Replicating __mm256_shuffle_epi8 Intrinsic
Radosław Smogura
mail at smogura.eu
Wed Jul 7 10:03:14 UTC 2021
Michel,
I wonder as well if you did consider using shuffles and vector operations to load int vector, instead of using bytesToIntLE. I wonder if loading to two vectors initially and permitting with shuffle would be better.
Kind regards,
Rado
________________________________
From: Michael Ennen <mike.ennen at gmail.com>
Sent: Wednesday, July 7, 2021 08:17
To: Radosław Smogura <mail at smogura.eu>
Cc: Viswanathan, Sandhya <sandhya.viswanathan at intel.com>; panama-dev at openjdk.java.net <panama-dev at openjdk.java.net>
Subject: Re: Replicating __mm256_shuffle_epi8 Intrinsic
I figured it out. It was a mismatch of little and big endian. I can reproduce the same shuffle result with:
IntVector read8(byte[] chunk, int offset) {
System.out.println("read8, offset = " + offset);
IntVector ret = IntVector.fromArray(SPECIES_256, new int[] {
bytesToIntLE(chunk, 0 + offset),
bytesToIntLE(chunk, 64 + offset),
bytesToIntLE(chunk, 128 + offset),
bytesToIntLE(chunk, 192 + offset),
bytesToIntLE(chunk, 256 + offset),
bytesToIntLE(chunk, 320 + offset),
bytesToIntLE(chunk, 384 + offset),
bytesToIntLE(chunk, 448 + offset)}, 0);
System.out.println("read8 in: " + bytesToIntLE(chunk, 0 + offset) + ", " + bytesToIntLE(chunk, 64 + offset) +
", " + bytesToIntLE(chunk, 128 + offset) + ", " + bytesToIntLE(chunk, 192 + offset) + ", " +
bytesToIntLE(chunk, 256 + offset) + ", " + bytesToIntLE(chunk, 320 + offset) + ", " +
bytesToIntLE(chunk, 384 + offset) + ", " + bytesToIntLE(chunk, 448 + offset));
var shuffle = VectorShuffle.fromArray(ByteVector.SPECIES_256, new int[]{
12,13,14,15, 8, 9,10,11,
4, 5, 6, 7, 0, 1, 2, 3,
12,13,14,15, 8, 9,10,11,
4, 5, 6, 7, 0, 1, 2, 3 }, 0);
ByteVector shuffled = ret.reinterpretAsBytes().rearrange(shuffle, shuffle.laneIsValid());
System.out.println("read8 after shuffle: " + IntVector.fromByteArray(SPECIES_256, shuffled.toArray(), 0, ByteOrder.BIG_ENDIAN));
return IntVector.fromByteArray(SPECIES_256, shuffled.toArray(), 0, ByteOrder.BIG_ENDIAN );
}
Thanks for all your help.
On Tue, Jul 6, 2021 at 11:10 PM Michael Ennen <mike.ennen at gmail.com<mailto:mike.ennen at gmail.com>> wrote:
Oh my gosh how embarrassing! I have been tweaking things so much in this code I really needed to step back and take a closer look.
I still don't get the right result (matching this: https://github.com/brcolow/bitcoin-sha256/blob/master/src/sha256_avx2.cpp#L70).
I will keep trying, though.
On Tue, Jul 6, 2021 at 2:48 PM Radosław Smogura <mail at smogura.eu<mailto:mail at smogura.eu>> wrote:
Hi Michael,
intoArray is not only for vector shuffle, and I think it's preffered way to load and store data (as Sandhya used).
Maybe this sound too simply, but I wonder if you are absolutely sure that this line should look like this, and it should not print shuffled vector? System.out.println("read8 returns: " + ret); :)
Kind regards,
Rado
________________________________
From: Michael Ennen <mike.ennen at gmail.com<mailto:mike.ennen at gmail.com>>
Sent: Tuesday, July 6, 2021 21:29
To: Radosław Smogura <mail at smogura.eu<mailto:mail at smogura.eu>>
Cc: Viswanathan, Sandhya <sandhya.viswanathan at intel.com<mailto:sandhya.viswanathan at intel.com>>; panama-dev at openjdk.java.net<mailto:panama-dev at openjdk.java.net> <panama-dev at openjdk.java.net<mailto:panama-dev at openjdk.java.net>>
Subject: Re: Replicating __mm256_shuffle_epi8 Intrinsic
I am a bit confused by your example code. selectFrom returns a `Vector`, but then you are calling `intoArray` which is a method only for `VectorShuffle`.
In addition to that - do you think you could use variable names from the example for clarity:
https://github.com/brcolow/vector-sha256/blob/master/src/main/java/com/brcolow/vectorsha256/VectorSHA256.java#L450
Thank you very much.
On Tue, Jul 6, 2021 at 8:23 AM Radosław Smogura <mail at smogura.eu<mailto:mail at smogura.eu>> wrote:
Hi Michael,
Shuffling can be problematic sometimes.
I wonder if you tried something like this
byteSwap = VectorShuffle.fromArray(BYTE_VECTOR_SPECIES, shuffleArr, 0);
final var byteSwapVector = byteSwap.toVector();
final var srcVector = ByteVector.fromArray(BYTE_VECTOR_SPECIES, src, i);
final var dstVector = byteSwapVector.selectFrom(srcVector);
dstVector.intoArray(dst, i);
Kind regards,
Rado
________________________________
From: panama-dev <panama-dev-retn at openjdk.java.net<mailto:panama-dev-retn at openjdk.java.net>> on behalf of Michael Ennen <mike.ennen at gmail.com<mailto:mike.ennen at gmail.com>>
Sent: Tuesday, July 6, 2021 06:54
To: Viswanathan, Sandhya <sandhya.viswanathan at intel.com<mailto:sandhya.viswanathan at intel.com>>
Cc: panama-dev at openjdk.java.net<mailto:panama-dev at openjdk.java.net> <panama-dev at openjdk.java.net<mailto:panama-dev at openjdk.java.net>>
Subject: Re: Replicating __mm256_shuffle_epi8 Intrinsic
I understand that representing the input and output as 32-bit integers is
kind of confusing, but the point is, is that the shuffle as written isn't
doing anything. I have also tried:
var shuffle = VectorShuffle.fromArray(ByteVector.SPECIES_256,
new int[]{
12,13,14,15, 8, 9,10,11,
4, 5, 6, 7, 0, 1, 2, 3,
12,13,14,15, 8, 9,10,11,
4, 5, 6, 7, 0, 1, 2, 3 }, 0)
But still the returned vector is the same.
On Sun, Jul 4, 2021 at 10:14 PM Michael Ennen <mike.ennen at gmail.com<mailto:mike.ennen at gmail.com>> wrote:
> Thanks for your assistance. I am having trouble replicating the same
> results from the first shuffle done in Bitcoin's SHA-AVX2:
>
> The following 8 integers are read in:
>
> Read8: 1684234849, 1886350957, 1684234849, 1886350957, 1684234849,
> 1886350957, 1684234849, 1886350957
>
> These 8 integers are shuffled with _mm256_shuffle_epi8 and the result is:
>
> 1835954032, 1633837924, 1835954032, 1633837924, 1835954032, 1633837924,
> 1835954032, 1633837924
>
> But using your suggested code:
>
> var shuffle = VectorShuffle.fromOp(ByteVector.SPECIES_256, (i ->
> ((8+i)%16)));
> ByteVector shuffled = ret.reinterpretAsBytes().rearrange(shuffle,
> shuffle.laneIsValid());
> return IntVector.fromByteArray(SPECIES_256, shuffled.toArray(), 0,
> ByteOrder.LITTLE_ENDIAN);
>
> I get:
>
> 1684234849, 1886350957, 1684234849, 1886350957, 1684234849, 1886350957,
> 1684234849, 1886350957
>
> That is, the numbers don't seem to be changed.
>
> Thanks for your help.
>
> On Thu, Jul 1, 2021 at 11:18 AM Viswanathan, Sandhya <
> sandhya.viswanathan at intel.com<mailto:sandhya.viswanathan at intel.com>> wrote:
>
>> Hi Michael,
>>
>> The rearrange() api should generate pshufb.
>>
>> e.g. for the following Java code:
>>
>> static final int SIZE = 1024;
>> static byte[] a = new byte[SIZE];
>> static byte[] r = new byte[SIZE];
>>
>> static final VectorSpecies<Byte> SPECIES = ByteVector.SPECIES_128;
>> static final VectorShuffle<Byte> HIGHTOLOW =
>> VectorShuffle.fromOp(SPECIES, (i -> ((8+i)%16)));
>>
>> static void workload() {
>> VectorShuffle<Byte> vshuf = HIGHTOLOW;
>>
>> for (int i = 0; i <= a.length - SPECIES.length(); i +=
>> SPECIES.length()) {
>> var av = ByteVector.fromArray(SPECIES, a, i);
>> var bv = av.rearrange(vshuf);
>> bv.intoArray(r, i);
>> }
>> }
>>
>> We generate the following code for the loop:
>> 0x00007fc388fa3180: vmovdqu 0x10(%rsi),%xmm1
>> 0x00007fc388fa3185: vmovdqu 0x10(%r14),%xmm2
>> 0x00007fc388fa318b: movslq %eax,%r10
>> 0x00007fc388fa318e: vmovdqu 0x10(%rbp,%r10,1),%xmm3
>> 0x00007fc388fa3195: vpcmpgtb %xmm2,%xmm1,%xmm1
>> 0x00007fc388fa3199: vptest %xmm0,%xmm1
>> 0x00007fc388fa319e: setne %r13b
>> 0x00007fc388fa31a2: movzbl %r13b,%r13d
>> 0x00007fc388fa31a6: test %r13d,%r13d
>> 0x00007fc388fa31a9: jne 0x00007fc388fa31e2
>> 0x00007fc388fa31ab: vpshufb %xmm2,%xmm3,%xmm3
>> 0x00007fc388fa31b0: vmovdqu %xmm3,0x10(%r8,%r10,1)
>> 0x00007fc388fa31b7: add $0x10,%eax
>> 0x00007fc388fa31ba: cmp %ebx,%eax
>> 0x00007fc388fa31bc: jl 0x00007fc388fa3180
>>
>> Best Regards,
>> Sandhya
>>
>>
>> -----Original Message-----
>> From: panama-dev <panama-dev-retn at openjdk.java.net<mailto:panama-dev-retn at openjdk.java.net>> On Behalf Of Michael
>> Ennen
>> Sent: Tuesday, June 29, 2021 11:20 PM
>> To: panama-dev at openjdk.java.net<mailto:panama-dev at openjdk.java.net>
>> Subject: Replicating __mm256_shuffle_epi8 Intrinsic
>>
>> I am trying to implement SHA-256 using the new Java Vector API.
>>
>> I have read the API docs but crossing the large mental gap of SIMD
>> instructions to the API for someone who knows very little SIMD has been
>> insurmountable for me.
>>
>> My question has been asked on Stack Overflow:
>>
>>
>> https://stackoverflow.com/questions/68135596/replicating-mm256-shuffle-epi8-intrinsic-with-java-vector-api-shuffle
>>
>> It is quite a simple (to ask anyway) question, which is, how to replicate
>> the _mm256_shuffle_epi8 intrinsic with the Java Vector API?
>>
>> Thanks very much.
>>
>> --
>> Michael Ennen
>>
>
>
> --
> Michael Ennen
>
--
Michael Ennen
--
Michael Ennen
--
Michael Ennen
--
Michael Ennen
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