webnn: Immediately copy constant data

Currently, the data of ArrayBufferViews passed to the constant() method
is copied during the build() method. This does not match the spec:
https://www.w3.org/TR/webnn/#dom-mlgraphbuilder-constant

Cq-Include-Trybots: luci.chromium.try:win11-blink-rel
Bug: 348598508
Change-Id: Ief7a686324375fb2027df8a30d2c97943149bbe6
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/5649032
Commit-Queue: Reilly Grant <[email protected]>
Reviewed-by: Reilly Grant <[email protected]>
Commit-Queue: Austin Sullivan <[email protected]>
Auto-Submit: Austin Sullivan <[email protected]>
Cr-Commit-Position: refs/heads/main@{#1318727}

webnn/validation_tests/constant-changed-buffer.https.any.js

@@ -0,0 +1,61 @@
+// META: title=ensure MLGraphBuilder.constant() handles buffers which change
+// META: global=window,dedicatedworker
+// META: script=../resources/utils_validation.js
+
+promise_test(async t => {
+  let backingBuffer = new ArrayBuffer(8);
+  let aBuffer = new Float32Array(backingBuffer, 0, 2);
+  aBuffer[0] = 2;
+  aBuffer[1] = 3;
+  const a = builder.constant({dataType: 'float32', dimensions: [2]}, aBuffer);
+
+  // Detach `aBuffer`. Constant data should already be copied, so changes to
+  // the buffer afterwards should not be reflected in the graph.
+  const unusedBuffer = backingBuffer.transfer();
+
+  const b = builder.input('b', {dataType: 'float32', dimensions: [2]});
+  const c = builder.add(a, b);
+  const graph = await builder.build({c});
+
+  const bBuffer = new Float32Array([5, 7]);
+  const cBuffer = new Float32Array(2);
+  const result = await context.compute(graph, {'b': bBuffer}, {'c': cBuffer});
+
+  const expectedResult = new Float32Array([7, 10]);
+  assert_array_equals(result.outputs.c, expectedResult);
+}, 'Constant data is unaffected by detaching the buffer');
+
+promise_test(async t => {
+  let aBuffer = new Float32Array([2, 3]);
+  const a = builder.constant({dataType: 'float32', dimensions: [2]}, aBuffer);
+
+  // Rewrite `aBuffer` contents. Constant data should already be copied, so
+  // changes to the buffer afterwards should not be reflected in the graph.
+  aBuffer[0] = 10;
+  aBuffer[1] = 20;
+
+  const b = builder.input('b', {dataType: 'float32', dimensions: [2]});
+  const c = builder.add(a, b);
+  const graph = await builder.build({c});
+
+  const bBuffer = new Float32Array([5, 7]);
+  const cBuffer = new Float32Array(2);
+  const result = await context.compute(graph, {'b': bBuffer}, {'c': cBuffer});
+
+  const expectedResult = new Float32Array([7, 10]);
+  assert_array_equals(result.outputs.c, expectedResult);
+}, 'Constant data is unaffected by changes to the buffer contents');
+
+promise_test(async t => {
+  let backingBuffer = new ArrayBuffer(8);
+  const aBuffer = new Float32Array(backingBuffer, 0, 2);
+  // Detach `aBuffer` _before_ calling `constant()`. This should throw, since
+  // detached buffers have a length of zero, which does not match the length of
+  // the descriptor. See
+  // https://webidl.spec.whatwg.org/#dfn-get-buffer-source-copy
+  const unusedBuffer = backingBuffer.transfer();
+
+  assert_throws_js(
+      TypeError,
+      () => builder.constant({dataType: 'float32', dimensions: [2]}, aBuffer));
+}, 'Constant data cannot use a detached buffer, which is empty');