cmd/compile: optimize math.Copysign on arm64
Add rewrite rules to optimize math.Copysign() when the second
argument is negative floating point constant.
For example, math.Copysign(c, -2): The previous compile output is
"AND $
9223372036854775807, R0, R0; ORR $-
9223372036854775808, R0, R0".
The optimized compile output is "ORR $-
9223372036854775808, R0, R0"
Math package benchmark results.
name old time/op new time/op delta
Copysign-8 2.61ns ± 2% 2.49ns ± 0% -4.55% (p=0.000 n=10+10)
Cos-8 43.0ns ± 0% 41.5ns ± 0% -3.49% (p=0.000 n=10+10)
Cosh-8 98.6ns ± 0% 98.1ns ± 0% -0.51% (p=0.000 n=10+10)
ExpGo-8 107ns ± 0% 105ns ± 0% -1.87% (p=0.000 n=10+10)
Exp2Go-8 100ns ± 0% 100ns ± 0% +0.39% (p=0.000 n=10+8)
Max-8 6.56ns ± 2% 6.45ns ± 1% -1.63% (p=0.002 n=10+10)
Min-8 6.66ns ± 3% 6.47ns ± 2% -2.82% (p=0.006 n=10+10)
Mod-8 107ns ± 1% 104ns ± 1% -2.72% (p=0.000 n=10+10)
Frexp-8 11.5ns ± 1% 11.0ns ± 0% -4.56% (p=0.000 n=8+10)
HypotGo-8 19.4ns ± 0% 19.4ns ± 0% +0.36% (p=0.019 n=10+10)
Ilogb-8 8.63ns ± 0% 8.51ns ± 0% -1.36% (p=0.000 n=10+10)
Jn-8 584ns ± 0% 585ns ± 0% +0.17% (p=0.000 n=7+8)
Ldexp-8 13.8ns ± 0% 13.5ns ± 0% -2.17% (p=0.002 n=8+10)
Logb-8 10.2ns ± 0% 9.9ns ± 0% -2.65% (p=0.000 n=10+7)
Nextafter64-8 7.54ns ± 0% 7.51ns ± 0% -0.37% (p=0.000 n=10+10)
Remainder-8 73.5ns ± 1% 70.4ns ± 1% -4.27% (p=0.000 n=10+10)
SqrtGoLatency-8 79.6ns ± 0% 76.2ns ± 0% -4.30% (p=0.000 n=9+10)
Yn-8 582ns ± 0% 579ns ± 0% -0.52% (p=0.000 n=10+10)
Change-Id: I0c9cd1ea87435e7b8bab94b4e79e6e29785f25b1
Reviewed-on: https://go-review.googlesource.com/132915
Reviewed-by: Cherry Zhang <cherryyz@google.com>
Run-TryBot: Cherry Zhang <cherryyz@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>