RFR (S) 8150463: StringConcat MH_INLINE_SIZED_EXACT should skip storage initialization

[Peter Levart]

Hi Aleksey,

Looks nice to me, but I'm not a Reviewer. Quite an improvement for 
longer strings.

Regards, Peter

On 03/24/2016 08:31 AM, Aleksey Shipilev wrote:
> On 03/16/2016 11:13 AM, Aleksey Shipilev wrote:
>> I'd like to improve our advanced String concat strategy,
>> MH_INLINE_SIZED_EXACT, with skipping the storage initialization:
>>    https://bugs.openjdk.java.net/browse/JDK-8150463
>>
>> Webrev:
>>    http://cr.openjdk.java.net/~shade/8150463/webrev.01/
>>
>> Performance had improved, as planned:
>>    http://cr.openjdk.java.net/~shade/8150463/perf.txt
>>
>> The rest of the difference against BC_SB strategy is code-generation
>> quirks, to be addressed separately. We pay some price for a runtime
>> final index check to strengthen against inadvertent bugs in
>> concatenation code.
>>
>> This patch does not affect the String concatenation at this point,
>> because we are still running with BC_SB strategy. I ran through
>> java/lang/String jtregs to see if MH_INLINE_SIZED_EXACT works as
>> expected. Therefore, I don't think this needs to wait for Jigsaw
>> integration. But, it can also wait, no problem. I'll let Jigsaw folks to
>> decide on integration timing.
> Anyone? I have re-based and re-tested the patch after Jigsaw
> integration, and it still works fine (the webrev identical):
>    http://cr.openjdk.java.net/~shade/8150463/webrev.01/
>
> Thanks,
> -Aleksey
>
>
>