Heterogeneous FPGA Compiler Flow for LUT-AIC Logic Mapping
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Solution Overview
Problem
Heterogeneous FPGA architectures face inefficiencies in resource utilization and maximum clock frequency due to suboptimal mapping of combinational logic to different types of logic elements, leading to excess die-area consumption and increased wire length.
Innovation Solution
A compiler flow that supports heterogeneous FPGA architecture by optimizing the mapping of combinational logic to a combination of lookup tables (LUTs) and AND-inverter cones (AICs), utilizing a synthesis, placement, and routing algorithm that accounts for the specific characteristics of each logic element to improve resource utilization and clock frequency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If combinational logic is mapped to different types of logic elements in heterogeneous FPGA architecture, then logic implementation flexibility is improved, but resource utilization efficiency deteriorates
Solution Approach 1:
The patent applies parameter changes by dynamically adjusting the mapping parameters of combinational logic to different logic elements based on their characteristics. The system evaluates parameters such as logic element type (LUT, AIC, carry chain), input/output fan-in/out constraints, and timing requirements to optimize the mapping configuration. This allows the compiler to select the most appropriate logic element type for each combinational logic node, thereby improving resource utilization while maintaining implementation flexibility.
2Adaptability or versatility
If combinational logic is mapped to different types of logic elements, then implementation versatility is improved, but die-area consumption increases
Solution Approach 1:
The patent implements local quality by assigning different logic element types to different regions or nodes of the design based on local requirements. Instead of uniformly mapping all combinational logic to the same logic element type, the system analyzes local characteristics such as fan-in/fan-out constraints, timing criticality, and resource availability at each node. This allows area-efficient mapping where each logic element is used in the location and configuration that best suits its capabilities and the local design requirements.
3Ease of manufacture
If suboptimal mapping of combinational logic is used, then compilation simplicity is maintained, but wire length increases
Solution Approach 1:
The patent applies preliminary action by performing optimization of logic element mapping and placement during the compilation phase, before the actual implementation. The compiler analyzes the design netlist, identifies combinational logic nodes, and pre-determines the optimal mapping to different logic element types considering wire length implications. This preliminary optimization ensures that the subsequent placement and routing stages start with an already optimized configuration, reducing overall wire length without requiring complex runtime adjustments.
4Ease of manufacture
If suboptimal mapping of combinational logic is used, then compilation simplicity is maintained, but maximum clock frequency decreases
Solution Approach 1:
The patent optimizes maximum clock frequency by dynamically changing mapping parameters during compilation. The system evaluates timing constraints, logic element propagation delays, and critical path requirements to determine the optimal mapping configuration. By selecting logic element types and configurations that minimize critical path delays and balance timing across the design, the compiler achieves higher maximum clock frequencies while maintaining automated compilation simplicity.
Data Source
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AI summary
Embodiments herein are directed to systems and techniques for supporting heterogeneous logic architecture in programmable devices, such as field-programmable gate arrays (FPGAs). heterogeneous logic architectures may include additional logic elements (e.g., AND-inverter cones (AICs)) in addition to lookup tables (LUTs). Accordingly, it may be desirable to provide a compiler flow that supports heterogeneous FPGA architecture, taking advantage of a combination of LUTs and other logic elements (e.g., AICs) to improve resource utilization (e.g., die area, wire length) and improve maximum clock frequency and compile time.