Probabilistic Optimization for High-Level Synthesis

Abstract

High-level synthesis (HLS) tools automatically transform a high-level program, for example in C/C++, into a low-level hardware description. A key challenge in HLS tools is scheduling, i.e. determining the start time of all the operations in the untimed program. There are three approaches to scheduling: static, dynamic and hybrid. Static scheduling has been well studied, however, statically analysing dynamic hardware behaviours is still challenging due to the unpredictability due to run-time dependencies. Existing approaches either assume the worst-case timing behaviour, which can cause significant performance loss or area overhead, or use simulation, which takes significant time to explore a sufficiently large number of program traces. In this work, we introduce a novel probabilistic model allowing HLS tools to efficiently estimate and optimize the cycle-level timing behaviour of HLS-generated hardware. Our framework offers insights to assist both hardware engineers and HLS tools when estimating and optimizing hardware performance.