RFR: 8248188: Add IntrinsicCandidate and API for Base64 decoding [v5]

[Vladimir Kozlov]

On Mon, 12 Oct 2020 21:41:37 GMT, CoreyAshford <github.com+51754783+CoreyAshford at openjdk.org> wrote:

>> This patch set encompasses the following commits:
>> 
>> - Adds a new HotSpot intrinsic candidate to the java.lang.Base64 class - decodeBlock(), and provides a flexible API for
>>   the intrinsic.  The API is similar to the existing encodeBlock intrinsic.
>> - Adds the code in HotSpot to check and martial the new intrinsic's arguments to the arch-specific intrinsic
>>   implementation
>> - Adds a Power64LE-specific implementation of the decodeBlock intrinsic.
>> - Adds a JMH microbenchmark for both Base64 encoding and encoding.
>> - Enhances the JTReg hotspot intrinsic "TestBase64.java" regression test to more fully test both decoding and encoding.
>
> CoreyAshford has updated the pull request incrementally with one additional commit since the last revision:
> 
>   Per Martin Doerr's v4 review: fix regression, and speed up return time for buffers that are too small
>   
>    - Check for case where the result of subtacting 12 off of the source
>      length produces a negative number.  To do this efficiently, I added the
>      instruction definition for mcrxrx, which is implemented on Power9+.
>   
>    - Rearrange the code so that minimal initialization is performed before
>      checking the size, so that the intrinsic can return quickly in the event
>      that the buffer is too small to process.

Please, update
src/jdk.internal.vm.compiler/share/classes/org.graalvm.compiler.hotspot.test/src/org/graalvm/compiler/hotspot/test/CheckGraalIntrinsics.java

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

Changes requested by kvn (Reviewer).

PR: https://git.openjdk.java.net/jdk/pull/293