Integrated: 8260337: Optimize ImageReader lookup, used by Class.getResource

[Claes Redestad]

On Mon, 25 Jan 2021 00:05:52 GMT, Claes Redestad <redestad at openjdk.org> wrote:

> This patch optimizes the code paths exercised by `String.class.getResource("String.class")` by:
> 
> - Adding an ASCII fast-path to methods verifying strings in the jimage, which can then be done allocation-free
> - Avoiding the allocation of the `long[8]` attributes when verifying only for the purpose of verifying a path exists
> - Using the `JNUA.create` fast-path in `SystemModuleReader` (which should be OK since we just verified the given name is a JRT path)
> - Remove a redundant check in `Class::resolveName` and fitting the `StringBuilder` to size

This pull request has now been integrated.

Changeset: 2f893c2b
Author:    Claes Redestad <redestad at openjdk.org>
URL:       https://git.openjdk.java.net/jdk/commit/2f893c2b
Stats:     393 lines in 8 files changed: 263 ins; 63 del; 67 mod

8260337: Optimize ImageReader lookup, used by Class.getResource

Reviewed-by: jlaskey, sundar

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PR: https://git.openjdk.java.net/jdk/pull/2212