)]}'
{
  "commit": "4bd9ee20a2fd4a8cce56bd8ad06eb5e795a44e76",
  "tree": "1328a06ec92fdf18a450d738370e5aa321e0396b",
  "parents": [
    "5b1e199db4bc8f83f3d2dc1ced3dee7576ceedc2"
  ],
  "author": {
    "name": "Vitaly Goldshteyn",
    "email": "goldvitaly@google.com",
    "time": "Wed Dec 10 11:53:20 2025 -0800"
  },
  "committer": {
    "name": "Copybara-Service",
    "email": "copybara-worker@google.com",
    "time": "Wed Dec 10 11:54:12 2025 -0800"
  },
  "message": "Special implementation for string hash with sizes greater than 64.\n\nAES instructions are used, when available. We load blocks of 64 bytes of the string into 4 independently hashed 128-bit vectors. We use AES encrypt and decrypt to mix the bits. Instructions are running in parallel.\n\nLast \u003c\u003d64 bytes are loaded to 4 (or 2 if rest length is \u003c\u003d32) overlapping vectors and encrypted additionally. At the end we mix by another encryption similar to the case in 33-64.\n\n```\nname                                     CYCLES/op     CYCLES/op   vs base\nBM_HASHING_Combine_contiguous_Fleet_hot  479.0m ± 1%   437.0m ± 0%   -8.77% (p\u003d0.000 n\u003d30)\nBM_HASHING_Combine_contiguous_Fleet_cold 1.700 ± 2%    1.526 ± 2%  -10.24% (p\u003d0.000 n\u003d30)\n\narcadia-rome:\nBM_HASHING_Combine_contiguous_Fleet_hot  465.0m ± 1%   452.0m ± 1%   -2.80% (p\u003d0.000 n\u003d30)\nBM_HASHING_Combine_contiguous_Fleet_cold 4.024 ± 1%    3.676 ± 0%   -8.66% (p\u003d0.000 n\u003d30)\n```\n\nASM analysis https://godbolt.org/z/5EzEnT46j shows 8 cycles savings for 128 byte string. We also perform 2x less load operations.\n\nPiperOrigin-RevId: 842818076\nChange-Id: Ib89f25e0bae2c8ba9ed340350408c27afe6fd222\n",
  "tree_diff": [
    {
      "type": "modify",
      "old_id": "500d1e0a64f12e180f5cb8f2afc6b25958f9b9b1",
      "old_mode": 33188,
      "old_path": "absl/hash/hash_test.cc",
      "new_id": "89e04703a9ce317db814603f4e78abe65f161d19",
      "new_mode": 33188,
      "new_path": "absl/hash/hash_test.cc"
    },
    {
      "type": "modify",
      "old_id": "6b02f193aaeafbab3f055eb62756cc9e85331fe4",
      "old_mode": 33188,
      "old_path": "absl/hash/internal/hash.cc",
      "new_id": "b8a001664cee69d1256cd909debd452afa91c6c3",
      "new_mode": 33188,
      "new_path": "absl/hash/internal/hash.cc"
    },
    {
      "type": "modify",
      "old_id": "cdd279b850f3302ed43ef80a92d40f51a5ed6a33",
      "old_mode": 33188,
      "old_path": "absl/hash/internal/low_level_hash_test.cc",
      "new_id": "d054337a13f2caaf9c2c738181fec6440f794324",
      "new_mode": 33188,
      "new_path": "absl/hash/internal/low_level_hash_test.cc"
    }
  ]
}