v8/test/mjsunit/elements-transition.js

// Copyright 2012 the V8 project authors. All rights reserved.
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// modification, are permitted provided that the following conditions are
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//
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// Flags: --allow-natives-syntax --smi-only-arrays

support_smi_only_arrays = %HasFastSmiElements(new Array(1,2,3,4,5,6,7,8));

if (support_smi_only_arrays) {
  print("Tests include smi-only arrays.");
} else {
  print("Tests do NOT include smi-only arrays.");
}

if (support_smi_only_arrays) {
  function test(test_double, test_object, set, length) {
    // We apply the same operations to two identical arrays.  The first array
    // triggers an IC miss, upon which the conversion stub is generated, but the
    // actual conversion is done in runtime.  The second array, arriving at
    // the previously patched IC, is then converted using the conversion stub.
    var array_1 = new Array(length);
    var array_2 = new Array(length);

    assertTrue(%HasFastSmiElements(array_1));
    assertTrue(%HasFastSmiElements(array_2));
    for (var i = 0; i < length; i++) {
      if (i == length - 5 && test_double) {
        // Trigger conversion to fast double elements at length-5.
        set(array_1, i, 0.5);
        set(array_2, i, 0.5);
        assertTrue(%HasFastDoubleElements(array_1));
        assertTrue(%HasFastDoubleElements(array_2));
      } else if (i == length - 3 && test_object) {
        // Trigger conversion to fast object elements at length-3.
        set(array_1, i, 'object');
        set(array_2, i, 'object');
        assertTrue(%HasFastObjectElements(array_1));
        assertTrue(%HasFastObjectElements(array_2));
      } else if (i != length - 7) {
        // Set the element to an integer but leave a hole at length-7.
        set(array_1, i, 2*i+1);
        set(array_2, i, 2*i+1);
      }
    }

    for (var i = 0; i < length; i++) {
      if (i == length - 5 && test_double) {
        assertEquals(0.5, array_1[i]);
        assertEquals(0.5, array_2[i]);
      } else if (i == length - 3 && test_object) {
        assertEquals('object', array_1[i]);
        assertEquals('object', array_2[i]);
      } else if (i != length - 7) {
        assertEquals(2*i+1, array_1[i]);
        assertEquals(2*i+1, array_2[i]);
      } else {
        assertEquals(undefined, array_1[i]);
        assertEquals(undefined, array_2[i]);
      }
    }

    assertEquals(length, array_1.length);
    assertEquals(length, array_2.length);
  }

  test(false, false, function(a,i,v){ a[i] = v; }, 20);
  test(true,  false, function(a,i,v){ a[i] = v; }, 20);
  test(false, true,  function(a,i,v){ a[i] = v; }, 20);
  test(true,  true,  function(a,i,v){ a[i] = v; }, 20);

  test(false, false, function(a,i,v){ a[i] = v; }, 10000);
  test(true,  false, function(a,i,v){ a[i] = v; }, 10000);
  test(false, true,  function(a,i,v){ a[i] = v; }, 10000);
  test(true,  true,  function(a,i,v){ a[i] = v; }, 10000);

  // Check COW arrays
  function get_cow() { return [1, 2, 3]; }

  function transition(x) { x[0] = 1.5; }

  var ignore = get_cow();
  transition(ignore);  // Handled by runtime.
  var a = get_cow();
  var b = get_cow();
  transition(a);  // Handled by IC.
  assertEquals(1.5, a[0]);
  assertEquals(1, b[0]);
} else {
  print("Test skipped because smi only arrays are not supported.");
}