RFR: 8265518: C1: Intrinsic support for Preconditions.checkIndex [v2]

Alan Bateman alanb at openjdk.java.net
Mon Apr 26 13:23:27 UTC 2021

On Fri, 23 Apr 2021 03:50:54 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 java_nio_Buffer in javaClasses.hpp

src/java.base/share/classes/java/nio/Buffer.java line 740:

> 738:      */
> 739:     final int checkIndex(int i) {                       // package-private
> 740:         return Objects.checkIndex(i, limit);

Changing Buffer.checkIndex to use Objects.checkIndex is okay.


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

More information about the hotspot-compiler-dev mailing list