| Commit message (Collapse) | Author | Age | Files | Lines | |
|---|---|---|---|---|---|
| * | Optimize `absl::Hash` by making `LowLevelHash` faster. | Shahriar Rouf | 2024-02-07 | 1 | -0/+4 |
| | | | | | | | | | | | | | | | | | Throughput of the 64 byte chunk loop inside `LowLevelHash` (or now in `LowLevelHashLenGt16`) gets limited by the loop carried dependency on `current_state`. By using 4 states instead of 2, we can reduce this duration by 1 cycle. On Skylake, it is reduced from 9 cycles to 8 cycles (12.5% faster asymptotically). To see the reduction in a simplified version of `LowLevelHash` implementation on Skylake: * Before: https://godbolt.org/z/Tcj9vsGax, llvm-mca (https://godbolt.org/z/3o78Msr63) shows 9 cycles / iteration. * After: https://godbolt.org/z/q4GM4EjPr, llvm-mca (https://godbolt.org/z/W5d1KEMzq) shows 8 cycles / iteration. * This CL is removing 1 xor (1 cycle) per iteration from the critical path. A block for 32 byte chunk is also added. Finally, just before returning, `Mix` is called 1 time instead of twice. PiperOrigin-RevId: 605090653 Change-Id: Ib7517ebb8bef7484066cd14cf41a943953e93377 | ||||
| * | Export of internal Abseil changes | Abseil Team | 2021-08-13 | 1 | -0/+50 |
| -- 3a9b4e8e5ecba532db5cc4ac12d12660307ce9fb by Derek Mauro <dmauro@google.com>: Use the Bazel @platforms repository for platform constraints Fixes #1000 PiperOrigin-RevId: 390644226 -- b34e4d2f8a86b54bd483ec4c9c3dd781ad2d8b68 by Abseil Team <absl-team@google.com>: debugging: add some handling for RISC-V The RISC-V architecture uses a downward growing stack and can host Linux using ELF files. Adjust a few sites accordingly to indicate how to handle the RISC-V architecture. PiperOrigin-RevId: 390631894 -- 5fa3a0961bf3dd0799c048956a0128f7b8113f1e by Samuel Benzaquen <sbenza@google.com>: Rename the buffer hash function to LowLevelHash. Although it started as wyhash, it will depart from it so it does not make sense to keep the name. PiperOrigin-RevId: 390483506 -- 2e7867a2301d58ad4cd5abcaa5fd6f0db973ae7b by Abseil Team <absl-team@google.com>: This is an internal change. PiperOrigin-RevId: 390349746 GitOrigin-RevId: 3a9b4e8e5ecba532db5cc4ac12d12660307ce9fb Change-Id: I322c3762552a2107e6c6b108c25c01e5efa8aecd | |||||
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