working command line with patch to get the shader log:
  R600_SB_DSKIP_START=94 R600_SB_DSKIP_END=94 R600_SB_DSKIP_MODE=63 glretrace
thea.trace

working command line without the patch to verify shader bug:
  R600_SB_DSKIP_START=94 R600_SB_DSKIP_END=94 R600_SB_DSKIP_MODE=1 glretrace
thea.trace

In the end I'm just using the llvm backend (R600_DEBUG=llvm). I just see a
minimal difference on this HW in game of ~0.5 frames (slower LLVM). Actually I
had other small rendering glitches with the SB shader backend, which I didn't
track down.

(In reply to Ilia Mirkin from comment #2)
> In case it's of any interest, I tested this on nouveau -- on nvc0 (GF108)
> the trace replays seemingly fine. On nv50 (GT215), I also get a failure on
> the map screen, but it's different -- everything is drawn except the
> background, so it appears as though it's all black(ish), with trees/etc
> drawn over it.

The original (large) apitrace had ambient occlusion (AO) activated AFAIK, but I
deleted it, so I don't know. AO was fixed for me with a patch in the last week.
As my hardware is already slow (just 15fps in the game), enabling this renders
the game unplayable, but now I get soft shadows at the price of ~50% frame
drop.