devel/llvm16: support polyhedral optimizations
The POLLY option enables the Polly optimizer. It is currently disabled
by default to allow a merge to quarterly without added risk. I plan to
enable it when I create devel/llvm17 in a couple weeks.
From the website (https://polly.llvm.org):
Polly is a high-level loop and data-locality optimizer and optimization infrastructure for LLVM. It uses an abstract mathematical representation based on integer polyhedra to analyze and optimize the memory access pattern of a program. We currently perform classical loop transformations, especially tiling and loop fusion to improve data-locality. Polly can also exploit OpenMP level parallelism, expose SIMDization opportunities.
PR: 272400