Hi compiler people,
is there some chance that javac could be enhanced to optimize better as discussed in this thread?
Than refactoring of up to now better readable code to ugly StringBuilder@append() code would be
superfluous.
I really like the String concatenation syntax, but unfortunately it often causes slower code and
bigger footprint.
Optimally javac would optimize mixed use of StringBuilder, StringJoiner, concatenation, toString(),
append(String), append(Collection) etc. to a single StringBuilder instance, so that the resulting
code, JITed or not, will have better performance.
Additionally javac could guess a reasonable initial capacity from the given
source code.
Am 29.08.2014 um 10:01 schrieb Wang Weijun:
So it's not that the optimization fails but there is no optimization on them
yet.
I do see the .append("x") case will be easy to deal with, but it looks like
historically javac has not been a place to do many optimizations. It mostly converts the
java source to byte codes in a 1-to-1 mapping and let VM do whatever it wants (to
optimize). When you talked about compiling multiple concatenation into using a single
StringBuilder, it's more like choosing the correct implementation rather than an
optimization.
I don't expect to see big change on this in the near future, so shall we go on
with the current enhancement?
Thanks
Max
On Aug 29, 2014, at 2:17, Ulf Zibis <ulf.zi...@cosoco.de> wrote:
I mean:
It does not output byte code that only uses a single char array to compose the
entire String in question.
With "optimization fails", I also mean, there is used an additional
"StringComposer" e.g. another StringBuilder or a StringJoiner in addition to the 1st
StringBuilder.
-Ulf
Am 27.08.2014 um 14:02 schrieb Pavel Rappo:
Could you please explain what you mean by "javac optimization fails" here?
-Pavel
On 27 Aug 2014, at 10:41, Ulf Zibis <ulf.zi...@cosoco.de> wrote:
4.) Now we see, that javac optimization fails again if StringBuilder,
concatenation, toString(), append(String), append(Collection) etc. and
StringJoiner use is mixed.
