x-thead-cmo-fail.s | 22 ++
> >> gas/testsuite/gas/riscv/x-thead-cmo.d | 30 ++
> >> gas/testsuite/gas/riscv/x-thead-cmo.s | 22 ++
> >> gas/testsuite/gas/riscv/x-thead-condmov.d | 11 +
> >> gas/testsuite/gas/riscv/x-thead-condmov.s | 3 +
> >> .../gas/riscv/x-thead-fmemidx-fail.d | 3 +
> >> .../gas/riscv/x-thead-fmemidx-fail.l | 18 +
> >> .../gas/riscv/x-thead-fmemidx-fail.s | 17 +
> >> gas/testsuite/gas/riscv/x-thead-fmemidx.d | 25 ++
> >> gas/testsuite/gas/riscv/x-thead-fmemidx.s | 17 +
> >> gas/testsuite/gas/riscv/x-thead-mac.d | 15 +
> >> gas/testsuite/gas/riscv/x-thead-mac.s | 7 +
> >> gas/testsuite/gas/riscv/x-thead-memidx-fail.d | 3 +
> >> gas/testsuite/gas/riscv/x-thead-memidx-fail.l | 14 +
> >> gas/testsuite/gas/riscv/x-thead-memidx-fail.s | 14 +
> >> gas/testsuite/gas/riscv/x-thead-memidx.d | 53 +++
> >> gas/testsuite/gas/riscv/x-thead-memidx.s | 48 +++
> >> .../gas/riscv/x-thead-mempair-fail.d | 3 +
> >> .../gas/riscv/x-thead-mempair-fail.l | 30 ++
> >> .../gas/riscv/x-thead-mempair-fail.s | 30 ++
> >> gas/testsuite/gas/riscv/x-thead-mempair.d | 14 +
> >> gas/testsuite/gas/riscv/x-thead-mempair.s | 6 +
> >> gas/testsuite/gas/riscv/x-thead-sync-fail.d | 3 +
> >> gas/testsuite/gas/riscv/x-thead-sync-fail.l | 6 +
> >> gas/testsuite/gas/riscv/x-thead-sync-fail.s | 6 +
> >> gas/testsuite/gas/riscv/x-thead-sync.d | 14 +
> >> gas/testsuite/gas/riscv/x-thead-sync.s | 6 +
> >> include/opcode/riscv-opc.h | 326 ++++++++++++++++++
> >> include/opcode/riscv.h | 27 ++
> >> opcodes/riscv-dis.c | 44 +++
> >> opcodes/riscv-opc.c | 155 +++++++++
> >> 55 files changed, 1394 insertions(+), 2 deletions(-)
> >> create mode 100644 gas/testsuite/gas/riscv/mcpu-fail-unknown.d
> >> create mode 100644 gas/testsuite/gas/riscv/mcpu-fail-unknown.l
> >> create mode 100644 gas/testsuite/gas/riscv/mcpu-ok-c906.d
> >> create mode 100644 gas/testsuite/gas/riscv/mcpu-ok-c910.d
> >> create mode 100644 gas/testsuite/gas/riscv/x-thead-ba-fail.d
> >> create mode 100644 gas/testsuite/gas/riscv/x-thead-ba-fail.l
> >> create mode 100644 gas/testsuite/gas/riscv/x-thead-ba-fail.s
> >> create mode 100644 gas/testsuite/gas/riscv/x-thead-ba.d
> >> create mode 100644 gas/testsuite/gas/riscv/x-thead-ba.s
> >> create mode 100644 gas/testsuite/gas/riscv/x-thead-bb-fail.d
> >> create mode 100644 gas/testsuite/gas/riscv/x-thead-bb-fail.l
> >> create mode 100644 gas/testsuite/gas/riscv/x-thead-bb-fail.s
> >> create mode 100644 gas/testsuite/gas/riscv/x-thead-bb.d
> >> create mode 100644 gas/testsuite/gas/riscv/x-thead-bb.s
> >> create mode 100644 gas/testsuite/gas/riscv/x-thead-bs-fail.d
> >> create mode 100644 gas/testsuite/gas/riscv/x-thead-bs-fail.l
> >> create mode 100644 gas/testsuite/gas/riscv/x-thead-bs-fail.s
> >> create mode 100644 gas/testsuite/gas/riscv/x-thead-bs.d
> >> create mode 100644 gas/testsuite/gas/riscv/x-thead-bs.s
> >> create mode 100644 gas/testsuite/gas/riscv/x-thead-cmo-fail.d
> >> create mode 100644 gas/testsuite/gas/riscv/x-thead-cmo-fail.l
> >> create mode 100644 gas/testsuite/gas/riscv/x-thead-cmo-fail.s
> >> create mode 100644 gas/testsuite/gas/riscv/x-thead-cmo.d
> >> create mode 100644 gas/testsuite/gas/riscv/x-thead-cmo.s
> >> create mode 100644 gas/testsuite/gas/riscv/x-thead-condmov.d
> >> create mode 100644 gas/testsuite/gas/riscv/x-thead-condmov.s
> >> create mode 100644 gas/testsuite/gas/riscv/x-thead-fmemidx-fail.d
> >> create mode 100644 gas/testsuite/gas/riscv/x-thead-fmemidx-fail.l
> >> create mode 100644 gas/testsuite/gas/riscv/x-thead-fmemidx-fail.s
> >> create mode 100644 gas/testsuite/gas/riscv/x-thead-fmemidx.d
> >> create mode 100644 gas/testsuite/gas/riscv/x-thead-fmemidx.s
> >> create mode 100644 gas/testsuite/gas/riscv/x-thead-mac.d
> >> create mode 100644 gas/testsuite/gas/riscv/x-thead-mac.s
> >> create mode 100644 gas/testsuite/gas/riscv/x-thead-memidx-fail.d
> >> create mode 100644 gas/testsuite/gas/riscv/x-thead-memidx-fail.l
> >> create mode 100644 gas/testsuite/gas/riscv/x-thead-memidx-fail.s
> >> create mode 100644 gas/testsuite/gas/riscv/x-thead-memidx.d
> >> create mode 100644 gas/testsuite/gas/riscv/x-thead-memidx.s
> >> create mode 100644 gas/testsuite/gas/riscv/x-thead-mempair-fail.d
> >> create mode 100644 gas/testsuite/gas/riscv/x-thead-mempair-fail.l
> >> create mode 100644 gas/testsuite/gas/riscv/x-thead-mempair-fail.s
> >> create mode 100644 gas/testsuite/gas/riscv/x-thead-mempair.d
> >> create mode 100644 gas/testsuite/gas/riscv/x-thead-mempair.s
> >> create mode 100644 gas/testsuite/gas/riscv/x-thead-sync-fail.d
> >> create mode 100644 gas/testsuite/gas/riscv/x-thead-sync-fail.l
> >> create mode 100644 gas/testsuite/gas/riscv/x-thead-sync-fail.s
> >> create mode 100644 gas/testsuite/gas/riscv/x-thead-sync.d
> >> create mode 100644 gas/testsuite/gas/riscv/x-thead-sync.s
> >>
> >> --
> >> 2.37.2
> >>
>
More information about the Binutils
mailing list