Just load the atomic bump counter directly instead of piping it through a shared variable, when workgroupUniformLoad is not available. The value is in fact dynamically uniform, but that depends on the stage not setting its own failure flag, a fairly subtle invariant.
I think there was a write-after-read hazard for the reuse of sh_part_count[0]. However, doing the experiment of just changing that doesn't fix the problem on mac. It's possible there's a shader compilation problem (possibly the same one as provoking the storageBarrier workaround in tile_alloc), or also possibly a logic error I'm not understanding.
In any case, this change does appear to fix the hangs on mac.
Fixes#267
A number of things were wrong:
* The args were missing to `run`
* The robust memory changes introduced uniformity errors
* `clear_buffer` is a todo for wgpu on wasm
* Some more time calls crept in
* Initializing both env_logger and console_logger fails
In addition, we conditionally opt the shaders into
`workgroupUniformLoad`, as that's available on wasm but not yet native.
Some of the things (args, uniformity errors) are important fixes. Other
things (clear_buffer, wUL being optional) are workarounds for wgpu
limitations and have TODO items to be removed when wgpu catches up.
* Add counts to offsets when comparing against buffer size limits
* Remove multiplication by 4 in blend buffer allocation (we use units of u32)
* Move buffer sizes from BumpAllocators to Config
* Add comments about early exit
This helps performance but not all performance issues have been resolved. Nontrivial CPU goes into write_buffer, and it's also possible that there isn't enough overlapping between CPU and GPU work.
* Move the vello crate to the root of the crate
* Add warning that README is work in progress
* Add newline in warning
* Move the unlicense into the shader folder
* Fixup wgsl-analyzer include paths
