Session Type
Technical Talk
Date & Time
Wednesday, October 11, 2023, 4:15 PM - 4:45 PM
Automatic program reoptimization support in LLVM ORC JIT

One of the prominent applications of the JIT compiler is the ability to compile “hot” functions utilizing various runtime profiling metrics gathered by slow versions of functions. The ORC API can be generalized further to make use of the profiling metrics and “reoptimize” the function hiding the reoptimization latency. For instance, one of the many applications of this technique is to compile functions at a lower optimization level for faster compilation speed and then reoptimize them to a higher level when those functions are frequently executed. This talk we demonstrate how we can express lazy JIT, speculative compilation, and re-optimization as "symbol redirection" problems. We demonstrate the improved ORC API for redirecting symbols. In addition, this technical talk will peek at internal details of how we implemented re-optimization support and showcase the demos such as real time clang-repl re-optimization from -O0 to -O3 or real time virtual call optimization through de-virtualization.

Location Name
Hall of Cities