yosys -import

synth_ice40 -nocarry
ice40_opt -unlut
abc -lut 4
opt_clean

yosys -import

synth_ice40 -nocarry
ice40_opt
ice40_unlut
simplemap
opt
abc -lut 4
opt_clean

Integrate yosys upstream unlut change.
Integrate yosys upstream unlut change.

Signed-off-by: Keith Rothman <1bc19627a439baf17510dc2d0b2d250c96d445a5@users.noreply.github.com>
