[torque] allow allocation of strings

This CL generalizes and improves how we handle allocations in Torque.

Overview of the changes:
- Remove obsolete special handling for JSObject classes, since it was
  incomplete: It breaks as soon as slack tracking is active.
- Handle array initialization using slices.
- Properly align allocation sizes. This enabled allocating strings.
- Port AllocateSeq{One,Two}ByteString to Torque, which is much easier
  now than the old CSA code since allocation size alignment and
  large-object space allocation just happen out-of-the-box.
- Remove obsolete or unnecessary intrinsics, some of them turn into
  macros in the torque_internal namespace.
- Distinguish between header size and overall size for ClassType,
  make size optional and only defined when it is statically known.


Bug: v8:10004 v8:7793
Change-Id: I623db233e7fb4deed54e8039ae0c24705e9a44e8
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1932356Reviewed-by: Nico Hartmann <nicohartmann@chromium.org>
Commit-Queue: Tobias Tebbi <tebbi@chromium.org>
Cr-Commit-Position: refs/heads/master@{#65397}

src/builtins/base.tq

@@ -190,6 +190,8 @@ type FrameArray extends FixedArray;
 
 const kTaggedSize: constexpr int31 generates 'kTaggedSize';
 const kDoubleSize: constexpr int31 generates 'kDoubleSize';
+const kVariableSizeSentinel:
+    constexpr int31 generates 'kVariableSizeSentinel';
 
 const kSmiTagSize: constexpr int31 generates 'kSmiTagSize';
 const V8_INFINITY: constexpr float64 generates 'V8_INFINITY';
@@ -920,12 +922,18 @@ extern macro FixedCOWArrayMapConstant(): Map;
 extern macro EmptyByteArrayConstant(): ByteArray;
 extern macro EmptyFixedArrayConstant(): EmptyFixedArray;
 extern macro PromiseCapabilityMapConstant(): Map;
+extern macro OneByteStringMapConstant(): Map;
+extern macro StringMapConstant(): Map;
 
 const kFixedArrayMap: Map = FixedArrayMapConstant();
 const kCOWMap: Map = FixedCOWArrayMapConstant();
 const kEmptyByteArray: ByteArray = EmptyByteArrayConstant();
 const kEmptyFixedArray: EmptyFixedArray = EmptyFixedArrayConstant();
 const kPromiseCapabilityMap: Map = PromiseCapabilityMapConstant();
+// The map of a non-internalized internal SeqOneByteString.
+const kOneByteStringMap: Map = OneByteStringMapConstant();
+// The map of a non-internalized internal SeqTwoByteString.
+const kStringMap: Map = StringMapConstant();
 
 extern macro IsPrototypeInitialArrayPrototype(implicit context: Context)(Map):
     bool;
@@ -1281,8 +1289,6 @@ transitioning macro GetMethod(implicit context: Context)(
 
 extern macro NumberToString(Number): String;
 extern macro IsOneByteStringInstanceType(InstanceType): bool;
-extern macro AllocateSeqOneByteString(uint32): String;
-extern macro AllocateSeqTwoByteString(uint32): String;
 
 // After converting an index to an integer, calculate a relative index:
 // return index < 0 ? max(length + index, 0) : min(index, length)

src/builtins/convert.tq

@@ -56,6 +56,9 @@ FromConstexpr<Smi, constexpr Smi>(s: constexpr Smi): Smi {
 FromConstexpr<uint32, constexpr int31>(i: constexpr int31): uint32 {
   return Unsigned(Int32Constant(i));
 }
+FromConstexpr<uint32, constexpr uint32>(i: constexpr uint32): uint32 {
+  return Unsigned(%FromConstexpr<int32>(i));
+}
 FromConstexpr<uintptr, constexpr int31>(i: constexpr int31): uintptr {
   return ChangeUint32ToWord(i);
 }
@@ -131,6 +134,9 @@ Convert<uintptr, uint32>(ui: uint32): uintptr {
 Convert<intptr, uint16>(ui: uint16): intptr {
   return Signed(ChangeUint32ToWord(ui));
 }
+Convert<intptr, uint8>(ui: uint8): intptr {
+  return Signed(ChangeUint32ToWord(ui));
+}
 Convert<int32, uint8>(i: uint8): int32 {
   return Signed(Convert<uint32>(i));
 }

src/builtins/torque-internal.tq

@@ -101,43 +101,62 @@ namespace torque_internal {
     unsafeMarker: Unsafe;
   }
 
-}  // namespace torque_internal
+  macro AddIndexedFieldSizeToObjectSize(
+      baseSize: intptr, arrayLength: intptr,
+      fieldSize: constexpr int32): intptr {
+    const arrayLength = Convert<int32>(arrayLength);
+    const byteLength = TryInt32Mul(arrayLength, fieldSize)
+        otherwise unreachable;
+    return TryIntPtrAdd(baseSize, Convert<intptr>(byteLength))
+        otherwise unreachable;
+  }
 
-// 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
-// than building the definition from C++.
-intrinsic %GetAllocationBaseSize<Class : type extends HeapObject>(map: Map):
-    intptr;
-intrinsic %Allocate<Class : type extends HeapObject>(size: intptr): Class;
-intrinsic %GetStructMap(instanceKind: constexpr InstanceType): Map;
-
-intrinsic %AddIndexedFieldSizeToObjectSize<T: type>(
-    baseSize: intptr, indexSize: T, fieldSize: int32): intptr {
-  const convertedIndexSize = Convert<int32>(indexSize);
-  const variableSize: int32 =
-      TryInt32Mul(convertedIndexSize, fieldSize) otherwise unreachable;
-  const convertedVariableSize = Convert<intptr>(variableSize);
-  return TryIntPtrAdd(baseSize, convertedVariableSize) otherwise unreachable;
-}
-
-intrinsic
-%InitializeFieldsFromIterator<Container: type, Index: type, Iterator: type>(
-    c: Container, length: Index, i: Iterator) {
-  try {
-    let mutableIterator = i;
-    let current: Index = 0;
-    while (current < length) {
-      // TODO(danno): The indexed accessor on the container requires that the
-      // '[]=' operator be defined explicitly for the Container
-      // (e.g. FixedArray). We should change this to use slice references
-      // once they are implemented.
-      c[current++] = mutableIterator.Next() otherwise NoMore;
-    }
+  macro AlignTagged(x: intptr): intptr {
+    // Round up to a multiple of kTaggedSize.
+    return (x + kObjectAlignmentMask) & ~kObjectAlignmentMask;
+  }
+
+  macro IsTaggedAligned(x: intptr): bool {
+    return (x & kObjectAlignmentMask) == 0;
   }
-  label NoMore deferred {
-    unreachable;
+
+  macro ValidAllocationSize(sizeInBytes: intptr, map: Map): bool {
+    if (sizeInBytes <= 0) return false;
+    if (!IsTaggedAligned(sizeInBytes)) return false;
+    const instanceSizeInWords = Convert<intptr>(map.instance_size_in_words);
+    return instanceSizeInWords == kVariableSizeSentinel ||
+        instanceSizeInWords * kTaggedSize == sizeInBytes;
   }
-}
+
+  type UninitializedHeapObject extends HeapObject;
+
+  extern macro AllocateAllowLOS(intptr): UninitializedHeapObject;
+  extern macro GetStructMap(constexpr InstanceType): Map;
+
+  macro Allocate(sizeInBytes: intptr, map: Map): UninitializedHeapObject {
+    assert(ValidAllocationSize(sizeInBytes, map));
+    return AllocateAllowLOS(sizeInBytes);
+  }
+
+  macro InitializeFieldsFromIterator<T: type, Iterator: type>(
+      target: Slice<T>, originIterator: Iterator) {
+    let targetIterator = target.Iterator();
+    let originIterator = originIterator;
+    while (true) {
+      const ref:&T = targetIterator.Next() otherwise break;
+      * ref = originIterator.Next() otherwise unreachable;
+    }
+  }
+  // Dummy implementations: do not initialize for UninitializedIterator.
+  InitializeFieldsFromIterator<char8, UninitializedIterator>(
+      _target: Slice<char8>, _originIterator: UninitializedIterator) {}
+  InitializeFieldsFromIterator<char16, UninitializedIterator>(
+      _target: Slice<char16>, _originIterator: UninitializedIterator) {}
+}  // namespace torque_internal
+
+// Indicates that an array-field should not be initialized.
+// For safety reasons, this is only allowed for untagged types.
+struct UninitializedIterator {}
 
 // %RawDownCast should *never* be used anywhere in Torque code except for
 // in Torque-based UnsafeCast operators preceeded by an appropriate

src/codegen/code-stub-assembler.cc

@@ -3349,60 +3349,6 @@ TNode<BoolT> CodeStubAssembler::IsZeroOrContext(SloppyTNode<Object> object) {
       [=] { return IsContext(CAST(object)); });
 }
 
-TNode<String> CodeStubAssembler::AllocateSeqOneByteString(
-    TNode<Uint32T> length, AllocationFlags flags) {
-  Comment("AllocateSeqOneByteString");
-  VARIABLE(var_result, MachineRepresentation::kTagged);
-
-  // Compute the SeqOneByteString size and check if it fits into new space.
-  Label if_lengthiszero(this), if_sizeissmall(this),
-      if_notsizeissmall(this, Label::kDeferred), if_join(this);
-  GotoIf(Word32Equal(length, Uint32Constant(0)), &if_lengthiszero);
-
-  TNode<IntPtrT> raw_size = GetArrayAllocationSize(
-      Signed(ChangeUint32ToWord(length)), UINT8_ELEMENTS,
-      SeqOneByteString::kHeaderSize + kObjectAlignmentMask);
-  TNode<IntPtrT> size =
-      WordAnd(raw_size, IntPtrConstant(~kObjectAlignmentMask));
-  Branch(IntPtrLessThanOrEqual(size, IntPtrConstant(kMaxRegularHeapObjectSize)),
-         &if_sizeissmall, &if_notsizeissmall);
-
-  BIND(&if_sizeissmall);
-  {
-    // Just allocate the SeqOneByteString in new space.
-    TNode<HeapObject> result =
-        AllocateInNewSpace(UncheckedCast<IntPtrT>(size), flags);
-    DCHECK(RootsTable::IsImmortalImmovable(RootIndex::kOneByteStringMap));
-    StoreMapNoWriteBarrier(result, RootIndex::kOneByteStringMap);
-    StoreObjectFieldNoWriteBarrier(result, SeqOneByteString::kLengthOffset,
-                                   length, MachineRepresentation::kWord32);
-    StoreObjectFieldNoWriteBarrier(result, SeqOneByteString::kHashFieldOffset,
-                                   Int32Constant(String::kEmptyHashField),
-                                   MachineRepresentation::kWord32);
-    var_result.Bind(result);
-    Goto(&if_join);
-  }
-
-  BIND(&if_notsizeissmall);
-  {
-    // We might need to allocate in large object space, go to the runtime.
-    TNode<Object> result =
-        CallRuntime(Runtime::kAllocateSeqOneByteString, NoContextConstant(),
-                    ChangeUint32ToTagged(length));
-    var_result.Bind(result);
-    Goto(&if_join);
-  }
-
-  BIND(&if_lengthiszero);
-  {
-    var_result.Bind(EmptyStringConstant());
-    Goto(&if_join);
-  }
-
-  BIND(&if_join);
-  return CAST(var_result.value());
-}
-
 TNode<String> CodeStubAssembler::AllocateSeqTwoByteString(
     uint32_t length, AllocationFlags flags) {
   Comment("AllocateSeqTwoByteString");
@@ -3421,60 +3367,6 @@ TNode<String> CodeStubAssembler::AllocateSeqTwoByteString(
   return CAST(result);
 }
 
-TNode<String> CodeStubAssembler::AllocateSeqTwoByteString(
-    TNode<Uint32T> length, AllocationFlags flags) {
-  Comment("AllocateSeqTwoByteString");
-  VARIABLE(var_result, MachineRepresentation::kTagged);
-
-  // Compute the SeqTwoByteString size and check if it fits into new space.
-  Label if_lengthiszero(this), if_sizeissmall(this),
-      if_notsizeissmall(this, Label::kDeferred), if_join(this);
-  GotoIf(Word32Equal(length, Uint32Constant(0)), &if_lengthiszero);
-
-  TNode<IntPtrT> raw_size = GetArrayAllocationSize(
-      Signed(ChangeUint32ToWord(length)), UINT16_ELEMENTS,
-      SeqOneByteString::kHeaderSize + kObjectAlignmentMask);
-  TNode<IntPtrT> size =
-      WordAnd(raw_size, IntPtrConstant(~kObjectAlignmentMask));
-  Branch(IntPtrLessThanOrEqual(size, IntPtrConstant(kMaxRegularHeapObjectSize)),
-         &if_sizeissmall, &if_notsizeissmall);
-
-  BIND(&if_sizeissmall);
-  {
-    // Just allocate the SeqTwoByteString in new space.
-    TNode<HeapObject> result =
-        AllocateInNewSpace(UncheckedCast<IntPtrT>(size), flags);
-    DCHECK(RootsTable::IsImmortalImmovable(RootIndex::kStringMap));
-    StoreMapNoWriteBarrier(result, RootIndex::kStringMap);
-    StoreObjectFieldNoWriteBarrier(result, SeqTwoByteString::kLengthOffset,
-                                   length, MachineRepresentation::kWord32);
-    StoreObjectFieldNoWriteBarrier(result, SeqTwoByteString::kHashFieldOffset,
-                                   Int32Constant(String::kEmptyHashField),
-                                   MachineRepresentation::kWord32);
-    var_result.Bind(result);
-    Goto(&if_join);
-  }
-
-  BIND(&if_notsizeissmall);
-  {
-    // We might need to allocate in large object space, go to the runtime.
-    TNode<Object> result =
-        CallRuntime(Runtime::kAllocateSeqTwoByteString, NoContextConstant(),
-                    ChangeUint32ToTagged(length));
-    var_result.Bind(result);
-    Goto(&if_join);
-  }
-
-  BIND(&if_lengthiszero);
-  {
-    var_result.Bind(EmptyStringConstant());
-    Goto(&if_join);
-  }
-
-  BIND(&if_join);
-  return CAST(var_result.value());
-}
-
 TNode<String> CodeStubAssembler::AllocateSlicedString(RootIndex map_root_index,
                                                       TNode<Uint32T> length,
                                                       TNode<String> parent,

src/codegen/code-stub-assembler.h

@@ -115,6 +115,7 @@ enum class PrimitiveType { kBoolean, kNumber, kString, kSymbol };
   V(number_to_string, number_to_string, NumberToString)                        \
   V(Object_string, Object_string, ObjectString)                                \
   V(object_to_string, object_to_string, ObjectToString)                        \
+  V(OneByteStringMap, one_byte_string_map, OneByteStringMap)                   \
   V(OneClosureCellMap, one_closure_cell_map, OneClosureCellMap)                \
   V(OnePointerFillerMap, one_pointer_filler_map, OnePointerFillerMap)          \
   V(PreparseDataMap, preparse_data_map, PreparseDataMap)                       \
@@ -137,6 +138,7 @@ enum class PrimitiveType { kBoolean, kNumber, kString, kSymbol };
   V(StoreHandler0Map, store_handler0_map, StoreHandler0Map)                    \
   V(string_string, string_string, StringString)                                \
   V(string_to_string, string_to_string, StringToString)                        \
+  V(StringMap, string_map, StringMap)                                          \
   V(SymbolMap, symbol_map, SymbolMap)                                          \
   V(TheHoleValue, the_hole_value, TheHole)                                     \
   V(then_string, then_string, ThenString)                                      \
@@ -803,6 +805,10 @@ class V8_EXPORT_PRIVATE CodeStubAssembler
   TNode<HeapObject> AllocateInNewSpace(int size, AllocationFlags flags = kNone);
   TNode<HeapObject> Allocate(TNode<IntPtrT> size,
                              AllocationFlags flags = kNone);
+  TNode<HeapObject> AllocateAllowLOS(TNode<IntPtrT> size) {
+    return Allocate(size, AllocationFlag::kAllowLargeObjectAllocation);
+  }
+
   TNode<HeapObject> Allocate(int size, AllocationFlags flags = kNone);
   TNode<HeapObject> InnerAllocate(TNode<HeapObject> previous, int offset);
   TNode<HeapObject> InnerAllocate(TNode<HeapObject> previous,
@@ -1756,13 +1762,12 @@ class V8_EXPORT_PRIVATE CodeStubAssembler
   // Allocate a SeqOneByteString with the given length.
   TNode<String> AllocateSeqOneByteString(uint32_t length,
                                          AllocationFlags flags = kNone);
-  TNode<String> AllocateSeqOneByteString(TNode<Uint32T> length,
-                                         AllocationFlags flags = kNone);
+  using TorqueGeneratedExportedMacrosAssembler::AllocateSeqOneByteString;
+
   // Allocate a SeqTwoByteString with the given length.
   TNode<String> AllocateSeqTwoByteString(uint32_t length,
                                          AllocationFlags flags = kNone);
-  TNode<String> AllocateSeqTwoByteString(TNode<Uint32T> length,
-                                         AllocationFlags flags = kNone);
+  using TorqueGeneratedExportedMacrosAssembler::AllocateSeqTwoByteString;
 
   // Allocate a SlicedOneByteString with the given length, parent and offset.
   // |length| and |offset| are expected to be tagged.

src/objects/js-objects.tq

@@ -38,11 +38,7 @@ macro NewJSObject(implicit context: Context)(): JSObject {
   const objectFunction: JSFunction = GetObjectFunction();
   const map: Map = Cast<Map>(objectFunction.prototype_or_initial_map)
       otherwise unreachable;
-  return new JSObject{
-    map,
-    properties_or_hash: kEmptyFixedArray,
-    elements: kEmptyFixedArray
-  };
+  return AllocateJSObjectFromMap(map);
 }
 
 @abstract

src/objects/name.tq

@@ -19,3 +19,6 @@ extern class Symbol extends Name {
 
 type PublicSymbol extends Symbol;
 type PrivateSymbol extends Symbol;
+
+const kNameEmptyHashField:
+    constexpr uint32 generates 'Name::kEmptyHashField';

src/objects/string.tq

@@ -56,3 +56,27 @@ extern class ThinString extends String {
 // A direct string can be accessed directly through CSA without going into the
 // C++ runtime. See also: ToDirectStringAssembler.
 type DirectString extends String;
+
+@export
+macro AllocateSeqOneByteString(length: uint32): String {
+  assert(length <= kStringMaxLength);
+  if (length == 0) return kEmptyString;
+  return new SeqOneByteString{
+    map: kOneByteStringMap,
+    hash_field: kNameEmptyHashField,
+    length: Signed(length),
+    chars: ...UninitializedIterator {}
+  };
+}
+
+@export
+macro AllocateSeqTwoByteString(length: uint32): String {
+  assert(length <= kStringMaxLength);
+  if (length == 0) return kEmptyString;
+  return new SeqTwoByteString{
+    map: kStringMap,
+    hash_field: kNameEmptyHashField,
+    length: Signed(length),
+    chars: ...UninitializedIterator {}
+  };
+}

src/torque/constants.h

@@ -35,6 +35,8 @@ static const char* const SMI_TYPE_STRING = "Smi";
 static const char* const TAGGED_TYPE_STRING = "Tagged";
 static const char* const STRONG_TAGGED_TYPE_STRING = "StrongTagged";
 static const char* const UNINITIALIZED_TYPE_STRING = "Uninitialized";
+static const char* const UNINITIALIZED_HEAP_OBJECT_TYPE_STRING =
+    "UninitializedHeapObject";
 static const char* const RAWPTR_TYPE_STRING = "RawPtr";
 static const char* const CONST_STRING_TYPE_STRING = "constexpr string";
 static const char* const STRING_TYPE_STRING = "String";
@@ -56,6 +58,8 @@ static const char* const TORQUE_INTERNAL_NAMESPACE_STRING = "torque_internal";
 static const char* const REFERENCE_TYPE_STRING = "Reference";
 static const char* const SLICE_TYPE_STRING = "Slice";
 static const char* const WEAK_TYPE_STRING = "Weak";
+static const char* const UNINITIALIZED_ITERATOR_TYPE_STRING =
+    "UninitializedIterator";
 static const char* const GENERIC_TYPE_INSTANTIATION_NAMESPACE_STRING =
     "_generic_type_instantiation_namespace";
 

src/torque/csa-generator.cc

@@ -198,13 +198,18 @@ void CSAGenerator::EmitInstruction(const CallIntrinsicInstruction& instruction,
     if (parameter_types.size() != 1) {
       ReportError("%RawDownCast must take a single parameter");
     }
-    if (!return_type->IsSubtypeOf(parameter_types[0])) {
+    const Type* original_type = parameter_types[0];
+    bool is_subtype =
+        return_type->IsSubtypeOf(original_type) ||
+        (original_type == TypeOracle::GetUninitializedHeapObjectType() &&
+         return_type->IsSubtypeOf(TypeOracle::GetHeapObjectType()));
+    if (!is_subtype) {
       ReportError("%RawDownCast error: ", *return_type, " is not a subtype of ",
-                  *parameter_types[0]);
+                  *original_type);
     }
     if (return_type->IsSubtypeOf(TypeOracle::GetTaggedType())) {
       if (return_type->GetGeneratedTNodeTypeName() !=
-          parameter_types[0]->GetGeneratedTNodeTypeName()) {
+          original_type->GetGeneratedTNodeTypeName()) {
         out_ << "TORQUE_CAST";
       }
     }
@@ -238,29 +243,6 @@ void CSAGenerator::EmitInstruction(const CallIntrinsicInstruction& instruction,
       s << "%FromConstexpr does not support return type " << *return_type;
       ReportError(s.str());
     }
-  } else if (instruction.intrinsic->ExternalName() ==
-             "%GetAllocationBaseSize") {
-    if (instruction.specialization_types.size() != 1) {
-      ReportError(
-          "incorrect number of type parameters for "
-          "%GetAllocationBaseSize (should be one)");
-    }
-    const ClassType* class_type =
-        ClassType::cast(instruction.specialization_types[0]);
-    // Special case classes that may not always have a fixed size (e.g.
-    // JSObjects). Their size must be fetched from the map.
-    if (class_type != TypeOracle::GetJSObjectType()) {
-      out_ << "CodeStubAssembler(state_).IntPtrConstant((";
-      args[0] = std::to_string(class_type->size());
-    } else {
-      out_ << "CodeStubAssembler(state_).TimesTaggedSize(CodeStubAssembler("
-              "state_).LoadMapInstanceSizeInWords(";
-    }
-  } else if (instruction.intrinsic->ExternalName() == "%Allocate") {
-    out_ << "ca_.UncheckedCast<" << return_type->GetGeneratedTNodeTypeName()
-         << ">(CodeStubAssembler(state_).Allocate";
-  } else if (instruction.intrinsic->ExternalName() == "%GetStructMap") {
-    out_ << "CodeStubAssembler(state_).GetStructMap";
   } else {
     ReportError("no built in intrinsic with name " +
                 instruction.intrinsic->ExternalName());
@@ -268,22 +250,11 @@ void CSAGenerator::EmitInstruction(const CallIntrinsicInstruction& instruction,
 
   out_ << "(";
   PrintCommaSeparatedList(out_, args);
-  if (instruction.intrinsic->ExternalName() == "%Allocate") out_ << ")";
-  if (instruction.intrinsic->ExternalName() == "%GetAllocationBaseSize")
-    out_ << "))";
   if (return_type->IsStructType()) {
     out_ << ").Flatten();\n";
   } else {
     out_ << ");\n";
   }
-  if (instruction.intrinsic->ExternalName() == "%Allocate") {
-    out_ << "    CodeStubAssembler(state_).InitializeFieldsWithRoot("
-         << results[0] << ", ";
-    out_ << "CodeStubAssembler(state_).IntPtrConstant("
-         << std::to_string(ClassType::cast(return_type)->size()) << "), ";
-    PrintCommaSeparatedList(out_, args);
-    out_ << ", RootIndex::kUndefinedValue);\n";
-  }
 }
 
 void CSAGenerator::EmitInstruction(const CallCsaMacroInstruction& instruction,

src/torque/declaration-visitor.cc

@@ -117,8 +117,12 @@ void DeclarationVisitor::Visit(ExternalBuiltinDeclaration* decl) {
 
 void DeclarationVisitor::Visit(ExternalRuntimeDeclaration* decl) {
   Signature signature = TypeVisitor::MakeSignature(decl);
-  if (signature.parameter_types.types.size() == 0 ||
-      !(signature.parameter_types.types[0] == TypeOracle::GetContextType())) {
+  if (signature.parameter_types.types.size() == 0) {
+    ReportError(
+        "Missing parameters for runtime function, at least the context "
+        "parameter is required.");
+  }
+  if (!(signature.parameter_types.types[0] == TypeOracle::GetContextType())) {
     ReportError(
         "first parameter to runtime functions has to be the context and have "
         "type Context, but found type ",

src/torque/declarations.cc

@@ -46,9 +46,9 @@ void CheckAlreadyDeclared(const std::string& name, const char* new_type) {
 }  // namespace
 
 std::vector<Declarable*> Declarations::LookupGlobalScope(
-    const std::string& name) {
+    const QualifiedName& name) {
   std::vector<Declarable*> d =
-      GlobalContext::GetDefaultNamespace()->Lookup(QualifiedName(name));
+      GlobalContext::GetDefaultNamespace()->Lookup(name);
   if (d.empty()) {
     std::stringstream s;
     s << "cannot find \"" << name << "\" in global scope";
@@ -76,7 +76,7 @@ const Type* Declarations::LookupType(const Identifier* name) {
   return alias->type();
 }
 
-const Type* Declarations::LookupGlobalType(const std::string& name) {
+const Type* Declarations::LookupGlobalType(const QualifiedName& name) {
   TypeAlias* declaration = EnsureUnique(
       FilterDeclarables<TypeAlias>(LookupGlobalScope(name)), name, "type");
   return declaration->type();
@@ -139,8 +139,9 @@ GenericType* Declarations::LookupUniqueGenericType(const QualifiedName& name) {
 
 GenericType* Declarations::LookupGlobalUniqueGenericType(
     const std::string& name) {
-  return EnsureUnique(FilterDeclarables<GenericType>(LookupGlobalScope(name)),
-                      name, "generic type");
+  return EnsureUnique(
+      FilterDeclarables<GenericType>(LookupGlobalScope(QualifiedName(name))),
+      name, "generic type");
 }
 
 base::Optional<GenericType*> Declarations::TryLookupGenericType(

src/torque/declarations.h

@@ -56,12 +56,12 @@ class Declarations {
     return d;
   }
 
-  static std::vector<Declarable*> LookupGlobalScope(const std::string& name);
+  static std::vector<Declarable*> LookupGlobalScope(const QualifiedName& name);
 
   static const TypeAlias* LookupTypeAlias(const QualifiedName& name);
   static const Type* LookupType(const QualifiedName& name);
   static const Type* LookupType(const Identifier* identifier);
-  static const Type* LookupGlobalType(const std::string& name);
+  static const Type* LookupGlobalType(const QualifiedName& name);
 
   static Builtin* FindSomeInternalBuiltinWithType(
       const BuiltinPointerType* type);

src/torque/implementation-visitor.h

@@ -170,6 +170,7 @@ class LocationReference {
 struct InitializerResults {
   std::vector<Identifier*> names;
   std::map<std::string, VisitResult> field_value_map;
+  std::map<std::string, VisitResult> array_lengths;
 };
 
 template <class T>
@@ -369,13 +370,19 @@ class ImplementationVisitor {
   InitializerResults VisitInitializerResults(
       const ClassType* class_type,
       const std::vector<NameAndExpression>& expressions);
-
-  void InitializeFieldFromSpread(VisitResult object, const Field& field,
+  LocationReference GenerateFieldReference(VisitResult object,
+                                           const NameAndType& field,
+                                           const ClassType* class_type);
+  VisitResult GenerateArrayLength(VisitResult object, const Field& field);
+  VisitResult GenerateArrayLength(const ClassType* class_type,
+                                  const InitializerResults& initializer_results,
+                                  const Field& field);
+  VisitResult GenerateObjectSize(const ClassType* class_type,
                                  const InitializerResults& initializer_results);
 
-  VisitResult AddVariableObjectSize(
-      VisitResult object_size, const ClassType* current_class,
-      const InitializerResults& initializer_results);
+  void InitializeFieldFromSpread(VisitResult object, const Field& field,
+                                 const InitializerResults& initializer_results,
+                                 const ClassType* class_type);
 
   void InitializeClass(const ClassType* class_type, VisitResult allocate_result,
                        const InitializerResults& initializer_results);

src/torque/instructions.cc

@@ -292,7 +292,9 @@ void UnsafeCastInstruction::TypeInstruction(Stack<const Type*>* stack,
 
 void CreateFieldReferenceInstruction::TypeInstruction(
     Stack<const Type*>* stack, ControlFlowGraph* cfg) const {
-  ExpectSubtype(stack->Top(), type);
+  if (stack->Top() != TypeOracle::GetUninitializedHeapObjectType()) {
+    ExpectSubtype(stack->Top(), type);
+  }
   stack->Push(TypeOracle::GetIntPtrType());
 }
 

src/torque/instructions.h

@@ -206,9 +206,12 @@ struct NamespaceConstantInstruction : InstructionBase {
 
 struct CreateFieldReferenceInstruction : InstructionBase {
   TORQUE_INSTRUCTION_BOILERPLATE()
-  CreateFieldReferenceInstruction(const Type* type, std::string field_name)
-      : type(type), field_name(std::move(field_name)) {}
-  const Type* type;
+  CreateFieldReferenceInstruction(const ClassType* type, std::string field_name)
+      : type(type), field_name(std::move(field_name)) {
+    // Trigger errors early.
+    this->type->LookupField(this->field_name);
+  }
+  const ClassType* type;
   std::string field_name;
 };
 

src/torque/type-oracle.h

@@ -190,6 +190,12 @@ class TypeOracle : public ContextualClass<TypeOracle> {
     return Get().GetBuiltinType(UNINITIALIZED_TYPE_STRING);
   }
 
+  static const Type* GetUninitializedHeapObjectType() {
+    return Get().GetBuiltinType(
+        QualifiedName({TORQUE_INTERNAL_NAMESPACE_STRING},
+                      UNINITIALIZED_HEAP_OBJECT_TYPE_STRING));
+  }
+
   static const Type* GetSmiType() {
     return Get().GetBuiltinType(SMI_TYPE_STRING);
   }
@@ -270,6 +276,10 @@ class TypeOracle : public ContextualClass<TypeOracle> {
     return Get().GetBuiltinType(JS_FUNCTION_TYPE_STRING);
   }
 
+  static const Type* GetUninitializedIteratorType() {
+    return Get().GetBuiltinType(UNINITIALIZED_ITERATOR_TYPE_STRING);
+  }
+
   static bool IsImplicitlyConvertableFrom(const Type* to, const Type* from) {
     for (GenericCallable* from_constexpr :
          Declarations::LookupGeneric(kFromConstexprMacroName)) {
@@ -295,9 +305,12 @@ class TypeOracle : public ContextualClass<TypeOracle> {
   static Namespace* CreateGenericTypeInstantiationNamespace();
 
  private:
-  const Type* GetBuiltinType(const std::string& name) {
+  const Type* GetBuiltinType(const QualifiedName& name) {
     return Declarations::LookupGlobalType(name);
   }
+  const Type* GetBuiltinType(const std::string& name) {
+    return GetBuiltinType(QualifiedName(name));
+  }
 
   Deduplicator<BuiltinPointerType> function_pointer_types_;
   std::vector<const BuiltinPointerType*> all_builtin_pointer_types_;

src/torque/type-visitor.cc

@@ -307,7 +307,8 @@ const ClassType* TypeVisitor::ComputeType(
     }
     const Type* super_type = TypeVisitor::ComputeType(*decl->super);
     const ClassType* super_class = ClassType::DynamicCast(super_type);
-    const Type* struct_type = Declarations::LookupGlobalType("Struct");
+    const Type* struct_type =
+        Declarations::LookupGlobalType(QualifiedName("Struct"));
     if (!super_class || super_class != struct_type) {
       ReportError("Intern class ", decl->name->value,
                   " must extend class Struct.");
@@ -385,7 +386,10 @@ Signature TypeVisitor::MakeSignature(const CallableDeclaration* declaration) {
 void TypeVisitor::VisitClassFieldsAndMethods(
     ClassType* class_type, const ClassDeclaration* class_declaration) {
   const ClassType* super_class = class_type->GetSuperClass();
-  size_t class_offset = super_class ? super_class->size() : 0;
+  size_t class_offset = super_class ? super_class->header_size() : 0;
+  size_t header_size = class_offset;
+  DCHECK_IMPLIES(super_class && !super_class->size(),
+                 class_declaration->fields.empty());
   bool seen_indexed_field = false;
   for (const ClassFieldExpression& field_expression :
        class_declaration->fields) {
@@ -467,9 +471,18 @@ void TypeVisitor::VisitClassFieldsAndMethods(
     }
     if (!field_expression.index) {
       class_offset += field_size;
+      // In-object properties are not considered part of the header.
+      if (!class_type->IsShape()) {
+        header_size = class_offset;
+      }
     }
   }
-  class_type->SetSize(class_offset);
+  DCHECK_GT(header_size, 0);
+  class_type->header_size_ = header_size;
+  if ((!super_class || super_class->size()) && !seen_indexed_field) {
+    DCHECK_GE(class_offset, header_size);
+    class_type->size_ = class_offset;
+  }
   class_type->GenerateAccessors();
   DeclareMethods(class_type, class_declaration->methods);
 }

src/torque/types.cc

@@ -434,7 +434,6 @@ ClassType::ClassType(const Type* parent, Namespace* nspace,
                      const std::string& generates, const ClassDeclaration* decl,
                      const TypeAlias* alias)
     : AggregateType(Kind::kClassType, parent, nspace, name),
-      size_(0),
       flags_(flags & ~(kInternalFlags)),
       generates_(generates),
       decl_(decl),

src/torque/types.h

@@ -608,12 +608,18 @@ class ClassType final : public AggregateType {
   bool IsShape() const { return flags_ & ClassFlag::kIsShape; }
   bool HasStaticSize() const;
   bool HasIndexedField() const override;
-  size_t size() const { return size_; }
+  size_t header_size() const {
+    if (!is_finalized_) Finalize();
+    return header_size_;
+  }
+  base::Optional<size_t> size() const {
+    if (!is_finalized_) Finalize();
+    return size_;
+  }
   const ClassType* GetSuperClass() const {
     if (parent() == nullptr) return nullptr;
     return parent()->IsClassType() ? ClassType::DynamicCast(parent()) : nullptr;
   }
-  void SetSize(size_t size) { size_ = size; }
   void GenerateAccessors();
   bool AllowInstantiation() const;
   const Field& RegisterField(Field field) override {
@@ -647,7 +653,8 @@ class ClassType final : public AggregateType {
             ClassFlags flags, const std::string& generates,
             const ClassDeclaration* decl, const TypeAlias* alias);
 
-  size_t size_;
+  size_t header_size_;
+  base::Optional<size_t> size_;
   mutable ClassFlags flags_;
   const std::string generates_;
   const ClassDeclaration* decl_;

test/unittests/torque/torque-unittest.cc

@@ -25,6 +25,7 @@ namespace torque_internal {
     const object: HeapObject;
     const offset: intptr;
   }
+  type UninitializedHeapObject extends HeapObject;
 }
 
 type Tagged generates 'TNode<MaybeObject>' constexpr 'MaybeObject';