function Cons1() { } Cons1.prototype.f = 42; function Cons2() { } Cons2.prototype.__defineGetter__("f", function() { counter++; return 84; }); function foo(o) { return o.f; } noInline(foo); var counter = 0; function test(o, expected, expectedCount) { var result = foo(o); if (result != expected) throw new Error("Bad result: " + result); if (counter != expectedCount) throw new Error("Bad counter value: " + counter); } for (var i = 0; i < 100000; ++i) { test(new Cons2(), 84, counter + 1); test(new Cons1(), 42, counter); }