v8/test/mjsunit/compiler/alloc-object.js

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// Flags: --allow-natives-syntax

// Test that inlined object allocation works for different layouts of
// objects (e.g. in object properties, slack tracking in progress or
// changing of function prototypes)

function test_helper(construct, a, b) {
  return new construct(a, b);
}

function test(construct) {
  %DeoptimizeFunction(test);
  %PrepareFunctionForOptimization(test_helper);
  test_helper(construct, 0, 0);
  test_helper(construct, 0, 0);
  %OptimizeFunctionOnNextCall(test_helper);
  // Test adding a new property after allocation was inlined.
  var o = test_helper(construct, 1, 2);
  o.z = 3;
  assertEquals(1, o.x);
  assertEquals(2, o.y);
  assertEquals(3, o.z);
  // Test changing the prototype after allocation was inlined.
  construct.prototype = { z:6 };
  var o = test_helper(construct, 4, 5);
  assertEquals(4, o.x);
  assertEquals(5, o.y);
  assertEquals(6, o.z);
  %DeoptimizeFunction(test_helper);
  %ClearFunctionFeedback(test_helper);
}

function finalize_slack_tracking(construct) {
  // Value chosen based on kGenerousAllocationCount = 8.
  for (var i = 0; i < 8; i++) {
    new construct(0, 0);
  }
}


// Both properties are pre-allocated in object properties.
function ConstructInObjectPreAllocated(a, b) {
  this.x = a;
  this.y = b;
}
finalize_slack_tracking(ConstructInObjectPreAllocated);
test(ConstructInObjectPreAllocated);


// Both properties are unused in object properties.
function ConstructInObjectUnused(a, b) {
  this.x = a < 0 ? 0 : a;
  this.y = b > 0 ? b : 0;
}
finalize_slack_tracking(ConstructInObjectUnused);
test(ConstructInObjectUnused);


// Test inlined allocation while slack tracking is still in progress.
function ConstructWhileSlackTracking(a, b) {
  this.x = a;
  this.y = b;
}
test(ConstructWhileSlackTracking);