the value of rendered image is all 0. with A800 but render succeed with CPU


render = pydiffvg.RenderFunction.apply
scene_args = pydiffvg.RenderFunction.serialize_scene(320, 320, shapes, shape_groups)
img = render(320, 320, 2, 2, 0, None, *scene_args)

when my codes are like this and i found that the 'img' is all '0.' (only happened with A800)
but when i set 'pydiffvg.set_use_gpu(False)', the img is rendered correctly.

Anyone knows what's the reason?
