v8/test/mjsunit/array-feedback.js

// Copyright 2012 the V8 project authors. All rights reserved.
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// Flags: --allow-natives-syntax --smi-only-arrays --expose-gc
// Flags: --noalways-opt

// Test element kind of objects.
// Since --smi-only-arrays affects builtins, its default setting at compile
// time sticks if built with snapshot.  If --smi-only-arrays is deactivated
// by default, only a no-snapshot build actually has smi-only arrays enabled
// in this test case.  Depending on whether smi-only arrays are actually
// enabled, this test takes the appropriate code path to check smi-only arrays.

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

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

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) {
  if (!support_smi_only_arrays &&
      expected == elements_kind.fast_smi_only) {
    expected = elements_kind.fast;
  }
  assertEquals(expected, getKind(obj), name_opt);
}

if (support_smi_only_arrays) {

  // Verify that basic elements kind feedback works for non-constructor
  // array calls (as long as the call is made through an IC, and not
  // a CallStub).
  (function (){
    function create0() {
      return Array();
    }

    // Calls through ICs need warm up through uninitialized, then
    // premonomorphic first.
    create0();
    a = create0();
    assertKind(elements_kind.fast_smi_only, a);
    a[0] = 3.5;
    b = create0();
    assertKind(elements_kind.fast_double, b);

    function create1(arg) {
      return Array(arg);
    }

    create1(0);
    create1(0);
    a = create1(0);
    assertFalse(isHoley(a));
    assertKind(elements_kind.fast_smi_only, a);
    a[0] = "hello";
    b = create1(10);
    assertTrue(isHoley(b));
    assertKind(elements_kind.fast, b);

    a = create1(100000);
    assertKind(elements_kind.dictionary, a);

    function create3(arg1, arg2, arg3) {
      return Array(arg1, arg2, arg3);
    }

    create3(1,2,3);
    create3(1,2,3);
    a = create3(1,2,3);
    a[0] = 3.035;
    assertKind(elements_kind.fast_double, a);
    b = create3(1,2,3);
    assertKind(elements_kind.fast_double, b);
    assertFalse(isHoley(b));
  })();


  // Verify that keyed calls work
  (function (){
    function create0(name) {
      return this[name]();
    }

    name = "Array";
    create0(name);
    create0(name);
    a = create0(name);
    a[0] = 3.5;
    b = create0(name);
    assertKind(elements_kind.fast_double, b);
  })();


  // Verify that feedback is turned off if the call site goes megamorphic.
  (function (){
    function foo(arg) { return arg(); }
    foo(Array);
    foo(function() {});
    foo(Array);

    gc();

    a = foo(Array);
    a[0] = 3.5;
    b = foo(Array);
    // b doesn't benefit from elements kind feedback at a megamorphic site.
    assertKind(elements_kind.fast_smi_only, b);
  })();


  // Verify that crankshaft consumes type feedback.
  (function (){
    function create0() {
      return Array();
    }

    create0();
    create0();
    a = create0();
    a[0] = 3.5;
    %OptimizeFunctionOnNextCall(create0);
    create0();
    create0();
    b = create0();
    assertKind(elements_kind.fast_double, b);
    assertOptimized(create0);

    function create1(arg) {
      return Array(arg);
    }

    create1(8);
    create1(8);
    a = create1(8);
    a[0] = 3.5;
    %OptimizeFunctionOnNextCall(create1);
    b = create1(8);
    assertKind(elements_kind.fast_double, b);
    assertOptimized(create1);

    function createN(arg1, arg2, arg3) {
      return Array(arg1, arg2, arg3);
    }

    createN(1, 2, 3);
    createN(1, 2, 3);
    a = createN(1, 2, 3);
    a[0] = 3.5;
    %OptimizeFunctionOnNextCall(createN);
    b = createN(1, 2, 3);
    assertKind(elements_kind.fast_double, b);
    assertOptimized(createN);
  })();

  // Verify that cross context calls work
  (function (){
    var realmA = Realm.current();
    var realmB = Realm.create();
    assertEquals(0, realmA);
    assertEquals(1, realmB);

    function instanceof_check(type) {
      assertTrue(type() instanceof type);
      assertTrue(type(5) instanceof type);
      assertTrue(type(1,2,3) instanceof type);
    }

    var realmBArray = Realm.eval(realmB, "Array");
    instanceof_check(Array);
    instanceof_check(Array);
    instanceof_check(Array);
    instanceof_check(realmBArray);
    instanceof_check(realmBArray);
    instanceof_check(realmBArray);
  })();
}