Debugging Optimized Code

Debugging Optimized Code
Build Models
Lost In Translation
Scheduling Optimizations
Loop Unrolling Optimizations
Common Sub-expression Elimination
The Light at the End of the Tunnel
Appendix A
Additional Optimization Options
Appendix B -- [Next]

Appendix B

This appendix provides benchmark results for Green Hills MULTI Compiler optimization strategies. A number of standard benchmarks were included, such as EEMBC, CoreMark, and Dhrystone, along with proprietary ones. All benchmarks were run on a PowerPC 440 based core and an ARM Cortex-A8 based core using Green Hills MULTI Compiler v5.2. Smaller percentage numbers are better.

Size Comparison

The results get better along the main debug vs. optimization axis, at which point they fork. -Ogeneral sits in the middle of the size vs. speed axis;-Ospeed takes a step back (as expected), but -Osize produces the best results.

Speed Comparison

The results get better as we slide down the debug vs. optimization axis until we get to -Ogeneral. At that point, we can get even more impressive speed results with -Ospeed. However, on the opposite spectrum of the size vs. speed axis, -Osize takes a step back by about almost 7% on PowerPC and 3% on ARM, which is expected.

References

• "Using the GNU Compiler Collection: For GCC version 4.6.1" - manual for GCC, the GNU Compiler Collection
• "MULTI: Building Applications for Embedded PowerPC" - product documentation for Green Hills Software MULTI
• Green Hills Software

Index

Debugging Optimized Code
Build Models
Lost In Translation
Scheduling Optimizations
Loop Unrolling Optimizations
Common Sub-expression Elimination
The Light at the End of the Tunnel
Appendix A
Additional Optimization Options
Appendix B