Refine global - register -global transfers

[tnowotny]

within the learn code, there can be repeated reference to dd_remapXX[iprePos]. Whenever it is used more than once, it would probably be efficient to fetch it into a local register.

[tnowotny]

1. load dd_remapXX[...] into a register by default.
2. But more generally, introduce an annotation "readonly XXX YYY" e.g. readonly scalar x; for variables. Those would not be written back to global memory; the register copy could be declared const

[tapaswenipathak]

Hi folks: Is this ticket still open?

[neworderofjamie]

Well, the read-only part has been implemented by #247 and the equivalent of dd_remap[iprepos] is now loaded into a register here. The issue is that that is done whether it is required or not as discussed in #248

[tapaswenipathak]

All PRs are there then right, can you ref the ticket in the PRs?