Integrated: 8295110: RISC-V: Mark out relocations as incompressible

[Xiaolin Zheng]

On Tue, 11 Oct 2022 05:32:51 GMT, Xiaolin Zheng <xlinzheng at openjdk.org> wrote:

> This patch marks all relocations incompressible as pre-discussions at [1] and converts instructions to their 2-byte compressible counterparts as much as possible when UseRVC is enabled.
> 
> Chaining PR #10421.
> 
> 1. Code size reduction rate: about ~17% now after this patch under RVC, meaning if there's a piece of code of 1000 bytes, it may shrink to 830 bytes when RVC is enabled. [2]
> 2. Performance: conservatively no regressions observed. [3]
> 
> The overloaded `relocate()` methods hide `IncompressibleRegion`s inside, to exclude instructions used at relocations from being compressed.
> 
> 
> Having tested several times hotspot tier1~tier4; Testing another turn on board.
> 
> 
> 
> [1] https://mail.openjdk.org/pipermail/riscv-port-dev/2022-September/000615.html
> [2] https://mail.openjdk.org/pipermail/riscv-port-dev/2022-September/000633.html
> [3] https://mail.openjdk.org/pipermail/riscv-port-dev/2022-October/000656.html

This pull request has now been integrated.

Changeset: 9005af3b
Author:    Xiaolin Zheng <xlinzheng at openjdk.org>
Committer: Fei Yang <fyang at openjdk.org>
URL:       https://git.openjdk.org/jdk/commit/9005af3b90fbd3607aeb83efe1c4a6ffa5d104f0
Stats:     312 lines in 12 files changed: 148 ins; 3 del; 161 mod

8295110: RISC-V: Mark out relocations as incompressible

Reviewed-by: fyang, yadongwang

-------------

PR: https://git.openjdk.org/jdk/pull/10643