digraph fence_sw_w_collapse2 { margin=0 //ranksep=.3; N1 [label="A: store(release)", shape=none]; N2 [style=invis, shape=point]; N3 [style=invis, shape=point]; N4 [label="B: fence(acquire)", shape=none]; N1 -> N4 [label="sw", color=blue, penwidth=3, constraint=false]; N1 -> N2 [color=invis, weight=100]; N3 -> N4 [color=invis, weight=100]; {rank=same; N2 N3} }