<i18n dev> Codereview request for 7096080: UTF8 update and new CESU-8 charset

[Ulf Zibis]

Am 11.10.2011 19:49, schrieb Xueming Shen:
>
> I don't know which one is better, I did a run on
>
>     private static boolean op1(int b) {
>         return (b >> 6) != -2;
>     }
>     private static boolean op2(int b) {
>         return (b & 0xc0) != 0x80;
>     }
>     private static boolean op3(byte b) {
>          return b >= (byte)0xc0;
>     }
>
> with 1000000 iteration on my linux machine,  and got the scores
>
> op1=1149
> op2=1147
> op3=1146
>
> I would interpret it as they are identical.
Me too. thanks for your effort.
Maybe the comparison would differ on different architectures.

So I would prefer opt3, because the others ...
1. in question need 1 more CPU register to save the original value of b for later usage
2. need 1 more constant to load into CPU
and opt 3 ...
3. is the best readable source code
4. in question seems best to help Hotspot finding best optimization on arbitrary architectures.

Additionally I guess using always byte variables would in question help HotSpot to optimize with 
1-byte-operand CPU instructions.

Don't you like to replace all "(bx & 0xc0) != 0x80" by "isNotContinuation(bx)" ?

-Ulf

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