Testing that Float[32|16]Array.p.copyWithin keep NaN payloads.

Author: iamstolis

graal-js/src/com.oracle.truffle.js.test/js/GR-76553.js

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+/*
+ * Copyright (c) 2026, Oracle and/or its affiliates. All rights reserved.
+ * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
+ *
+ * Licensed under the Universal Permissive License v 1.0 as shown at http://oss.oracle.com/licenses/upl.
+ */
+
+/**
+ * @option ecmascript-version=staging
+ */
+
+load("assert.js");
+
+(function copyWithinPreservesFloat32NaNPayload() {
+    const buffer = new ArrayBuffer(8);
+    const dataView = new DataView(buffer);
+    dataView.setUint32(0, 0x7f801234, true);
+
+    const float32Array = new Float32Array(buffer);
+    float32Array.copyWithin(1, 0, 1);
+
+    assertSame(0x7f801234, dataView.getUint32(4, true));
+})();
+
+(function copyWithinPreservesFloat16NaNPayload() {
+    const buffer = new ArrayBuffer(4);
+    const dataView = new DataView(buffer);
+    dataView.setUint16(0, 0x7c01, true);
+
+    const float16Array = new Float16Array(buffer);
+    float16Array.copyWithin(1, 0, 1);
+
+    assertSame(0x7c01, dataView.getUint16(2, true));
+})();

graal-js/src/com.oracle.truffle.js.test/js/GR-76553_direct.js

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+/*
+ * Copyright (c) 2026, Oracle and/or its affiliates. All rights reserved.
+ * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
+ *
+ * Licensed under the Universal Permissive License v 1.0 as shown at http://oss.oracle.com/licenses/upl.
+ */
+
+/**
+ * @option direct-byte-buffer
+ * @option ecmascript-version=staging
+ */
+
+load("GR-76553.js");