Integrated: 8283681: Improve ZonedDateTime offset handling

[Claes Redestad]

On Fri, 25 Mar 2022 12:28:58 GMT, Claes Redestad <redestad at openjdk.org> wrote:

> Richard Startin prompted me to have a look at a case where java.time underperforms relative to joda time (https://twitter.com/richardstartin/status/1506975932271190017). 
> 
> It seems the java.time test of his suffer from heavy allocations due ZoneOffset::getRules allocating a new ZoneRules object every time and escape analysis failing to do the thing in his test. The patch here adds a simple specialization so that when creating ZonedDateTimes using a ZoneOffset we don't query the rules at all. This removes the risk of extra allocations and slightly speeds up ZonedDateTime creation for both ZoneOffset (+14%) and ZoneRegion (+5%) even when EA works like it should (the case in the here provided microbenchmark).

This pull request has now been integrated.

Changeset: 7bac0a87
Author:    Claes Redestad <redestad at openjdk.org>
URL:       https://git.openjdk.java.net/jdk/commit/7bac0a878d918745ed036954cbbee590ce810c71
Stats:     156 lines in 5 files changed: 152 ins; 0 del; 4 mod

8283681: Improve ZonedDateTime offset handling

Reviewed-by: scolebourne, naoto, rriggs

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PR: https://git.openjdk.java.net/jdk/pull/7957