[jdk17u-dev] RFR: 8309254: Implement fast-path for ASCII-compatible CharsetEncoders on RISC-V

Tue Jul 11 09:13:25 UTC 2023

I would like to backport [JDK-8309254](https://bugs.openjdk.org/browse/JDK-8309254). 
The backport is not clean because 17u has no  [JDK-8302908](https://bugs.openjdk.org/browse/JDK-8302908), which use v0 as mask register.
The test `test/hotspot/jtreg/compiler/intrinsics/string/TestEncodeIntrinsics.java` passed and command log with "-XX:+PrintOptoAssembly" output is similar to the mainline:

...
240     Encode ISO array R12, R11, R13 -> R10 # KILL R12, R11, R13, R28, V1-V3
...
0118    Encode ASCII array R12, R11, R13 -> R10 # KILL R12, R11, R13, R25, V1-V3
...

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Commit messages:
 - 8309254: Implement fast-path for ASCII-compatible CharsetEncoders on RISC-V

Changes: https://git.openjdk.org/jdk17u-dev/pull/1567/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk17u-dev&pr=1567&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8309254
  Stats: 47 lines in 4 files changed: 30 ins; 0 del; 17 mod
  Patch: https://git.openjdk.org/jdk17u-dev/pull/1567.diff
  Fetch: git fetch https://git.openjdk.org/jdk17u-dev.git pull/1567/head:pull/1567

PR: https://git.openjdk.org/jdk17u-dev/pull/1567