RFR: JDK-8032012, , String.toLowerCase/toUpperCase performance improvement

[Xueming Shen]

Fair enough. I don't think it's going to be a measurable difference. I 
have updated the webrev
to use the Character.isSurrogate() for better readability.

http://cr.openjdk.java.net/~sherman/8032012/webrev

-Sherman

On 2/5/14 6:21 PM, Vitaly Davidovich wrote:
>
> i2c conversion should not cost anything; it'll just make jit use low 
> 16 bits of the registers for (unsigned) comparisons.  I haven't 
> checked this though, but that's what I'd expect.
>
> Sent from my phone
>
> On Feb 5, 2014 7:27 PM, "Xueming Shen" <xueming.shen at oracle.com 
> <mailto:xueming.shen at oracle.com>> wrote:
>
>     On 02/05/2014 03:28 PM, Ulf Zibis wrote:
>
>         Additionally you could use Character.isSurrogate() and
>         Character.isSupplementaryCode<point() at appropriate places.
>         Both are better optimized for JIT.
>
>
>     j.l.C.isSupplementaryCodePoint() checks up boundary of supp, we
>     probably don't need it
>     here, as the returning code point is either a ERROR or a valid
>     unicode code point.
>
>     I'm not sure about the j.l.C.isSurrogate(), which takes a char and
>     we have an int here.
>     I would expect the javac will inline the constants for me, but I
>     don't know whether jit
>     can inline and then optimize away the explicit casting i2c. Not a
>     big deal though.
>
>     -sherman
>
>
>
>
>         -Ulf
>
>
>         Am 05.02.2014 22:30, schrieb Xueming Shen:
>
>             Hi Remi,
>
>             Good suggestion. Now the "common case" path is much simple
>             and faster :-)
>             I'm seeing a 5%-10% boost for the normal-non-surrogates
>             case. And it appears
>             the bmp+surr mixed is getting faster as well. Though I
>             would assume the it
>             would get slower in case of "no-case-folding" +
>             surrogates. But the common
>             case wins here.
>
>             http://cr.openjdk.java.net/~sherman/8032012/webrev/
>             <http://cr.openjdk.java.net/%7Esherman/8032012/webrev/>
>
>
>