Integrated: 8255150: Add utility methods to check long indexes and ranges

[Roland Westrelin]

On Mon, 2 Nov 2020 10:47:18 GMT, Roland Westrelin <roland at openjdk.org> wrote:

> This change add 3 new methods in Objects:
> 
> public static long checkIndex(long index, long length)
> public static long checkFromToIndex(long fromIndex, long toIndex, long length)
> public static long checkFromIndexSize(long fromIndex, long size, long length)
> 
> This mirrors the int utility methods that were added by JDK-8135248
> with the same motivations.
> 
> As is the case with the int checkIndex(), the long checkIndex() method
> is JIT compiled as an intrinsic. It allows the JIT to compile
> checkIndex to an unsigned comparison and properly recognize it as
> a range check that then becomes a candidate for the existing range check
> optimizations. This has proven to be important for panama's
> MemorySegment API and a prototype of this change (with some extra c2
> improvements) showed that panama micro benchmark results improve
> significantly.
> 
> This change includes:
> 
> - the API change
> - the C2 intrinsic
> - tests for the API and the C2 intrinsic
> 
> This is a joint work with Paul who reviewed and reworked the API change
> and filled the CSR.

This pull request has now been integrated.

Changeset: a7422ac2
Author:    Roland Westrelin <roland at openjdk.org>
URL:       https://git.openjdk.java.net/jdk/commit/a7422ac2
Stats:     897 lines in 30 files changed: 846 ins; 4 del; 47 mod

8255150: Add utility methods to check long indexes and ranges

Co-authored-by: Paul Sandoz <psandoz at openjdk.org>
Reviewed-by: jvernee, dlong, vlivanov

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PR: https://git.openjdk.java.net/jdk/pull/1003