v8/test/mjsunit/elements-transition-hoisting.js

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// Flags: --allow-natives-syntax --smi-only-arrays --expose-gc

// Ensure that ElementsKind transitions in various situations are hoisted (or
// not hoisted) correctly, don't change the semantics programs and don't trigger
// deopt through hoisting in important situations.

support_smi_only_arrays = %HasFastSmiOnlyElements(new Array(1,2,3,4,5,6));

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

// Force existing ICs from previous stress runs to be flushed, otherwise the
// assumptions in this test about when deoptimizations get triggered are not
// valid.
gc();

if (support_smi_only_arrays) {
  // Make sure that a simple elements array transitions inside a loop before
  // stores to an array gets hoisted in a way that doesn't generate a deopt in
  // simple cases.}
  function testDoubleConversion4(a) {
    var object = new Object();
    a[0] = 0;
    var count = 3;
    do {
      a[0] = object;
    } while (--count > 0);
  }

  testDoubleConversion4(new Array(5));
  %OptimizeFunctionOnNextCall(testDoubleConversion4);
  testDoubleConversion4(new Array(5));
  testDoubleConversion4(new Array(5));
  assertTrue(2 != %GetOptimizationStatus(testDoubleConversion4));

  // Make sure that non-element related map checks that are not preceded by
  // transitions in a loop still get hoisted in a way that doesn't generate a
  // deopt in simple cases.
  function testExactMapHoisting(a) {
    var object = new Object();
    a.foo = 0;
    a[0] = 0;
    a[1] = 1;
    var count = 3;
    do {
      a.foo = object; // This map check should be hoistable
      a[1] = object;
      result = a.foo == object && a[1] == object;
    } while (--count > 0);
  }

  testExactMapHoisting(new Array(5));
  %OptimizeFunctionOnNextCall(testExactMapHoisting);
  testExactMapHoisting(new Array(5));
  testExactMapHoisting(new Array(5));
  assertTrue(2 != %GetOptimizationStatus(testExactMapHoisting));

  // Make sure that non-element related map checks do NOT get hoisted if they
  // depend on an elements transition before them and it's not possible to hoist
  // that transition.
  function testExactMapHoisting2(a) {
    var object = new Object();
    a.foo = 0;
    a[0] = 0;
    a[1] = 1;
    var count = 3;
    do {
      if (a.bar === undefined) {
        a[1] = 2.5;
      }
      a.foo = object; // This map check should NOT be hoistable because it
                      // includes a check for the FAST_ELEMENTS map as well as
                      // the FAST_DOUBLE_ELEMENTS map, which depends on the
                      // double transition above in the if, which cannot be
                      // hoisted.
    } while (--count > 0);
  }

  testExactMapHoisting2(new Array(5));
  %OptimizeFunctionOnNextCall(testExactMapHoisting2);
  testExactMapHoisting2(new Array(5));
  testExactMapHoisting2(new Array(5));
  assertTrue(2 != %GetOptimizationStatus(testExactMapHoisting2));

  // Make sure that non-element related map checks do get hoisted if they use
  // the transitioned map for the check and all transitions that they depend
  // upon can hoisted, too.
  function testExactMapHoisting3(a) {
    var object = new Object();
    a.foo = 0;
    a[0] = 0;
    a[1] = 1;
    var count = 3;
    do {
      a[1] = 2.5;
      a.foo = object; // This map check should be hoistable because all elements
                      // transitions in the loop can also be hoisted.
    } while (--count > 0);
  }

  var add_transition = new Array(5);
  add_transition.foo = 0;
  add_transition[0] = new Object(); // For FAST_ELEMENT transition to be created
  testExactMapHoisting3(new Array(5));
  %OptimizeFunctionOnNextCall(testExactMapHoisting3);
  testExactMapHoisting3(new Array(5));
  testExactMapHoisting3(new Array(5));
  assertTrue(2 != %GetOptimizationStatus(testExactMapHoisting3));

  function testDominatingTransitionHoisting1(a) {
    var object = new Object();
    a[0] = 0;
    var count = 3;
    do {
      if (a.baz != true) {
        a[1] = 2.5;
      }
      a[0] = object;
    } while (--count > 3);
  }

  testDominatingTransitionHoisting1(new Array(5));
  %OptimizeFunctionOnNextCall(testDominatingTransitionHoisting1);
  testDominatingTransitionHoisting1(new Array(5));
  testDominatingTransitionHoisting1(new Array(5));
  assertTrue(2 != %GetOptimizationStatus(testDominatingTransitionHoisting1));

  function testHoistingWithSideEffect(a) {
    var object = new Object();
    a[0] = 0;
    var count = 3;
    do {
      assertTrue(true);
      a[0] = object;
    } while (--count > 3);
  }

  testHoistingWithSideEffect(new Array(5));
  %OptimizeFunctionOnNextCall(testHoistingWithSideEffect);
  testHoistingWithSideEffect(new Array(5));
  testHoistingWithSideEffect(new Array(5));
  assertTrue(2 != %GetOptimizationStatus(testHoistingWithSideEffect));
}