Pipeline mode output value used argument in same functions causes throw on GPU

[robertleeplummerjr]

As outlined in https://jsfiddle.net/robertleeplummerjr/jtoyua1w/7/ the following throws an error:

What is wrong?

const gpu = new GPU();
const kernel = gpu.createKernel(function(v) {
  return 1 + v[this.thread.x];
}, {
  output: [1],
  pipeline: true
});
const { context } = kernel;
const result1 = kernel([1]);
checkError(context);
console.log(result1.toArray());
const result2 = kernel(result1);
checkError(context);
console.log(result2.toArray());
// this makes a warning
const result3 = kernel(result2);
checkError(context);
console.log(result3.toArray());


function checkError(context) {
  const error = context.getError();
  if (error > 0) {
    throw new Error(`The error is ${ error }`);
  }
}

NOTE: this is kind of confusing, but what happens is:

1. A standard kernel is built
2. A kernel is ran and returns a texture
3. That output texture is used with the same kernel
4. Because the input type differs from the initial run, a new internal kernel is built just in time to handle this new value.
5. The new kernel returns a texture.
6. That texture is used with the same kernel, because the output of the same kernel is compatible with this same input type, the kernel is trying to overwrite the very value it is reading from, and since the kernel isn't creating a new texture each time (ie: immutable: true) the kernel has a warning, and essentially throws.
7. The output can be different in different browsers, I think Firefox is smart enough to handle this scenario, but Chrome dies, for example.

Where does it happen?

How do we replicate the issue?

How important is this (1-5)?

5 We should simply have a check that checks for this exact scenario and resolves it internally, so the end user doesn't have to think about it.

Expected behavior (i.e. solution)

Other Comments