RFR: JDK-8314901: AES-GCM interleaved implementation using AVX2 instructions [v2]

[Sandhya Viswanathan]

On Wed, 13 Sep 2023 20:25:22 GMT, Smita Kamath <svkamath at openjdk.org> wrote:

>> Hi All, 
>> I would like to submit AES-GCM optimization for x86_64 architectures using AVX2 instructions. This optimization interleaves AES and GHASH operations.
>> 
>> Below are the performance numbers on my desktop system with -XX:UseAVX=2 option:
>> 
>> |Benchmark | Data Size | Base version (ops/s) | Patched version (ops/s) | Speedup
>> |-------------|------------|---------------|------------------|-----------|
>> |full.AESGCMBench.decrypt | 8192 | 526274.678 | 670014.543 | 1.27
>> full.AESGCMBench.encrypt | 8192 | 538293.315 | 680716.207 | 1.26
>> small.AESGCMBench.decrypt | 8192 |  527854.353 |663131.48 | 1.25
>> small.AESGCMBench.encrypt | 8192 |  548193.804 | 683624.232 |1.24
>> full.AESGCMBench.decryptMultiPart | 8192 |  299865.766 | 299815.851 | 0.99
>> full.AESGCMBench.encryptMultiPart | 8192 |  534406.564 |539235.462 | 1.00
>> small.AESGCMBench.decryptMultiPart | 8192 |  299960.202 |298913.629 | 0.99
>> small.AESGCMBench.encryptMultiPart | 8192 | 542669.258 | 540552.293 | 0.99
>>   |   |   |   |  
>> full.AESGCMBench.decrypt | 16384 |  307266.364 |390397.778 | 1.27
>> full.AESGCMBench.encrypt | 16384 | 311491.901 | 397279.681 | 1.27
>> small.AESGCMBench.decrypt | 16384 |  306257.801 | 389531.665 |1.27
>> small.AESGCMBench.encrypt | 16384 |  311468.972 | 397804.753 | 1.27
>> full.AESGCMBench.decryptMultiPart | 16384 |  159634.341 | 181271.487 | 1.13
>> full.AESGCMBench.encryptMultiPart | 16384 | 308980.992 | 385606.113 | 1.24
>> small.AESGCMBench.decryptMultiPart | 16384 | 160476.064 |181019.205 |  1.12
>> small.AESGCMBench.encryptMultiPart | 16384 | 308382.656 | 391126.417 | 1.26
>>   |   |   |   |  
>> full.AESGCMBench.decrypt | 32768 |  162284.703 | 213257.481 |1.31
>> full.AESGCMBench.encrypt | 32768 |  164833.104 | 215568.639 | 1.30
>> small.AESGCMBench.decrypt | 32768 |  164416.491 | 213422.347 | 1.29
>> small.AESGCMBench.encrypt | 32768 |  166619.205 | 214584.208 |1.28
>> full.AESGCMBench.decryptMultiPart | 32768 |  83306.239 | 93762.988 |1.12
>> full.AESGCMBench.encryptMultiPart | 32768 | 166109.391 |211701.969 |  1.27
>> small.AESGCMBench.decryptMultiPart | 32768 | 83792.559 | 94530.786 | 1.12
>> small.AESGCMBench.encryptMultiPart | 32768 |  162975.904 |212085.047 | 1.30
>>   |   |   |   |  
>> full.AESGCMBench.decrypt | 65536 | 85765.835 | 112244.611 | 1.30
>> full.AESGCMBench.encrypt | 65536 |  86471.805 | 113320.536 |1.31
>> small.AESGCMBench.decrypt | 65536 |  84490.816 | 112122.358 |1.32
>> small.AESGCMBench.encrypt | 65536 | 85403.025 | 112741.811 |  1.32
>> full.AES...
>
> Smita Kamath has updated the pull request incrementally with one additional commit since the last revision:
> 
>   Removed isEncrypt boolean variable

src/hotspot/cpu/x86/stubGenerator_x86_64_aes.cpp line 3399:

> 3397:     __ vpshufb(xmm6, xmm6, t5, Assembler::AVX_128bit); //perform a 16Byte swap
> 3398:     __ vpshufb(xmm7, xmm7, t5, Assembler::AVX_128bit); //perform a 16Byte swap
> 3399:     __ vpshufb(xmm8, xmm8, t5, Assembler::AVX_128bit); //perform a 16Byte swap

This could be written in a loop:
for (int rnum = 1; rnum <= 8; rnum++) {
    __ vpshufb(as_XMMRegister(rnum), as_XMMRegister(rnum), t5, Assembler::AVX_128bit);
}
Similar technique can be used in some places below.

src/hotspot/cpu/x86/stubGenerator_x86_64_aes.cpp line 4040:

> 4038:   __ aesenc(xmm6, t_key);
> 4039:   __ aesenc(xmm7, t_key);
> 4040:   __ aesenc(xmm8, t_key);

This code is repeated multiple times so can be generated through a method like aesenc_step_avx2(t_key);

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

PR Review Comment: https://git.openjdk.org/jdk/pull/15410#discussion_r1325200254
PR Review Comment: https://git.openjdk.org/jdk/pull/15410#discussion_r1325180777