CFV: New Project: RISC-V Port

[Yangfei (Felix)]

I hereby propose the creation of the "RISC-V Port" Project with Fei Yang
as the Lead and Porters Group as the sponsoring group [1].

The goal of the project will be to provide a full featured port of OpenJDK
on the RISC-V platform.  The current project would only target Linux. RISC-V
ISA is actually a family of related ISAs of which there are currently four
base ISAs [2].  Those base ISAs can be combined with a set of standard
extensions. RV64G and RV32G are defined as general-purpose ISAs.  This port
will support RV64GV , i.e., RV64G ISA plus the "V" standard extension for
vector operations [3].  And the implementation will be fully compatible with
RISC-V ISA specifications.  This port may support other ISA variants like
RV32G depending on community interest.

We (Huawei Technologies) already have a complete (i.e. template interpreter,
C1 and C2 JIT) RISC-V port.  This work is based on reasonably recent snapshot
of JDK mainline and resides in the riscv-port-branch of jdk-sandbox:

https://github.com/openjdk/jdk-sandbox/tree/riscv-port-branch

We've passed JTReg tests on QEMU and HiFive Unleashed board.  So it should be
good enough to run most Java programs.  The VectorAPI and ForeignAPI features
are not supported for now.  Support for vector operations is experimental, we
need to do more testing for this part.  We've provided full build instructions
[4], but we'll help you if you get stuck.  Aleksey Shipilev is building
riscv-port-branch nightlies here [5].  We want people to try it out.

We intend to continuously rebase the source code to the latest JDK mainline, and
then, after a round of in-project reviews, suggest it for integration into JDK
mainline.  If this project is approved, I believe we still have time to submit
the integration JEP targeting JDK 18.  We would welcome your advice and
guidance about this.

We will consider 17u and 11u backports, after JDK mainline integration is done.
This, of course, depends on whether the 17u and 11u maintainers would approve
such backport.

Fei Yang has been working on OpenJDK for aarch64 port project since year 2015
and is an OpenJDK committer [6].  He is currently a major developer for OpenJDK
RISC-V port and has reviewed most of the code changes internally.  Previously,
he is also a GCC committer [7] and has contributed various performance and
bugfixes since year 2013.

The proposed initial set of reviewers are:

Fei Yang
Aleksey Shipilev
Edward Nevill
 
Votes are due by 9:00 UTC on Monday 25, October 2021
 
Only current OpenJDK Members [8] are eligible to vote on this
motion.  Votes must be cast in the open on the discuss list.
Replying to this message is sufficient if your mail program
honors the Reply-To header.
 
For Lazy Consensus voting instructions, see [9].

Fei Yang

[1] https://mail.openjdk.java.net/pipermail/discuss/2021-October/005964.html
[2] https://github.com/riscv/riscv-isa-manual
[3] https://github.com/riscv/riscv-v-spec/releases/download/v1.0/riscv-v-spec-1.0.pdf
[4] http://cr.openjdk.java.net/~fyang/openjdk-riscv-port/BuildRISCVJDK.md
[5] https://builds.shipilev.net/openjdk-jdk-riscv
[6] http://openjdk.java.net/census#fyang
[7] https://github.com/gcc-mirror/gcc/blob/master/MAINTAINERS
[8] http://openjdk.java.net/census#members
[9] http://openjdk.java.net/projects/#new-project-vote