RFR: 8265518: C1: Intrinsic support for Preconditions.checkIndex [v4]

Daniel Fuchs dfuchs at openjdk.java.net
Thu Apr 29 09:33:58 UTC 2021

On Thu, 29 Apr 2021 02:53:18 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:
>   remove extra newline

test/hotspot/jtreg/compiler/c1/TestCheckIndexC1Intrinsic.java line 60:

> 58:         } catch (IndexOutOfBoundsException e) {
> 59:             // got it!
> 60:         }

In all places where `Precondition.checkIndex` is expected to throw, an AssertionError should  be generated if it doesn't throw:

        try {
            Preconditions.checkIndex(1, 1, null);
            throw new AssertionError("Expected IndexOutOfBoundsException not thrown");
        } catch (IndexOutOfBoundsException e) {
            // got it!


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

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