String concatenation tweaks

Aleksey Shipilev aleksey.shipilev at
Mon May 25 19:01:52 UTC 2015

On 05/24/2015 06:33 PM, Remi Forax wrote:
> Here is my version (see at the end of this message).

Thanks! Merged it into the patchset with minor polish:

The performance is interesting. It seems to break OptimizeStringConcat,
and so it's a performance win only on non-optimized chains, like
string_string_long. The allocation pressure is slightly higher as well,
seems to be because int[] from the collector is not scalarized.

You may want to tune it more, JMH benchmarks are here:

...and -prof perfasm, -prof perfnorm, and -prof gc are your friends.


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