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Source-level instrumentation for in-system debug of high-level synthesis designs for FPGA

University of British Columbia

High-Level Synthesis (HLS) has emerged as a promising technology to reduce the time and complexity that is associated with the design of digital logic circuits. HLS tools are capable of allocating resources and scheduling operations from a software-like behavioral specification. In order to maintain the productivity promised by HLS, it is important that the designer can debug the system in the context of the high-level code. Currently, software simulations offer a quick and familiar method to target logic and syntax bugs, while software/hardware co-simulations are useful for synthesis verification. However, to analyze the behaviour of the circuit as it is running, the user is forced to understand waveforms from the synthesized design. Debugging a system as it is running requires inserting instrumentation circuitry that gathers data regarding the operation of the circuit, and a database that maps the record entries to the original high-level variables. Previous work has proposed adding this instrumentation at the Register Transfer Level (RTL) or in the high-level source code. Source-level instrumentation provides advantages in portability, transparency, and customization. However, previous work using source-level transformations has focused on the ability to expose signals for observation rather than the construction of the instrumentation itself, thereby limiting these advantages by requiring lower-level code manipulation. This work shows how trace buffers and related circuitry can be inserted by automatically modifying the source-level specification of the design. The transformed code can then be synthesized using the regular HLS flow to generate the instrumented hardware description. The portability of the instrumentation is shown with synthesis results for Vivado HLS and LegUp, and compiled for Xilinx and Altera devices correspondingly. Using these HLS tools, the impact on circuit size varies from 15.3% to 52.5% and the impact on circuit speed ranges from 5.8% to 30%. We also introduce a low overhead technique named Array Duplicate Minimization (ADM) to improve trace memory efficiency. ADM improves overall debug observability by removing up to 31.7% of data duplication created between the trace memory and the circuit{'}s memory structures.

Text

2016-10-06

Attribution-NonCommercial-NoDerivatives 4.0 International

http://hdl.handle.net/2429/59380

Electrical and Computer Engineering

University of British Columbia

UBCV

http://creativecommons.org/licenses/by-nc-nd/4.0/