type of special virtual register port or datapath that masks out the
required predicate bits closer to the regfile.
+another disadvantage is that the CR regfile needs to be expanded from 8x 4bit CRs to a minimum of 64x or preferably 128x 4-bit CRs. Beyond that rhey can be transferred using vectirised mfcr and mtcrf into INT regs. this is a huge number of CR regs, each of which will need a DM column in the FU-REGs Matrix. however this cost can be mitigated through regfile cacheing, bringing FU-REGs column numbers back down to "sane".
+
### Predicated SIMD HI32-LO32 FUs
an analysis of changing the element widths (for SIMD) gives the following