1 files changed, 87 insertions, 0 deletions
diff --git a/js/src/tests/non262/argumentsLengthOpt.js b/js/src/tests/non262/argumentsLengthOpt.js
new file mode 100644
index 0000000000..16385fa5a4
--- /dev/null
+++ b/js/src/tests/non262/argumentsLengthOpt.js
@@ -0,0 +1,87 @@
+// Test cases for arguments.length optimization.
+
+function f1() {
+    return arguments.length;
+}
+
+function f2(a, b, c) {
+    return arguments.length;
+}
+
+// arrow functions don't have their own arguments, and so capture the enclosing
+// scope.
+function f3(a, b, c, d) {
+    return (() => arguments.length)();
+}
+
+// Test a function which mutates arguments.length
+function f4(a, b, c, d) {
+    arguments.length = 42;
+    return arguments.length;
+}
+
+// Manually read out arguments; should disable the length opt
+function f5() {
+    for (var i = 0; i < arguments.length; i++) {
+        if (arguments[i] == 10) { return true }
+    }
+    return false;
+}
+
+function f6() {
+    function inner() {
+        return arguments.length;
+    }
+    return inner(1, 2, 3);
+}
+
+// edge cases of the arguments bindings:
+function f7() {
+    var arguments = 42;
+    return arguments;
+}
+
+function f8() {
+    var arguments = [1, 2];
+    return arguments.length;
+}
+
+function f9() {
+    eval("arguments.length = 42");
+    return arguments.length;
+}
+
+function test() {
+    assertEq(f1(), 0);
+    assertEq(f1(1), 1);
+    assertEq(f1(1, 2), 2);
+    assertEq(f1(1, 2, 3), 3);
+
+    assertEq(f2(), 0);
+    assertEq(f2(1, 2, 3), 3);
+
+    assertEq(f3(), 0);
+    assertEq(f3(1, 2, 3), 3);
+
+    assertEq(f4(), 42);
+    assertEq(f4(1, 2, 3), 42);
+
+    assertEq(f5(), false);
+    assertEq(f5(1, 2, 3, 10), true);
+    assertEq(f5(1, 2, 3, 10, 20), true);
+    assertEq(f5(1, 2, 3, 9, 20, 30), false);
+
+    assertEq(f6(), 3)
+    assertEq(f6(1, 2, 3, 4), 3)
+
+    assertEq(f7(), 42);
+
+    assertEq(f8(), 2);
+
+    assertEq(f9(), 42);
+}
+
+test();
+
+if (typeof reportCompare === "function")
+    reportCompare(0, 0, "ok");