faa9d1eca9
The existing code used ints for the (slow) decimal conversion and assumed that they were 32bit wide. This change uses uints and the appropriate width (32 or 64bit) depending on platform. The performance difference is in the noise for the usual (optimized) case which does not use the slow path conversion: benchmark old ns/op new ns/op delta BenchmarkFormatFloatDecimal 298 299 +0.34% BenchmarkFormatFloat 388 392 +1.03% BenchmarkFormatFloatExp 365 364 -0.27% BenchmarkFormatFloatNegExp 364 362 -0.55% BenchmarkFormatFloatBig 482 476 -1.24% BenchmarkAppendFloatDecimal 100 102 +2.00% BenchmarkAppendFloat 199 201 +1.01% BenchmarkAppendFloatExp 174 175 +0.57% BenchmarkAppendFloatNegExp 169 174 +2.96% BenchmarkAppendFloatBig 286 286 +0.00% BenchmarkAppendFloat32Integer 99.9 102 +2.10% BenchmarkAppendFloat32ExactFraction 161 164 +1.86% BenchmarkAppendFloat32Point 199 201 +1.01% BenchmarkAppendFloat32Exp 167 168 +0.60% BenchmarkAppendFloat32NegExp 163 169 +3.68% BenchmarkAppendFloat64Fixed1 137 134 -2.19% BenchmarkAppendFloat64Fixed2 144 146 +1.39% BenchmarkAppendFloat64Fixed3 138 140 +1.45% BenchmarkAppendFloat64Fixed4 144 145 +0.69% The performance difference is significant if the fast path conversion is explicitly turned off (ftoa.go:101): benchmark old ns/op new ns/op delta BenchmarkFormatFloatDecimal 459 427 -6.97% BenchmarkFormatFloat 1560 1180 -24.36% BenchmarkFormatFloatExp 5501 3128 -43.14% BenchmarkFormatFloatNegExp 24085 14360 -40.38% BenchmarkFormatFloatBig 1409 1081 -23.28% BenchmarkAppendFloatDecimal 248 226 -8.87% BenchmarkAppendFloat 1315 982 -25.32% BenchmarkAppendFloatExp 5274 2869 -45.60% BenchmarkAppendFloatNegExp 23905 14054 -41.21% BenchmarkAppendFloatBig 1194 860 -27.97% BenchmarkAppendFloat32Integer 167 175 +4.79% BenchmarkAppendFloat32ExactFraction 182 184 +1.10% BenchmarkAppendFloat32Point 556 564 +1.44% BenchmarkAppendFloat32Exp 1134 918 -19.05% BenchmarkAppendFloat32NegExp 2679 1801 -32.77% BenchmarkAppendFloat64Fixed1 274 238 -13.14% BenchmarkAppendFloat64Fixed2 494 368 -25.51% BenchmarkAppendFloat64Fixed3 1833 1008 -45.01% BenchmarkAppendFloat64Fixed4 6133 3596 -41.37% Change-Id: I829b8abcca882b1c10d8ae421d3249597c31f3c9 Reviewed-on: https://go-review.googlesource.com/3811 Reviewed-by: Russ Cox <rsc@golang.org> |
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