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3 Commits

Author SHA1 Message Date
costan
2964b803b8 leveldb: Fix alignment code in SSE4.2-optimized CRC32C. 
When faced with a pointer that is misaligned by K bytes (pointer % 8 ==
K), the code previously moved forward by K bytes. In order to end up
with an aligned pointer, the code must move by 8 - K bytes.

This lands https://github.com/google/leveldb/pull/488

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Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=166295921
 2017-08-24 15:00:52 -07:00
costan
eb4f0972fd leveldb: Fix compilation warnings in port_posix_sse.cc on x86 (32-bit). 
LE_LOAD64 is only used when _mm_crc32_u64 is available, on 64-bit x86 processors.

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Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=148906169
 2017-03-01 11:37:43 -08:00
costan
ea175e28f8 Implement support for Intel crc32 instruction (SSE 4.2) 
This change authored by vadimskipin and submitted via:

    https://github.com/google/leveldb/pull/309

Changes made to support iOS builds and other architectures
without support for SSE 4.2.

db_bench reports original crc32 speed at:

    crc32c : 3.610 micros/op; 1082.0 MB/s (4K per op)

with this change performance has increased to:

    crc32c : 0.843 micros/op; 4633.6 MB/s (4K per op)

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Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=148694935
 2017-02-28 14:08:46 -08:00