Dynamic Common Sub-Expression Elimination during Scheduling in High-Level Synthesis

We introduce a new approach, “Dynamic Common Sub-expression Elimination (CSE)”, that dynamically eliminates common sub- expressions based on new opportunities created during scheduling of control-intensive designs. Classical CSE techniques fail to eliminate several common sub-expressions in control-intensive designs due to the presence of a complex mix of control and data-flow. Aggressive speculative code motions employed to schedule controlintensive designs often re-order, speculate and duplicate operations, hence changing the control flow between the operations with common sub-expressions. This leads to new opportunities for applying CSE dynamically. We have implemented dynamic CSE in a high-level synthesis framework called Spark and present results for experiments performed using various combinations of CSE and dynamic CSE. The benchmarks used consist of four functional blocks derived from two moderately complex industrial-strength applications, namely, MPEG-1 and the GIMP im...

• Type: Conference
• Year: 2002
• Where: ISSS
• Authors: Alexandru Nicolau, Nikil D. Dutt, Rajesh Gupta, Nick Savoiu, Mehrdad Reshadi, Sumit Gupta
• Keywords: Common Sub-expressions, CSE Techniques, Dynamic Cse, Hardware, ISSS 2002