RFR (S) 8145428: Optimize StringUTF16 compress/copy methods for C1

[Aleksey Shipilev]

Hi Roger,

Um, do you really want to spell out "thou shalt run thee benchmarks
while changing the String hotpath" in source code comments?

I disagree: documenting development processes in the source code is odd.
But equally odd is the suggestion that a common development practice
would *not* involve running benchmarks when changing the ubiquitous
codepath in the standard library, *or* studying the prior history for
the code under modification. Some knowledge really is common.

Can we pretty please get this done, and move on to other interesting things?

Thanks,
-Aleksey

On 12/17/2015 05:55 PM, Roger Riggs wrote:
> Hi Alexsey,
> 
> The 'expected to run benchmarks' might the operative comment in the code.
> 'Common' knowledge sometimes isn't so common.
> 
> Roger
> 
> 
> On 12/17/2015 2:54 AM, Aleksey Shipilev wrote:
>> On 12/17/2015 02:34 AM, Ulf wrote:
>>> I'm wondering why moving the increment operation to an extra line wound
>>> enhance performance.
>> Because C1 is very straightforward, and code movement like that is a
>> poor man's instruction scheduling, that pads out the data dependency
>> between index update and indexed access. I don't think it deserves a
>> comment -- it is expected one will run the benchmarks when changing that
>> code.
>>
>> Thanks,
>> -Aleksey
>>
>