sha3.c: add initial avx2 backend (slow)

bench results (oof)
-------------------
scalar (gcc):
  > make clean all BACKEND=1 && ./bench
  ...
  info: cpucycles: version=20240318 implementation=amd64-pmc persecond=4800000000
  info: backend=scalar num_trials=2000 src_lens=64,256,1024,4096,16384 dst_lens=32
  function,dst_len,64,256,1024,4096,16384
  sha3_224,28,19.5,10.0,10.0,8.9,8.8
  sha3_256,32,19.5,10.0,9.9,9.5,9.3
  sha3_384,48,19.5,14.7,12.3,12.2,12.0
  sha3_512,64,19.5,19.4,18.2,17.2,17.1
  shake128,32,19.7,9.9,8.7,7.8,7.6
  shake256,32,20.2,10.1,10.0,9.6,9.3

scalar (clang):
  > make clean all BACKEND=1 CC=clang && ./bench
  info: cpucycles: version=20240318 implementation=amd64-pmc persecond=4800000000
  info: backend=scalar num_trials=2000 src_lens=64,256,1024,4096,16384 dst_lens=32
  function,dst_len,64,256,1024,4096,16384
  sha3_224,28,19.7,9.9,9.8,8.8,8.7
  sha3_256,32,19.7,9.9,9.8,9.4,9.2
  sha3_384,48,19.7,14.6,12.1,12.0,11.8
  sha3_512,64,19.7,19.3,17.8,16.9,16.9
  shake128,32,19.7,9.8,8.6,7.7,7.5
  shake256,32,19.7,9.9,9.8,9.4,9.2

avx2 (gcc):
  > make clean all BACKEND=6 && ./bench
  info: cpucycles: version=20240318 implementation=amd64-pmc persecond=4800000000
  info: backend=avx2 num_trials=2000 src_lens=64,256,1024,4096,16384 dst_lens=32
  function,dst_len,64,256,1024,4096,16384
  sha3_224,28,80.0,40.5,40.9,37.2,36.6
  sha3_256,32,79.8,40.5,40.9,39.8,38.9
  sha3_384,48,80.1,61.0,51.2,51.3,50.7
  sha3_512,64,79.9,81.5,76.7,73.0,73.1
  shake128,32,86.0,43.6,38.6,34.5,33.9
  shake256,32,86.0,43.6,44.1,42.8,41.9

avx2 (clang):
  > make clean all BACKEND=6 CC=clang && ./bench
  info: cpucycles: version=20240318 implementation=amd64-pmc persecond=4800000000
  info: backend=avx2 num_trials=2000 src_lens=64,256,1024,4096,16384 dst_lens=32
  function,dst_len,64,256,1024,4096,16384
  sha3_224,28,62.0,31.6,31.9,29.0,28.5
  sha3_256,32,61.9,31.6,32.0,31.1,30.3
  sha3_384,48,62.6,47.7,40.1,40.2,39.8
  sha3_512,64,62.0,63.8,60.2,57.2,57.3
  shake128,32,62.5,31.7,27.9,24.9,24.5
  shake256,32,62.0,31.5,31.9,31.0,30.3

the culprit is using gather in the pi step for permutes, so those will
need to be rewritten as permutes:

  > perf annotate -Mintel --stdio --quiet permute_n_avx2 | grep gatherqq
     24.09 :   207e:   vpgatherqq ymm0,QWORD PTR [rdi+ymm3*8],ymm6
     14.07 :   20a0:   vpgatherqq ymm4,QWORD PTR [rdi+ymm3*8],ymm6
     13.36 :   20aa:   vpgatherqq ymm8,QWORD PTR [rdi+ymm7*8],ymm6
     13.50 :   20c4:   vpgatherqq ymm3,QWORD PTR [rdi+ymm7*8],ymm6
     13.61 :   20ce:   vpgatherqq ymm7,QWORD PTR [rdi+ymm1*8],ymm6

0 files changed, 0 insertions, 0 deletions