RFR(S): ZGC: C2: Oop instance cloning causing skipped compiles

[Nils Eliasson]

Hi,

I found a few bugs after the enabling of the clone intrinsic in ZGC.

1) The arraycopy clone_basic has the parameters adjusted to work as a 
memcopy. For an oop the src is pointing inside the oop to where we want 
to start copying. But when we want to do a runtime call to clone - the 
parameters are supposed to be the actual src oop and dst oop, and the 
size should be the instance size.

For now I have made a workaround. What should be done later is using the 
offset in the arraycopy node to encode where the payload is, so that the 
base pointers are always correct. But that would require changes to the 
BarrierSet classes of all GCs. So I leave that for next release.

2) The size parameter of the TypeFunc for the runtime call has the wrong 
type. It was originally Long but missed the upper Half, it was fixed to 
INT (JDK-8233834), but that is wrong and causes the compiles to be 
skipped. We didn't notice that since they failed silently. That is also 
why we didn't notice problem #1 too.

https://bugs.openjdk.java.net/browse/JDK-8234520

http://cr.openjdk.java.net/~neliasso/8234520/webrev.01/

Please review!

Nils