UC Santa Cruz

Live Graph (lgraph) is a graph optimized for live synthesis (Live Synthesize Graph or

lgraph for short). By live, we mean that small changes in the design should have results

in few seconds. The goal is that any code change can have its synthesis and simulation

setup ready under 30 seconds with a goal of under 4 seconds in most cases.

Notice that this is a different goal from having an incremental synthesis where many

edges are added and removed. The typical graph reconstruction is on the order of

thousands of nodes.

lgraph is optimized for synthesis, allowing forward and backward traversals in the

nodes (bidirectional graph).

Once the graph is built, some optimization can be applied to the input design, including

Dead Code Elimination (DCE), Common Sub-expression Elimination (CSE),

Copy Propagation, Fluid flop insertion and so forth.