[builtins] Reland Array.prototype.splice() Torque implementation.

Before, splice was implemented with a C++ fast path and a
comprehensive JavaScript version.

This impl. is entirely in Torque with a fastpath for SMI,
DOUBLE and OBJECT arrays, and a comprehensive slow path.
The same level of "sparse" array support as given by the
array.js implementation is included.

Cq-Include-Trybots: luci.v8.try:v8_linux_noi18n_rel_ng
Change-Id: Ia7334a30b401988309e9909cfa0069da0bb6fb9f
Reviewed-on: https://chromium-review.googlesource.com/1169466Reviewed-by: Tobias Tebbi <tebbi@chromium.org>
Reviewed-by: Jakob Gruber <jgruber@chromium.org>
Commit-Queue: Tobias Tebbi <tebbi@chromium.org>
Cr-Commit-Position: refs/heads/master@{#55263}

BUILD.gn

@@ -888,6 +888,7 @@ torque_files = [
   "src/builtins/array-copywithin.tq",
   "src/builtins/array-foreach.tq",
   "src/builtins/array-shift.tq",
+  "src/builtins/array-splice.tq",
   "src/builtins/typed-array.tq",
   "src/builtins/data-view.tq",
   "test/torque/test-torque.tq",

src/bootstrapper.cc

@@ -1741,13 +1741,8 @@ void Genesis::InitializeGlobal(Handle<JSGlobalObject> global_object,
                           1, false);
     SimpleInstallFunction(isolate_, proto, "slice",
                           Builtins::kArrayPrototypeSlice, 2, false);
-    if (FLAG_enable_experimental_builtins) {
-      SimpleInstallFunction(isolate_, proto, "splice",
-                            Builtins::kArraySpliceTorque, 2, false);
-    } else {
-      SimpleInstallFunction(isolate_, proto, "splice", Builtins::kArraySplice,
-                            2, false);
-    }
+    SimpleInstallFunction(isolate_, proto, "splice", Builtins::kArraySplice, 2,
+                          false);
     SimpleInstallFunction(isolate_, proto, "includes", Builtins::kArrayIncludes,
                           1, false);
     SimpleInstallFunction(isolate_, proto, "indexOf", Builtins::kArrayIndexOf,

src/builtins/array-foreach.tq

@@ -62,6 +62,10 @@ module array {
           cast<Callable>(callback) otherwise Unexpected;
       const k: Smi = cast<Smi>(initialK) otherwise Unexpected;
       const number_length: Number = cast<Number>(length) otherwise Unexpected;
+      // The unsafe cast is safe because all continuation points in forEach are
+      // after the ToObject(O) call that ensures we are dealing with a
+      // JSReceiver.
+      let jsreceiver: JSReceiver = unsafe_cast<JSReceiver>(object);
 
       return ArrayForEachTorqueContinuation(
           context, receiver, number_length, callbackfn, thisArg, k);

src/builtins/base.tq

@@ -107,6 +107,10 @@ type FixedUint8ClampedArray extends FixedTypedArray;
 type FixedBigUint64Array extends FixedTypedArray;
 type FixedBigInt64Array extends FixedTypedArray;
 
+const kFixedArrays: constexpr ExtractFixedArrayFlags generates
+'ExtractFixedArrayFlag::kFixedArrays';
+const kFixedDoubleArrays: constexpr ExtractFixedArrayFlags generates
+'ExtractFixedArrayFlag::kFixedDoubleArrays';
 const kAllFixedArrays: constexpr ExtractFixedArrayFlags generates
 'ExtractFixedArrayFlag::kAllFixedArrays';
 
@@ -169,6 +173,7 @@ extern macro Is64(): constexpr bool;
 
 extern macro Print(constexpr string);
 extern macro Print(constexpr string, Object);
+extern macro Comment(constexpr string);
 extern macro Print(Object);
 extern macro DebugBreak();
 extern macro ToInteger_Inline(Context, Object): Number;
@@ -187,7 +192,8 @@ extern macro ThrowTypeError(Context, constexpr MessageTemplate): never;
 extern macro ThrowTypeError(Context, constexpr MessageTemplate, Object): never;
 extern macro ThrowTypeError(
     Context, constexpr MessageTemplate, Object, Object, Object): never;
-extern macro ArraySpeciesCreate(Context, Object, Number): Object;
+extern macro ArraySpeciesCreate(Context, Object, Number): JSReceiver;
+extern macro InternalArrayCreate(Context, Number): JSArray;
 extern macro EnsureArrayPushable(Map): ElementsKind labels Bailout;
 
 extern builtin ToObject(Context, Object): JSReceiver;
@@ -197,7 +203,9 @@ extern macro IsTheHole(Object): bool;
 extern macro IsString(HeapObject): bool;
 extern builtin ToString(Context, Object): String;
 
-extern runtime CreateDataProperty(Context, Object, Object, Object);
+extern runtime NormalizeElements(Context, JSObject);
+extern runtime TransitionElementsKindWithKind(Context, JSObject, Smi);
+extern runtime CreateDataProperty(Context, JSReceiver, Object, Object);
 
 extern macro LoadRoot(constexpr RootListIndex): Object;
 extern macro StoreRoot(constexpr RootListIndex, Object): Object;
@@ -224,6 +232,10 @@ extern operator '>=' macro SmiGreaterThanOrEqual(Smi, Smi): bool;
 extern operator '==' macro ElementsKindEqual(
     constexpr ElementsKind, constexpr ElementsKind): constexpr bool;
 extern operator '==' macro ElementsKindEqual(ElementsKind, ElementsKind): bool;
+operator '!=' macro ElementsKindNotEqual(
+    k1: ElementsKind, k2: ElementsKind): bool {
+  return !ElementsKindEqual(k1, k2);
+}
 extern macro IsFastElementsKind(constexpr ElementsKind): constexpr bool;
 extern macro IsDoubleElementsKind(constexpr ElementsKind): constexpr bool;
 
@@ -242,11 +254,14 @@ extern operator '>=' macro UintPtrGreaterThanOrEqual(uintptr, uintptr): bool;
 extern operator '==' macro Float64Equal(float64, float64): bool;
 extern operator '!=' macro Float64NotEqual(float64, float64): bool;
 
+extern operator
+'==' macro BranchIfNumberEqual(Number, Number): never labels Taken, NotTaken;
 extern operator
 '<' macro BranchIfNumberLessThan(Number, Number): never labels Taken, NotTaken;
 extern operator
 '<=' macro BranchIfNumberLessThanOrEqual(Number, Number): never labels Taken,
     NotTaken;
+
 extern operator
 '>' macro BranchIfNumberGreaterThan(Number, Number): never labels Taken,
     NotTaken;
@@ -313,8 +328,8 @@ extern operator '.length' macro GetArgumentsLength(constexpr Arguments): intptr;
 extern operator
 '[]' macro GetArgumentValue(constexpr Arguments, intptr): Object;
 
-extern operator 'is<Smi>' macro TaggedIsSmi(Object): bool;
-extern operator 'isnt<Smi>' macro TaggedIsNotSmi(Object): bool;
+extern macro TaggedIsSmi(Object): bool;
+extern macro TaggedIsNotSmi(Object): bool;
 extern macro TaggedIsPositiveSmi(Object): bool;
 
 extern macro HeapObjectToJSDataView(HeapObject): JSDataView labels CastError;
@@ -322,18 +337,20 @@ extern macro TaggedToHeapObject(Object): HeapObject labels CastError;
 extern macro TaggedToSmi(Object): Smi labels CastError;
 extern macro HeapObjectToJSArray(HeapObject): JSArray labels CastError;
 extern macro HeapObjectToCallable(HeapObject): Callable labels CastError;
-extern macro HeapObjectToFixedArray(HeapObject):
-    FixedArray labels CastError;
+extern macro HeapObjectToFixedArray(HeapObject): FixedArray labels CastError;
 extern macro HeapObjectToFixedDoubleArray(HeapObject):
     FixedDoubleArray labels CastError;
 extern macro TaggedToNumber(Object): Number labels CastError;
 
-macro cast_HeapObject<A : type>(o : HeapObject) : A labels CastError;
-cast_HeapObject<HeapObject>(o : HeapObject) : HeapObject labels CastError { return o; }
+macro cast_HeapObject<A : type>(o: HeapObject): A labels CastError;
+cast_HeapObject<HeapObject>(o: HeapObject): HeapObject labels CastError {
+  return o;
+}
 cast_HeapObject<FixedArray>(o: HeapObject): FixedArray labels CastError {
   return HeapObjectToFixedArray(o) otherwise CastError;
 }
-cast_HeapObject<FixedDoubleArray>(o: HeapObject): FixedDoubleArray labels CastError {
+cast_HeapObject<FixedDoubleArray>(o: HeapObject):
+    FixedDoubleArray labels CastError {
   return HeapObjectToFixedDoubleArray(o) otherwise CastError;
 }
 cast_HeapObject<JSDataView>(o: HeapObject): JSDataView labels CastError {
@@ -353,8 +370,8 @@ macro cast<A : type>(o: HeapObject): A labels CastError {
 // cast_HeapObject allows this default-implementation to be non-recursive.
 // Otherwise the generated CSA code might run into infinite recursion.
 macro cast<A : type>(o: Object): A labels CastError {
-  return cast_HeapObject<A>(
-    TaggedToHeapObject(o) otherwise CastError) otherwise CastError;
+  return cast_HeapObject<A>(TaggedToHeapObject(o) otherwise CastError)
+      otherwise CastError;
 }
 cast<Smi>(o: Object): Smi labels CastError {
   return TaggedToSmi(o) otherwise CastError;
@@ -460,6 +477,13 @@ from_constexpr<Object>(s: constexpr string): Object {
 macro convert<A : type>(i: constexpr int31): A {
   return i;
 }
+extern macro ConvertElementsKindToInt(ElementsKind): int32;
+
+macro convert<A : type>(elements_kind: ElementsKind): A;
+convert<int32>(elements_kind: ElementsKind): int32 {
+  return ConvertElementsKindToInt(elements_kind);
+}
+
 macro convert<A : type>(i: int32): A;
 convert<Number>(i: int32): Number {
   return ChangeInt32ToTagged(i);
@@ -546,6 +570,9 @@ unsafe_cast<HeapNumber>(n: Number): HeapNumber {
   return UnsafeCastNumberToHeapNumber(n);
 }
 macro unsafe_cast<A : type>(o: Object): A;
+unsafe_cast<Object>(o: Object): Object {
+  return o;
+}
 unsafe_cast<FixedArray>(o: Object): FixedArray {
   return UnsafeCastObjectToFixedArray(o);
 }
@@ -628,10 +655,13 @@ extern operator
 extern operator
 '[]=' macro StoreFixedArrayElement(FixedArray, intptr, Object): void;
 extern operator
-'[]=' macro StoreFixedArrayElement(
-    FixedArray, constexpr int31, Object): void;
+'[]=' macro StoreFixedArrayElement(FixedArray, constexpr int31, Object): void;
 extern operator
 '[]=' macro StoreFixedArrayElementSmi(FixedArray, Smi, Object): void;
+operator '[]=' macro StoreFixedDoubleArrayNumber(
+    a: FixedDoubleArray, index: Smi, value: Number): void {
+  a[index] = convert<float64>(value);
+}
 
 extern macro StoreFixedArrayElementSmi(FixedArray, Smi, Object,
   constexpr WriteBarrierMode): void;
@@ -660,6 +690,28 @@ extern macro IsFastSmiOrTaggedElementsKind(ElementsKind): bool;
 extern macro IsFastSmiElementsKind(ElementsKind): bool;
 extern macro IsHoleyFastElementsKind(ElementsKind): bool;
 
+macro AllowDoubleElements(kind: ElementsKind): ElementsKind {
+  if (kind == PACKED_SMI_ELEMENTS) {
+    return PACKED_DOUBLE_ELEMENTS;
+  } else if (kind == HOLEY_SMI_ELEMENTS) {
+    return HOLEY_DOUBLE_ELEMENTS;
+  }
+  return kind;
+}
+
+macro AllowNonNumberElements(kind: ElementsKind): ElementsKind {
+  if (kind == PACKED_SMI_ELEMENTS) {
+    return PACKED_ELEMENTS;
+  } else if (kind == HOLEY_SMI_ELEMENTS) {
+    return HOLEY_ELEMENTS;
+  } else if (kind == PACKED_DOUBLE_ELEMENTS) {
+    return PACKED_ELEMENTS;
+  } else if (kind == HOLEY_DOUBLE_ELEMENTS) {
+    return HOLEY_ELEMENTS;
+  }
+  return kind;
+}
+
 extern macro AllocateZeroedFixedArray(intptr): FixedArray;
 extern macro AllocateZeroedFixedDoubleArray(intptr): FixedDoubleArray;
 
@@ -675,8 +727,13 @@ extern macro AllocateJSArray(constexpr ElementsKind, Map, Smi, Smi): JSArray;
 extern macro IsElementsKindGreaterThan(
     ElementsKind, constexpr ElementsKind): bool;
 
+extern operator
+'[]=' macro StoreFixedDoubleArrayElementSmi(
+    FixedDoubleArray, Smi, float64): void;
+
 extern macro LoadDoubleWithHoleCheck(FixedDoubleArray, Smi): float64
 labels IfHole;
+extern macro StoreFixedDoubleArrayHoleSmi(FixedDoubleArray, Smi): void;
 
 extern macro Call(Context, Callable, Object): Object;
 extern macro Call(Context, Callable, Object, Object): Object;
@@ -687,8 +744,7 @@ extern macro Call(
 extern macro Call(
     Context, Callable, Object, Object, Object, Object, Object, Object): Object;
 
-extern macro ExtractFixedArray(
-    FixedArray, Smi, Smi, Smi, constexpr ExtractFixedArrayFlags): FixedArray;
+extern macro ExtractFixedArray(FixedArrayBase, Smi, Smi, Smi): FixedArrayBase;
 
 extern builtin ExtractFastJSArray(Context, JSArray, Smi, Smi): JSArray;
 
@@ -723,11 +779,17 @@ labels IfHole {
   }
 }
 
+extern macro TransitionElementsKind(
+    JSObject, Map, ElementsKind, ElementsKind): void labels Bailout;
+
 extern macro IsCallable(HeapObject): bool;
 extern macro IsJSArray(HeapObject): bool;
+extern macro IsJSReceiver(HeapObject): bool;
 extern macro TaggedIsCallable(Object): bool;
 extern macro IsDetachedBuffer(JSArrayBuffer): bool;
 extern macro IsHeapNumber(HeapObject): bool;
+extern macro IsFixedArray(HeapObject): bool;
+extern macro IsNumber(Object): bool;
 extern macro IsExtensibleMap(Map): bool;
 extern macro IsCustomElementsReceiverInstanceType(int32): bool;
 extern macro Typeof(Object): Object;

src/builtins/builtins-array.cc

@@ -23,34 +23,6 @@ namespace internal {
 
 namespace {
 
-inline bool ClampedToInteger(Isolate* isolate, Object* object, int* out) {
-  // This is an extended version of ECMA-262 7.1.11 handling signed values
-  // Try to convert object to a number and clamp values to [kMinInt, kMaxInt]
-  if (object->IsSmi()) {
-    *out = Smi::ToInt(object);
-    return true;
-  } else if (object->IsHeapNumber()) {
-    double value = HeapNumber::cast(object)->value();
-    if (std::isnan(value)) {
-      *out = 0;
-    } else if (value > kMaxInt) {
-      *out = kMaxInt;
-    } else if (value < kMinInt) {
-      *out = kMinInt;
-    } else {
-      *out = static_cast<int>(value);
-    }
-    return true;
-  } else if (object->IsNullOrUndefined(isolate)) {
-    *out = 0;
-    return true;
-  } else if (object->IsBoolean()) {
-    *out = object->IsTrue(isolate);
-    return true;
-  }
-  return false;
-}
-
 inline bool IsJSArrayFastElementMovingAllowed(Isolate* isolate,
                                               JSArray* receiver) {
   return JSObject::PrototypeHasNoElements(isolate, receiver);
@@ -530,67 +502,6 @@ BUILTIN(ArrayUnshift) {
   return Smi::FromInt(new_length);
 }
 
-BUILTIN(ArraySplice) {
-  HandleScope scope(isolate);
-  Handle<Object> receiver = args.receiver();
-  if (V8_UNLIKELY(
-          !EnsureJSArrayWithWritableFastElements(isolate, receiver, &args, 3,
-                                                 args.length() - 3) ||
-          // If this is a subclass of Array, then call out to JS.
-          !Handle<JSArray>::cast(receiver)->HasArrayPrototype(isolate) ||
-          // If anything with @@species has been messed with, call out to JS.
-          !isolate->IsArraySpeciesLookupChainIntact())) {
-    return CallJsIntrinsic(isolate, isolate->array_splice(), args);
-  }
-  Handle<JSArray> array = Handle<JSArray>::cast(receiver);
-
-  int argument_count = args.length() - 1;
-  int relative_start = 0;
-  if (argument_count > 0) {
-    DisallowHeapAllocation no_gc;
-    if (!ClampedToInteger(isolate, args[1], &relative_start)) {
-      AllowHeapAllocation allow_allocation;
-      return CallJsIntrinsic(isolate, isolate->array_splice(), args);
-    }
-  }
-  int len = Smi::ToInt(array->length());
-  // clip relative start to [0, len]
-  int actual_start = (relative_start < 0) ? Max(len + relative_start, 0)
-                                          : Min(relative_start, len);
-
-  int actual_delete_count;
-  if (argument_count == 1) {
-    // SpiderMonkey, TraceMonkey and JSC treat the case where no delete count is
-    // given as a request to delete all the elements from the start.
-    // And it differs from the case of undefined delete count.
-    // This does not follow ECMA-262, but we do the same for compatibility.
-    DCHECK_GE(len - actual_start, 0);
-    actual_delete_count = len - actual_start;
-  } else {
-    int delete_count = 0;
-    DisallowHeapAllocation no_gc;
-    if (argument_count > 1) {
-      if (!ClampedToInteger(isolate, args[2], &delete_count)) {
-        AllowHeapAllocation allow_allocation;
-        return CallJsIntrinsic(isolate, isolate->array_splice(), args);
-      }
-    }
-    actual_delete_count = Min(Max(delete_count, 0), len - actual_start);
-  }
-
-  int add_count = (argument_count > 1) ? (argument_count - 2) : 0;
-  int new_length = len - actual_delete_count + add_count;
-
-  if (new_length != len && JSArray::HasReadOnlyLength(array)) {
-    AllowHeapAllocation allow_allocation;
-    return CallJsIntrinsic(isolate, isolate->array_splice(), args);
-  }
-  ElementsAccessor* accessor = array->GetElementsAccessor();
-  Handle<JSArray> result_array = accessor->Splice(
-      array, actual_start, actual_delete_count, &args, add_count);
-  return *result_array;
-}
-
 // Array Concat -------------------------------------------------------------
 
 namespace {

src/builtins/builtins-definitions.h

@@ -318,8 +318,6 @@ namespace internal {
   CPP(ArrayShift)                                                              \
   /* ES6 #sec-array.prototype.slice */                                         \
   TFJ(ArrayPrototypeSlice, SharedFunctionInfo::kDontAdaptArgumentsSentinel)    \
-  /* ES6 #sec-array.prototype.splice */                                        \
-  CPP(ArraySplice)                                                             \
   /* ES6 #sec-array.prototype.unshift */                                       \
   CPP(ArrayUnshift)                                                            \
   /* Support for Array.from and other array-copying idioms */                  \

src/code-stub-assembler.cc

@@ -4166,6 +4166,33 @@ void CodeStubAssembler::FillFixedArrayWithValue(
       mode);
 }
 
+void CodeStubAssembler::StoreFixedDoubleArrayHole(
+    TNode<FixedDoubleArray> array, Node* index, ParameterMode parameter_mode) {
+  CSA_SLOW_ASSERT(this, MatchesParameterMode(index, parameter_mode));
+  Node* offset =
+      ElementOffsetFromIndex(index, PACKED_DOUBLE_ELEMENTS, parameter_mode,
+                             FixedArray::kHeaderSize - kHeapObjectTag);
+  CSA_ASSERT(this, IsOffsetInBounds(
+                       offset, LoadAndUntagFixedArrayBaseLength(array),
+                       FixedDoubleArray::kHeaderSize, PACKED_DOUBLE_ELEMENTS));
+  Node* double_hole =
+      Is64() ? ReinterpretCast<UintPtrT>(Int64Constant(kHoleNanInt64))
+             : ReinterpretCast<UintPtrT>(Int32Constant(kHoleNanLower32));
+  // TODO(danno): When we have a Float32/Float64 wrapper class that
+  // preserves double bits during manipulation, remove this code/change
+  // this to an indexed Float64 store.
+  if (Is64()) {
+    StoreNoWriteBarrier(MachineRepresentation::kWord64, array, offset,
+                        double_hole);
+  } else {
+    StoreNoWriteBarrier(MachineRepresentation::kWord32, array, offset,
+                        double_hole);
+    StoreNoWriteBarrier(MachineRepresentation::kWord32, array,
+                        IntPtrAdd(offset, IntPtrConstant(kPointerSize)),
+                        double_hole);
+  }
+}
+
 void CodeStubAssembler::FillFixedArrayWithSmiZero(TNode<FixedArray> array,
                                                   TNode<IntPtrT> length) {
   CSA_ASSERT(this, WordEqual(length, LoadAndUntagFixedArrayBaseLength(array)));
@@ -9973,6 +10000,10 @@ void CodeStubAssembler::BranchIfNumberRelationalComparison(
                     // Both {left} and {right} are Smi, so just perform a fast
                     // Smi comparison.
                     switch (op) {
+                      case Operation::kEqual:
+                        BranchIfSmiEqual(smi_left, smi_right, if_true,
+                                         if_false);
+                        break;
                       case Operation::kLessThan:
                         BranchIfSmiLessThan(smi_left, smi_right, if_true,
                                             if_false);
@@ -10019,6 +10050,10 @@ void CodeStubAssembler::BranchIfNumberRelationalComparison(
   BIND(&do_float_comparison);
   {
     switch (op) {
+      case Operation::kEqual:
+        Branch(Float64Equal(var_left_float.value(), var_right_float.value()),
+               if_true, if_false);
+        break;
       case Operation::kLessThan:
         Branch(Float64LessThan(var_left_float.value(), var_right_float.value()),
                if_true, if_false);
@@ -11927,6 +11962,15 @@ Node* CodeStubAssembler::ArraySpeciesCreate(TNode<Context> context,
                      len);
 }
 
+Node* CodeStubAssembler::InternalArrayCreate(TNode<Context> context,
+                                             TNode<Number> len) {
+  Node* native_context = LoadNativeContext(context);
+  Node* const constructor = LoadContextElement(
+      native_context, Context::INTERNAL_ARRAY_FUNCTION_INDEX);
+  return ConstructJS(CodeFactory::Construct(isolate()), context, constructor,
+                     len);
+}
+
 Node* CodeStubAssembler::IsDetachedBuffer(Node* buffer) {
   CSA_ASSERT(this, HasInstanceType(buffer, JS_ARRAY_BUFFER_TYPE));
 

src/code-stub-assembler.h

@@ -1191,6 +1191,19 @@ class V8_EXPORT_PRIVATE CodeStubAssembler : public compiler::CodeAssembler {
       TNode<FixedDoubleArray> object, Node* index, TNode<Float64T> value,
       ParameterMode parameter_mode = INTPTR_PARAMETERS);
 
+  void StoreFixedDoubleArrayElementSmi(TNode<FixedDoubleArray> object,
+                                       TNode<Smi> index,
+                                       TNode<Float64T> value) {
+    StoreFixedDoubleArrayElement(object, index, value, SMI_PARAMETERS);
+  }
+
+  void StoreFixedDoubleArrayHole(TNode<FixedDoubleArray> array, Node* index,
+                                 ParameterMode mode = INTPTR_PARAMETERS);
+  void StoreFixedDoubleArrayHoleSmi(TNode<FixedDoubleArray> array,
+                                    TNode<Smi> index) {
+    StoreFixedDoubleArrayHole(array, index, SMI_PARAMETERS);
+  }
+
   Node* StoreFeedbackVectorSlot(
       Node* object, Node* index, Node* value,
       WriteBarrierMode barrier_mode = UPDATE_WRITE_BARRIER,
@@ -1426,6 +1439,7 @@ class V8_EXPORT_PRIVATE CodeStubAssembler : public compiler::CodeAssembler {
 
   Node* ArraySpeciesCreate(TNode<Context> context, TNode<Object> originalArray,
                            TNode<Number> len);
+  Node* InternalArrayCreate(TNode<Context> context, TNode<Number> len);
 
   void FillFixedArrayWithValue(ElementsKind kind, Node* array, Node* from_index,
                                Node* to_index,
@@ -1501,6 +1515,10 @@ class V8_EXPORT_PRIVATE CodeStubAssembler : public compiler::CodeAssembler {
     return UncheckedCast<FixedDoubleArray>(base);
   }
 
+  TNode<Int32T> ConvertElementsKindToInt(TNode<Int32T> elements_kind) {
+    return UncheckedCast<Int32T>(elements_kind);
+  }
+
   enum class ExtractFixedArrayFlag {
     kFixedArrays = 1,
     kFixedDoubleArrays = 2,
@@ -1541,12 +1559,11 @@ class V8_EXPORT_PRIVATE CodeStubAssembler : public compiler::CodeAssembler {
           ExtractFixedArrayFlag::kAllFixedArrays,
       ParameterMode parameter_mode = INTPTR_PARAMETERS);
 
-  TNode<FixedArrayBase> ExtractFixedArray(
-      TNode<FixedArrayBase> source, TNode<Smi> first, TNode<Smi> count,
-      TNode<Smi> capacity,
-      ExtractFixedArrayFlags extract_flags =
-          ExtractFixedArrayFlag::kAllFixedArrays) {
-    return ExtractFixedArray(source, first, count, capacity, extract_flags,
+  TNode<FixedArrayBase> ExtractFixedArray(TNode<FixedArrayBase> source,
+                                          TNode<Smi> first, TNode<Smi> count,
+                                          TNode<Smi> capacity) {
+    return ExtractFixedArray(source, first, count, capacity,
+                             ExtractFixedArrayFlag::kAllFixedArrays,
                              SMI_PARAMETERS);
   }
 
@@ -2534,6 +2551,12 @@ class V8_EXPORT_PRIVATE CodeStubAssembler : public compiler::CodeAssembler {
                               ElementsKind to_kind, bool is_jsarray,
                               Label* bailout);
 
+  void TransitionElementsKind(TNode<JSReceiver> object, TNode<Map> map,
+                              ElementsKind from_kind, ElementsKind to_kind,
+                              Label* bailout) {
+    TransitionElementsKind(object, map, from_kind, to_kind, true, bailout);
+  }
+
   void TrapAllocationMemento(Node* object, Label* memento_found);
 
   TNode<IntPtrT> PageFromAddress(TNode<IntPtrT> address);
@@ -2625,26 +2648,32 @@ class V8_EXPORT_PRIVATE CodeStubAssembler : public compiler::CodeAssembler {
   void BranchIfNumberRelationalComparison(Operation op, Node* left, Node* right,
                                           Label* if_true, Label* if_false);
 
-  void BranchIfNumberLessThan(Node* left, Node* right, Label* if_true,
-                              Label* if_false) {
+  void BranchIfNumberEqual(TNode<Number> left, TNode<Number> right,
+                           Label* if_true, Label* if_false) {
+    BranchIfNumberRelationalComparison(Operation::kEqual, left, right, if_true,
+                                       if_false);
+  }
+
+  void BranchIfNumberLessThan(TNode<Number> left, TNode<Number> right,
+                              Label* if_true, Label* if_false) {
     BranchIfNumberRelationalComparison(Operation::kLessThan, left, right,
                                        if_true, if_false);
   }
 
-  void BranchIfNumberLessThanOrEqual(Node* left, Node* right, Label* if_true,
-                                     Label* if_false) {
+  void BranchIfNumberLessThanOrEqual(TNode<Number> left, TNode<Number> right,
+                                     Label* if_true, Label* if_false) {
     BranchIfNumberRelationalComparison(Operation::kLessThanOrEqual, left, right,
                                        if_true, if_false);
   }
 
-  void BranchIfNumberGreaterThan(Node* left, Node* right, Label* if_true,
-                                 Label* if_false) {
+  void BranchIfNumberGreaterThan(TNode<Number> left, TNode<Number> right,
+                                 Label* if_true, Label* if_false) {
     BranchIfNumberRelationalComparison(Operation::kGreaterThan, left, right,
                                        if_true, if_false);
   }
 
-  void BranchIfNumberGreaterThanOrEqual(Node* left, Node* right, Label* if_true,
-                                        Label* if_false) {
+  void BranchIfNumberGreaterThanOrEqual(TNode<Number> left, TNode<Number> right,
+                                        Label* if_true, Label* if_false) {
     BranchIfNumberRelationalComparison(Operation::kGreaterThanOrEqual, left,
                                        right, if_true, if_false);
   }

src/contexts.h

@@ -72,7 +72,6 @@ enum ContextLookupFlags {
 
 #define NATIVE_CONTEXT_IMPORTED_FIELDS(V)                                      \
   V(ARRAY_SHIFT_INDEX, JSFunction, array_shift)                                \
-  V(ARRAY_SPLICE_INDEX, JSFunction, array_splice)                              \
   V(ARRAY_UNSHIFT_INDEX, JSFunction, array_unshift)                            \
   V(ARRAY_ENTRIES_ITERATOR_INDEX, JSFunction, array_entries_iterator)          \
   V(ARRAY_FOR_EACH_ITERATOR_INDEX, JSFunction, array_for_each_iterator)        \

src/flag-definitions.h

@@ -873,8 +873,6 @@ DEFINE_BOOL(expose_trigger_failure, false, "expose trigger-failure extension")
 DEFINE_INT(stack_trace_limit, 10, "number of stack frames to capture")
 DEFINE_BOOL(builtins_in_stack_traces, false,
             "show built-in functions in stack traces")
-DEFINE_BOOL(enable_experimental_builtins, false,
-            "enable new csa-based experimental builtins")
 DEFINE_BOOL(disallow_code_generation_from_strings, false,
             "disallow eval and friends")
 DEFINE_BOOL(expose_async_hooks, false, "expose async_hooks object")

src/js/array.js

@@ -200,35 +200,6 @@ function ConvertToString(use_locale, x, locales, options) {
   return TO_STRING(x);
 }
 
-
-// This function implements the optimized splice implementation that can use
-// special array operations to handle sparse arrays in a sensible fashion.
-function SparseSlice(array, start_i, del_count, len, deleted_elements) {
-  // Move deleted elements to a new array (the return value from splice).
-  var indices = %GetArrayKeys(array, start_i + del_count);
-  if (IS_NUMBER(indices)) {
-    var limit = indices;
-    for (var i = start_i; i < limit; ++i) {
-      var current = array[i];
-      if (!IS_UNDEFINED(current) || i in array) {
-        %CreateDataProperty(deleted_elements, i - start_i, current);
-      }
-    }
-  } else {
-    var length = indices.length;
-    for (var k = 0; k < length; ++k) {
-      var key = indices[k];
-      if (key >= start_i) {
-        var current = array[key];
-        if (!IS_UNDEFINED(current) || key in array) {
-          %CreateDataProperty(deleted_elements, key - start_i, current);
-        }
-      }
-    }
-  }
-}
-
-
 // This function implements the optimized splice implementation that can use
 // special array operations to handle sparse arrays in a sensible fashion.
 function SparseMove(array, start_i, del_count, len, num_additional_args) {
@@ -565,83 +536,6 @@ function ArraySliceFallback(start, end) {
   return null;
 }
 
-function ComputeSpliceStartIndex(start_i, len) {
-  if (start_i < 0) {
-    start_i += len;
-    return start_i < 0 ? 0 : start_i;
-  }
-
-  return start_i > len ? len : start_i;
-}
-
-
-function ComputeSpliceDeleteCount(delete_count, num_arguments, len, start_i) {
-  // SpiderMonkey, TraceMonkey and JSC treat the case where no delete count is
-  // given as a request to delete all the elements from the start.
-  // And it differs from the case of undefined delete count.
-  // This does not follow ECMA-262, but we do the same for
-  // compatibility.
-  var del_count = 0;
-  if (num_arguments == 1)
-    return len - start_i;
-
-  del_count = TO_INTEGER(delete_count);
-  if (del_count < 0)
-    return 0;
-
-  if (del_count > len - start_i)
-    return len - start_i;
-
-  return del_count;
-}
-
-
-function ArraySpliceFallback(start, delete_count) {
-  var num_arguments = arguments.length;
-  var array = TO_OBJECT(this);
-  var len = TO_LENGTH(array.length);
-  var start_i = ComputeSpliceStartIndex(TO_INTEGER(start), len);
-  var del_count = ComputeSpliceDeleteCount(delete_count, num_arguments, len,
-                                           start_i);
-  var num_elements_to_add = num_arguments > 2 ? num_arguments - 2 : 0;
-
-  const new_len = len - del_count + num_elements_to_add;
-  if (new_len >= 2**53) throw %make_type_error(kInvalidArrayLength);
-
-  var deleted_elements = ArraySpeciesCreate(array, del_count);
-  deleted_elements.length = del_count;
-
-  var changed_elements = del_count;
-  if (num_elements_to_add != del_count) {
-    // If the slice needs to do a actually move elements after the insertion
-    // point, then include those in the estimate of changed elements.
-    changed_elements += len - start_i - del_count;
-  }
-  if (UseSparseVariant(array, len, IS_ARRAY(array), changed_elements)) {
-    %NormalizeElements(array);
-    if (IS_ARRAY(deleted_elements)) %NormalizeElements(deleted_elements);
-    SparseSlice(array, start_i, del_count, len, deleted_elements);
-    SparseMove(array, start_i, del_count, len, num_elements_to_add);
-  } else {
-    SimpleSlice(array, start_i, del_count, len, deleted_elements);
-    SimpleMove(array, start_i, del_count, len, num_elements_to_add);
-  }
-
-  // Insert the arguments into the resulting array in
-  // place of the deleted elements.
-  var i = start_i;
-  var arguments_index = 2;
-  var arguments_length = arguments.length;
-  while (arguments_index < arguments_length) {
-    array[i++] = arguments[arguments_index++];
-  }
-  array.length = new_len;
-
-  // Return the deleted elements.
-  return deleted_elements;
-}
-
-
 function InnerArraySort(array, length, comparefn) {
   // In-place QuickSort algorithm.
   // For short (length <= 10) arrays, insertion sort is used for efficiency.
@@ -942,7 +836,6 @@ utils.Export(function(to) {
   "array_values_iterator", ArrayValues,
   // Fallback implementations of Array builtins.
   "array_shift", ArrayShiftFallback,
-  "array_splice", ArraySpliceFallback,
   "array_unshift", ArrayUnshiftFallback,
 ]);
 

src/runtime/runtime-array.cc

@@ -30,6 +30,16 @@ RUNTIME_FUNCTION(Runtime_TransitionElementsKind) {
   return *object;
 }
 
+RUNTIME_FUNCTION(Runtime_TransitionElementsKindWithKind) {
+  HandleScope scope(isolate);
+  DCHECK_EQ(2, args.length());
+  CONVERT_ARG_HANDLE_CHECKED(JSObject, object, 0);
+  CONVERT_ARG_HANDLE_CHECKED(Smi, elements_kind_smi, 1);
+  ElementsKind to_kind = static_cast<ElementsKind>(elements_kind_smi->value());
+  JSObject::TransitionElementsKind(object, to_kind);
+  return *object;
+}
+
 namespace {
 // Find the next free position. undefined and holes are both considered
 // free spots. Returns "Nothing" if an exception occurred.

src/runtime/runtime.h

@@ -36,21 +36,22 @@ namespace internal {
 // A variable number of arguments is specified by a -1, additional restrictions
 // are specified by inline comments
 
-#define FOR_EACH_INTRINSIC_ARRAY(F) \
-  F(ArrayIncludes_Slow, 3, 1)       \
-  F(ArrayIndexOf, 3, 1)             \
-  F(ArrayIsArray, 1, 1)             \
-  F(ArraySpeciesConstructor, 1, 1)  \
-  F(EstimateNumberOfElements, 1, 1) \
-  F(GetArrayKeys, 2, 1)             \
-  F(GrowArrayElements, 2, 1)        \
-  F(HasComplexElements, 1, 1)       \
-  F(IsArray, 1, 1)                  \
-  F(MoveArrayContents, 2, 1)        \
-  F(NewArray, -1 /* >= 3 */, 1)     \
-  F(NormalizeElements, 1, 1)        \
-  F(PrepareElementsForSort, 2, 1)   \
-  F(TransitionElementsKind, 2, 1)   \
+#define FOR_EACH_INTRINSIC_ARRAY(F)       \
+  F(ArrayIncludes_Slow, 3, 1)             \
+  F(ArrayIndexOf, 3, 1)                   \
+  F(ArrayIsArray, 1, 1)                   \
+  F(ArraySpeciesConstructor, 1, 1)        \
+  F(EstimateNumberOfElements, 1, 1)       \
+  F(GetArrayKeys, 2, 1)                   \
+  F(GrowArrayElements, 2, 1)              \
+  F(HasComplexElements, 1, 1)             \
+  F(IsArray, 1, 1)                        \
+  F(MoveArrayContents, 2, 1)              \
+  F(NewArray, -1 /* >= 3 */, 1)           \
+  F(NormalizeElements, 1, 1)              \
+  F(PrepareElementsForSort, 2, 1)         \
+  F(TransitionElementsKind, 2, 1)         \
+  F(TransitionElementsKindWithKind, 2, 1) \
   F(TrySliceSimpleNonFastElements, 3, 1)
 
 #define FOR_EACH_INTRINSIC_ATOMICS(F)  \

test/mjsunit/array-splice.js

@@ -445,3 +445,21 @@
                 "array.hasOwnProperty(Math.pow(2, 32) - 2)");
   }
 })();
+
+// Verify that fast implementations aren't confused by empty DOUBLE element arrays
+(function() {
+
+  function foo(dontAddAnything) {
+    let a = [];
+    if (dontAddAnything === undefined) {
+      a[1] = 0.5;
+    }
+    return a.splice(0, 0, 3.5);
+  }
+
+  // Learn via allocation site tracking to create double arrays in foo().
+  foo();
+  foo();
+  // force splice to copy the input array.
+  foo(true);
+})();

test/test262/test262.status

@@ -474,9 +474,6 @@
   # https://bugs.chromium.org/p/v8/issues/detail?id=7993
   'intl402/RelativeTimeFormat/prototype/toStringTag/toStringTag': [FAIL],
 
-  # https://bugs.chromium.org/p/v8/issues/detail?id=7814
-  'built-ins/Array/prototype/splice/property-traps-order-with-species': [FAIL],
-
   # https://bugs.chromium.org/p/v8/issues/detail?id=6705
   'built-ins/Object/assign/strings-and-symbol-order': [FAIL],
 
@@ -518,8 +515,6 @@
   # https://bugs.chromium.org/p/v8/issues/detail?id=6538
   'built-ins/Array/prototype/unshift/throws-if-integer-limit-exceeded': [SKIP],
   'built-ins/Array/prototype/reverse/length-exceeding-integer-limit-with-proxy': [FAIL],
-  'built-ins/Array/prototype/splice/create-species-length-exceeding-integer-limit': [FAIL],
-  'built-ins/Array/prototype/splice/throws-if-integer-limit-exceeded': [SKIP],
 
   # https://bugs.chromium.org/p/v8/issues/detail?id=6541
   'language/export/escaped-as-export-specifier': [FAIL],