$ bin/gl-3.2-layered-rendering-clear-color-all-types 3d single_level -fbo -auto

Clearing each layer individually
Probing level 0, layer 0
Probing level 0, layer 1
Probing level 0, layer 2
Probing level 0, layer 3
Clearing all layers in miplevel 0 at once
Probing level 0, layer 0
Probing level 0, layer 1
Probing level 0, layer 2
Probe color at (0,0)
  Expected: 0.000000 1.000000 0.000000 1.000000
  Observed: 1.000000 0.000000 0.000000 1.000000
Probing level 0, layer 3
Probe color at (0,0)
  Expected: 0.000000 1.000000 0.000000 1.000000
  Observed: 1.000000 0.000000 0.000000 1.000000

This happen with mesa compiled with -O3. With -Og is perfectly fine.
Kernel: 3.12.18
Mesa: git (1646f4d0fb0efec04dce62b6dd4d974206acc8ac)
Card: Radeon HD 6550 (3870K APU)