[riscv-port] RFR: 8277392: riscv: Port missing trampoline logic from AArch64 platform

[Fei Yang]

On Thu, 18 Nov 2021 12:38:35 GMT, zhengxiaolinX <duke at openjdk.java.net> wrote:

> Hi team,
> 
> Java calls will jump to the trampoline stub even if the target address is directly reachable by using a simple `jal` before this patch. After adding back the logic from the AArch64 platform, we find a nearly 4% performance enhancement on SPECjbb2005/15. Tested tests under hotspot/ and jdk/. [Original Patch](https://github.com/riscv-collab/riscv-openjdk/pull/8)
> 
> Thanks,
> Xiaolin

Looks good. Thanks.

Marked as reviewed by fyang (Lead).

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Changes requested by fyang (Lead).

PR: https://git.openjdk.java.net/riscv-port/pull/8