**What are push constants?**
Push constants is a way to quickly provide a small amount of uniform data to shaders.
It should be much quicker than UBOs but a huge limitation is the size of data - spec
requires 128 bytes to be available for a push constant range.
**What are the challenges with push constants?**
The challenge with push constants is that the limited available size. According to
the Vulkan spec each platform should at least have 128 bytes reserved for push
constants. Current Mesa/AMD drivers supports 256 bytes, but Mesa/Intel is only 128
bytes.
**What is our solution?**
Some shaders of Blender uses more than these boundaries. When more data is needed
push constants will not be used, but the shader will be patched to use an uniform
buffer instead. This mechanism will be part of the Vulkan backend and shader
developers should not see any difference on API level.
**Known limitations**
Current state of the vulkan backend does not track resources that are in the
command queue. This patch includes some test cases that identified this issue as
well. See #104771.
Pull Request #104880
