[torque] add %SizeOf intrinsic

This replaces the fragile hand-coded SizeOf function.

Bug: v8:7793
Change-Id: I6bd84f367182b947486192f8968c56723f29efaa
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1924265
Reviewed-by: Nico Hartmann <nicohartmann@chromium.org>
Commit-Queue: Tobias Tebbi <tebbi@chromium.org>
Cr-Commit-Position: refs/heads/master@{#65089}

src/builtins/torque-internal.tq

@@ -3,24 +3,15 @@
 // found in the LICENSE file.
 
 namespace torque_internal {
-  // TODO(gsps): Synthesize SizeOf<T> in the compiler
-
-  macro SizeOf<T: type>(): constexpr int31;
-  SizeOf<Object>(): constexpr int31 {
-    return kTaggedSize;
-  }
-  SizeOf<float64>(): constexpr int31 {
-    return kDoubleSize;
-  }
-  SizeOf<DescriptorEntry>(): constexpr int31 {
-    return kTaggedSize * 3;
-  }
-
   // Unsafe is a marker that we require to be passed when calling internal APIs
   // that might lead to unsoundness when used incorrectly. Unsafe markers should
   // therefore not be instantiated anywhere outside of this namespace.
   struct Unsafe {}
 
+  // Size of a type in memory (on the heap). For class types, this is the size
+  // of the pointer, not of the instance.
+  intrinsic %SizeOf<T: type>(): constexpr int31;
+
   struct Reference<T: type> {
     const object: HeapObject;
     const offset: intptr;
@@ -39,7 +30,7 @@ namespace torque_internal {
     TryAtIndex(index: intptr):&T labels OutOfBounds {
       if (Convert<uintptr>(index) < Convert<uintptr>(this.length)) {
         return UnsafeNewReference<T>(
-            this.object, this.offset + index * SizeOf<T>());
+            this.object, this.offset + index * %SizeOf<T>());
       } else {
         goto OutOfBounds;
       }
@@ -64,7 +55,7 @@ namespace torque_internal {
     }
 
     Iterator(): SliceIterator<T> {
-      const end = this.offset + this.length * SizeOf<T>();
+      const end = this.offset + this.length * %SizeOf<T>();
       return SliceIterator<T>{
         object: this.object,
         start: this.offset,
@@ -99,7 +90,7 @@ namespace torque_internal {
         goto NoMore;
       } else {
         const result = UnsafeNewReference<T>(this.object, this.start);
-        this.start += SizeOf<T>();
+        this.start += %SizeOf<T>();
         return result;
       }
     }

src/objects/descriptor-array.tq

@@ -9,7 +9,6 @@ extern class EnumCache extends Struct {
   indices: FixedArray;
 }
 
-// Keep in sync with hand-coded SizeOf<DescriptorEntry> in torque-internal.tq.
 @export
 struct DescriptorEntry {
   key: Name|Undefined;

src/torque/csa-generator.cc

@@ -242,7 +242,7 @@ void CSAGenerator::EmitInstruction(const CallIntrinsicInstruction& instruction,
              "%GetAllocationBaseSize") {
     if (instruction.specialization_types.size() != 1) {
       ReportError(
-          "incorrect number of specialization classes for "
+          "incorrect number of type parameters for "
           "%GetAllocationBaseSize (should be one)");
     }
     const ClassType* class_type =

src/torque/implementation-visitor.cc

@@ -2360,7 +2360,19 @@ VisitResult ImplementationVisitor::GenerateCall(
       return VisitResult(return_type, assembler().TopRange(slot_count));
     }
   } else if (auto* intrinsic = Intrinsic::DynamicCast(callable)) {
-    if (intrinsic->ExternalName() == "%RawConstexprCast") {
+    if (intrinsic->ExternalName() == "%SizeOf") {
+      if (specialization_types.size() != 1) {
+        ReportError("%SizeOf must take a single type parameter");
+      }
+      const Type* type = specialization_types[0];
+      std::string size_string;
+      if (base::Optional<std::tuple<size_t, std::string>> size = SizeOf(type)) {
+        size_string = std::get<1>(*size);
+      } else {
+        Error("size of ", *type, " is not known.");
+      }
+      return VisitResult(return_type, size_string);
+    } else if (intrinsic->ExternalName() == "%RawConstexprCast") {
       if (intrinsic->signature().parameter_types.types.size() != 1 ||
           constexpr_arguments.size() != 1) {
         ReportError(

src/torque/type-visitor.cc

@@ -155,7 +155,7 @@ const StructType* TypeVisitor::ComputeType(
             false,
             field.const_qualified,
             false};
-    auto optional_size = f.GetOptionalFieldSizeInformation();
+    auto optional_size = SizeOf(f.name_and_type.type);
     // Structs may contain fields that aren't representable in packed form. If
     // so, then this field and any subsequent fields should have their offsets
     // marked as invalid.

src/torque/types.cc

@@ -718,7 +718,7 @@ VisitResult VisitResult::NeverResult() {
 }
 
 std::tuple<size_t, std::string> Field::GetFieldSizeInformation() const {
-  auto optional = GetOptionalFieldSizeInformation();
+  auto optional = SizeOf(this->name_and_type.type);
   if (optional.has_value()) {
     return *optional;
   }
@@ -727,55 +727,52 @@ std::tuple<size_t, std::string> Field::GetFieldSizeInformation() const {
   return std::make_tuple(0, "#no size");
 }
 
-base::Optional<std::tuple<size_t, std::string>>
-Field::GetOptionalFieldSizeInformation() const {
+base::Optional<std::tuple<size_t, std::string>> SizeOf(const Type* type) {
   std::string size_string;
-  const Type* field_type = this->name_and_type.type;
-  size_t field_size = 0;
-  if (field_type->IsSubtypeOf(TypeOracle::GetTaggedType())) {
-    field_size = TargetArchitecture::TaggedSize();
+  size_t size;
+  if (type->IsSubtypeOf(TypeOracle::GetTaggedType())) {
+    size = TargetArchitecture::TaggedSize();
     size_string = "kTaggedSize";
-  } else if (field_type->IsSubtypeOf(TypeOracle::GetRawPtrType())) {
-    field_size = TargetArchitecture::RawPtrSize();
+  } else if (type->IsSubtypeOf(TypeOracle::GetRawPtrType())) {
+    size = TargetArchitecture::RawPtrSize();
     size_string = "kSystemPointerSize";
-  } else if (field_type->IsSubtypeOf(TypeOracle::GetVoidType())) {
-    field_size = 0;
+  } else if (type->IsSubtypeOf(TypeOracle::GetVoidType())) {
+    size = 0;
     size_string = "0";
-  } else if (field_type->IsSubtypeOf(TypeOracle::GetInt8Type())) {
-    field_size = kUInt8Size;
+  } else if (type->IsSubtypeOf(TypeOracle::GetInt8Type())) {
+    size = kUInt8Size;
     size_string = "kUInt8Size";
-  } else if (field_type->IsSubtypeOf(TypeOracle::GetUint8Type())) {
-    field_size = kUInt8Size;
+  } else if (type->IsSubtypeOf(TypeOracle::GetUint8Type())) {
+    size = kUInt8Size;
     size_string = "kUInt8Size";
-  } else if (field_type->IsSubtypeOf(TypeOracle::GetInt16Type())) {
-    field_size = kUInt16Size;
+  } else if (type->IsSubtypeOf(TypeOracle::GetInt16Type())) {
+    size = kUInt16Size;
     size_string = "kUInt16Size";
-  } else if (field_type->IsSubtypeOf(TypeOracle::GetUint16Type())) {
-    field_size = kUInt16Size;
+  } else if (type->IsSubtypeOf(TypeOracle::GetUint16Type())) {
+    size = kUInt16Size;
     size_string = "kUInt16Size";
-  } else if (field_type->IsSubtypeOf(TypeOracle::GetInt32Type())) {
-    field_size = kInt32Size;
+  } else if (type->IsSubtypeOf(TypeOracle::GetInt32Type())) {
+    size = kInt32Size;
     size_string = "kInt32Size";
-  } else if (field_type->IsSubtypeOf(TypeOracle::GetUint32Type())) {
-    field_size = kInt32Size;
+  } else if (type->IsSubtypeOf(TypeOracle::GetUint32Type())) {
+    size = kInt32Size;
     size_string = "kInt32Size";
-  } else if (field_type->IsSubtypeOf(TypeOracle::GetFloat64Type())) {
-    field_size = kDoubleSize;
+  } else if (type->IsSubtypeOf(TypeOracle::GetFloat64Type())) {
+    size = kDoubleSize;
     size_string = "kDoubleSize";
-  } else if (field_type->IsSubtypeOf(TypeOracle::GetIntPtrType())) {
-    field_size = TargetArchitecture::RawPtrSize();
+  } else if (type->IsSubtypeOf(TypeOracle::GetIntPtrType())) {
+    size = TargetArchitecture::RawPtrSize();
     size_string = "kIntptrSize";
-  } else if (field_type->IsSubtypeOf(TypeOracle::GetUIntPtrType())) {
-    field_size = TargetArchitecture::RawPtrSize();
+  } else if (type->IsSubtypeOf(TypeOracle::GetUIntPtrType())) {
+    size = TargetArchitecture::RawPtrSize();
     size_string = "kIntptrSize";
-  } else if (const StructType* struct_type =
-                 StructType::DynamicCast(field_type)) {
-    field_size = struct_type->PackedSize();
-    size_string = std::to_string(field_size);
+  } else if (const StructType* struct_type = StructType::DynamicCast(type)) {
+    size = struct_type->PackedSize();
+    size_string = std::to_string(size);
   } else {
     return {};
   }
-  return std::make_tuple(field_size, size_string);
+  return std::make_tuple(size, size_string);
 }
 
 }  // namespace torque

src/torque/types.h

@@ -183,11 +183,6 @@ struct Field {
   // reliance of string types is quite clunky.
   std::tuple<size_t, std::string> GetFieldSizeInformation() const;
 
-  // Like GetFieldSizeInformation, but rather than raising an error if the
-  // field's size is unknown, it returns no value.
-  base::Optional<std::tuple<size_t, std::string>>
-  GetOptionalFieldSizeInformation() const;
-
   SourcePosition pos;
   const AggregateType* aggregate;
   base::Optional<NameAndType> index;
@@ -734,6 +729,8 @@ TypeVector LowerParameterTypes(const TypeVector& parameters);
 TypeVector LowerParameterTypes(const ParameterTypes& parameter_types,
                                size_t vararg_count = 0);
 
+base::Optional<std::tuple<size_t, std::string>> SizeOf(const Type* type);
+
 }  // namespace torque
 }  // namespace internal
 }  // namespace v8