OptiScope: Performance Accountability for Optimizing Compilers

Compilers employ many aggressive code transformations to achieve highly optimized code. However, because of complex target architectures and unpredictable optimization interactions, these transformations may not always be beneficial. Current analysis methods measure performance at the application level and ignore optimization effects at the function and loop level. To better measure and understand these effects, we present OptiScope, a compiler independent tool to identify performance opportunities by comparing programs built with different compilers or optimization flags. The analysis includes hundreds of different metrics and uses a novel loop correlation technique for binary programs (produced from the same source by different compilers) to isolate measurements to specific regions. We present several case studies using OptiScope to identify key differences between different compiler suites, versions, and target architectures. The examples demonstrate performance improvement opportunities between 32.5% to 893% on select regions of SPEC 2006 benchmarks.