[builtins] Improve performance of array.prototype.filter and map

src/code-stub-assembler.cc

 // Copyright 2016 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/code-stub-assembler.h"
 #include "src/code-factory.h"
 #include "src/frames-inl.h"
 #include "src/frames.h"
 
 namespace v8 {
 namespace internal {
@@ skipping 1441 matching lines @@
 Node* CodeStubAssembler::StoreFixedDoubleArrayElement(
     Node* object, Node* index_node, Node* value, ParameterMode parameter_mode) {
   CSA_ASSERT(this, IsFixedDoubleArray(object));
   Node* offset =
       ElementOffsetFromIndex(index_node, FAST_DOUBLE_ELEMENTS, parameter_mode,
                              FixedArray::kHeaderSize - kHeapObjectTag);
   MachineRepresentation rep = MachineRepresentation::kFloat64;
   return StoreNoWriteBarrier(rep, object, offset, value);
 }
 
-Node* CodeStubAssembler::BuildAppendJSArray(ElementsKind kind, Node* context,
-                                            Node* array,
+Node* CodeStubAssembler::EnsureArrayPushable(Node* receiver, Label* bailout) {
+  // Disallow pushing onto prototypes. It might be the JSArray prototype.
+  // Disallow pushing onto non-extensible objects.
+  Comment("Disallow pushing onto prototypes");
+  Node* map = LoadMap(receiver);
+  Node* bit_field2 = LoadMapBitField2(map);
+  int mask = static_cast<int>(Map::IsPrototypeMapBits::kMask) |
+             (1 << Map::kIsExtensible);
+  Node* test = Word32And(bit_field2, Int32Constant(mask));
+  GotoIf(Word32NotEqual(test, Int32Constant(1 << Map::kIsExtensible)), bailout);
+
+  // Disallow pushing onto arrays in dictionary named property mode. We need
+  // to figure out whether the length property is still writable.
+  Comment("Disallow pushing onto arrays in dictionary named property mode");
+  GotoIf(IsDictionaryMap(map), bailout);
+
+  // Check whether the length property is writable. The length property is the
+  // only default named property on arrays. It's nonconfigurable, hence is
+  // guaranteed to stay the first property.
+  Node* descriptors = LoadMapDescriptors(map);
+  Node* details =
+      LoadFixedArrayElement(descriptors, DescriptorArray::ToDetailsIndex(0));
+  GotoIf(IsSetSmi(details, PropertyDetails::kAttributesReadOnlyMask), bailout);
+
+  Node* kind = DecodeWord32<Map::ElementsKindBits>(bit_field2);
+  return kind;
+}
+
+Node* CodeStubAssembler::BuildAppendJSArray(ElementsKind kind, Node* array,
                                             CodeStubArguments& args,
                                             Variable& arg_index,
                                             Label* bailout) {
   Comment("BuildAppendJSArray: %s", ElementsKindToString(kind));
   Label pre_bailout(this);
   Label success(this);
   Variable var_tagged_length(this, MachineRepresentation::kTagged);
   ParameterMode mode = OptimalParameterMode();
   Variable var_length(this, OptimalParameterRepresentation(),
                       TaggedToParameter(LoadJSArrayLength(array), mode));
@@ skipping 16 matching lines @@
   Goto(&fits);
   Bind(&fits);
   Node* elements = var_elements.value();
 
   // Push each argument onto the end of the array now that there is enough
   // capacity.
   CodeStubAssembler::VariableList push_vars({&var_length}, zone());
   args.ForEach(
       push_vars,
       [this, kind, mode, elements, &var_length, &pre_bailout](Node* arg) {
-        if (IsFastSmiElementsKind(kind)) {
-          GotoIf(TaggedIsNotSmi(arg), &pre_bailout);
-        } else if (IsFastDoubleElementsKind(kind)) {
-          GotoIfNotNumber(arg, &pre_bailout);
-        }
-        if (IsFastDoubleElementsKind(kind)) {
-          Node* double_value = ChangeNumberToFloat64(arg);
-          StoreFixedDoubleArrayElement(elements, var_length.value(),
-                                       Float64SilenceNaN(double_value), mode);
-        } else {
-          WriteBarrierMode barrier_mode = IsFastSmiElementsKind(kind)
-                                              ? SKIP_WRITE_BARRIER
-                                              : UPDATE_WRITE_BARRIER;
-          StoreFixedArrayElement(elements, var_length.value(), arg,
-                                 barrier_mode, 0, mode);
-        }
+        TryStoreArrayElement(kind, mode, &pre_bailout, elements,
+                             var_length.value(), arg);
         Increment(var_length, 1, mode);
       },
       first, nullptr);
   {
     Node* length = ParameterToTagged(var_length.value(), mode);
     var_tagged_length.Bind(length);
     StoreObjectFieldNoWriteBarrier(array, JSArray::kLengthOffset, length);
     Goto(&success);
   }
 
   Bind(&pre_bailout);
   {
     Node* length = ParameterToTagged(var_length.value(), mode);
     var_tagged_length.Bind(length);
     Node* diff = SmiSub(length, LoadJSArrayLength(array));
     StoreObjectFieldNoWriteBarrier(array, JSArray::kLengthOffset, length);
     arg_index.Bind(IntPtrAdd(arg_index.value(), SmiUntag(diff)));
     Goto(bailout);
   }
 
   Bind(&success);
   return var_tagged_length.value();
 }
 
+void CodeStubAssembler::TryStoreArrayElement(ElementsKind kind,
+                                             ParameterMode mode, Label* bailout,
+                                             Node* elements, Node* index,
+                                             Node* value) {
+  if (IsFastSmiElementsKind(kind)) {
+    GotoIf(TaggedIsNotSmi(value), bailout);
+  } else if (IsFastDoubleElementsKind(kind)) {
+    GotoIfNotNumber(value, bailout);
+  }
+  if (IsFastDoubleElementsKind(kind)) {
+    Node* double_value = ChangeNumberToFloat64(value);
+    StoreFixedDoubleArrayElement(elements, index,
+                                 Float64SilenceNaN(double_value), mode);
+  } else {
+    WriteBarrierMode barrier_mode =
+        IsFastSmiElementsKind(kind) ? SKIP_WRITE_BARRIER : UPDATE_WRITE_BARRIER;
+    StoreFixedArrayElement(elements, index, value, barrier_mode, 0, mode);
+  }
+}
+
+Node* CodeStubAssembler::BuildAppendJSArray(ElementsKind kind, Node* array,
+                                            Node* value, Label* bailout) {
+  Comment("BuildAppendJSArray: %s", ElementsKindToString(kind));
+  Label success(this);
+  Variable var_tagged_length(this, MachineRepresentation::kTagged);
+  ParameterMode mode = OptimalParameterMode();
+  Variable var_length(this, OptimalParameterRepresentation(),
+                      TaggedToParameter(LoadJSArrayLength(array), mode));
+  Variable var_elements(this, MachineRepresentation::kTagged,
+                        LoadElements(array));
+  Node* capacity =
+      TaggedToParameter(LoadFixedArrayBaseLength(var_elements.value()), mode);
+
+  // Resize the capacity of the fixed array if it doesn't fit.
+  Label fits(this, &var_elements);
+  Node* growth = IntPtrOrSmiConstant(1, mode);

[danno, 2017/04/03 15:35:27]

This prologue and grow code looks quite similar between the two versions of
BuildAppendJSArray. Could you perhaps factor it out too? (parameterized of
course by the amount to grow)?

[mvstanton, 2017/04/06 08:57:36]

Done.

+  Node* new_length = IntPtrOrSmiAdd(growth, var_length.value(), mode);
+  GotoIfNot(IntPtrOrSmiGreaterThan(new_length, capacity, mode), &fits);
+  Node* new_capacity = CalculateNewElementsCapacity(new_length, mode);
+  var_elements.Bind(GrowElementsCapacity(array, var_elements.value(), kind,
+                                         kind, capacity, new_capacity, mode,
+                                         bailout));
+  Goto(&fits);
+  Bind(&fits);
+  Node* elements = var_elements.value();
+
+  // Push each argument onto the end of the array now that there is enough
+  // capacity.
+  TryStoreArrayElement(kind, mode, bailout, elements, var_length.value(),
+                       value);
+  Increment(var_length, 1, mode);
+
+  {
+    Node* length = ParameterToTagged(var_length.value(), mode);
+    var_tagged_length.Bind(length);
+    StoreObjectFieldNoWriteBarrier(array, JSArray::kLengthOffset, length);
+    Goto(&success);
+  }
+
+  Bind(&success);
+  return var_tagged_length.value();
+}
+
 Node* CodeStubAssembler::AllocateHeapNumber(MutableMode mode) {
   Node* result = Allocate(HeapNumber::kSize, kNone);
   Heap::RootListIndex heap_map_index =
       mode == IMMUTABLE ? Heap::kHeapNumberMapRootIndex
                         : Heap::kMutableHeapNumberMapRootIndex;
   StoreMapNoWriteBarrier(result, heap_map_index);
   return result;
 }
 
 Node* CodeStubAssembler::AllocateHeapNumberWithValue(Node* value,
@@ skipping 6898 matching lines @@
         formatted.c_str(), TENURED);
     CallRuntime(Runtime::kGlobalPrint, NoContextConstant(),
                 HeapConstant(string));
   }
   CallRuntime(Runtime::kDebugPrint, NoContextConstant(), tagged_value);
 #endif
 }
 
 }  // namespace internal
 }  // namespace v8