hg: shenandoah/jdk9/hotspot: jweak handling misses barriers.

[Aleksey Shipilev]

On 04/20/2017 10:04 AM, Andrew Haley wrote:
> On 19/04/17 18:54, ashipile at redhat.com wrote:
>> Changeset: a4ae173af91d
>> Author:    shade
>> Date:      2017-04-19 19:52 +0200
>> URL:       http://hg.openjdk.java.net/shenandoah/jdk9/hotspot/rev/a4ae173af91d
>>
>> jweak handling misses barriers.
>>
>> ! src/cpu/aarch64/vm/sharedRuntime_aarch64.cpp
>> ! src/cpu/aarch64/vm/templateInterpreterGenerator_aarch64.cpp
>> ! src/cpu/x86/vm/macroAssembler_x86.cpp
>> ! src/share/vm/prims/jvmtiTagMap.cpp
>> ! src/share/vm/runtime/jniHandles.cpp
>>
> 
> Can we improve
> 
>    if (UseG1GC || UseShenandoahGC)
> 
> to
> 
>    if (theCollector.needsWriteBarriers())
> 
> or something?

That is inventing the GC interface, and we don't know the correct form for it yet.

Blindly introducing it gives us nothing, I think. New uses would still be
missed. Existing uses would have different forms, depending on what barriers are
enabled in Shenandoah. Whatever we do, it would have to be re-adapted to GC
interface later anyway. Just spreading "|| UseShenandoahGC" around seems to be
the lesser evil.

Thanks,
-Aleksey