diff options
Diffstat (limited to 'absl/hash/internal/low_level_hash.cc')
| -rw-r--r-- | absl/hash/internal/low_level_hash.cc | 12 |
1 files changed, 0 insertions, 12 deletions
diff --git a/absl/hash/internal/low_level_hash.cc b/absl/hash/internal/low_level_hash.cc index e05e7885..c917457a 100644 --- a/absl/hash/internal/low_level_hash.cc +++ b/absl/hash/internal/low_level_hash.cc @@ -15,7 +15,6 @@ #include "absl/hash/internal/low_level_hash.h" #include "absl/base/internal/unaligned_access.h" -#include "absl/numeric/bits.h" #include "absl/numeric/int128.h" namespace absl { @@ -23,20 +22,9 @@ ABSL_NAMESPACE_BEGIN namespace hash_internal { static uint64_t Mix(uint64_t v0, uint64_t v1) { -#if !defined(__aarch64__) - // The default bit-mixer uses 64x64->128-bit multiplication. absl::uint128 p = v0; p *= v1; return absl::Uint128Low64(p) ^ absl::Uint128High64(p); -#else - // The default bit-mixer above would perform poorly on some ARM microarchs, - // where calculating a 128-bit product requires a sequence of two - // instructions with a high combined latency and poor throughput. - // Instead, we mix bits using only 64-bit arithmetic, which is faster. - uint64_t p = v0 ^ absl::rotl(v1, 40); - p *= v1 ^ absl::rotl(v0, 39); - return p ^ (p >> 11); -#endif } uint64_t LowLevelHash(const void* data, size_t len, uint64_t seed, |