Integrated: 8299844: RISC-V: Implement _onSpinWait intrinsic

[Yadong Wang]

On Tue, 10 Jan 2023 09:52:40 GMT, Yadong Wang <yadongwang at openjdk.org> wrote:

> Implement _onSpinWait() intrinsic for RISC-V, and it can be implemented by using PAUSE instruction from Zihintpause Extension, which is ratified and a mandatory extension of RVA22U64 (https://github.com/riscv/riscv-profiles/blob/main/profiles.adoc#rva22u64-mandatory-extensions).
> Software can use the PAUSE instruction to reduce energy consumption while executing spinwait
> code sequences (https://github.com/riscv/riscv-isa-manual/blob/master/src/zihintpause.tex).
> 
> Add a test case of test/hotspot/jtreg/compiler/onSpinWait/TestOnSpinWaitRISCV64.java, passed on QEMU.

This pull request has now been integrated.

Changeset: af564e46
Author:    Yadong Wang <yadongwang at openjdk.org>
Committer: Fei Yang <fyang at openjdk.org>
URL:       https://git.openjdk.org/jdk/commit/af564e46b006fcd57ec7391cd1438b3b9311b1d6
Stats:     133 lines in 8 files changed: 120 ins; 0 del; 13 mod

8299844: RISC-V: Implement _onSpinWait intrinsic

Reviewed-by: fjiang, fyang, luhenry

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PR: https://git.openjdk.org/jdk/pull/11921