Bounds checks on `textureLoad` unneeded in Metal after 2.2?

[jimblandy]

Starting in the Metal Shading Language Specification 2.2, the section on Texture Functions describes the behavior of out-of-bounds read and write calls to textures. The behavior described seems to be compatible with WGSL's requirements, meaning that it is not necessary for wgpu to have Naga inject bounds checks on these operations.

In version 2.2 of the spec, the language appears on p. 142 of the PDF.

[jimblandy]

I don't know what the source is for this code, but it seems to suggest that Metal Shading Language 2.2 became available in macOS 10.15 and iOS 13.0.

[jimblandy]

Firefox is one of the main customers for bounds checks. WebGPU only appears in recent versions of Firefox, which only support macOS 10.15 and above.

[jimblandy]

The robust way to support this would be to have wgpu-hal simply turn off Naga bounds checks based on the MSL version.