IRGen: Emit reflection metadata for certain builtin types when -enable-reflection-builtins flag is passed in

These types are not directly referenced as fields of aggregate types,
but are needed for reflection type lowering.

Also, use a SetVector to collect referenced builtin types, instead of
a SmallPtrSet, to ensure compiler output is deterministic.

cmake/modules/AddSwift.cmake

@@ -406,6 +406,8 @@ function(_compile_swift_files dependency_target_out_var_name)
   if(SWIFTFILE_IS_STDLIB_CORE)
     list(APPEND swift_flags
         "-nostdimport" "-parse-stdlib" "-module-name" "Swift")
+    list(APPEND swift_flags
+        "-Xfrontend" "-enable-reflection-builtins")
     list(APPEND swift_flags "-Xfrontend" "-group-info-path"
                             "-Xfrontend" "${GROUP_INFO_JSON_FILE}")
     if (NOT SWIFT_STDLIB_ENABLE_RESILIENCE)

include/swift/AST/IRGenOptions.h

@@ -146,6 +146,10 @@ public:
   /// Emit names of struct stored properties and enum cases.
   unsigned EnableReflectionNames : 1;
 
+  /// Emit metadata for certain builtin types. Only for use by
+  /// standard library.
+  unsigned EnableReflectionBuiltins : 1;
+
   /// List of backend command-line options for -embed-bitcode.
   std::vector<uint8_t> CmdArgs;
 
@@ -166,7 +170,8 @@ public:
                    PrintInlineTree(false), EmbedMode(IRGenEmbedMode::None),
                    HasValueNamesSetting(false), ValueNames(false),
                    EnableReflectionMetadata(false), EnableReflectionNames(false),
-                   CmdArgs(), UseIncrementalLLVMCodeGen(true)
+                   EnableReflectionBuiltins(false), CmdArgs(),
+                   UseIncrementalLLVMCodeGen(true)
                    {}
 
   /// Gets the name of the specified output filename.

include/swift/Option/FrontendOptions.td

@@ -197,6 +197,10 @@ def enable_reflection_names : Flag<["-"], "enable-reflection-names">,
   HelpText<"Enable emission of names of stored properties and enum cases in"
            "reflection metadata">;
 
+def enable_reflection_builtins : Flag<["-"], "enable-reflection-builtins">,
+  HelpText<"Enable emission of reflection metadata for builtin types"
+           " (standard library only)">;
+
 def stack_promotion_checks : Flag<["-"], "emit-stack-promotion-checks">,
   HelpText<"Emit runtime checks for correct stack promotion of objects.">;
 

lib/Frontend/CompilerInvocation.cpp

@@ -1282,6 +1282,9 @@ static bool ParseIRGenArgs(IRGenOptions &Opts, ArgList &Args,
     if (Args.hasArg(OPT_enable_reflection_names)) {
       Opts.EnableReflectionNames = true;
     }
+    if (Args.hasArg(OPT_enable_reflection_builtins)) {
+      Opts.EnableReflectionBuiltins = true;
+    }
   }
 
   return false;

lib/IRGen/GenReflection.cpp

@@ -31,7 +31,7 @@ using namespace irgen;
 
 class ReflectionMetadataBuilder : public ConstantBuilder<> {
 protected:
-  SmallPtrSetImpl<CanType> &BuiltinTypes;
+  llvm::SetVector<CanType> &BuiltinTypes;
 
   // Collect any builtin types referenced from this type.
   void addBuiltinTypeRefs(CanType type) {
@@ -54,7 +54,7 @@ protected:
 
 public:
   ReflectionMetadataBuilder(IRGenModule &IGM,
-                            SmallPtrSetImpl<CanType> &BuiltinTypes)
+                            llvm::SetVector<CanType> &BuiltinTypes)
     : ConstantBuilder(IGM), BuiltinTypes(BuiltinTypes) {}
 };
 
@@ -127,7 +127,7 @@ public:
   AssociatedTypeMetadataBuilder(IRGenModule &IGM,
     ArrayRef<const NominalTypeDecl *> NominalTypeDecls,
     ArrayRef<const ExtensionDecl *> ExtensionDecls,
-    SmallPtrSetImpl<CanType> &BuiltinTypes)
+    llvm::SetVector<CanType> &BuiltinTypes)
     : ReflectionMetadataBuilder(IGM, BuiltinTypes),
       NominalTypeDecls(NominalTypeDecls),
       ExtensionDecls(ExtensionDecls) {}
@@ -237,7 +237,7 @@ class FieldTypeMetadataBuilder : public ReflectionMetadataBuilder {
 public:
   FieldTypeMetadataBuilder(IRGenModule &IGM,
                            ArrayRef<const NominalTypeDecl *> NominalTypeDecls,
-                           SmallPtrSetImpl<CanType> &BuiltinTypes)
+                           llvm::SetVector<CanType> &BuiltinTypes)
     : ReflectionMetadataBuilder(IGM, BuiltinTypes),
       NominalTypeDecls(NominalTypeDecls) {}
 
@@ -273,7 +273,7 @@ class BuiltinTypeMetadataBuilder : public ReflectionMetadataBuilder {
   void addBuiltinType(CanType builtinType) {
     addTypeRef(builtinType->getASTContext().TheBuiltinModule, builtinType);
 
-    auto &ti = cast<LoadableTypeInfo>(IGM.getTypeInfoForUnlowered(builtinType));
+    auto &ti = cast<FixedTypeInfo>(IGM.getTypeInfoForUnlowered(builtinType));
     addConstantInt32(ti.getFixedSize().getValue());
     addConstantInt32(ti.getFixedAlignment().getValue());
     addConstantInt32(ti.getFixedStride().getValue());
@@ -288,7 +288,7 @@ class BuiltinTypeMetadataBuilder : public ReflectionMetadataBuilder {
 
 public:
   BuiltinTypeMetadataBuilder(IRGenModule &IGM,
-                             SmallPtrSetImpl<CanType> &BuiltinTypes)
+                             llvm::SetVector<CanType> &BuiltinTypes)
     : ReflectionMetadataBuilder(IGM, BuiltinTypes) {}
 
   llvm::GlobalVariable *emit() {
@@ -381,7 +381,8 @@ llvm::Constant *IRGenModule::getAddrOfStringForTypeRef(StringRef Str) {
 
 void IRGenModule::emitReflectionMetadataRecords() {
   auto DoNotHaveDecls = NominalTypeDecls.empty() && ExtensionDecls.empty();
-  if (!Opts.EnableReflectionMetadata || DoNotHaveDecls)
+  if (!Opts.EnableReflectionMetadata ||
+      (!Opts.EnableReflectionBuiltins && DoNotHaveDecls))
     return;
 
   // We collect all referenced builtin types and emit records for them.
@@ -389,7 +390,7 @@ void IRGenModule::emitReflectionMetadataRecords() {
   // builtin types.
   //
   // FIXME: This metadata should be in the runtime instead.
-  SmallPtrSet<CanType, 4> BuiltinTypes;
+  llvm::SetVector<CanType> BuiltinTypes;
 
   {
     FieldTypeMetadataBuilder builder(*this, NominalTypeDecls, BuiltinTypes);
@@ -408,7 +409,13 @@ void IRGenModule::emitReflectionMetadataRecords() {
       addUsedGlobal(var);
   }
 
-  {
+  if (Opts.EnableReflectionBuiltins) {
+    BuiltinTypes.insert(Context.TheNativeObjectType);
+    BuiltinTypes.insert(Context.TheUnknownObjectType);
+    BuiltinTypes.insert(Context.TheBridgeObjectType);
+    BuiltinTypes.insert(Context.TheRawPointerType);
+    BuiltinTypes.insert(Context.TheUnsafeValueBufferType);
+
     BuiltinTypeMetadataBuilder builder(*this, BuiltinTypes);
     auto var = builder.emit();
     if (var)