internal/lz4block: Short literal copying in arm64 decoder #162
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This borrows a trick from the amd64 decoder: copy short literals by always copying 16 bytes, using the space beyond the literal's length as scratch space (but only when we're >=16 bytes from the end of src, dst). Benchmark results on RPi4B: name old speed new speed delta UncompressPg1661-4 101MB/s ± 1% 138MB/s ± 0% +36.46% (p=0.000 n=10+9) UncompressDigits-4 453MB/s ± 0% 525MB/s ± 0% +15.81% (p=0.000 n=10+10) UncompressTwain-4 110MB/s ± 0% 156MB/s ± 0% +41.42% (p=0.000 n=10+10) UncompressRand-4 1.14GB/s ± 1% 1.13GB/s ± 1% ~ (p=0.075 n=10+10) Also moved a SUBS to just before the associated branch to allow instruction fusion on ARMs that do that.
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Nice one. |
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This borrows a trick from the amd64 decoder: copy short literals by always copying 16 bytes, using the space beyond the literal's length as scratch space (but only when we're >=16 bytes from the end of src, dst).
Benchmark results on RPi4B:
Also moved a SUBS to just before the associated branch to allow instruction fusion on ARMs that do that.