1e28dce80a
This improves the performance for byte.Compare by rewriting the cmpbody function in runtime/asm_ppc64x.s. The previous code had a simple loop which loaded a pair of bytes and compared them, which is inefficient for long buffers. The updated function checks for 8 or 32 byte chunks and then loads and compares double words where possible. Because the byte.Compare result indicates greater or less than, the doubleword loads must take endianness into account, using a byte reversed load in the little endian case. Fixes #17433 benchmark old ns/op new ns/op delta BenchmarkBytesCompare/8-16 13.6 7.16 -47.35% BenchmarkBytesCompare/16-16 25.7 7.83 -69.53% BenchmarkBytesCompare/32-16 38.1 7.78 -79.58% BenchmarkBytesCompare/64-16 63.0 10.6 -83.17% BenchmarkBytesCompare/128-16 112 13.0 -88.39% BenchmarkBytesCompare/256-16 211 28.1 -86.68% BenchmarkBytesCompare/512-16 410 38.6 -90.59% BenchmarkBytesCompare/1024-16 807 60.2 -92.54% BenchmarkBytesCompare/2048-16 1601 103 -93.57% Change-Id: I121acc74fcd27c430797647b8d682eb0607c63eb Reviewed-on: https://go-review.googlesource.com/30949 Reviewed-by: David Chase <drchase@google.com> |
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