Fwd: RFR: 8175917: [JVMCI] Avoid long JNI handle chains

[Vladimir Kozlov]

Looks good. Who with OpenJDK id reviewed it in Labs? I need to list them 
in changeset.

Thanks,
Vladimir

On 3/2/17 7:47 AM, Christian Haeubl wrote:
> Hi,
>
> Please review the following patch for
> https://bugs.openjdk.java.net/browse/JDK-8175917:
> http://cr.openjdk.java.net/~never/8175917/webrev.001/
>
> Bug description:
> When Truffle uses JMVCI and Graal for compiling a guest language (e.g.
> JavaScript), Graal heavily uses partial escape analysis. In such cases,
> the JVMCI method "installCode" uses lots of local JNI references when
> generating the corresponding debug information so that the thread's
> top-level JNI handle buffer will have a large size. This unnecessarily
> increases the footprint and significantly decreases the performance (as
> long as https://bugs.openjdk.java.net/browse/JDK-8175318 is not fixed).
>
> Fix:
> Around the JVMCI method "installCode", we do something similar to JNI's
> PushLocalFrame/PopLocalFrame. So, the large JNI handle buffer is
> released when the method exits and the thread's top-level JNI handle
> buffer is not getting enlarged.
>
> Tests:
> The changes were tested locally by executing JVMCI bootstrapping and
> parts of Graal / Truffle.
>
> Thanks,
> Christian