github-mirrors/VictoriaMetrics
1
0
Fork 0
mirror of https://github.com/VictoriaMetrics/VictoriaMetrics.git synced 2025-02-19 15:30:17 +00:00
Code Issues Projects Releases Packages Wiki Activity

lib/decimal: optimize maxUpExponent() by eliminating division from hot path

Browse source
This commit is contained in:
Aliaksandr Valialkin 2020-09-19 13:49:16 +03:00
parent df547bf345
commit 604e8f6114
1 changed files with 20 additions and 22 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

42
lib/decimal/decimal.go
View file

@ -239,6 +239,8 @@ type vaeBuf struct {
var vaeBufPool sync.Pool var vaeBufPool sync.Pool
const int64Max = int64(1<<63 - 1)
func maxUpExponent(v int64) int16 { func maxUpExponent(v int64) int16 {
if v == 0 { if v == 0 {
// Any exponent allowed. // Any exponent allowed.
@ -251,46 +253,42 @@ func maxUpExponent(v int64) int16 {
// Handle corner case for v=-1<<63 // Handle corner case for v=-1<<63
return 0 return 0
} }
maxMultiplier := ((1 << 63) - 1) / uint64(v)
switch { switch {
case maxMultiplier >= 1e19: case v <= int64Max/1e18:
return 19
case maxMultiplier >= 1e18:
return 18 return 18
case maxMultiplier >= 1e17: case v <= int64Max/1e17:
return 17 return 17
case maxMultiplier >= 1e16: case v <= int64Max/1e16:
return 16 return 16
case maxMultiplier >= 1e15: case v <= int64Max/1e15:
return 15 return 15
case maxMultiplier >= 1e14: case v <= int64Max/1e14:
return 14 return 14
case maxMultiplier >= 1e13: case v <= int64Max/1e13:
return 13 return 13
case maxMultiplier >= 1e12: case v <= int64Max/1e12:
return 12 return 12
case maxMultiplier >= 1e11: case v <= int64Max/1e11:
return 11 return 11
case maxMultiplier >= 1e10: case v <= int64Max/1e10:
return 10 return 10
case maxMultiplier >= 1e9: case v <= int64Max/1e9:
return 9 return 9
case maxMultiplier >= 1e8: case v <= int64Max/1e8:
return 8 return 8
case maxMultiplier >= 1e7: case v <= int64Max/1e7:
return 7 return 7
case maxMultiplier >= 1e6: case v <= int64Max/1e6:
return 6 return 6
case maxMultiplier >= 1e5: case v <= int64Max/1e5:
return 5 return 5
case maxMultiplier >= 1e4: case v <= int64Max/1e4:
return 4 return 4
case maxMultiplier >= 1e3: case v <= int64Max/1e3:
return 3 return 3
case maxMultiplier >= 1e2: case v <= int64Max/1e2:
return 2 return 2
case maxMultiplier >= 1e1: case v <= int64Max/1e1:
return 1 return 1
default: default:
return 0 return 0