CP works. Shaders don't work. The hardware hangs in the vertex shader. The draw
call doesn't even enable the rasterizer.

radeon/si.c:si_setup_spi looks very wrong to me:
- The function sets SPI_STATIC_THREAD_MGMT_3, which only configures CUs for LS
and HS stages.
- I don't understand why SPI_STATIC_THREAD_MGMT_3 is set 16 times?
- SPI_STATIC_THREAD_MGMT_1 (PS,VS) and SPI_STATIC_THREAD_MGMT_2 (GS,ES) are not
set at all.

It looks like that's the root cause of this bug.