RFR 8136924 Vectorized support for array equals/compare/mismatch using Unsafe

[Vladimir Kozlov]

I reviewed 8143355 today and my main question is where are range checks?

Thanks,
Vladimir

On 11/25/15 1:53 AM, Paul Sandoz wrote:
> Hi,
>
> And this is the review for the Java part:
>
>    http://cr.openjdk.java.net/~psandoz/jdk9/JDK-8136924-arrays-mismatch-vectorized-unsafe/webrev/
>
> Which will be updated to add @HotSpotIntrinsicCandidate when JDK-8143355 is pushed. [1]
>
> The plan is all reviewed changes will be pushed to hs-comp and then we follow up:
>
>    1) adding the intrinsic to other platforms
>
>    2) improving C1 (perhaps even the interpreter?) since the intrinsic is a stub which IIUC makes it easier to plug in.
>
>    3) take a swing at consolidating other equal/compare intrinsics, such as those for char[]/String-based equal/compare
>
>    4) adding methods to String such as mismatch method.
>
> I can help by pushing all reviewed patches. I will kick off a JPRT run with all patches applied.
>
> I did evaluate/test the HotSpot patch (stared at the patch and generated code for UseAVX < 2, and measured) and reviewed with my limited knowledge of HotSpot.
>
> Paul.
>
> [1]
> diff -r 01b49c2960fd src/java.base/share/classes/java/util/ArraysSupport.java
> --- a/src/java.base/share/classes/java/util/ArraysSupport.java	Tue Nov 17 15:42:53 2015 +0100
> +++ b/src/java.base/share/classes/java/util/ArraysSupport.java	Tue Nov 17 17:05:09 2015 +0100
> @@ -24,7 +24,7 @@
>   */
> package java.util;
>
> -//import jdk.internal.HotSpotIntrinsicCandidate;
> +import jdk.internal.HotSpotIntrinsicCandidate;
> import jdk.internal.misc.Unsafe;
>
> class ArraysSupport {
> @@ -72,7 +72,7 @@
>       * If a mismatch is not found the negation of one plus the number of
>       * remaining pairs of elements to be checked in the tail of the two arrays.
>       */
> -//    @HotSpotIntrinsicCandidate
> +    @HotSpotIntrinsicCandidate
>      static int vectorizedMismatch(Object a, long aOffset,
>                                    Object b, long bOffset,
>                                    int length,
>
>> On 25 Nov 2015, at 01:00, Deshpande, Vivek R <vivek.r.deshpande at intel.com> wrote:
>>
>> Hi all
>>
>> We would like to contribute a patch from Intel which optimizes vectorizedMismatch() method in java.util.ArraysSupport.java for X86 architecture using AVX instructions.
>> The improvement gives more than 2x gain over Unsafe implementation for long arrays.
>> The bug is blocked by bug: vectorized support for array equals/compare/mismatch using Unsafe (https://bugs.openjdk.java.net/browse/JDK-8136924.)
>> Could you please review and sponsor this patch.
>>
>> Bug-id:
>> https://bugs.openjdk.java.net/browse/JDK-8143355
>> webrev:
>> http://cr.openjdk.java.net/~mcberg/8143355/webrev.01/
>>
>> Thanks and regards,
>> Vivek
>