[torque] Implement simple automatic index operators

In the process, cleanup the StoreFixedArray* operators
and change most FixedArray element accesses so that
they explicitly use the '.objects' and '.floats'
fields.

Bug: v8:7793
Change-Id: I3e45a9b7536ec76e1413b7e508d79a56b37604ff
Reviewed-on: https://chromium-review.googlesource.com/c/1460948
Commit-Queue: Daniel Clifford <danno@chromium.org>
Reviewed-by: Tobias Tebbi <tebbi@chromium.org>
Cr-Commit-Position: refs/heads/master@{#59649}

src/builtins/array-join.tq

@@ -36,7 +36,7 @@ namespace array_join {
       context: Context, receiver: JSReceiver, k: Number): Object {
     const array: JSArray = UnsafeCast<JSArray>(receiver);
     const fixedArray: FixedArray = UnsafeCast<FixedArray>(array.elements);
-    const element: Object = fixedArray[UnsafeCast<Smi>(k)];
+    const element: Object = fixedArray.objects[UnsafeCast<Smi>(k)];
     return element == Hole ? kEmptyString : element;
   }
 
@@ -134,7 +134,7 @@ namespace array_join {
     const length: intptr = fixedArray.length_intptr;
     assert(index <= length);
     if (index < length) {
-      fixedArray[index] = element;
+      fixedArray.objects[index] = element;
       return fixedArray;
     } else
       deferred {
@@ -142,7 +142,7 @@ namespace array_join {
         assert(index < newLength);
         const newfixedArray: FixedArray =
             ExtractFixedArray(fixedArray, 0, length, newLength, kFixedArrays);
-        newfixedArray[index] = element;
+        newfixedArray.objects[index] = element;
         return newfixedArray;
       }
   }
@@ -231,7 +231,7 @@ namespace array_join {
     // Fast path when there's only one buffer element.
     if (buffer.index == 1) {
       const fixedArray: FixedArray = buffer.fixedArray;
-      typeswitch (fixedArray[0]) {
+      typeswitch (fixedArray.objects[0]) {
         // When the element is a string, just return it and completely avoid
         // allocating another string.
         case (str: String): {
@@ -442,11 +442,11 @@ namespace array_join {
       stack: FixedArray, receiver: JSReceiver): Boolean {
     const capacity: intptr = stack.length_intptr;
     for (let i: intptr = 0; i < capacity; i++) {
-      const previouslyVisited: Object = stack[i];
+      const previouslyVisited: Object = stack.objects[i];
 
       // Add `receiver` to the first open slot
       if (previouslyVisited == Hole) {
-        stack[i] = receiver;
+        stack.objects[i] = receiver;
         return True;
       }
 
@@ -470,8 +470,8 @@ namespace array_join {
     try {
       const stack: FixedArray = LoadJoinStack()
           otherwise IfUninitialized;
-      if (stack[0] == Hole) {
-        stack[0] = receiver;
+      if (stack.objects[0] == Hole) {
+        stack.objects[0] = receiver;
       } else if (JoinStackPush(stack, receiver) == False)
         deferred {
           goto ReceiverNotAdded;
@@ -480,7 +480,7 @@ namespace array_join {
     label IfUninitialized {
       const stack: FixedArray =
           AllocateFixedArrayWithHoles(kMinJoinStackSize, kNone);
-      stack[0] = receiver;
+      stack.objects[0] = receiver;
       SetJoinStack(stack);
     }
     goto ReceiverAdded;
@@ -492,7 +492,7 @@ namespace array_join {
       stack: FixedArray, receiver: JSReceiver): Object {
     const len: intptr = stack.length_intptr;
     for (let i: intptr = 0; i < len; i++) {
-      if (stack[i] == receiver) {
+      if (stack.objects[i] == receiver) {
         // Shrink the Join Stack if the stack will be empty and is larger than
         // the minimum size.
         if (i == 0 && len > kMinJoinStackSize) deferred {
@@ -501,7 +501,7 @@ namespace array_join {
             SetJoinStack(newStack);
           }
         else {
-          stack[i] = Hole;
+          stack.objects[i] = Hole;
         }
         return Undefined;
       }
@@ -517,7 +517,7 @@ namespace array_join {
 
     // Builtin call was not nested (receiver is the first entry) and
     // did not contain other nested arrays that expanded the stack.
-    if (stack[0] == receiver && len == kMinJoinStackSize) {
+    if (stack.objects[0] == receiver && len == kMinJoinStackSize) {
       StoreFixedArrayElement(stack, 0, Hole, SKIP_WRITE_BARRIER);
     } else
       deferred {

src/builtins/array-lastindexof.tq

@@ -11,7 +11,7 @@ namespace array_lastindexof {
       elements: FixedArrayBase, index: Smi): Object
       labels IfHole {
     const elements: FixedArray = UnsafeCast<FixedArray>(elements);
-    const element: Object = elements[index];
+    const element: Object = elements.objects[index];
     if (element == Hole) goto IfHole;
     return element;
   }

src/builtins/array-map.tq

@@ -136,9 +136,9 @@ namespace array_map {
             SmiUntag(length), kAllowLargeObjectAllocation);
         a = new JSArray{map, this.fixedArray};
         for (let i: Smi = 0; i < validLength; i++) {
-          typeswitch (this.fixedArray[i]) {
+          typeswitch (this.fixedArray.objects[i]) {
             case (n: Number): {
-              elements[i] = Float64SilenceNaN(Convert<float64>(n));
+              elements.floats[i] = Float64SilenceNaN(Convert<float64>(n));
             }
             case (h: HeapObject): {
               assert(h == Hole);
@@ -159,16 +159,16 @@ namespace array_map {
     StoreResult(implicit context: Context)(index: Smi, result: Object) {
       typeswitch (result) {
         case (s: Smi): {
-          this.fixedArray[index] = s;
+          this.fixedArray.objects[index] = s;
         }
         case (s: HeapNumber): {
           this.onlySmis = false;
-          this.fixedArray[index] = s;
+          this.fixedArray.objects[index] = s;
         }
         case (s: HeapObject): {
           this.onlySmis = false;
           this.onlyNumbers = false;
-          this.fixedArray[index] = s;
+          this.fixedArray.objects[index] = s;
         }
       }
     }

src/builtins/array-reverse.tq

@@ -8,23 +8,24 @@ namespace array_reverse {
 
   LoadElement<array::FastPackedSmiElements, Smi>(implicit context: Context)(
       elements: FixedArrayBase, index: Smi): Smi {
-    const elems: FixedArray = UnsafeCast<FixedArray>(elements);
-    return UnsafeCast<Smi>(elems[index]);
+    const elements: FixedArray = UnsafeCast<FixedArray>(elements);
+    return UnsafeCast<Smi>(elements.objects[index]);
   }
 
   LoadElement<array::FastPackedObjectElements, Object>(
       implicit context: Context)(elements: FixedArrayBase, index: Smi): Object {
-    const elems: FixedArray = UnsafeCast<FixedArray>(elements);
-    return elems[index];
+    const elements: FixedArray = UnsafeCast<FixedArray>(elements);
+    return elements.objects[index];
   }
 
   LoadElement<array::FastPackedDoubleElements, float64>(
       implicit context: Context)(elements: FixedArrayBase, index: Smi):
       float64 {
-    const elems: FixedDoubleArray = UnsafeCast<FixedDoubleArray>(elements);
+    const elements: FixedDoubleArray = UnsafeCast<FixedDoubleArray>(elements);
     // This macro is only used for PACKED_DOUBLE, loading the hole should
     // be impossible.
-    return LoadDoubleWithHoleCheck(elems, index) otherwise unreachable;
+    return LoadDoubleWithHoleCheck(elements, index)
+        otherwise unreachable;
   }
 
   macro StoreElement<ElementsAccessor: type, T: type>(
@@ -40,15 +41,15 @@ namespace array_reverse {
   StoreElement<array::FastPackedObjectElements, Object>(
       implicit context:
           Context)(elements: FixedArrayBase, index: Smi, value: Object) {
-    const elems: FixedArray = UnsafeCast<FixedArray>(elements);
-    elems[index] = value;
+    const elements: FixedArray = UnsafeCast<FixedArray>(elements);
+    elements.objects[index] = value;
   }
 
   StoreElement<array::FastPackedDoubleElements, float64>(
       implicit context:
           Context)(elements: FixedArrayBase, index: Smi, value: float64) {
     const elems: FixedDoubleArray = UnsafeCast<FixedDoubleArray>(elements);
-    StoreFixedDoubleArrayElementWithSmiIndex(elems, index, value);
+    StoreFixedDoubleArrayElementSmi(elems, index, value);
   }
 
   // Fast-path for all PACKED_* elements kinds. These do not need to check

src/builtins/array-slice.tq

@@ -43,13 +43,13 @@ namespace array_slice {
     // defined arguments
     const end: Smi = start + count;
     const unmappedElements: FixedArray =
-        Cast<FixedArray>(sloppyElements[kSloppyArgumentsArgumentsIndex])
+        Cast<FixedArray>(sloppyElements.objects[kSloppyArgumentsArgumentsIndex])
         otherwise Bailout;
     const unmappedElementsLength: Smi = unmappedElements.length;
     if (SmiAbove(end, unmappedElementsLength)) goto Bailout;
 
-    const argumentsContext: Context =
-        UnsafeCast<Context>(sloppyElements[kSloppyArgumentsContextIndex]);
+    const argumentsContext: Context = UnsafeCast<Context>(
+        sloppyElements.objects[kSloppyArgumentsContextIndex]);
 
     const arrayMap: Map = LoadJSArrayElementsMap(HOLEY_ELEMENTS, context);
     const result: JSArray =
@@ -62,10 +62,10 @@ namespace array_slice {
     // Fill in the part of the result that map to context-mapped parameters.
     for (let current: Smi = start; current < to; ++current) {
       const e: Object =
-          sloppyElements[current + kSloppyArgumentsParameterMapStart];
+          sloppyElements.objects[current + kSloppyArgumentsParameterMapStart];
       const newElement: Object = e != Hole ?
           argumentsContext[UnsafeCast<Smi>(e)] :
-          unmappedElements[current];
+          unmappedElements.objects[current];
       StoreFixedArrayElementSmi(
           resultElements, indexOut++, newElement, SKIP_WRITE_BARRIER);
     }

src/builtins/array.tq

@@ -43,19 +43,10 @@ namespace array {
   }
 
   macro LoadElementOrUndefined(a: FixedArray, i: Smi): Object {
-    const e: Object = a[i];
+    const e: Object = a.objects[i];
     return e == Hole ? Undefined : e;
   }
 
-  macro LoadElementOrUndefined(a: FixedArray, i: intptr): Object {
-    const e: Object = a[i];
-    return e == Hole ? Undefined : e;
-  }
-
-  macro LoadElementOrUndefined(a: FixedArray, i: constexpr int31): Object {
-    return LoadElementOrUndefined(a, Convert<intptr>(i));
-  }
-
   macro LoadElementOrUndefined(a: FixedDoubleArray, i: Smi): NumberOrUndefined {
     try {
       const f: float64 = LoadDoubleWithHoleCheck(a, i) otherwise IfHole;
@@ -66,34 +57,18 @@ namespace array {
     }
   }
 
-  macro LoadElementOrUndefined(a: FixedDoubleArray, i: intptr):
-      NumberOrUndefined {
-    try {
-      const f: float64 = LoadDoubleWithHoleCheck(a, i) otherwise IfHole;
-      return AllocateHeapNumberWithValue(f);
-    }
-    label IfHole {
-      return Undefined;
-    }
-  }
-
-  macro LoadElementOrUndefined(a: FixedDoubleArray, i: constexpr int31):
-      NumberOrUndefined {
-    return LoadElementOrUndefined(a, Convert<intptr>(i));
-  }
-
   macro StoreArrayHole(elements: FixedDoubleArray, k: Smi): void {
     StoreFixedDoubleArrayHoleSmi(elements, k);
   }
 
   macro StoreArrayHole(elements: FixedArray, k: Smi): void {
-    elements[k] = Hole;
+    elements.objects[k] = Hole;
   }
 
   macro CopyArrayElement(
       elements: FixedArray, newElements: FixedArray, from: Smi, to: Smi): void {
-    const e: Object = elements[from];
-    newElements[to] = e;
+    const e: Object = elements.objects[from];
+    newElements.objects[to] = e;
   }
 
   macro CopyArrayElement(
@@ -102,7 +77,7 @@ namespace array {
     try {
       const floatValue: float64 = LoadDoubleWithHoleCheck(elements, from)
           otherwise FoundHole;
-      newElements[to] = floatValue;
+      newElements.floats[to] = floatValue;
     }
     label FoundHole {
       StoreArrayHole(newElements, to);

src/builtins/base.tq

@@ -67,10 +67,13 @@ type RootIndex generates 'TNode<Int32T>' constexpr 'RootIndex';
 
 type Map extends HeapObject generates 'TNode<Map>';
 
-type FixedArrayBase extends HeapObject generates 'TNode<FixedArrayBase>';
-type FixedArray extends FixedArrayBase generates 'TNode<FixedArray>';
-type FixedDoubleArray extends FixedArrayBase
-    generates 'TNode<FixedDoubleArray>';
+extern class FixedArrayBase extends HeapObject { length: Smi; }
+
+extern class FixedArray extends FixedArrayBase { objects[length]: Object; }
+
+extern class FixedDoubleArray extends FixedArrayBase {
+  floats[length]: float64;
+}
 
 // These intrinsics should never be called from Torque code. They're used
 // internally by the 'new' operator and only declared here because it's simpler
@@ -176,8 +179,8 @@ type FixedTypedArrayBase extends FixedArrayBase
     generates 'TNode<FixedTypedArrayBase>';
 type FixedTypedArray extends FixedTypedArrayBase
     generates 'TNode<FixedTypedArray>';
-type SloppyArgumentsElements extends FixedArray
-    generates 'TNode<FixedArray>';
+extern class SloppyArgumentsElements extends FixedArray
+    generates 'TNode<FixedArray>' {}
 type NumberDictionary extends HeapObject
     generates 'TNode<NumberDictionary>';
 
@@ -1241,46 +1244,50 @@ extern operator '.elements_kind' macro LoadElementsKind(JSTypedArray):
 extern operator '.length' macro LoadJSTypedArrayLength(JSTypedArray): Smi;
 extern operator '.length' macro LoadFastJSArrayLength(FastJSArray): Smi;
 
-extern operator '.length' macro LoadFixedArrayBaseLength(FixedArrayBase): Smi;
 extern operator '.length_intptr' macro LoadAndUntagFixedArrayBaseLength(
     FixedArrayBase): intptr;
-extern operator '[]' macro LoadFixedArrayElement(FixedArray, intptr): Object;
-extern operator '[]' macro LoadFixedArrayElement(FixedArray, Smi): Object;
-extern operator '[]' macro LoadFixedArrayElement(
+extern operator '.objects[]' macro LoadFixedArrayElement(
+    FixedArray, intptr): Object;
+extern operator '.objects[]' macro LoadFixedArrayElement(
+    FixedArray, Smi): Object;
+extern operator '.objects[]' macro LoadFixedArrayElement(
     FixedArray, constexpr int31): Object;
-extern operator '[]=' macro StoreFixedArrayElement(
+extern operator '.objects[]=' macro StoreFixedArrayElement(
     FixedArray, intptr, Smi): void;
-extern operator '[]=' macro StoreFixedArrayElement(FixedArray, Smi, Smi): void;
-extern operator '[]=' macro StoreFixedArrayElement(
+extern operator '.objects[]=' macro StoreFixedArrayElement(
+    FixedArray, Smi, Smi): void;
+extern operator '.objects[]=' macro StoreFixedArrayElement(
     FixedArray, intptr, HeapObject): void;
-extern operator '[]=' macro StoreFixedArrayElement(
+extern operator '.objects[]=' macro StoreFixedArrayElement(
     FixedArray, constexpr int31, Smi): void;
-extern operator '[]=' macro StoreFixedArrayElement(
+extern operator '.objects[]=' macro StoreFixedArrayElement(
     FixedArray, constexpr int31, HeapObject): void;
-extern operator '[]=' macro StoreFixedArrayElementSmi(
+extern operator '.objects[]=' macro StoreFixedArrayElementSmi(
     FixedArray, Smi, Object): void;
-operator '[]=' macro StoreFixedDoubleArrayNumber(
-    a: FixedDoubleArray, index: Smi, value: Number): void {
-  a[index] = Convert<float64>(value);
-}
-
-extern macro StoreFixedArrayElementSmi(
+extern operator '.objects[]=' macro StoreFixedArrayElementSmi(
     FixedArray, Smi, Object, constexpr WriteBarrierMode): void;
+extern macro StoreFixedArrayElement(
+    FixedArray, intptr, Object, constexpr WriteBarrierMode): void;
+extern operator '.floats[]=' macro StoreFixedDoubleArrayElement(
+    FixedDoubleArray, intptr, float64): void;
+extern operator '.floats[]=' macro StoreFixedDoubleArrayElementSmi(
+    FixedDoubleArray, Smi, float64): void;
+operator '.floats[]=' macro StoreFixedDoubleArrayElementSmi(
+    a: FixedDoubleArray, i: Smi, n: Number): void {
+  StoreFixedDoubleArrayElementSmi(a, i, Convert<float64>(n));
+}
+operator '[]=' macro StoreFixedDoubleArrayDirect(
+    a: FixedDoubleArray, i: Smi, v: Number) {
+  a.floats[i] = Convert<float64>(v);
+}
+operator '[]=' macro StoreFixedArrayDirect(a: FixedArray, i: Smi, v: Object) {
+  a.objects[i] = v;
+}
 
 extern operator '.instance_type' macro LoadMapInstanceType(Map): int32;
 
-extern macro LoadFixedDoubleArrayElement(FixedDoubleArray, Smi): float64;
 extern macro Float64SilenceNaN(float64): float64;
 
-extern macro StoreFixedDoubleArrayElement(
-    FixedDoubleArray, Object, float64, constexpr ParameterMode);
-extern macro StoreFixedArrayElement(
-    FixedArray, intptr, Object, constexpr WriteBarrierMode): void;
-
-macro StoreFixedDoubleArrayElementWithSmiIndex(
-    array: FixedDoubleArray, index: Smi, value: float64) {
-  StoreFixedDoubleArrayElement(array, index, value, SMI_PARAMETERS);
-}
 extern macro GetNumberDictionaryNumberOfElements(NumberDictionary): Smi;
 extern macro GetIteratorMethod(implicit context: Context)(HeapObject): Object
     labels IfIteratorUndefined;
@@ -1348,9 +1355,6 @@ extern macro AllocateJSArray(constexpr ElementsKind, Map, intptr, Smi): JSArray;
 extern macro AllocateJSArray(constexpr ElementsKind, Map, Smi, Smi): JSArray;
 extern macro AllocateJSObjectFromMap(Map): JSObject;
 
-extern operator '[]=' macro StoreFixedDoubleArrayElementSmi(
-    FixedDoubleArray, Smi, float64): void;
-
 extern macro LoadDoubleWithHoleCheck(FixedDoubleArray, Smi): float64
     labels IfHole;
 extern macro LoadDoubleWithHoleCheck(FixedDoubleArray, intptr): float64
@@ -1437,7 +1441,7 @@ LoadElementNoHole<FixedArray>(implicit context: Context)(
   try {
     let elements: FixedArray =
         Cast<FixedArray>(a.elements) otherwise Unexpected;
-    let e: Object = elements[index];
+    let e: Object = elements.objects[index];
     if (e == Hole) {
       goto IfHole;
     }

src/builtins/typed-array.tq

@@ -126,23 +126,23 @@ namespace typed_array {
       if (left < middle && right >= to) {
         // If the left run has elements, but the right does not, we take
         // from the left.
-        target[targetIndex] = source[left++];
+        target.objects[targetIndex] = source.objects[left++];
       } else if (left < middle) {
         // If both have elements, we need to compare.
-        const leftElement: Object = source[left];
-        const rightElement: Object = source[right];
+        const leftElement: Object = source.objects[left];
+        const rightElement: Object = source.objects[right];
         if (CallCompare(leftElement, rightElement) <= 0) {
-          target[targetIndex] = leftElement;
+          target.objects[targetIndex] = leftElement;
           left++;
         } else {
-          target[targetIndex] = rightElement;
+          target.objects[targetIndex] = rightElement;
           right++;
         }
       } else {
         // No elements on the left, but the right does, so we take
         // from the right.
         assert(left == middle);
-        target[targetIndex] = source[right++];
+        target.objects[targetIndex] = source.objects[right++];
       }
     }
   }
@@ -253,14 +253,15 @@ namespace typed_array {
 
     for (let i: Smi = 0; i < len; ++i) {
       const element: Object = loadfn(context, array, i);
-      work1[i] = element;
-      work2[i] = element;
+      work1.objects[i] = element;
+      work2.objects[i] = element;
     }
 
     TypedArrayMergeSort(work2, 0, len, work1);
 
     // work1 contains the sorted numbers. Write them back.
-    for (let i: Smi = 0; i < len; ++i) storefn(context, array, i, work1[i]);
+    for (let i: Smi = 0; i < len; ++i)
+      storefn(context, array, i, work1.objects[i]);
 
     return array;
   }

src/objects/fixed-array.h

@@ -9,6 +9,7 @@
 #include "src/objects/instance-type.h"
 #include "src/objects/slots.h"
 #include "src/objects/smi.h"
+#include "torque-generated/class-definitions-from-dsl.h"
 
 // Has to be the last include (doesn't have include guards):
 #include "src/objects/object-macros.h"
@@ -97,14 +98,10 @@ class FixedArrayBase : public HeapObject {
 #endif  // V8_HOST_ARCH_32_BIT
 
   // Layout description.
-#define FIXED_ARRAY_BASE_FIELDS(V) \
-  V(kLengthOffset, kTaggedSize)    \
-  /* Header size. */               \
-  V(kHeaderSize, 0)
-
   DEFINE_FIELD_OFFSET_CONSTANTS(HeapObject::kHeaderSize,
                                 FIXED_ARRAY_BASE_FIELDS)
-#undef FIXED_ARRAY_BASE_FIELDS
+
+  static const int kHeaderSize = kSize;
 
  protected:
   // Special-purpose constructor for subclasses that have fast paths where

src/torque/ast.h

@@ -694,6 +694,7 @@ struct StructFieldExpression {
 
 struct ClassFieldExpression {
   NameAndTypeExpression name_and_type;
+  base::Optional<std::string> index;
   bool weak;
 };
 

src/torque/declaration-visitor.cc

@@ -287,6 +287,11 @@ void DeclarationVisitor::DeclareMethods(
 
   if (constructor_this_type->Constructors().size() != 0) return;
 
+  // TODO(danno): Currently, default constructors for classes with
+  // open-ended arrays at the end are not supported. For now, if one is
+  // encountered, don't actually create the constructor.
+  if (container_type->HasIndexedField()) return;
+
   // Generate default constructor.
   Signature constructor_signature;
   constructor_signature.parameter_types.var_args = false;
@@ -302,6 +307,7 @@ void DeclarationVisitor::DeclareMethods(
   std::vector<Expression*> super_arguments;
   for (auto current_type : hierarchy) {
     for (auto& f : current_type->fields()) {
+      DCHECK(!f.index);
       std::string parameter_name("p" + std::to_string(parameter_number++));
       constructor_signature.parameter_names.push_back(parameter_name);
       constructor_signature.parameter_types.types.push_back(
@@ -368,6 +374,7 @@ void DeclarationVisitor::Visit(ClassDeclaration* decl) {
     // The generates clause must create a TNode<>
     std::string generates = decl->name;
     if (decl->generates) {
+      generates = *decl->generates;
       if (generates.length() < 7 || generates.substr(0, 6) != "TNode<" ||
           generates.substr(generates.length() - 1, 1) != ">") {
         ReportError("generated type \"", generates,
@@ -533,6 +540,7 @@ void DeclarationVisitor::FinalizeStructFieldsAndMethods(
     const Type* field_type = Declarations::GetType(field.name_and_type.type);
     struct_type->RegisterField({field.name_and_type.type->pos,
                                 struct_type,
+                                base::nullopt,
                                 {field.name_and_type.name, field_type},
                                 offset,
                                 false});
@@ -546,6 +554,7 @@ void DeclarationVisitor::FinalizeClassFieldsAndMethods(
     ClassType* class_type, ClassDeclaration* class_declaration) {
   const ClassType* super_class = class_type->GetSuperClass();
   size_t class_offset = super_class ? super_class->size() : 0;
+  bool seen_indexed_field = false;
   for (ClassFieldExpression& field_expression : class_declaration->fields) {
     CurrentSourcePosition::Scope position_activator(
         field_expression.name_and_type.type->pos);
@@ -553,15 +562,39 @@ void DeclarationVisitor::FinalizeClassFieldsAndMethods(
         Declarations::GetType(field_expression.name_and_type.type);
     if (!class_declaration->is_extern) {
       if (!field_type->IsSubtypeOf(TypeOracle::GetTaggedType())) {
-        ReportError("Non-extern classes do not support untagged fields.");
+        ReportError("non-extern classes do not support untagged fields");
       }
       if (field_expression.weak) {
-        ReportError("Non-extern classes do not support weak fields.");
+        ReportError("non-extern classes do not support weak fields");
+      }
     }
+    if (field_expression.index) {
+      if (seen_indexed_field ||
+          (super_class && super_class->HasIndexedField())) {
+        ReportError(
+            "only one indexable field is currently supported per class");
+      }
+      seen_indexed_field = true;
+      const Field* index_field =
+          &(class_type->LookupField(*field_expression.index));
+      class_type->RegisterField(
+          {field_expression.name_and_type.type->pos,
+           class_type,
+           index_field,
+           {field_expression.name_and_type.name, field_type},
+           class_offset,
+           field_expression.weak});
+    } else {
+      if (seen_indexed_field) {
+        ReportError("cannot declare non-indexable field \"",
+                    field_expression.name_and_type.name,
+                    "\" after an indexable field "
+                    "declaration");
       }
       const Field& field = class_type->RegisterField(
           {field_expression.name_and_type.type->pos,
            class_type,
+           base::nullopt,
            {field_expression.name_and_type.name, field_type},
            class_offset,
            field_expression.weak});
@@ -578,6 +611,7 @@ void DeclarationVisitor::FinalizeClassFieldsAndMethods(
       }
       class_offset += field_size;
     }
+  }
   class_type->SetSize(class_offset);
 
   StructType* this_struct_type = Declarations::DeclareStruct(
@@ -595,15 +629,18 @@ void DeclarationVisitor::FinalizeClassFieldsAndMethods(
     this_struct_type->RegisterField(
         {CurrentSourcePosition::Get(),
          super_struct_type,
+         base::nullopt,
          {kConstructorStructSuperFieldName, super_struct_type},
          struct_offset,
          false});
     struct_offset += LoweredSlotCount(super_struct_type);
   }
   for (auto& field : class_type->fields()) {
+    if (field.index) continue;
     const Type* field_type = field.name_and_type.type;
     this_struct_type->RegisterField({field.pos,
                                      class_type,
+                                     base::nullopt,
                                      {field.name_and_type.name, field_type},
                                      struct_offset,
                                      false});
@@ -616,6 +653,7 @@ void DeclarationVisitor::FinalizeClassFieldsAndMethods(
   // function and define a corresponding '.field' operator. The
   // implementation iterator will turn the snippits into code.
   for (auto& field : class_type->fields()) {
+    if (field.index) continue;
     CurrentSourcePosition::Scope position_activator(field.pos);
     IdentifierExpression* parameter =
         MakeNode<IdentifierExpression>(std::string{"o"});

src/torque/implementation-visitor.cc

@@ -1729,15 +1729,30 @@ LocationReference ImplementationVisitor::GetLocationReference(
         ProjectStructField(reference.temporary(), expr->field),
         reference.temporary_description());
   }
-  return LocationReference::FieldAccess(GenerateFetchFromLocation(reference),
+  VisitResult object_result = GenerateFetchFromLocation(reference);
+  if (const ClassType* class_type =
+          ClassType::DynamicCast(object_result.type())) {
+    if (class_type->HasField(expr->field)) {
+      const Field& field = (class_type->LookupField(expr->field));
+      if (field.index) {
+        return LocationReference::IndexedFieldAccess(object_result,
                                                      expr->field);
+      }
+    }
+  }
+  return LocationReference::FieldAccess(object_result, expr->field);
 }
 
 LocationReference ImplementationVisitor::GetLocationReference(
     ElementAccessExpression* expr) {
-  VisitResult array = Visit(expr->array);
+  LocationReference reference = GetLocationReference(expr->array);
   VisitResult index = Visit(expr->index);
-  return LocationReference::ArrayAccess(array, index);
+  if (reference.IsIndexedFieldAccess()) {
+    return LocationReference::IndexedFieldIndexedAccess(reference, index);
+  } else {
+    return LocationReference::ArrayAccess(GenerateFetchFromLocation(reference),
+                                          index);
+  }
 }
 
 LocationReference ImplementationVisitor::GetLocationReference(
@@ -1806,6 +1821,10 @@ VisitResult ImplementationVisitor::GenerateFetchFromLocation(
   } else if (reference.IsVariableAccess()) {
     return GenerateCopy(reference.variable());
   } else {
+    if (reference.IsIndexedFieldAccess()) {
+      ReportError(
+          "fetching a value directly from an indexed field isn't allowed");
+    }
     DCHECK(reference.IsCallAccess());
     return GenerateCall(reference.eval_function(),
                         Arguments{reference.call_arguments(), {}});
@@ -1824,6 +1843,8 @@ void ImplementationVisitor::GenerateAssignToLocation(
         GenerateImplicitConvert(variable.type(), assignment_value);
     assembler().Poke(variable.stack_range(), converted_value.stack_range(),
                      variable.type());
+  } else if (reference.IsIndexedFieldAccess()) {
+    ReportError("assigning a value directly to an indexed field isn't allowed");
   } else {
     DCHECK(reference.IsTemporary());
     ReportError("cannot assign to temporary ",

src/torque/implementation-visitor.h

@@ -54,6 +54,26 @@ class LocationReference {
     result.eval_function_ = "." + fieldname;
     result.assign_function_ = "." + fieldname + "=";
     result.call_arguments_ = {object};
+    result.index_field_ = base::nullopt;
+    return result;
+  }
+  static LocationReference IndexedFieldIndexedAccess(
+      const LocationReference& indexed_field, VisitResult index) {
+    LocationReference result;
+    DCHECK(indexed_field.IsIndexedFieldAccess());
+    std::string fieldname = *indexed_field.index_field_;
+    result.eval_function_ = "." + fieldname + "[]";
+    result.assign_function_ = "." + fieldname + "[]=";
+    result.call_arguments_ = indexed_field.call_arguments_;
+    result.call_arguments_.push_back(index);
+    result.index_field_ = fieldname;
+    return result;
+  }
+  static LocationReference IndexedFieldAccess(VisitResult object,
+                                              std::string fieldname) {
+    LocationReference result;
+    result.call_arguments_ = {object};
+    result.index_field_ = fieldname;
     return result;
   }
 
@@ -82,6 +102,13 @@ class LocationReference {
     return *temporary_description_;
   }
 
+  bool IsArrayField() const { return index_field_.has_value(); }
+  bool IsIndexedFieldAccess() const {
+    return IsArrayField() && !IsCallAccess();
+  }
+  bool IsIndexedFieldIndexedAccess() const {
+    return IsArrayField() && IsCallAccess();
+  }
   bool IsCallAccess() const {
     bool is_call_access = eval_function_.has_value();
     DCHECK_EQ(is_call_access, assign_function_.has_value());
@@ -107,6 +134,7 @@ class LocationReference {
   base::Optional<std::string> eval_function_;
   base::Optional<std::string> assign_function_;
   VisitResultVector call_arguments_;
+  base::Optional<std::string> index_field_;
 
   LocationReference() = default;
 };
@@ -252,8 +280,8 @@ class ImplementationVisitor : public FileVisitor {
   VisitResult Visit(CallExpression* expr, bool is_tail = false);
   VisitResult Visit(CallMethodExpression* expr);
   VisitResult Visit(IntrinsicCallExpression* intrinsic);
-  VisitResult Visit(LoadObjectFieldExpression* intrinsic);
-  VisitResult Visit(StoreObjectFieldExpression* intrinsic);
+  VisitResult Visit(LoadObjectFieldExpression* expr);
+  VisitResult Visit(StoreObjectFieldExpression* expr);
   const Type* Visit(TailCallStatement* stmt);
 
   VisitResult Visit(ConditionalExpression* expr);

src/torque/torque-parser.cc

@@ -1134,8 +1134,10 @@ base::Optional<ParseResult> MakeNameAndType(
 base::Optional<ParseResult> MakeClassField(ParseResultIterator* child_results) {
   auto weak = child_results->NextAs<bool>();
   auto name = child_results->NextAs<std::string>();
+  auto index = child_results->NextAs<base::Optional<std::string>>();
   auto type = child_results->NextAs<TypeExpression*>();
-  return ParseResult{ClassFieldExpression{{std::move(name), type}, weak}};
+  return ParseResult{
+      ClassFieldExpression{{std::move(name), type}, index, weak}};
 }
 
 base::Optional<ParseResult> MakeStructField(
@@ -1331,8 +1333,12 @@ struct TorqueGrammar : Grammar {
   Symbol nameAndType = {
       Rule({&identifier, Token(":"), &type}, MakeNameAndType)};
 
+  Symbol* optionalArraySpecifier = {
+      Optional<std::string>(Sequence({Token("["), &identifier, Token("]")}))};
+
   Symbol classField = {
-      Rule({CheckIf(Token("weak")), &identifier, Token(":"), &type, Token(";")},
+      Rule({CheckIf(Token("weak")), &identifier, optionalArraySpecifier,
+            Token(":"), &type, Token(";")},
            MakeClassField)};
 
   Symbol structField = {

src/torque/type-oracle.h

@@ -172,6 +172,10 @@ class TypeOracle : public ContextualClass<TypeOracle> {
     return Get().GetBuiltinType(UINT8_TYPE_STRING);
   }
 
+  static const Type* GetFloat64Type() {
+    return Get().GetBuiltinType(FLOAT64_TYPE_STRING);
+  }
+
   static const Type* GetNeverType() {
     return Get().GetBuiltinType(NEVER_TYPE_STRING);
   }

src/torque/types.cc

@@ -226,6 +226,18 @@ std::vector<const AggregateType*> AggregateType::GetHierarchy() {
   return hierarchy;
 }
 
+bool AggregateType::HasField(const std::string& name) const {
+  for (auto& field : fields_) {
+    if (field.name_and_type.name == name) return true;
+  }
+  if (parent() != nullptr) {
+    if (auto parent_class = ClassType::DynamicCast(parent())) {
+      return parent_class->HasField(name);
+    }
+  }
+  return false;
+}
+
 const Field& AggregateType::LookupField(const std::string& name) const {
   for (auto& field : fields_) {
     if (field.name_and_type.name == name) return field;
@@ -235,7 +247,7 @@ const Field& AggregateType::LookupField(const std::string& name) const {
       return parent_class->LookupField(name);
     }
   }
-  ReportError("no field ", name, "found");
+  ReportError("no field ", name, " found");
 }
 
 std::string StructType::GetGeneratedTypeName() const {
@@ -261,6 +273,33 @@ std::string StructType::ToExplicitString() const {
   return result.str();
 }
 
+ClassType::ClassType(const Type* parent, Namespace* nspace,
+                     const std::string& name, bool is_extern, bool transient,
+                     const std::string& generates)
+    : AggregateType(Kind::kClassType, parent, nspace, name),
+      this_struct_(nullptr),
+      is_extern_(is_extern),
+      transient_(transient),
+      size_(0),
+      has_indexed_field_(false),
+      generates_(generates) {
+  CheckForDuplicateFields();
+  if (parent) {
+    if (const ClassType* super_class = ClassType::DynamicCast(parent)) {
+      if (super_class->HasIndexedField()) {
+        has_indexed_field_ = true;
+      }
+    }
+  }
+}
+
+bool ClassType::HasIndexedField() const {
+  if (has_indexed_field_) return true;
+  const ClassType* super_class = GetSuperClass();
+  if (super_class) return super_class->HasIndexedField();
+  return false;
+}
+
 std::string ClassType::GetGeneratedTNodeTypeName() const {
   if (!IsExtern()) return generates_;
   std::string prefix = nspace()->IsDefaultNamespace()
@@ -525,6 +564,10 @@ std::tuple<size_t, std::string, std::string> Field::GetFieldSizeInformation()
     field_size = kUInt8Size;
     size_string = "kUInt8Size";
     machine_type = "MachineType::Uint8()";
+  } else if (field_type == TypeOracle::GetFloat64Type()) {
+    field_size = kDoubleSize;
+    size_string = "kDoubleSize";
+    machine_type = "MachineType::Float64()";
   } else if (field_type == TypeOracle::GetIntPtrType()) {
     field_size = kIntptrSize;
     size_string = "kIntptrSize";

src/torque/types.h

@@ -45,6 +45,7 @@ static const char* const INT16_TYPE_STRING = "int16";
 static const char* const UINT16_TYPE_STRING = "uint16";
 static const char* const INT8_TYPE_STRING = "int8";
 static const char* const UINT8_TYPE_STRING = "uint8";
+static const char* const FLOAT64_TYPE_STRING = "float64";
 static const char* const CONST_INT31_TYPE_STRING = "constexpr int31";
 static const char* const CONST_INT32_TYPE_STRING = "constexpr int32";
 static const char* const CONST_FLOAT64_TYPE_STRING = "constexpr float64";
@@ -168,6 +169,7 @@ struct Field {
 
   SourcePosition pos;
   const AggregateType* aggregate;
+  base::Optional<const Field*> index;
   NameAndType name_and_type;
   size_t offset;
   bool is_weak;
@@ -404,9 +406,11 @@ class AggregateType : public Type {
   const Type* NonConstexprVersion() const override { return this; }
 
   bool IsConstexpr() const override { return false; }
+  virtual bool HasIndexedField() const { return false; }
 
   void SetFields(std::vector<Field> fields) { fields_ = std::move(fields); }
   const std::vector<Field>& fields() const { return fields_; }
+  bool HasField(const std::string& name) const;
   const Field& LookupField(const std::string& name) const;
   const std::string& name() const { return name_; }
   Namespace* nspace() const { return namespace_; }
@@ -415,7 +419,7 @@ class AggregateType : public Type {
     return "_method_" + name_ + "_" + name;
   }
 
-  const Field& RegisterField(Field field) {
+  virtual const Field& RegisterField(Field field) {
     fields_.push_back(field);
     return fields_.back();
   }
@@ -474,6 +478,7 @@ class ClassType final : public AggregateType {
   std::string GetGeneratedTNodeTypeName() const override;
   bool IsExtern() const { return is_extern_; }
   bool IsTransient() const override { return transient_; }
+  bool HasIndexedField() const override;
   size_t size() const { return size_; }
   StructType* struct_type() const { return this_struct_; }
   const ClassType* GetSuperClass() const {
@@ -483,24 +488,23 @@ class ClassType final : public AggregateType {
   void SetSize(size_t size) { size_ = size; }
   void SetThisStruct(StructType* this_struct) { this_struct_ = this_struct; }
   bool AllowInstantiation() const;
+  const Field& RegisterField(Field field) override {
+    if (field.index) {
+      has_indexed_field_ = true;
+    }
+    return AggregateType::RegisterField(field);
+  }
 
  private:
   friend class TypeOracle;
   ClassType(const Type* parent, Namespace* nspace, const std::string& name,
-            bool is_extern, bool transient, const std::string& generates)
-      : AggregateType(Kind::kClassType, parent, nspace, name),
-        this_struct_(nullptr),
-        is_extern_(is_extern),
-        transient_(transient),
-        size_(0),
-        generates_(generates) {
-    CheckForDuplicateFields();
-  }
+            bool is_extern, bool transient, const std::string& generates);
 
   StructType* this_struct_;
   bool is_extern_;
   bool transient_;
   size_t size_;
+  bool has_indexed_field_;
   const std::string generates_;
 };
 

third_party/v8/builtins/array-sort.tq

@@ -191,14 +191,14 @@ namespace array {
       context: Context, sortState: SortState, index: Smi): Object {
     const object = UnsafeCast<JSObject>(sortState.receiver);
     const elements = UnsafeCast<FixedArray>(object.elements);
-    return elements[index];
+    return elements.objects[index];
   }
 
   Load<FastSmiOrObjectElements>(
       context: Context, sortState: SortState, index: Smi): Object {
     const object = UnsafeCast<JSObject>(sortState.receiver);
     const elements = UnsafeCast<FixedArray>(object.elements);
-    const result: Object = elements[index];
+    const result: Object = elements.objects[index];
     if (IsTheHole(result)) {
       // The pre-processing step removed all holes by compacting all elements
       // at the start of the array. Finding a hole means the cmp function or
@@ -242,7 +242,7 @@ namespace array {
       Object {
     const elements = sortState.tempArray;
     assert(IsFixedArray(elements));
-    return elements[index];
+    return elements.objects[index];
   }
 
   transitioning builtin Store<ElementsAccessor: type>(
@@ -263,7 +263,7 @@ namespace array {
       context: Context, sortState: SortState, index: Smi, value: Object): Smi {
     const object = UnsafeCast<JSObject>(sortState.receiver);
     const elements = UnsafeCast<FixedArray>(object.elements);
-    elements[index] = value;
+    elements.objects[index] = value;
     return kSuccess;
   }
 
@@ -274,7 +274,7 @@ namespace array {
     const heapVal = UnsafeCast<HeapNumber>(value);
     // Make sure we do not store signalling NaNs into double arrays.
     const val = Float64SilenceNaN(Convert<float64>(heapVal));
-    StoreFixedDoubleArrayElementWithSmiIndex(elements, index, val);
+    StoreFixedDoubleArrayElementSmi(elements, index, val);
     return kSuccess;
   }
 
@@ -303,7 +303,7 @@ namespace array {
   Store<TempArrayElements>(
       context: Context, sortState: SortState, index: Smi, value: Object): Smi {
     const elements = sortState.tempArray;
-    elements[index] = value;
+    elements.objects[index] = value;
     return kSuccess;
   }
 
@@ -424,20 +424,20 @@ namespace array {
 
   macro GetPendingRunBase(implicit context:
                               Context)(pendingRuns: FixedArray, run: Smi): Smi {
-    return UnsafeCast<Smi>(pendingRuns[run << 1]);
+    return UnsafeCast<Smi>(pendingRuns.objects[run << 1]);
   }
 
   macro SetPendingRunBase(pendingRuns: FixedArray, run: Smi, value: Smi) {
-    pendingRuns[run << 1] = value;
+    pendingRuns.objects[run << 1] = value;
   }
 
   macro GetPendingRunLength(implicit context: Context)(
       pendingRuns: FixedArray, run: Smi): Smi {
-    return UnsafeCast<Smi>(pendingRuns[(run << 1) + 1]);
+    return UnsafeCast<Smi>(pendingRuns.objects[(run << 1) + 1]);
   }
 
   macro SetPendingRunLength(pendingRuns: FixedArray, run: Smi, value: Smi) {
-    pendingRuns[(run << 1) + 1] = value;
+    pendingRuns.objects[(run << 1) + 1] = value;
   }
 
   macro PushRun(implicit context:
@@ -558,7 +558,7 @@ namespace array {
 
     while (srcIdx < to) {
       const element = CallLoad(load, srcIdx++) otherwise Bailout;
-      tempArray[dstIdx++] = element;
+      tempArray.objects[dstIdx++] = element;
     }
   }
 
@@ -578,7 +578,7 @@ namespace array {
     let to: Smi = srcPos + length;
     try {
       while (srcIdx < to) {
-        CallStore(store, dstIdx++, tempArray[srcIdx++]) otherwise Bailout;
+        CallStore(store, dstIdx++, tempArray.objects[srcIdx++]) otherwise Bailout;
       }
       return kSuccess;
     }
@@ -1107,7 +1107,7 @@ namespace array {
 
           let elementB = CallLoad(load, cursorB) otherwise Bailout;
           let order =
-              CallCompareFn(elementB, tempArray[cursorTemp]) otherwise Bailout;
+              CallCompareFn(elementB, tempArray.objects[cursorTemp]) otherwise Bailout;
 
           if (order < 0) {
             CopyElement(load, store, cursorB, dest) otherwise Bailout;
@@ -1121,7 +1121,7 @@ namespace array {
             if (lengthB == 0) goto Succeed;
             if (nofWinsB >= minGallop) break;
           } else {
-            CallStore(store, dest, tempArray[cursorTemp]) otherwise Bailout;
+            CallStore(store, dest, tempArray.objects[cursorTemp]) otherwise Bailout;
 
             ++cursorTemp;
             ++dest;
@@ -1169,7 +1169,7 @@ namespace array {
           if (--lengthB == 0) goto Succeed;
 
           nofWinsB =
-              CallGallopLeft(load, tempArray[cursorTemp], cursorB, lengthB, 0)
+              CallGallopLeft(load, tempArray.objects[cursorTemp], cursorB, lengthB, 0)
               otherwise Bailout;
           assert(nofWinsB >= 0);
           if (nofWinsB > 0) {
@@ -1181,7 +1181,7 @@ namespace array {
 
             if (lengthB == 0) goto Succeed;
           }
-          CallStore(store, dest++, tempArray[cursorTemp++]) otherwise Bailout;
+          CallStore(store, dest++, tempArray.objects[cursorTemp++]) otherwise Bailout;
           if (--lengthA == 1) goto CopyB;
         }
         ++minGallop;  // Penalize it for leaving galloping mode
@@ -1197,7 +1197,7 @@ namespace array {
       assert(lengthA == 1 && lengthB > 0);
       // The last element of run A belongs at the end of the merge.
       CallCopyWithinSortArray(cursorB, dest, lengthB) otherwise Bailout;
-      CallStore(store, dest + lengthB, tempArray[cursorTemp]) otherwise Bailout;
+      CallStore(store, dest + lengthB, tempArray.objects[cursorTemp]) otherwise Bailout;
     }
   }
 
@@ -1250,7 +1250,7 @@ namespace array {
 
           let elementA = CallLoad(load, cursorA) otherwise Bailout;
           let order =
-              CallCompareFn(tempArray[cursorTemp], elementA) otherwise Bailout;
+              CallCompareFn(tempArray.objects[cursorTemp], elementA) otherwise Bailout;
 
           if (order < 0) {
             CopyElement(load, store, cursorA, dest) otherwise Bailout;
@@ -1264,7 +1264,7 @@ namespace array {
             if (lengthA == 0) goto Succeed;
             if (nofWinsA >= minGallop) break;
           } else {
-            CallStore(store, dest, tempArray[cursorTemp]) otherwise Bailout;
+            CallStore(store, dest, tempArray.objects[cursorTemp]) otherwise Bailout;
 
             --cursorTemp;
             --dest;
@@ -1292,7 +1292,7 @@ namespace array {
           sortState.minGallop = minGallop;
 
           let k: Smi = CallGallopRight(
-              load, tempArray[cursorTemp], baseA, lengthA, lengthA - 1)
+              load, tempArray.objects[cursorTemp], baseA, lengthA, lengthA - 1)
               otherwise Bailout;
           assert(k >= 0);
           nofWinsA = lengthA - k;
@@ -1306,7 +1306,7 @@ namespace array {
             lengthA = lengthA - nofWinsA;
             if (lengthA == 0) goto Succeed;
           }
-          CallStore(store, dest--, tempArray[cursorTemp--]) otherwise Bailout;
+          CallStore(store, dest--, tempArray.objects[cursorTemp--]) otherwise Bailout;
           if (--lengthB == 1) goto CopyA;
 
           let key = CallLoad(load, cursorA) otherwise Bailout;
@@ -1350,7 +1350,7 @@ namespace array {
       dest = dest - lengthA;
       cursorA = cursorA - lengthA;
       CallCopyWithinSortArray(cursorA + 1, dest + 1, lengthA) otherwise Bailout;
-      CallStore(store, dest, tempArray[cursorTemp]) otherwise Bailout;
+      CallStore(store, dest, tempArray.objects[cursorTemp]) otherwise Bailout;
     }
   }