[flyingfoxyy]

Summary

lutabsorb let the installed LUT library override an explicit -K: the default LUT size was computed as min(6, LutMax), and when -K exceeded LutMax it was truncated to LutMax with only a warning. Since ABC installs a built-in 4-input LUT library at startup (If_Init), lutabsorb -K 6 actually ran with K=4 and skipped every candidate node with more than 4 fanins.

This makes -K behave the same way as in the if command: when -K is given, the LUT library is disabled and the requested LUT size is honored exactly. When -K is not given, the library is still used for the default LUT size and the area check. Without a library there is no area model, so the verbose per-round line and the final summary no longer print an area gain.

Test

Without -K, the default library is still used (K = 4 with the built-in library). With -K 6 the size is honored:

abc 01> if -K 6 -a
abc 02> lutabsorb -v -K 6
Round 1: removed 3 nodes.
lutabsorb: K=6 M=8 R=1  nodes 569 -> 566 (-3)

With a library (built-in or read with read_lut), the area gain is still reported:

abc 01> read_lut lut6.txt
abc 02> lutabsorb -v
Round 1: removed 3 nodes, area gain 3.00.
lutabsorb: K=6 M=8 R=1  nodes 569 -> 566 (-3)  area gain 3.00

test/issues/issue70.sh passes.