Does not work (and no errors thrown) on Safari with Webgpu enabled

[phelbas]

Well, I'll have a closer look but perhaps note that in the main page that this works on Chrome webgpu but not the current version of Safari webgpu with the webgpu feature enabled and it is not clear why as there are no errors. The sort compute just does not start and the result array is unsorted. It is not clear what feature safari webgpu might be lacking that could break it.

[phelbas]

Here is the fix to make it compatible with Safari webgpu, and therefore probably IOS as well:

The minimal fix is just changing line 12 in radix-sort-esm.js:

Before:
var temp: array<u32, ITEMS_PER_WORKGROUP*2>;

After:
const TEMP_ARRAY_SIZE: u32 = 256;
var temp: array<u32, TEMP_ARRAY_SIZE>;

Issue comment:

Safari doesn't properly substitute override constants when used in var
array size declarations. The array ends up with size 0/undefined, so shader writes
silently fail.

Fix: Use a const for the array size instead of an expression involving override
constants.

Affected lines in radix-sort-esm.js:

• Line 12: prefixSumSource (main code path)
• Line 135: prefixSumNoBankConflictSource (if avoid_bank_conflicts: true)
• Line 478: radixSortSource (main code path)
• Line 577: radixSortCoalescedSource (if local_shuffle: true)
• Line 740: checkSortSource (if check_order: true)

[phelbas]

Note that to use this fix, the now-hardcoded values have to match the workgroup_size you configure the radix sort for. So to have a complete sort using these fixed values, you must pass in workgroup_size: { x: 8, y: 8 }, // Match Safari hardcoded values to new RadixSortKernel({