mirror of
https://github.com/RGBCube/serenity
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1e90379008
This is similar to "unique" shapes, which were removed in commit
3d92c26445.
The key difference is that dictionary shapes don't have a serial number,
but instead have a "cacheable" flag.
Shapes become dictionaries after 64 transitions have occurred, at which
point no further transitions occur.
As long as properties are only added to a dictionary shape, it remains
cacheable. (Since if we've cached the shape pointer in an IC somewhere,
we know the IC is still valid.)
Deleting a property from a dictionary shape causes it to become an
uncacheable dictionary.
Note that deleting a property from a non-dictionary shape still performs
a delete transition.
This fixes an issue on Discord where Object.freeze() would eventually
OOM us, since they add more than 16000 properties to a single object
before freezing it.
It also yields a 15% speedup on Octane/pdfjs.js :^)
85 lines
2.4 KiB
JavaScript
85 lines
2.4 KiB
JavaScript
test("length is 1", () => {
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expect(Object.freeze).toHaveLength(1);
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});
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describe("normal behavior", () => {
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test("returns given argument", () => {
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const o = {};
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expect(Object.freeze(42)).toBe(42);
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expect(Object.freeze("foobar")).toBe("foobar");
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expect(Object.freeze(o)).toBe(o);
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});
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test("prevents addition of new properties", () => {
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const o = {};
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expect(o.foo).toBeUndefined();
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Object.freeze(o);
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o.foo = "bar";
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expect(o.foo).toBeUndefined();
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});
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test("prevents deletion of existing properties", () => {
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const o = { foo: "bar" };
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expect(o.foo).toBe("bar");
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Object.freeze(o);
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delete o.foo;
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expect(o.foo).toBe("bar");
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});
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test("prevents changing attributes of existing properties", () => {
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const o = { foo: "bar" };
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Object.freeze(o);
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expect(Object.defineProperty(o, "foo", {})).toBe(o);
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expect(Object.defineProperty(o, "foo", { configurable: false })).toBe(o);
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expect(() => {
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Object.defineProperty(o, "foo", { configurable: true });
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}).toThrowWithMessage(TypeError, "Object's [[DefineOwnProperty]] method returned false");
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});
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test("prevents changing value of existing properties", () => {
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const o = { foo: "bar" };
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expect(o.foo).toBe("bar");
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Object.freeze(o);
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o.foo = "baz";
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expect(o.foo).toBe("bar");
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});
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// #6469
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test("works with indexed properties", () => {
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const a = ["foo"];
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expect(a[0]).toBe("foo");
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Object.freeze(a);
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a[0] = "bar";
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expect(a[0]).toBe("foo");
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});
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test("works with properties that are already non-configurable", () => {
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const o = {};
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Object.defineProperty(o, "foo", {
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value: "bar",
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configurable: false,
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writable: true,
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enumerable: true,
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});
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expect(o.foo).toBe("bar");
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Object.freeze(o);
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o.foo = "baz";
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expect(o.foo).toBe("bar");
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});
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});
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test("does not override frozen function name", () => {
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const func = Object.freeze(function () {
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return 12;
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});
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const obj = Object.freeze({ name: func });
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expect(obj.name()).toBe(12);
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});
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test("freeze with huge number of properties doesn't crash", () => {
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const o = {};
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for (let i = 0; i < 50_000; ++i) {
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o["prop" + i] = 1;
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}
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Object.freeze(o);
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});
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