AMD has released Radeon Software for Linux 19.20 with support for Red Hat Enterprise Linux 8

Radeon Software for Linux 19.20 Highlights
Provides RHEL 8 / CentOS 8 support

Package Contents
AMDGPU All-Open and AMDGPU-Pro Driver

Compatible 64-bit Operating Systems
RedHat Enterprise Linux 8.0
RedHat Enterprise Linux 7.6
CentOS 8.0
CentOS 7.6
Ubuntu 18.04.2
SLED/SLES 15

  Radeon Software for Linux 19.20 released