YosysHQ / icestorm

Project IceStorm - Lattice iCE40 FPGAs Bitstream Documentation (Reverse Engineered)
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icetime: Ignore false paths through LUTs based on function #294

Closed gatecat closed 2 years ago

gatecat commented 2 years ago

This is required to avoid falsely reported combinational loops with YosysHQ/nextpnr#966, which allows an unrelated driving LUT2 and SB_CARRY to be packed into the same LC, with the inputs used for the carry being don't cares in the LUT function.