RFR 8222989 [lworld] Calling convention - C2 to C1 (oop params)

[Ioi Lam]

https://bugs.openjdk.java.net/browse/JDK-8222989
http://cr.openjdk.java.net/~iklam/valhalla/8222989-c1-calling-convention-oops.v01/

Many files are changed, but mostly are just for passing an extra 'tmp3'
parameter to BarrierSetAssembler::store_at(). The old G1 implementation
hard-codes tmp3==r8, but this conflicts with the Java calling convention
that uses r8 for passing parameters.

My next step is to handle GC that happens when the C1 entry points allocate
buffered objects of inline class types. See JDK-8223110

Thanks
- Ioi