RFR: 8255150: Add utility methods to check long indexes and ranges [v6]
Roland Westrelin
roland at openjdk.java.net
Fri Nov 13 09:04:11 UTC 2020
> 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.
Roland Westrelin has updated the pull request with a new target base due to a merge or a rebase. The pull request now contains 24 commits:
- Merge branch 'master' of https://git.openjdk.java.net/jdk into JDK-8255150
- exclude compiler test when run with -Xcomp
- CastLL should define carry_depency
- intrinsic comments
- Jorn's comments
- Update headers and add intrinsic to Graal test ignore list
- move compiler test and add bug to test
- non x86_64 arch support
- c2 test case
- intrinsic
- ... and 14 more: https://git.openjdk.java.net/jdk/compare/b4d01867...90493e6e
-------------
Changes: https://git.openjdk.java.net/jdk/pull/1003/files
Webrev: https://webrevs.openjdk.java.net/?repo=jdk&pr=1003&range=05
Stats: 897 lines in 30 files changed: 846 ins; 4 del; 47 mod
Patch: https://git.openjdk.java.net/jdk/pull/1003.diff
Fetch: git fetch https://git.openjdk.java.net/jdk pull/1003/head:pull/1003
PR: https://git.openjdk.java.net/jdk/pull/1003
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