Status update from kd-11 (2020-09-28)

Hi,

It's kd-11 with another update on RSX emulation for the month of September 2020. 

As usual, we will begin with a short recap of the major changes that have been introduced since my last update. Here are the major highlights:

1. Support for extended range depth formats (depth-float) was added for both 16-bit and 24+8 formats. This fixed a lot of bugs with the infinity ward engine and other games that use similar techniques.

2. A regression that broke MGS4 was identified and fixed.

3. Some changes were made to support the newest Vulkan SDK. This brings us up to Vulkan 1.2.148 in terms of SDK compatibility.

4. A major overhaul was made for the OpenGL backend regarding texture handling.

5. Improved Read Color Buffer and Read Depth Buffer options to fix graphics corruption in some games like Warhawk.

6. Some optimization work was done on texture handling routines of OpenGL renderer.

7. Shadow sampling was updated to support PS3-correct PCF shadows (smooth shadows) on hardware that does not support packed integer depth stencil (pretty much all non-NVIDIA hardware)

8. Vulkan image handling was optimized and rewritten. Some operations are now much faster and more correct now. This fixed crashes in Rachet and Clank ACiT and Resistance 2.

And for the changes with the largest impact:

1. The shader decompiler was updated with optimizations to the emitted code. This results in GPU code that is about 30% smaller, 10% faster and compiles up to twice as fast on some drivers. While the performance tuning and optmization was mostly done on the Radeon platform due to the availability of GPUOpen which gives developers free access to many useful resources. All hardware and drivers have been confirmed to benefit to some degree and I will continue improving this in the near future.

2. RSX reservations were rewritten. The PR for this work is still open and has been in WIP status. I expect to have it completed by the end of this week. There are decent performance gains for games that require the "Accurate RSX reservations" option. See [this PR] for more details.

What's next?

Keeping with the roadmap I have outlined before, shader work is still the primary focus for the next few weeks. Current efforts are on massively improving the compile and link times, lowering the overall number of shaders required and moving to a proper multithreaded compiler backend. With this in place, integrating the shader interpreter becomes a lot easier, and we get closer to our goal of a stutter-free first-time gaming experience.

Following that job, the following items are in the queue:

1. Finish 3D TV support. The basic work was already done, this shouldn't take me long to complete.

2. Overhaul texture cache to allow modern features such as persistent storage, VRAM budget management and modding support.

3. Blit engine and DMA optimizations. There is a lot of potential here.

Thank you all for your continued support.

Regards,

kd-11