We want to make sure we never complete more than one
instruction per cycle, or write back more than one GPR
or CR per cycle.
Signed-off-by: Anton Blanchard <anton@linux.ibm.com>
We only need two write ports for load with update instructions.
Having two write ports just for this instruction is expensive.
For now we will force them to be the only instruction in the
pipeline, and take two cycles of writeback.
Signed-off-by: Anton Blanchard <anton@linux.ibm.com>
Handle the CR as a single field with per nibble enables. Forward any
writes in the same cycle.
If this proves to be an issue for timing, we may want to revisit
this in the future. For now, it keeps things simple.
Signed-off-by: Anton Blanchard <anton@linux.ibm.com>
