RFR: 8198949: Modularize arraycopy stub routine GC barriers (original) (raw)
Erik Österlund erik.osterlund at oracle.com
Fri Mar 9 16:58:19 UTC 2018
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Hi,
The GC barriers for arraycopy stub routines are not as modular as they could be. They currently use switch statements to check which GC barrier set is being used, and call one or another barrier based on that, with registers already allocated in such a way that it can only be used for write barriers.
My solution to the problem is to introduce a platform-specific GC barrier set code generator. The abstract super class is BarrierSetCodeGen, and you can get it from the active BarrierSet. A virtual call to the BarrierSetCodeGen generates the relevant GC barriers for the arraycopy stub routines.
The BarrierSetCodeGen inheritance hierarchy exactly matches the corresponding BarrierSet inheritance hierarchy. In other words, every BarrierSet class has a corresponding BarrierSetCodeGen class.
The various switch statements that generate different GC barriers depending on the enum type of the barrier set have been changed to call a corresponding virtual member function in the BarrierSetCodeGen class instead.
Thanks to Martin Doerr and Roman Kennke for providing platform specific code for PPC, S390 and AArch64.
Webrev: http://cr.openjdk.java.net/~eosterlund/8198949/webrev.00/
CR: https://bugs.openjdk.java.net/browse/JDK-8198949
Thanks, /Erik
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