[wgsl-in] Missing built-in integer function implementations

[hanawatson]

Hi - not sure if this is already known and on a to-do list somewhere, but while working on a WGSL fuzzing project I noticed naga has no implementation for a couple of built-in integer functions (https://gpuweb.github.io/gpuweb/wgsl/#integer-builtin-functions):

• countLeadingZeros
• countTrailingZeros

code example (analogous for countTrailingZeros):

@stage(compute) @workgroup_size(1)
fn compute_main() {
    var test_var = countLeadingZeros(53);
}

resultant error from attempting to compile with naga:

error: no definition in scope for identifier: 'countLeadingZeros'
  ┌─ test.wgsl:3:20
  │
3 │     var test_var = countLeadingZeros(53);
  │                    ^^^^^^^^^^^^^^^^^ unknown identifier

Could not parse WGSL

[teoxoy]

They are indeed missing, thanks for the report!

[fornwall]

@teoxoy This seems to have been fixed (#2226 and #2243).

[teoxoy]

Thanks for the reminder!