Architecture description and packing for logic blocks with hierarchy, modes and complex interconnect

The development of future FPGA fabrics with more sophisticated and complex logic blocks requires a new CAD flow that permits the expression of that complexity and the ability to synthesize to it. In this paper, we present a new logic block description language that can depict complex intra-block interconnect, hierarchy and modes of operation. These features are necessary to support modern and future FPGA complex soft logic blocks, memory and hard blocks. The key part of the CAD flow associated with this complexity is the packer, which takes the logical atomic pieces of the complex blocks and groups them into whole physical entities. We present an area-driven generic packing tool that can pack the logical atoms into any heterogeneous FPGA described in the new language, including many different kinds of soft and hard logic blocks. We gauge its area quality by comparing the results achieved with a lower bound on the number of blocks required, and then illustrate its explorative capability in two ways: on fracturable LUT soft logic architectures, and on hard block memory architectures. The new infrastructure attaches to a flow that begins with a Verilog front-end, permitting the use of benchmarks that are significantly larger than the usual ones, and can target heterogenous FPGAs.