System Information
MACPRO OSX EL CAPITAIN 10.11.6
DUAL AMD FirePro D700

Blender Version
Broken: 2.79 rc2
Worked: --

When I turn Denoise on the begining of the render is fine but when the denoise pass kicks in it make evething black.

Just turn Denoise on and render.
Based on a (as simple as possible) attached .blend file with minimum amount of steps