Return values of atomic* functions are not properly handled when pointerNode is a struct storage buffer

[HongchengZhao]

Description

There still exists some bugs with #30971, the return value of atomic* functions are not properly handled when pointerNode is a struct storage buffer. I find it has something to do with the pointerNode's type being void.

Reproduction steps

1. See the code below

Code

const DrawIndirectInfo = struct(
    {
      vertexCount: "uint",
      instanceCount: { type: "uint", atomic: true },
      firstVertex: "uint",
      firstInstance: "uint",
      offset: "uint",
    },
    "DrawIndirectInfo"
  );
  
const indirect = new THREE.IndirectStorageBufferAttribute(new Uint32Array(5), 5);
const drawBuffer = storage(indirect, DrawIndirectInfo).label("drawBuffer");
const foo = instancedArray(1, "uint").toAtomic().label("foo");

const updateDrawBuffer = Fn(() => {
    If(instanceIndex.equal(0), () => {
        const count = atomicAdd(drawBuffer.get("instanceCount"), uint(1)).toConst("count");

        const bar = atomicAdd(foo.element(0), uint(1)).toConst("bar");
      });
 })().debug((builder, code) => console.log(code)).compute(1, [1]);

renderer.computeAsync(updateDrawBuffer);

Live example

• jsfiddle-dev WebGPURenderer

Screenshots

Version

176

Device

No response

Browser

No response

OS

No response

[Spiri0]

Missing in your code geometry.setIndirect( indirect ); Without this, the indirect buffer won't affect your geometry. But that's not the cause of your error. Incidentally, for an indexed geometry, it's indexCount, not vertexCount. And you don't initialize the indexes in your shader with the number of indexes of the geometry. So you wouldn't see anything even if the code were running.
I tested it with wgslFn and it works but that doesn't help you since you want Fn.
I don't know if these lines are correct because I have done very little with Fn.

    const count = atomicAdd(drawBuffer.get("instanceCount"), uint(1)).toConst("count");

    const bar = atomicAdd(foo.element(0), uint(1)).toConst("bar");

@renauldRohlinger will surely be able to say more about this