nextpnr-ice40 --pre-pack data/clocks.py --seed 2 --placer heap \
	--up5k --package sg48  \
	-l /home/tnt/projects/ice40/ice40-playground/projects/riscv_usb/build-tmp/riscv_usb.pnr.rpt \
	--json /home/tnt/projects/ice40/ice40-playground/projects/riscv_usb/build-tmp/riscv_usb.json \
	--pcf /home/tnt/projects/ice40/ice40-playground/projects/riscv_usb/data/top-icebreaker.pcf \
	--asc /home/tnt/projects/ice40/ice40-playground/projects/riscv_usb/build-tmp/riscv_usb.asc
Info: Importing module $__ICE40_FULL_ADDER
Info: Rule checker, verifying imported design
Info: Importing module SB_CARRY
ERROR: multiple drivers on net 'CO' (carry.CO and $logic_or$/opt/icestorm/bin/../share/yosys/ice40/cells_sim.v:141$1686.Y)
ERROR: Loading design failed.
0 warnings, 2 errors