RFR (L) JEP 280: Indify String Concatenation (integration)

[Aleksey Shipilev]

(dropping corelibs-dev and hotspot-dev)

On 01/29/2016 04:32 PM, Erik Joelsson wrote:
> On 2016-01-27 14:55, Aleksey Shipilev wrote:
>>   c) (XS) Build changes that force emitting the "legacy" inline
>> StringBuilder concat in a few cases (e.g. when pre-JDK 9 bytecode is
>> expected):
>>     http://cr.openjdk.java.net/~shade/8085796/webrev.root.00/
> In what context do we need pre-JDK 9 bytecode for java.base and
> jdk.compiler?

Circularity issues, one critical and one manageable.

Critical: java.base is excepted to let JDK bootstrap properly, otherwise
processing a String concat expression within the j.l.invoke
infrastructure that handles ISC would fail because of the circularity.

Manageable: jdk.compiler is excepted to test the rest of JDK properly
first. The bug in ISC that breaks a compiler would introduce breakages
in many things that are compiled with it, sometimes during the
compilation itself. Which, in best case, fails some limited amount of
regression tests, but frequently fails the OpenJDK build itself. We may
want to reconsider this going forward, after ISC stabilizes:
  https://bugs.openjdk.java.net/browse/JDK-8148605

Cheers,
-Aleksey