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| author |  Connal de Souza <connaldesouza@google.com> | 2023-02-23 09:52:08 -0800 |
|---|---|---|
| committer |  Copybara-Service <copybara-worker@google.com> | 2023-02-23 09:53:06 -0800 |
| commit | 0f35765048ea9b9fce70dc7c7781bed3321d99cd (patch) | |
| tree | f9c2e149a20718aadd295e2974d58bf067d19651 /absl/container | |
| parent | 0ecfe2358af39dcc61c581d242d11d3f7211683e (diff) | |
Optimize ConvertSpecialToEmptyAndFullToDeleted on Arm
BM_DropDeletes 73.4µs ± 0% 68.9µs ± 1% -6.22% (p=0.008 n=5+5)
PiperOrigin-RevId: 511813266
Change-Id: Id28cece454d583e2dfe060e27cfc4720f987f009
Diffstat (limited to 'absl/container')
| -rw-r--r-- | absl/container/internal/raw_hash_set.h | 7 |
1 files changed, 4 insertions, 3 deletions
diff --git a/absl/container/internal/raw_hash_set.h b/absl/container/internal/raw_hash_set.h index e5306a4f..f4de2d65 100644 --- a/absl/container/internal/raw_hash_set.h +++ b/absl/container/internal/raw_hash_set.h @@ -675,9 +675,10 @@ struct GroupAArch64Impl { void ConvertSpecialToEmptyAndFullToDeleted(ctrl_t* dst) const { uint64_t mask = vget_lane_u64(vreinterpret_u64_u8(ctrl), 0); constexpr uint64_t msbs = 0x8080808080808080ULL; - constexpr uint64_t lsbs = 0x0101010101010101ULL; - auto x = mask & msbs; - auto res = (~x + (x >> 7)) & ~lsbs; + constexpr uint64_t slsbs = 0x0202020202020202ULL; + constexpr uint64_t midbs = 0x7e7e7e7e7e7e7e7eULL; + auto x = slsbs & (mask >> 6); + auto res = (x + midbs) | msbs; little_endian::Store64(dst, res); } |