RFR: 8267125: AES Galois CounterMode (GCM) interleaved implementation using AVX512 + VAES instructions [v4]

[Valerie Peng]

On Wed, 14 Jul 2021 21:02:01 GMT, Smita Kamath <svkamath at openjdk.org> wrote:

>> I would like to submit AES-GCM optimization for x86_64 architectures supporting AVX3+VAES (Evex encoded AES). This optimization interleaves AES and GHASH operations.
>> Performance gain of ~1.5x - 2x for message sizes 8k and above.
>
> Smita Kamath has updated the pull request incrementally with one additional commit since the last revision:
> 
>   Updated AES-GCM intrinsic to match latest Java Code

src/java.base/share/classes/com/sun/crypto/provider/GaloisCounterMode.java line 629:

> 627:         GCTR gctr;
> 628:         GHASH ghash;
> 629:         GCMOperation op;

It seems clearer to initialize "op" in GCMEngine ctor since it's declared here. There is already logic in its method checking whether we are doing encryption or decryption.

src/java.base/share/classes/com/sun/crypto/provider/GaloisCounterMode.java line 650:

> 648:         int originalOutOfs = 0;
> 649:         byte[] in;
> 650:         byte[] out;

The name "in", "out" are almost used in all calls, it's hard to tell when these two are actually used. Can we rename them to make them more unique?

src/java.base/share/classes/com/sun/crypto/provider/GaloisCounterMode.java line 724:

> 722:             } else {
> 723:                 ct = in;
> 724:             }

This can just be:
byte[] ct = (encryption? out : in);

Since you only use this 'ct' variable inside the else block on line  746, move this down to that block.

src/java.base/share/classes/com/sun/crypto/provider/GaloisCounterMode.java line 743:

> 741:                             dst.array(), dst.arrayOffset() + dst.position(),
> 742:                             gctr, ghash);
> 743:                     }

Can we use another ByteBuffer variable to avoid almost-duplicate calls?

ByteBuffer ct = (encryption? dst : src);
rlen -= GaloisCounterMode.implGCMCrypt(src.array(),
                            src.arrayOffset() + src.position(), src.remaining(),
                            ct.array(), ct.arrayOffset() + ct.position(),
                            dst.array(), dst.arrayOffset() + dst.position(),
                            gctr, ghash);

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PR: https://git.openjdk.java.net/jdk/pull/4019