LEAP-Backend

LEAP (Logic nEtwork-Aware Pipelining) is a framework for exploiting logic synthesis and technology mapping to improve the performance of high-level synthesis (HLS) tools. LEAP is implemented in Python and is open-source under the MIT license.

This is the backend for the LEAP project. It contains the folloinwg necessary algorithms to process the subject graph.

• blif handles the read/write of BLIF files and provides interface to manipulate the logic network.
• cute is a packge for cut enumeration.
• map is the LUT mapping algorithm with Boolean simulation.
• milp contains several MILP models for timing regulation whose optimization is powered by Gurobi.

Installation

1. (recommended) Download backend as a submodule of the main project.

2. Install and use it elsewhere.

pip install -e .

Getting Started

The example can be executed using python examples/mapbuf.py. This example:

1. Takes the BLIF file examples/add2/add2.blif as input (synthesized from examples/add2/add2.v).
2. Reads the schedulability constraints from examples/add2/add2.json.
3. Maps the logic network to a LUT-based FPGA with maxLeaves=3 and clockPeriod=1ns (1 LUT level is 0.7ns).
4. Writes the optimized BLIF file to examples/add2/add2_opt.blif.

if __name__ == "__main__":
    from backend import *
    
    input_file = "examples/add2/add2.blif"
    input_sched_constr = "examples/add2/add2.json"
    output_file = "examples/add2/add2_opt.blif"

    graph = read_blif(input_file)
    model = MapBufModel(graph, json.load(open(input_sched_constr)), 1, {"maxLeaves": 3})
    model.solve()
    model.dumpGraph(output_file)

    import subprocess

    # CEC check works if no buffer is inserted
    # subprocess.run(f"abc -c 'cec {input_file} {output_file}'", shell=True)
    subprocess.run(f"abc -c 'read {output_file}; print_stats'", shell=True)

An advanced example can be found in examples/mem. Where:

1. The DIP specifies mem_addr and mem_rd_en has the same label.
2. The CIP specifies the mem_data arrives at least 1 cycle after mem_addr and mem_rd_en.