RFR: 8308765: RISC-V: Expand size of stub routines for zgc only

[Fei Yang]

On Mon, 29 May 2023 14:55:47 GMT, Yadong Wang <yadongwang at openjdk.org> wrote:

> Size of stub routines is over expanded after https://bugs.openjdk.org/browse/JDK-8307058. It should return to a proper size, and only increase when zgc enabled on riscv, same as that on aarch64 and x86 port.
> This PR also guarantees that li16u instructions can only accept 16 bits immediate values when patched or encoded.
> 
> The new size of stubs are tested with -XX:+UseZGC -XX:+ZGenerational -XX:-UseRVC, and checked with -Xlog:stubs.
> 
> Tier 1~3 passed on the unmatched boards.

Looks fine.

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Marked as reviewed by fyang (Reviewer).

PR Review: https://git.openjdk.org/jdk/pull/14203#pullrequestreview-1452134380