weakmap-nursery-value.js

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// Bug 1715471

// This test relies on triggering GC at precise points. GC zeal modes

// interfere with this.

gczeal(0);

// This test requires enqueueMark, which is only available in a debugging

// build.

if (!this.enqueueMark) quit(0);

var wm = new WeakMap();

// Force materialization of the map struct. Otherwise it would be allocated

// black during the incremental GC when we do wm.set.

wm.set({}, {});

var tenuredKey = Object.create(null);

gc(); // Tenure the WeakMap and key.

// Enter the GC, since otherwise the minor GC at the beginning would tenure our

// value before it had a chance to be entered into the ephemeron edge list.

startgc(1);

while (gcstate() === "Prepare") gcslice(1);

// Create a WeakMap entry with a value in the nursery.

var nurseryValue = Object.create(null);

wm.set(tenuredKey, nurseryValue);

// We want to mark the weakmap first, before the key or value are marked, so

// that the tenuredKey -> nurseryValue edge will be added to the ephemeron edge

// table.

enqueueMark(wm);

gcslice(1000);

minorgc();