v8/test/mjsunit/array-constructor-feedback.js

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// Flags: --allow-natives-syntax --expose-gc

// Test element kind of objects.

var elements_kind = {
  fast_smi_only            :  'fast smi only elements',
  fast                     :  'fast elements',
  fast_double              :  'fast double elements',
  dictionary               :  'dictionary elements',
  external_byte            :  'external byte elements',
  external_unsigned_byte   :  'external unsigned byte elements',
  external_short           :  'external short elements',
  external_unsigned_short  :  'external unsigned short elements',
  external_int             :  'external int elements',
  external_unsigned_int    :  'external unsigned int elements',
  external_float           :  'external float elements',
  external_double          :  'external double elements',
  external_pixel           :  'external pixel elements'
}

function getKind(obj) {
  if (%HasFastSmiElements(obj)) return elements_kind.fast_smi_only;
  if (%HasFastObjectElements(obj)) return elements_kind.fast;
  if (%HasFastDoubleElements(obj)) return elements_kind.fast_double;
  if (%HasDictionaryElements(obj)) return elements_kind.dictionary;
}

function isHoley(obj) {
  if (%HasFastHoleyElements(obj)) return true;
  return false;
}

function assertKind(expected, obj, name_opt) {
  assertEquals(expected, getKind(obj), name_opt);
}

// Test: If a call site goes megamorphic, it retains the ability to
// use allocation site feedback (if FLAG_allocation_site_pretenuring
// is on).
(function() {
  function bar(t, len) {
    return new t(len);
  }

  a = bar(Array, 10);
  a[0] = 3.5;
  b = bar(Array, 1);
  assertKind(elements_kind.fast_double, b);
  c = bar(Object, 3);
  b = bar(Array, 10);
  // TODO(mvstanton): re-enable when FLAG_allocation_site_pretenuring
  // is on in the build.
  // assertKind(elements_kind.fast_double, b);
})();


// Test: ensure that crankshafted array constructor sites are deopted
// if another function is used.
(function() {
  function bar0(t) {
    return new t();
  }
  a = bar0(Array);
  a[0] = 3.5;
  b = bar0(Array);
  assertKind(elements_kind.fast_double, b);
    %OptimizeFunctionOnNextCall(bar0);
  b = bar0(Array);
  assertKind(elements_kind.fast_double, b);
  assertOptimized(bar0);
  // bar0 should deopt
  b = bar0(Object);
  assertUnoptimized(bar0)
  // When it's re-optimized, we should call through the full stub
  bar0(Array);
    %OptimizeFunctionOnNextCall(bar0);
  b = bar0(Array);
  // This only makes sense to test if we allow crankshafting
  if (4 != %GetOptimizationStatus(bar0)) {
    // We also lost our ability to record kind feedback, as the site
    // is megamorphic now.
    assertKind(elements_kind.fast_smi_only, b);
    assertOptimized(bar0);
    b[0] = 3.5;
    c = bar0(Array);
    assertKind(elements_kind.fast_smi_only, c);
  }
})();


// Test: Ensure that inlined array calls in crankshaft learn from deopts
// based on the move to a dictionary for the array.
(function() {
  function bar(len) {
    return new Array(len);
  }
  a = bar(10);
  a[0] = "a string";
  a = bar(10);
  assertKind(elements_kind.fast, a);
    %OptimizeFunctionOnNextCall(bar);
  a = bar(10);
  assertKind(elements_kind.fast, a);
  assertOptimized(bar);
  bar(100000);
  assertOptimized(bar);

  // If the argument isn't a smi, things should still work.
  a = bar("oops");
  assertOptimized(bar);
  assertKind(elements_kind.fast, a);

  function barn(one, two, three) {
    return new Array(one, two, three);
  }

  barn(1, 2, 3);
  barn(1, 2, 3);
    %OptimizeFunctionOnNextCall(barn);
  barn(1, 2, 3);
  assertOptimized(barn);
  a = barn(1, "oops", 3);
  assertOptimized(barn);
})();


// Test: When a method with array constructor is crankshafted, the type
// feedback for elements kind is baked in. Verify that transitions don't
// change it anymore
(function() {
  function bar() {
    return new Array();
  }
  a = bar();
  bar();
    %OptimizeFunctionOnNextCall(bar);
  b = bar();
  // This only makes sense to test if we allow crankshafting
  if (4 != %GetOptimizationStatus(bar)) {
    assertOptimized(bar);
      %DebugPrint(3);
    b[0] = 3.5;
    c = bar();
    assertKind(elements_kind.fast_smi_only, c);
    assertOptimized(bar);
  }
})();


// Test: create arrays in two contexts, verifying that the correct
// map for Array in that context will be used.
(function() {
  function bar() { return new Array(); }
  bar();
  bar();
    %OptimizeFunctionOnNextCall(bar);
  a = bar();
  assertTrue(a instanceof Array);

  var contextB = Realm.create();
  Realm.eval(contextB, "function bar2() { return new Array(); };");
  Realm.eval(contextB, "bar2(); bar2();");
  Realm.eval(contextB, "%OptimizeFunctionOnNextCall(bar2);");
  Realm.eval(contextB, "bar2();");
  assertFalse(Realm.eval(contextB, "bar2();") instanceof Array);
  assertTrue(Realm.eval(contextB, "bar2() instanceof Array"));
})();

// Test: create array with packed feedback, then optimize function, which
// should deal with arguments that create holey arrays.
(function() {
  function bar(len) { return new Array(len); }
  bar(0);
  bar(0);
    %OptimizeFunctionOnNextCall(bar);
  a = bar(0);
  assertOptimized(bar);
  assertFalse(isHoley(a));
  a = bar(1);  // ouch!
  assertOptimized(bar);
  assertTrue(isHoley(a));
  a = bar(100);
  assertTrue(isHoley(a));
  a = bar(0);
  assertOptimized(bar);
  // Crankshafted functions don't use mementos, so feedback still
  // indicates a packed array is desired. (unless --nocrankshaft is in use).
  if (4 != %GetOptimizationStatus(bar)) {
    assertFalse(isHoley(a));
  }
})();

// Test: Make sure that crankshaft continues with feedback for large arrays.
(function() {
  function bar(len) { return new Array(len); }
  var size = 100001;
  // Perform a gc, because we are allocating a very large array and if a gc
  // happens during the allocation we could lose our memento.
  gc();
  bar(size)[0] = 'string';
  var res = bar(size);
  assertKind(elements_kind.fast, bar(size));
    %OptimizeFunctionOnNextCall(bar);
  assertKind(elements_kind.fast, bar(size));
  // But there is a limit, based on the size of the old generation, currently
  // 22937600, but double it to prevent the test being too brittle.
  var large_size = 22937600 * 2;
  assertKind(elements_kind.dictionary, bar(large_size));
})();