[builtins] implement Array.prototype.includes in TurboFan

src/objects.cc

 // Copyright 2015 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "src/objects.h"
 
 #include <cmath>
 #include <iomanip>
 #include <memory>
 #include <sstream>
@@ skipping 18979 matching lines @@
 
 bool JSReceiver::HasProxyInPrototype(Isolate* isolate) {
   for (PrototypeIterator iter(isolate, this, kStartAtReceiver,
                               PrototypeIterator::END_AT_NULL);
        !iter.IsAtEnd(); iter.AdvanceIgnoringProxies()) {
     if (iter.GetCurrent<Object>()->IsJSProxy()) return true;
   }
   return false;
 }
 
+Maybe<bool> JSReceiver::IncludesValue(Isolate* isolate,
+                                      Handle<JSReceiver> object,
+                                      Handle<Object> value,
+                                      Handle<Object> from_index) {

[Camillo Bruni, 2016/08/01 07:23:47]

nit: Any particular reason this has to be on JSReceiver?
Otherwise I'm fine with pushing the implementation back into runtime-arrays.cc
or at least have the JSReceiver directly take sane input values (aka. uint32 /
int64) since we usually do the argument conversion in the builtins/runtime
functions.

[caitp, 2016/08/01 15:10:45]

had moved it here to make it easy to share the c++ impl between teo builtins in
patchset #13. I've now moved it back to runtime-array.cc

+  // Let len be ? ToLength(? Get(O, "length")).
+  int64_t len;
+  {
+    Handle<Object> len_;
+    if (object->map()->instance_type() == JS_ARRAY_TYPE) {
+      len_ = handle(JSArray::cast(*object)->length(), isolate);

[Camillo Bruni, 2016/08/01 07:23:47]

nit: A JSArray can only have sane length values (0 to 2^32-1 see
JSArray::SetLength), thus you can avoid the handlification and only use the
ToLength path for all the other objects.

[caitp, 2016/08/01 15:10:45]

updated to use ToArrayLength() for JS_ARRAY_TYPE

+    } else {
+      ASSIGN_RETURN_ON_EXCEPTION_VALUE(
+          isolate, len_,
+          Object::GetProperty(object, isolate->factory()->length_string()),
+          Nothing<bool>());
+    }
+    ASSIGN_RETURN_ON_EXCEPTION_VALUE(
+        isolate, len_, Object::ToLength(isolate, len_), Nothing<bool>());
+    len = static_cast<int64_t>(len_->Number());
+    DCHECK_EQ(len, len_->Number());
+  }
+
+  if (len == 0) return Just(false);
+
+  // Let n be ? ToInteger(fromIndex). (If fromIndex is undefined, this step
+  // produces the value 0.)
+  int64_t start_from;
+  {
+    ASSIGN_RETURN_ON_EXCEPTION_VALUE(isolate, from_index,
+                                     Object::ToInteger(isolate, from_index),
+                                     Nothing<bool>());
+    double fp = from_index->Number();
+    if (fp > len) return Just(false);
+    start_from = static_cast<int64_t>(fp);
+  }
+
+  int64_t index;
+  if (start_from >= 0) {
+    index = start_from;
+  } else {
+    index = len + start_from;
+    if (index < 0) {
+      index = 0;
+    }
+  }
+
+  // If the receiver is not a special receiver type, and the length is a valid
+  // element index, perform fast operation tailored to specific ElementsKinds.
+  if (object->map()->instance_type() > LAST_SPECIAL_RECEIVER_TYPE &&
+      len < kMaxUInt32 &&
+      JSObject::PrototypeHasNoElements(isolate, JSObject::cast(*object))) {
+    Handle<JSObject> obj = Handle<JSObject>::cast(object);
+    ElementsAccessor* elements = obj->GetElementsAccessor();
+    return elements->IncludesValue(isolate, obj, value,
+                                   static_cast<uint32_t>(index),
+                                   static_cast<uint32_t>(len));
+  }
+
+  // Otherwise, perform slow lookups for special receiver types
+  for (; index < len; ++index) {
+    // Let elementK be the result of ? Get(O, ! ToString(k)).
+    Handle<Object> element_k;
+    {
+      Handle<Object> index_obj = isolate->factory()->NewNumberFromInt64(index);
+      bool success;
+      LookupIterator it = LookupIterator::PropertyOrElement(
+          isolate, object, index_obj, &success);
+      DCHECK(success);
+      ASSIGN_RETURN_ON_EXCEPTION_VALUE(
+          isolate, element_k, Object::GetProperty(&it), Nothing<bool>());
+    }
+
+    // If SameValueZero(searchElement, elementK) is true, return true.
+    if (value->SameValueZero(*element_k)) return Just(true);
+  }
+  return Just(false);
+}
+
 }  // namespace internal
 }  // namespace v8