)]}'
{
  "commit": "cf015c9b764fae69f2140ff2504cb9a4e3de06fc",
  "tree": "da8d5488587c7714c6c4efb28491809cc2041f82",
  "parents": [
    "688a56ef1c983f17afd32fb27863ff7950ab902c"
  ],
  "author": {
    "name": "Evan Brown",
    "email": "ezb@google.com",
    "time": "Wed Oct 28 15:30:26 2026 -0700"
  },
  "committer": {
    "name": "Copybara-Service",
    "email": "copybara-worker@google.com",
    "time": "Wed Oct 28 15:31:13 2026 -0700"
  },
  "message": "Constant-fold zero-initialized second CRC32 lane in CombineContiguousImpl.\n\nOn 64-bit CRC32 targets, `CombineContiguousImpl` initializes the second CRC32 stream from `absl::gbswap_64(state)` even when `state` has known zero upper 32 bits (such as SwissTable\u0027s per-table seed), because LLVM does not narrow `_mm_crc32_u64`\u0027s 64-bit initial-state operand to its low 32 bits via DemandedBits. This leaves an unnecessary data dependency from loading the table seed to the second CRC32 stream on 9–32 byte keys.\n\nConstant-fold `static_cast\u003cuint32_t\u003e(crcs.second)` via `__builtin_constant_p` in `CombineContiguousImpl` when known at compile time, breaking the seed-load dependency to the second CRC32 stream without adding a zero-extension when `crcs.second` is not a compile-time constant.\n\nPiperOrigin-RevId: 1009217950\n",
  "tree_diff": [
    {
      "type": "modify",
      "old_id": "5bbb5d16133850338cdb7f9d68b61bf9fbffb64a",
      "old_mode": 33188,
      "old_path": "absl/hash/internal/hash.h",
      "new_id": "b30260d620f24c731fe9ef97936d78dc2861903d",
      "new_mode": 33188,
      "new_path": "absl/hash/internal/hash.h"
    }
  ]
}