test/mjsunit/store-dictionary.js

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// Test dictionary store ICs.

// Function that stores property 'x' on an object.
function store(obj) { obj.x = 42; }

// Create object and force it to dictionary mode by deleting property.
var o = { x: 32, y: 33 };
delete o.y;

// Make the store ic in the 'store' function go into dictionary store
// case.
for (var i = 0; i < 3; i++) {
  store(o);
}
assertEquals(42, o.x);

// Test that READ_ONLY property attribute is respected. Make 'x'
// READ_ONLY.
Object.defineProperty(o, 'x', { value: 32, writable: false });

// Attempt to store using the store ic in the 'store' function.
store(o);

// Check that the store did not change the value.
assertEquals(32, o.x);

// Check that bail-out code works.
// Smi.
store(1);
// Fast case object.
o = new Object();
store(o);
assertEquals(42, o.x);
// Slow case object without x property.
delete o.x;
store(o);
assertEquals(42, o.x);