Architecture Exploration of High-Performance Floating-Point Fused Multiply-Add Units and their Automatic Use in High-Level Synthesis

Multiply-add operations form a crucial part of many digital signal processing and control engineering applications. Since their performance is crucial for the application-level speed-up, it is worthwhile to explore a wide spectrum of implementations alternatives, trading increased area/energy usage to speed-up units on the critical path of the computation. This paper examines existing solutions and proposes two new architectures for floating-point fused multiply-adds, and also considers the impact of different in-fabric features of recent FPGA architectures. The units rely on different degrees of carry-save arithmetic improve performance by up to 2.5x over the closest state-of-the-art competitor. They are evaluated at the application level by modifying an existing high-level synthesis system to automatically insert the new units for computations on the critical path of three different convex solvers.