RFR: 8255150: Add utility methods to check long indexes and ranges [v7]

Roland Westrelin roland at openjdk.java.net
Tue Nov 17 08:33:20 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 27 commits:

 - Merge branch 'master' of https://git.openjdk.java.net/jdk into JDK-8255150
 - Merge branch 'master' into JDK-8255150
 - Merge branch 'master' into JDK-8255150
 - 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
 - ... and 17 more: https://git.openjdk.java.net/jdk/compare/4553fa0b...feb32943

-------------

Changes: https://git.openjdk.java.net/jdk/pull/1003/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk&pr=1003&range=06
  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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