I recently pushed two patches upstream related to the enablement of the OpenPOWER ISA 3.0 (POWER9) instructions.
The first one, commit 526f342, enables instructions in the assembler. This includes new compares, loads, math operations, register moves, the new hardware-supported random number generator instruction, and the new copy/paste facility.
The second one, commit 6661cf6, enables the new internal/cpu package for IBM POWER architecture. This package provides runtime CPU identification and capabilities detection and we will use it to write new runtime performance optimizations specific for POWER9 without breaking the code for workloads running on the baseline POWER8 systems.
Both will be available in go1.10 when it is released. Or you can grab the current upstream code and build it yourself on your POWER9 system to start experimenting with the patches.