RFR: 8265518: C1: Intrinsic support for Preconditions.checkIndex [v6]

Paul Sandoz psandoz at openjdk.java.net
Fri Apr 30 17:33:52 UTC 2021

On Fri, 30 Apr 2021 02:19:30 GMT, Yi Yang <yyang at openjdk.org> wrote:

>> The JDK codebase re-created many variants of checkIndex(`grep -I -r 'cehckIndex' jdk/`). A notable variant is java.nio.Buffer.checkIndex, which annotated with @IntrinsicCandidate and it only has a corresponding C1 intrinsic version.
>> In fact, there is an utility method `jdk.internal.util.Preconditions.checkIndex`(wrapped by java.lang.Objects.checkIndex) that behaves the same as these variants of checkIndex, we can replace these re-created variants of checkIndex by Objects.checkIndex, it would significantly reduce duplicated code and enjoys performance improvement because Preconditions.checkIndex is @IntrinsicCandidate and it has a corresponding intrinsic method in HotSpot.
>> But, the problem is currently HotSpot only implements the C2 version of Preconditions.checkIndex. To reuse it global-widely in JDK code, I think we can firstly implement its C1 counterpart. There are also a few kinds of stuff we can do later:
>> 1. Replace all variants of checkIndex by Objects.checkIndex in the whole JDK codebase.
>> 2. Remove Buffer.checkIndex and obsolete/deprecate InlineNIOCheckIndex flag
>> Testing: cds, compiler and jdk
> Yi Yang has updated the pull request incrementally with one additional commit since the last revision:
>   better check1-4

It was my hope this would eventually happen when we added `Objects.checkIndex` and the underlying intrinsic. Very good!


PR: https://git.openjdk.java.net/jdk/pull/3615

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