From: Andrew Waterman <andrew@sifive.com>
To: Jeff Law <jeffreyalaw@gmail.com>
Cc: Philipp Tomsich <philipp.tomsich@vrull.eu>,
binutils@sourceware.org, Kito Cheng <kito.cheng@sifive.com>,
Nelson Chu <nelson.chu@sifive.com>,
Christoph Muellner <christoph.muellner@vrull.eu>
Subject: Re: [RFC PATCH v1] RISC-V: Support Zicond extension
Date: Wed, 25 Jan 2023 17:02:22 -0800 [thread overview]
Message-ID: <CA++6G0DdsuSN5MjSHwZM-bA9Py_mVGEocufj0N=e0dZ51vZ7-w@mail.gmail.com> (raw)
In-Reply-To: <7dfcdb8b-f8ba-f0ae-b71f-f6fef1acac13@gmail.com>
On Wed, Jan 25, 2023 at 4:27 PM Jeff Law via Binutils
<binutils@sourceware.org> wrote:
>
>
>
> On 1/20/23 17:29, Philipp Tomsich wrote:
> > *** Zicond is not FROZEN at this time. Do not merge until FROZEN. ***
> >
> > This implements the Zicond (conditional integer operations) extension,
> > as of version 1.0-draft-20230120.
> >
> > The Zicond extension acts as a building block for branchless sequences
> > including conditional-arithmetic, conditional-logic and
> > conditional-select/move.
> > The following instructions constitute Zicond:
> > - czero.eqz rd, rs1, rs2 => rd = (rs2 == 0) ? 0 : rs1
> > - czero.nez rd, rs1, rs2 => rd = (rs2 != 0) ? 0 : rs1
> >
> > See
> > https://github.com/riscv/riscv-zicond/releases/download/v1.0-draft-20230120/riscv-zicond_1.0-draft-20230120.pdf
> > for the proposed specification and usage details.
> >
> > bfd/ChangeLog:
> >
> > * elfxx-riscv.c (riscv_multi_subset_supports): Recognize
> > INSN_CLASS_XVENTANACONDOPS.
> > (riscv_multi_subset_supports_ext): Recognize
> > INSN_CLASS_XVENTANACONDOPS,
> >
> > gas/ChangeLog:
> >
> > * testsuite/gas/riscv/zicond.d: New test.
> > * testsuite/gas/riscv/zicond.s: New test.
> >
> > include/ChangeLog:
> >
> > * opcode/riscv-opc.h (MATCH_CZERO_EQZ): Define.
> > (MASK_CZERO_EQZ): Define.
> > (MATCH_CZERO_NEZ): Define,
> > (MASK_CZERO_NEZ): Define.
> > (DECLARE_INSN): Add czero.eqz and czero.nez.
> > * opcode/riscv.h (enum riscv_insn_class): Add
> > INSN_CLASS_ZICOND
> >
> > opcodes/ChangeLog:
> >
> > * riscv-opc.c: Add czero.eqz and czero.nez.
> Given this extension is derived from the Ventana condops extension, I
> may be somewhat biased.
This is very much a standardized version of Ventana's custom condops
extension, modulo some details.
> The mnemonics and encoding is obviously
> different, but the behavior is the same (perhaps differing in timing
> characteristics, but I think that's outside of what we care about here).
>
> I assume nobody cares about gdbsim, so nothing to do there. With that
> assumption this is fine to go forward once the spec freezes.
As for a status update, the RVI architecture-review committee recently
voted to approve the extension, so the official freeze should be
forthcoming.
>
> jeff
>
next prev parent reply other threads:[~2023-01-26 1:02 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-01-21 0:29 Philipp Tomsich
2023-01-26 0:26 ` Jeff Law
2023-01-26 1:02 ` Andrew Waterman [this message]
2023-03-01 1:58 ` Nelson Chu
2023-03-01 2:03 ` Palmer Dabbelt
2023-06-19 14:21 ` Philipp Tomsich
2023-06-21 4:25 ` Jeff Law
2023-06-21 4:38 ` Palmer Dabbelt
2023-06-27 13:27 ` Jeff Law
2023-06-27 14:32 ` Philipp Tomsich
2023-06-27 23:12 ` Jeff Law
2023-06-27 23:33 ` Palmer Dabbelt
2023-06-27 14:48 ` Palmer Dabbelt
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to='CA++6G0DdsuSN5MjSHwZM-bA9Py_mVGEocufj0N=e0dZ51vZ7-w@mail.gmail.com' \
--to=andrew@sifive.com \
--cc=binutils@sourceware.org \
--cc=christoph.muellner@vrull.eu \
--cc=jeffreyalaw@gmail.com \
--cc=kito.cheng@sifive.com \
--cc=nelson.chu@sifive.com \
--cc=philipp.tomsich@vrull.eu \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for read-only IMAP folder(s) and NNTP newsgroup(s).