61a08fc6ce
This patch implements the algorithm from Ulf Adams, "Ryū: Fast Float-to-String Conversion" (doi:10.1145/3192366.3192369) for formatting floating-point numbers with a fixed number of decimal digits. It is not a direct translation of the reference C implementation but still follows the original paper. In particular, it uses full 128-bit powers of 10, which allows for more precision in the other modes (fixed ftoa, atof). name old time/op new time/op delta AppendFloat/Decimal-4 49.6ns ± 3% 59.3ns ± 0% +19.59% (p=0.008 n=5+5) AppendFloat/Float-4 122ns ± 1% 91ns ± 1% -25.92% (p=0.008 n=5+5) AppendFloat/Exp-4 89.3ns ± 1% 100.0ns ± 1% +11.98% (p=0.008 n=5+5) AppendFloat/NegExp-4 88.3ns ± 2% 97.1ns ± 1% +9.87% (p=0.008 n=5+5) AppendFloat/LongExp-4 143ns ± 2% 103ns ± 0% -28.17% (p=0.016 n=5+4) AppendFloat/Big-4 144ns ± 1% 110ns ± 1% -23.26% (p=0.008 n=5+5) AppendFloat/BinaryExp-4 46.2ns ± 2% 46.0ns ± 1% ~ (p=0.603 n=5+5) AppendFloat/32Integer-4 49.1ns ± 1% 58.7ns ± 1% +19.57% (p=0.008 n=5+5) AppendFloat/32ExactFraction-4 95.6ns ± 1% 88.6ns ± 1% -7.30% (p=0.008 n=5+5) AppendFloat/32Point-4 122ns ± 1% 87ns ± 1% -28.63% (p=0.008 n=5+5) AppendFloat/32Exp-4 88.6ns ± 2% 95.0ns ± 1% +7.29% (p=0.008 n=5+5) AppendFloat/32NegExp-4 87.2ns ± 1% 91.3ns ± 1% +4.63% (p=0.008 n=5+5) AppendFloat/32Shortest-4 107ns ± 1% 82ns ± 0% -24.08% (p=0.008 n=5+5) AppendFloat/Slowpath64-4 1.00µs ± 1% 0.10µs ± 0% -89.92% (p=0.016 n=5+4) AppendFloat/SlowpathDenormal64-4 34.1µs ± 3% 0.1µs ± 1% -99.72% (p=0.008 n=5+5) Fixes #15672 Change-Id: Ib90dfa245f62490a6666671896013cf3f9a1fb22 Reviewed-on: https://go-review.googlesource.com/c/go/+/170080 Trust: Emmanuel Odeke <emmanuel@orijtech.com> Trust: Nigel Tao <nigeltao@golang.org> Run-TryBot: Emmanuel Odeke <emmanuel@orijtech.com> TryBot-Result: Go Bot <gobot@golang.org> Reviewed-by: Nigel Tao <nigeltao@golang.org>
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