Superblock-Based Source Code Optimizations for WCET Reduction

—Superblocks represent regions in a program code that consist of multiple basic blocks. Compilers benefit from this structure since it enables optimization across block boundaries. This increased optimization potential was thoroughly studied in the past for average-case execution time (ACET) reduction at assembly level. In this paper, the concept of superblocks is exploited for the optimization of embedded real-time systems that have to meet stringent timing constraints specified by the worst-case execution time (WCET). To achieve this goal, our superblock formation is based on a novel trace selection algorithm which is driven by WCET data. Moreover, we translate superblocks for the first time from assembly to source code level. This approach enables an early code restructuring in the optimizer, providing more optimization opportunities for both subsequent source code and assembly level transformations. An adaption of the traditional optimizations common subexpression and dead cod...

• Type: Journal
• Year: 2010
• Where: IEEECIT
• Authors: Paul Lokuciejewski, Timon Kelter, Peter Marwedel
• Keywords: Assembly Level, Execution Time, IEEECIT 2010, Information Technology, WCET Reduction