Validating GCSE in the scheduling of high-level synthesis

Abstract

High-level synthesis (HLS) compiles a algorithmic description (C or C++) into a digital hardware implementation (VHDL or Verilog) through a sequence of transformations. However, the complex compiling process may introduce an error in the produced register-transfer level (RTL) implementation. Global common subexpression elimination (GCSE) as a commonly used code motion technique in the scheduling of HLS is an error-prone and complex process that need to be validated. In this paper, we propose an equivalence checking method to validate GCSE with non-common variables used in the rest code in the scheduling of HLS by enhancing the path equivalence criteria. The source and target programs are modeled using Finite State Machine with Datapath (FSMD) that is essentially a Control and Data Flow Graph (CDFG). The experimental results show that our method can indeed validate the GCSE with non-common variables used in the rest code in HLS which has not been solved in the existing papers.