Intel Begins Landing GFNI Support In GCC 8
Galois Field NI / Galois Field Affine Transformation (GFNI) is one of the new processor ISA extensions expected for the Icelake processors that will succeed next year's Cannonlake hardware. The Intel implementation appears to be an AVX-512 version of the GFNI algorithms as used within cryptography/encryption areas.
Those interested in the technicalities of it can find this university whitepaper about Galois Field. There aren't many more GFNI details readily available, at least within Intel's context.
While Icelake processors likely won't make it out until 2019, the initial GFNI bits have landed in GCC while the three other patches for GFNI enablement are still sitting on the mailing list. The rest of the patches should be merged in time for next year's GCC 8.1 stable release.