There's two problems here:

Depth prepass hits the feedback loop detection.

The game binds the depth buffer as texture 0 for the depth prepass. That depth prepass is done using a D3DFMT_NULL texture, so color values are irrelevant. We don't currently remove the fragment shader for such passes but we also cannot do that here because the game also happens to enable alpha testing for this pass. It also uses a complicated fixed function configuration with 7 active texture stages. I assume it's the same configuration as when it does a regular color draw. In practice, the value of texture 0 is not used because it does the following for alpha:

Texture stage 0: Load texture value into CURRENT.

Texture stage 1: SELECTARG2 with Arg2 being CURRENT, store in CURRENT.

Texture stage 2: CONSTANT, store in TEMP.

Texture stage 3: SELECTARG2 with Arg2 being TEMP, store in CURRENT. So now the loaded texture value has been completely replaced by the constant.

I think if we also look at color values (rgb), the game actually uses the texture value but this is a depth-only pass after all.

Our feedback loop detection code isn't smart enough to figure this out, so we flag that first pass as a feedback loop and insert a barrier after every draw. This makes us end up with like 220 barriers for the depth prepass.

It uses the most complex fixed function setups I've seen so far.

The game uses fixed function configurations with more than 4 active texture stages for seemingly the majority of the screen. It even uses configurations with all 8 texture stages activated. We only optimize draws with up to 4 active texture stages because the assumption was that games draw almost all of their geometry using configurations like that. That assumption also held so far, in all games, I've looked at, 95-100% of draws were optimized.

We might be able to disable the feedback loop here because:

• Only RT is D3DFMT_NULL
• the only reason why we can't flat out ignore the pixel shader (the FF ubershader) is because the game has alpha testing enabled. So we only care about the fixed function alpha texture ops.
• the feedback loop is because of depth: it writes depth and samples the same depth buffer
• but here's the important part: as far as I can tell there's no way to get one of the RGB components into alpha with fixed function
• So according to the Vulkan spec the only thing the game gets from the sampling is 1.0

I think it technically overrides all values it got from the sampling anyway but that's way trickier to prove than the approach above.

Might get nasty wrt. image layouts if EXT_unified_image_layouts isn't supported though. :/

(Also, so far this is just a theory and I'm not 100% sure.)