Need reviewer for forward port of 6815768 (File.getXXXSpace) and 6815768 (String.hashCode)

[Ulf Zibis]

Am 26.02.2010 20:32, schrieb Alan Bateman:
> Ulf Zibis wrote:
> For these other suggestions it would be great to create
> micro-benchmarks and try our your changes.
>
> For now though, as I said, I'm just fixing the method to avoid the
> store for the empty string case.

I've added benchmark for "same" strings:

LONG.substring(1).<init>      warmup =    6.170 ms
LONG.substring(1).hashCode()  warmup =   80.545 ms
LONG.substring(1).hashCode1() warmup =   27.564 ms
LONG.substring(1).hashCode2() warmup =  103.577 ms
LONG.substring(1).hashCode3() warmup =   63.706 ms
LONG.substring(1).hashCode4() warmup =   83.302 ms
LONG.substring(1).hashCode5() warmup =   52.357 ms
LONG.substring(1).hashCode6() warmup =   86.450 ms

LONG.substring(1).<init>      time =    101.919 ms
LONG.substring(1).hashCode()  time =    931.121 ms
LONG.substring(1).hashCode1() time =    635.150 ms
LONG.substring(1).hashCode2() time =    563.309 ms
LONG.substring(1).hashCode3() time =    599.341 ms
LONG.substring(1).hashCode4() time =    581.050 ms
LONG.substring(1).hashCode5() time =    608.527 ms
LONG.substring(1).hashCode6() time =    542.390 ms
hashCodes sum = 1197450336

SAME1==SAME2<init> warmup =   98.305 ms
SAME1.equals(SAME2)  warmup =   43.749 ms
SAME1.equals1(SAME2) warmup =  154.050 ms
SAME1.equals2(SAME2) warmup =   83.096 ms
SAME1.equals3(SAME2) warmup =  348.704 ms
SAME1.equals4(SAME2) warmup =  114.798 ms
SAME1.equals5(SAME2) warmup =   77.480 ms

SAME1==SAME2<init> time =     97.395 ms
SAME1.equals(SAME2)  time =    120.363 ms
SAME1.equals1(SAME2) time =    271.393 ms
SAME1.equals2(SAME2) time =    131.297 ms
SAME1.equals3(SAME2) time =    539.923 ms
SAME1.equals4(SAME2) time =    175.093 ms
SAME1.equals5(SAME2) time =    159.624 ms

LONG1.equals(LONG2)  warmup =   41.916 ms
LONG1.equals1(LONG2) warmup =   75.950 ms
LONG1.equals2(LONG2) warmup =   65.594 ms
LONG1.equals3(LONG2) warmup =   17.908 ms
LONG1.equals4(LONG2) warmup =   16.399 ms
LONG1.equals5(LONG2) warmup =   16.334 ms

LONG1.equals(LONG2)  time =     67.612 ms
LONG1.equals1(LONG2) time =    124.927 ms
LONG1.equals2(LONG2) time =    142.572 ms
LONG1.equals3(LONG2) time =     35.580 ms
LONG1.equals4(LONG2) time =     30.342 ms
LONG1.equals5(LONG2) time =     23.478 ms

Do you have any idea, why equals1() is so much slower than equals() ??
I can't believe that the single compare 'if (n != 0)' raises the time so much.

See new revision:
https://java-nio-charset-enhanced.dev.java.net/source/browse/java-nio-charset-enhanced/branches/j7_EUC_TW/src/java/lang/String.java?rev=960&view=markup

-Ulf