[aarch64-port-dev ] [16] RFR[S]: 8251216: Implement MD5 intrinsics on AArch64

[Stuart Monteith]

On 11/08/2020 11:06, Andrew Haley wrote:
> On 09/08/2020 04:19, Ludovic Henry wrote:
>> Hello,
>>
>> Bug: https://bugs.openjdk.java.net/browse/JDK-8251216
>> Webrev: http://cr.openjdk.java.net/~luhenry/8251216/webrev.00
>>
>> Testing: Linux-AArch64, fastdebug, test/hotspot/jtreg/compiler/intrinsics/sha/ test/hotspot/jtreg:tier1 test/jdk:tier1
>>
>> This patch implements the MD5 intrinsic on AArch64 following its implementation on x86 [1]. The performance
>> improvements are the following (on Linux-AArch64 on a Marvell TX2):
>>
>> -XX:-UseMD5Intrinsics
>> Benchmark              (digesterName)  (length)  (provider)   Mode  Cnt     Score    Error   Units
>> MessageDigests.digest             md5        64     DEFAULT  thrpt   10  1616.238 ± 28.082  ops/ms
>> MessageDigests.digest             md5      1024     DEFAULT  thrpt   10   215.030 ±  0.691  ops/ms
>> MessageDigests.digest             md5   1048576     DEFAULT  thrpt   10     0.228 ±  0.001  ops/ms
>>
>> -XX:+UseMD5Intrinsics
>> Benchmark              (digesterName)  (length)  (provider)   Mode  Cnt     Score    Error   Units
>> MessageDigests.digest             md5        64     DEFAULT  thrpt   10  2005.233 ± 40.513  ops/ms => 24% speedup
>> MessageDigests.digest             md5      1024     DEFAULT  thrpt   10   275.979 ±  0.455  ops/ms => 28% speedup
>> MessageDigests.digest             md5   1048576     DEFAULT  thrpt   10     0.279 ±  0.001  ops/ms => 22% speedup
>>
>> Thank you,
>> Ludovic
>>
>> [1] https://bugs.openjdk.java.net/browse/JDK-8250902
>>
>
> How did you test this? I'm looking through the test suite, but I can't
> find the test vectors. They must be in there somewhere.
>
> https://www.nist.gov/itl/ssd/software-quality-group/nsrl-test-data
>

I've been looking over this patch too. The fundamental unit test is:
    test/hotspot/jtreg/compiler/intrinsics/sha/TestDigest.java

The method "testDigest" generates an byte array of a given size, with each element filled with it's own index & 0xff.
The test is then run once, assumed uncompiled, it is then "warmed up" and the first generated digest is compared against
the digest presumably generated by the intrinsic. This is the same test for all of the message digest algorithms.

I'd say the test is no worse than what has gone before. There are additional tests under the jdk library tests, but
nothing that addresses the correctness of the MD5 algorithm implementation itself.

In terms of the status-quo, that patch looks ok to me. I think if the testing is to be expanded, it should be expanded
to all of the message digest algorithms.

BR,
        Stuart
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