RFR(L): 8205044: [lworld] Interpreter and compiler support for acmp with value type operands

[Tobias Hartmann]

Hi,

please review the following patch:
https://bugs.openjdk.java.net/browse/JDK-8205044
http://cr.openjdk.java.net/~thartmann/8205044/webrev.00/

I've ported this code from the Exp branch [1]. We therefore still use the klass pointer alignment
trick to determine if an oop points to a value type. We can later enhance this to use the mark word.

Thanks,
Tobias

[1]
http://mail.openjdk.java.net/pipermail/valhalla-dev/2018-March/003935.html
http://mail.openjdk.java.net/pipermail/valhalla-dev/2018-February/003824.html