RFR(M): 8168083: PPC64: Cleanup template interpreter after 8154580 and 8154867

[Doerr, Martin]

Hi,

I'd like to clean up the template interpreter on PPC64 a little bit after changes which were pushed into jdk9:

8154580 introduced copying the java mirror into the interpreter frame. Some code can be implemented shorter. Before this change, the size of the ijava state was designed to be a multiple of 16. We should remove the comment as this is no longer true. I have checked that this is not really required (generate_fixed_frame inserts frame padding if needed).

8154867 is the PPC64 port of "better byte behavior". The shorter TOS states are not treated appropriately (which is not critical because the template interpreter also uses itos for shorter types). This part of the change was requested by Coleen, but it didn't make it into the original webrev.

Webrev is here:
http://cr.openjdk.java.net/~mdoerr/8168083_PPC64_interp_cleanup/webrev.00/

Please review.

Thanks and best regards,
Martin