netlist-graph

Graph-based netlist analysis tool for SKY130 post-synthesis netlists.

Installation

cd scripts/netlist_graph
uv sync

Usage

Search for nets

uv run netlist-graph search <netlist.v> <pattern>

Trace drivers (backwards)

uv run netlist-graph drivers <netlist.v> <net> [-d depth]

Trace loads (forwards)

uv run netlist-graph loads <netlist.v> <net> [-d depth]

Find path between nets

uv run netlist-graph path <netlist.v> <source> <target>

Generate trace configuration

Generate signal type and driver information:

# Simple output
uv run netlist-graph trace <netlist.v> <signal1> <signal2> ...

# Generate JSON for programmatic use
uv run netlist-graph trace <netlist.v> ibus__cyc rst_n_sync.rst --json

Generate watchlist file

Create a JSON watchlist for signal monitoring:

uv run netlist-graph watchlist <netlist.v> <output.json> <signal1> <signal2> ...

Example:

uv run netlist-graph watchlist design.v watch.json ibus__cyc rst_n_sync gpio_out

Interactive mode

uv run netlist-graph interactive <netlist.v>

Commands in interactive mode:

• d <net> - find drivers
• l <net> - find loads
• p <src> <tgt> - find path
• s <pattern> - search nets
• c <net> - cone of influence
• q - quit

Examples

# Find what drives the ibus_cyc signal
uv run netlist-graph drivers tests/timing_test/minimal_build/6_final.v "ibus__cyc" -d 8

# Trace reset synchronizer path
uv run netlist-graph drivers tests/timing_test/minimal_build/6_final.v "rst_n_sync.rst"

# Find path from reset input to CPU
uv run netlist-graph path tests/timing_test/minimal_build/6_final.v "gpio_in[40]" "ibus__cyc"

# Generate watchlist for debugging
uv run netlist-graph watchlist tests/timing_test/minimal_build/6_final.v watch.json \
    ibus__cyc rst_n_sync.rst gpio_out[0] gpio_out[1]

Signal Types

The tool classifies signals based on their drivers:

• reg - Driven by a flip-flop (dfxtp, dfrtp, etc.)
• mem - Driven by SRAM
• comb - Combinational logic (gates, buffers)