record to the label structure to hold the port number. One major
issue stemming from this was reported in github issue #203 by Anton
Blanchard. This commit fixes that error.
this limited ports to 16384, which seemed reasonable at the time.
However, the sky130_sram_macro layouts connect power and ground in a
way that when coupled with "extract unique" can generate tens of
thousands of ports and overrun the bit field, showing that automation
can do the unexpected. The solution was to split out the port number
from the label record as its own 32-bit value.
Tim Edwards