Created
December 26, 2013 11:28
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it's not about a deep optimization. That test shows you that you can freely write more readable code and it will be fast. the winner if(a == null) a = new Object(); don't use a||=new Object(); a = a || new Object(), because it looks like |\||\|\+_)+_)(_(*(^&(*&%&*^%$%^$ :D
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| package { | |
| import flash.display.Sprite; | |
| import flash.text.TextField; | |
| import flash.text.TextFieldAutoSize; | |
| import flash.utils.getTimer; | |
| public class ConditionTest extends Sprite { | |
| public function ConditionTest() { | |
| testTime(); | |
| } | |
| /** | |
| * My results: | |
| func1: 1951 | |
| func2: 1921 | |
| func3: 1931 | |
| func4: 1901 | |
| func5: 1907 | |
| func6: 1929 | |
| func7: 1928 | |
| */ | |
| private function testTime():void { | |
| var timeText:TextField = new TextField(); | |
| timeText.autoSize = TextFieldAutoSize.LEFT; | |
| timeText.wordWrap = true; | |
| addChild(timeText); | |
| var i:uint; | |
| var count:uint = 30000000; | |
| var t:Number; | |
| var result:Number; | |
| var a:Sprite = new Sprite(); | |
| t = getTimer(); | |
| for (i = 0; i < count; i++) { | |
| a ||= new Sprite(); | |
| } | |
| result = getTimer()-t; | |
| timeText.appendText("func1: "+result+"\n"); | |
| t = getTimer(); | |
| for (i = 0; i < count; i++) { | |
| if (!a) a = new Sprite(); | |
| } | |
| result = getTimer()-t; | |
| timeText.appendText("func2: "+result+"\n"); | |
| t = getTimer(); | |
| for (i = 0; i < count; i++) { | |
| a = a || new Sprite(); | |
| } | |
| result = getTimer()-t; | |
| timeText.appendText("func3: "+result+"\n"); | |
| t = getTimer(); | |
| for (i = 0; i < count; i++) { | |
| if (a == null) a = new Sprite(); | |
| } | |
| result = getTimer()-t; | |
| timeText.appendText("func4: "+result+"\n"); | |
| t = getTimer(); | |
| for (i = 0; i < count; i++) { | |
| if (a != null) { | |
| } else { | |
| a = new Sprite(); | |
| } | |
| } | |
| result = getTimer()-t; | |
| timeText.appendText("func5: "+result+"\n"); | |
| t = getTimer(); | |
| for (i = 0; i < count; i++) { | |
| a = (a) ? a : new Sprite(); | |
| } | |
| result = getTimer()-t; | |
| timeText.appendText("func6: "+result+"\n"); | |
| t = getTimer(); | |
| for (i = 0; i < count; i++) { | |
| a = (!a) ? new Sprite() : a; | |
| } | |
| result = getTimer()-t; | |
| timeText.appendText("func7: "+result+"\n"); | |
| } | |
| private function func1():void { | |
| var a:Sprite; | |
| a ||= new Sprite(); | |
| } | |
| // private function func1():void | |
| // { | |
| // @3 getlocal 0 | |
| // @4 pushscope | |
| // @5 pushnull | |
| // @6 coerce Sprite | |
| // @7 setlocal 1 | |
| // @10 getlocal 1 (a) | |
| // @11 coerce Sprite | |
| // @12 dup | |
| // @13 convert_b | |
| // @14 iftrue @19 | |
| // @15 pop | |
| // @16 findpropstrict Sprite | |
| // @17 constructprop Sprite, 0 args | |
| // @18 coerce Sprite | |
| // @19 coerce Sprite | |
| // @20 setlocal 1 (a) | |
| // @22 returnvoid | |
| // } | |
| private function func2():void { | |
| var a:Sprite; | |
| if (!a) a = new Sprite(); | |
| } | |
| // private function func2():void | |
| // { | |
| // @3 getlocal 0 | |
| // @4 pushscope | |
| // @5 pushnull | |
| // @6 coerce Sprite | |
| // @7 setlocal 1 | |
| // @10 getlocal 1 (a) | |
| // @11 not | |
| // @12 iffalse @17 | |
| // @13 findpropstrict Sprite | |
| // @14 constructprop Sprite, 0 args | |
| // @15 coerce Sprite | |
| // @16 setlocal 1 (a) | |
| // @18 returnvoid | |
| // } | |
| private function func3():void { | |
| var a:Sprite; | |
| a = a || new Sprite(); | |
| } | |
| // private function func3():void | |
| // { | |
| // @3 getlocal 0 | |
| // @4 pushscope | |
| // @5 pushnull | |
| // @6 coerce Sprite | |
| // @7 setlocal 1 | |
| // @10 getlocal 1 (a) | |
| // @11 coerce Sprite | |
| // @12 dup | |
| // @13 convert_b | |
| // @14 iftrue @19 | |
| // @15 pop | |
| // @16 findpropstrict Sprite | |
| // @17 constructprop Sprite, 0 args | |
| // @18 coerce Sprite | |
| // @19 coerce Sprite | |
| // @20 setlocal 1 (a) | |
| // @22 returnvoid | |
| // } | |
| private function func4():void { | |
| var a:Sprite; | |
| if (a == null) a = new Sprite(); | |
| } | |
| // private function func4():void | |
| // { | |
| // @3 getlocal 0 | |
| // @4 pushscope | |
| // @5 pushnull | |
| // @6 coerce Sprite | |
| // @7 setlocal 1 | |
| // @10 getlocal 1 (a) | |
| // @11 pushnull | |
| // @12 ifne @17 | |
| // @13 findpropstrict Sprite | |
| // @14 constructprop Sprite, 0 args | |
| // @15 coerce Sprite | |
| // @16 setlocal 1 (a) | |
| // @18 returnvoid | |
| // } | |
| private function func5():void { | |
| var a:Sprite; | |
| if (a != null) { | |
| } else { | |
| a = new Sprite(); | |
| } | |
| } | |
| // private function func5():void | |
| // { | |
| // @3 getlocal 0 | |
| // @4 pushscope | |
| // @5 pushnull | |
| // @6 coerce Sprite | |
| // @7 setlocal 1 | |
| // @10 getlocal 1 (a) | |
| // @11 pushnull | |
| // @12 ifne @18 | |
| // @14 findpropstrict Sprite | |
| // @15 constructprop Sprite, 0 args | |
| // @16 coerce Sprite | |
| // @17 setlocal 1 (a) | |
| // @19 returnvoid | |
| // } | |
| private function func6():void { | |
| var a:Sprite; | |
| a = (a) ? a : new Sprite(); | |
| } | |
| // private function func6():void | |
| // { | |
| // @3 getlocal 0 | |
| // @4 pushscope | |
| // @5 pushnull | |
| // @6 coerce Sprite | |
| // @7 setlocal 1 | |
| // @10 getlocal 1 (a) | |
| // @11 convert_b | |
| // @12 iffalse @16 | |
| // @13 getlocal 1 (a) | |
| // @14 coerce Sprite | |
| // @15 jump @19 | |
| // @16 findpropstrict Sprite | |
| // @17 constructprop Sprite, 0 args | |
| // @18 coerce Sprite | |
| // @19 coerce Sprite | |
| // @20 setlocal 1 (a) | |
| // @22 returnvoid | |
| // } | |
| private function func7():void { | |
| var a:Sprite; | |
| a = (!a) ? new Sprite() : a; | |
| } | |
| // private function func7():void | |
| // { | |
| // @3 getlocal 0 | |
| // @4 pushscope | |
| // @5 pushnull | |
| // @6 coerce Sprite | |
| // @7 setlocal 1 | |
| // @10 getlocal 1 (a) | |
| // @11 not | |
| // @12 iffalse @17 | |
| // @13 findpropstrict Sprite | |
| // @14 constructprop Sprite, 0 args | |
| // @15 coerce Sprite | |
| // @16 jump @19 | |
| // @17 getlocal 1 (a) | |
| // @18 coerce Sprite | |
| // @19 coerce Sprite | |
| // @20 setlocal 1 (a) | |
| // @22 returnvoid | |
| // } | |
| } | |
| } |
Что касается скорости, то от запуска к запуску распределение мест по скорости слишком часто меняется. Нельзя делать каких либо выводов.
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ASC 2.0 Лучше оптимизирует именно такие конструкции
private function func1():void {
var a:Sprite;
a ||= new Sprite();
}
Если верить ffdec то останется от такой функции только
getlocal_0
pushscope
pushnull
setlocal_1
getlocal_1
iftrue ofs000f
findpropstrict Qname(PackageNamespace("flash.display"),"Sprite")
constructprop Qname(PackageNamespace("flash.display"),"Sprite") 0
setlocal_1
ofs000f:returnvoid
вместо
getlocal_0
pushscope
pushnull
coerce Qname(PackageNamespace("flash.display"),"Sprite")
setlocal_1
getlocal_1
coerce Qname(PackageNamespace("flash.display"),"Sprite")
dup
iftrue ofs0016
pop
findpropstrict Qname(PackageNamespace("flash.display"),"Sprite")
constructprop Qname(PackageNamespace("flash.display"),"Sprite") 0
coerce Qname(PackageNamespace("flash.display"),"Sprite")
ofs0016:coerce Qname(PackageNamespace("flash.display"),"Sprite")
setlocal_1
returnvoid