Optional features

You can enable optional features by setting the following variables to 1 before compilation:

• OWL_ENABLE_EXPMODE=1: turn on experiment features like -flto
• OWL_ENABLE_DEVMODE=1: turn on all the warnings in development
• OWL_ENABLE_OPENMP=1: turn on OpenMP support in core module and the automatic parameter tuning (AEOS)

• OWL_CFLAGS allows to change the default flags passed to the C targets, it defaults to

  OWL_CFLAGS="-g -O3 -Ofast -march=native -mfpmath=sse -funroll-loops -ffast-math -DSFMT_MEXP=19937 -msse2 -fno-strict-aliasing -Wno-tautological-constant-out-of-range-compare"`

• OWL_AEOS_CFLAGS allows to change the default flags passed to the C targets when compiling AEOS. It defaults to

  OWL_AEOS_CFLAGS="-g -O3 -Ofast -march=native -funroll-loops -ffast-math -DSFMT_MEXP=19937 -fno-strict-aliasing"

• OWL_DISABLE_LAPACKE_LINKING_FLAG=1 disables the -llapacke flag in the linking options. This is useful when you have lapacke installed on non-standard localtion.

If you are not using opam, you should run make clean before recompiling the library after having changed any of those environment variables.

For examples of use of this feature, you can refer to the Docker.ubuntu and Docker.ubuntu.arm docker files, or to the snippet in https://github.com/owlbarn/owl/issues/394#issuecomment-471364916 (which also shows how to use it within esy).