[torque] Generate bitfield definitions as macros

The list of forward declarations required in the generated file
bit-fields-tq.h is already somewhat unwieldy and will run into serious
problems when we attempt to use enums that are defined within classes,
such as JSDateTimeFormat::DateTimeStyle. After a brief discussion today,
the cleanest solution we arrived at is to generate macros instead.

Change-Id: I654e10efbab5a1a0a340fa565c51ff1da34badaa
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2050830Reviewed-by: Tobias Tebbi <tebbi@chromium.org>
Reviewed-by: Nico Hartmann <nicohartmann@chromium.org>
Commit-Queue: Seth Brenith <seth.brenith@microsoft.com>
Cr-Commit-Position: refs/heads/master@{#66240}

src/objects/debug-objects.h

@@ -24,10 +24,10 @@ class BytecodeArray;
 
 // The DebugInfo class holds additional information for a function being
 // debugged.
-class DebugInfo : public TorqueGeneratedDebugInfo<DebugInfo, Struct>,
-                  public TorqueGeneratedDebugInfoFlagsFields {
+class DebugInfo : public TorqueGeneratedDebugInfo<DebugInfo, Struct> {
  public:
   NEVER_READ_ONLY_SPACE
+  DEFINE_TORQUE_GENERATED_DEBUG_INFO_FLAGS()
   using Flags = base::Flags<Flag>;
 
   // A bitfield that lists uses of the current instance.

src/objects/map.h

@@ -253,7 +253,9 @@ class Map : public HeapObject {
   DECL_PRIMITIVE_ACCESSORS(relaxed_bit_field, byte)
 
   // Bit positions for |bit_field|.
-  using Bits1 = TorqueGeneratedMapBitFields1Fields;
+  struct Bits1 {
+    DEFINE_TORQUE_GENERATED_MAP_BIT_FIELDS1()
+  };
 
   //
   // Bit field 2.
@@ -261,7 +263,9 @@ class Map : public HeapObject {
   DECL_PRIMITIVE_ACCESSORS(bit_field2, byte)
 
   // Bit positions for |bit_field2|.
-  using Bits2 = TorqueGeneratedMapBitFields2Fields;
+  struct Bits2 {
+    DEFINE_TORQUE_GENERATED_MAP_BIT_FIELDS2()
+  };
 
   //
   // Bit field 3.
@@ -273,7 +277,9 @@ class Map : public HeapObject {
   V8_INLINE void clear_padding();
 
   // Bit positions for |bit_field3|.
-  using Bits3 = TorqueGeneratedMapBitFields3Fields;
+  struct Bits3 {
+    DEFINE_TORQUE_GENERATED_MAP_BIT_FIELDS3()
+  };
 
   // Ensure that Torque-defined bit widths for |bit_field3| are as expected.
   STATIC_ASSERT(Bits3::EnumLengthBits::kSize == kDescriptorIndexBitCount);

src/objects/name.h

@@ -139,9 +139,10 @@ class Name : public TorqueGeneratedName<Name, PrimitiveHeapObject> {
 };
 
 // ES6 symbols.
-class Symbol : public TorqueGeneratedSymbol<Symbol, Name>,
-               public TorqueGeneratedSymbolFlagsFields {
+class Symbol : public TorqueGeneratedSymbol<Symbol, Name> {
  public:
+  DEFINE_TORQUE_GENERATED_SYMBOL_FLAGS()
+
   // [is_private]: Whether this is a private symbol.  Private symbols can only
   // be used to designate own properties of objects.
   DECL_BOOLEAN_ACCESSORS(is_private)

src/objects/scope-info.h

@@ -37,8 +37,10 @@ class Zone;
 
 // This object provides quick access to scope info details for runtime
 // routines.
-class ScopeInfo : public FixedArray, public TorqueGeneratedScopeFlagsFields {
+class ScopeInfo : public FixedArray {
  public:
+  DEFINE_TORQUE_GENERATED_SCOPE_FLAGS()
+
   DECL_CAST(ScopeInfo)
   DECL_PRINTER(ScopeInfo)
 

src/objects/shared-function-info.h

@@ -167,10 +167,10 @@ class InterpreterData : public Struct {
 
 // SharedFunctionInfo describes the JSFunction information that can be
 // shared by multiple instances of the function.
-class SharedFunctionInfo : public HeapObject,
-                           public TorqueGeneratedSharedFunctionInfoFlagsFields {
+class SharedFunctionInfo : public HeapObject {
  public:
   NEVER_READ_ONLY_SPACE
+  DEFINE_TORQUE_GENERATED_SHARED_FUNCTION_INFO_FLAGS()
 
   // This initializes the SharedFunctionInfo after allocation. It must
   // initialize all fields, and leave the SharedFunctionInfo in a state where

src/torque/csa-generator.cc

@@ -858,9 +858,12 @@ void CSAGenerator::EmitInstruction(const StoreReferenceInstruction& instruction,
 namespace {
 std::string GetBitFieldSpecialization(const BitFieldStructType* container,
                                       const BitField& field) {
-  std::string suffix = field.num_bits == 1 ? "Bit" : "Bits";
-  return "TorqueGenerated" + container->name() +
-         "Fields::" + CamelifyString(field.name_and_type.name) + suffix;
+  std::stringstream stream;
+  stream << "base::BitField<"
+         << field.name_and_type.type->GetConstexprGeneratedTypeName() << ", "
+         << field.offset << ", " << field.num_bits << ", "
+         << container->GetConstexprGeneratedTypeName() << ">";
+  return stream.str();
 }
 }  // namespace
 

src/torque/implementation-visitor.cc

@@ -3250,20 +3250,11 @@ void ImplementationVisitor::GenerateBitFields(
     header << "#include \"src/base/bit-field.h\"\n\n";
     NamespaceScope namespaces(header, {"v8", "internal"});
 
-    // TODO(v8:7793): Once we can define enums in Torque, we should be able to
-    // do something nicer than hard-coding these predeclarations. Until then,
-    // any enum used as a bitfield must be included in this list.
-    header << R"(
-enum class FunctionSyntaxKind : uint8_t;
-enum class BailoutReason : uint8_t;
-enum FunctionKind : uint8_t;
-
-)";
-
     for (const auto& type : TypeOracle::GetBitFieldStructTypes()) {
       bool all_single_bits = true;  // Track whether every field is one bit.
 
-      header << "struct TorqueGenerated" << type->name() << "Fields {\n";
+      header << "#define DEFINE_TORQUE_GENERATED_"
+             << CapifyStringWithUnderscores(type->name()) << "() \\\n";
       std::string type_name = type->GetConstexprGeneratedTypeName();
       for (const auto& field : type->fields()) {
         const char* suffix = field.num_bits == 1 ? "Bit" : "Bits";
@@ -3273,21 +3264,21 @@ enum FunctionKind : uint8_t;
         header << "  using " << CamelifyString(field.name_and_type.name)
                << suffix << " = base::BitField<" << field_type_name << ", "
                << field.offset << ", " << field.num_bits << ", " << type_name
-               << ">;\n";
+               << ">; \\\n";
       }
 
       // If every field is one bit, we can also generate a convenient enum.
       if (all_single_bits) {
-        header << "  enum Flag {\n";
-        header << "    kNone = 0,\n";
+        header << "  enum Flag { \\\n";
+        header << "    kNone = 0, \\\n";
         for (const auto& field : type->fields()) {
           header << "    k" << CamelifyString(field.name_and_type.name)
-                 << " = 1 << " << field.offset << ",\n";
+                 << " = 1 << " << field.offset << ", \\\n";
         }
-        header << "  };\n";
+        header << "  }; \\\n";
       }
 
-      header << "};\n\n";
+      header << "\n";
     }
   }
   const std::string output_header_path = output_directory + "/" + file_name;