Integrated: 8326653: Remove jdk.internal.reflect.UTF8

[Claes Redestad]

On Mon, 26 Feb 2024 11:05:10 GMT, Claes Redestad <redestad at openjdk.org> wrote:

> jdk.internal.reflect.UTF8 is used for encoding String to encoded UTF-8 when generating some classes. 
> 
> Since JDK 9 we have a fast-path (which avoids creating encoders) for UTF-8-encoding strings which is bootstrapped very early, so it seems safe to rewire this and remove the UTF8 helper class whose stated raison d'être is to avoid bootstrapping issues.
> 
> This cleanup also removes a latent bug since the custom encoder isn't able to deal with classfile constants containing surrogate pairs.
> 
> For a quick comparison I copied the UTF8 code to the `StringEncode` microbenchmark and set up a benchmark testing the same inputs as `encodeAllMixed`:
> 
> 
> Benchmark                                (charsetName)  Mode  Cnt       Score      Error  Units
> StringEncode.encodeAllMixed                      UTF-8  avgt   10   12894,551 ±  164,816  ns/op
> StringEncode.encodeUTF8InternalAllMixed          UTF-8  avgt   10  236614,548 ± 1445,975  ns/op
> 
> 
> I.e. `String.getBytes(UTF_8.instance)` is about 18x faster on mixed inputs. The benchmark is available in 595b464 but as a quick sanity check not intended for integration. 
> 
> Testing: tier1-3

This pull request has now been integrated.

Changeset: c042f086
Author:    Claes Redestad <redestad at openjdk.org>
URL:       https://git.openjdk.org/jdk/commit/c042f0863247633e98ace9757fb8531145286e66
Stats:     81 lines in 2 files changed: 2 ins; 78 del; 1 mod

8326653: Remove jdk.internal.reflect.UTF8

Reviewed-by: rriggs, alanb

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PR: https://git.openjdk.org/jdk/pull/18006