gfx-rs
Relax vector, matrix and array OOB validation
Relax vector, matrix and array OOB validation by handling OOB accesses at runtime.
The following example should work; however, validation currently errors because the index is out of bounds.
@compute @workgroup_size(1)
fn main() {
let idx = 9;
let v = vec2<f32>();
let m = mat2x2<f32>();
let a = array<f32,1>();
let vi = v[idx];
let mi = m[idx];
let ai = a[idx];
}
[edit] Note that WGSL says that let-bound identifiers cannot be constant expressions, so the shader translation time bounds checking rules do not apply to this example.
Related
- gfx-rs/wgpu#4381
- gfx-rs/wgpu#4389
- #6396
Note that this issue only covers the excessive validation. There may be missing bounds checks, and those should be filed as separate issues.
Curious, why should this work?
Do you just mean it should pass validation? And then the bounds-check policy is used to determine what should happen with vi, mi, etc.?
I think this would be a regression. If you can detect OOB accesses, as these clearly are, at shader translation time, why not report them?
@bavalpey: It's for compliance with the WebGPU spec., which forces safe (but implementation-defined) behavior: https://www.w3.org/TR/WGSL/#out-of-bounds-access-sec
