nl_opt: Verilog Compiler Driver for Netlist Optimization Development

Description

This Verilog frontend tool can drive netlist optimizations on a pass-by-pass basis.

Getting Started

Try running an nl_opt pattern on this example verilog:

module top (
  a,
  b,
  y
);
  input a;
  wire a;
  input b;
  wire b;
  output y;
  wire y;
  wire inst_0_ZN;
  wire inst_1_ZN;
  AND2 inst_0 (
    .A1(a),
    .A2(b),
    .ZN(inst_0_ZN)
  );
  AND2 inst_1 (
    .A1(inst_0_ZN),
    .A2(inst_0_ZN),
    .ZN(inst_1_ZN)
  );
  assign y = inst_1_ZN;
endmodule

Save it to ex.v

Then run nl_opt ex.v --passes clean,print-verilog

Help

Netlist optimization debugging tool

Usage: nl_opt [OPTIONS] [INPUT] [OUTPUT]

Arguments:
  [INPUT]
          Verilog file to read from (or use stdin)

  [OUTPUT]
          Optional Verilog file to output to

Options:
  -x, --no-xilinx
          Do not parse with Xilinx-specific port names

      --verify-each
          Verify after every pass (not just the last)

  -v, --verbose
          Verbose logging

  -p, --passes <PASSES>
          A list of passes to run in order

          Possible values:
          - cell-stats:        Prints stats on all the cell types in the netlist
          - clean:             A pass that cleans the netlist
          - dot-graph:         A pass that prints the dot graph of the netlist
          - fold-all-patterns: Runs all built-in patterns to a fixed point
          - insert-inv:        Insert a pair of inverters at every node
          - list-nets:         List all nets in the netlist
          - print-verilog:     A dummy pass that emits the Verilog of the netlist
          - rename-nets:       Renames nets/instances sequentially 
          - strip-attributes:  Strip cell attributes except 'dont_touch` and `keep`

      --non-ansi
          Emit the verilog in non-ANSI style

  -h, --help
          Print help (see a summary with '-h')

  -V, --version
          Print version