Add Builtin.addressOfRawLayout

Author: Azoy

include/swift/AST/Builtins.def

@@ -1107,6 +1107,13 @@ BUILTIN_MISC_OPERATION_WITH_SILGEN(InjectEnumTag, "injectEnumTag", "", Special)
 /// `any Actor` existential that refers to the local actor.
 BUILTIN_MISC_OPERATION_WITH_SILGEN(DistributedActorAsAnyActor, "distributedActorAsAnyActor", "n", Special)
 
+/// addressOfRawLayout: <T: ~Copyable>(_: borrowing T) -> Builtin.RawPointer
+///
+/// Returns a raw pointer to the address of the raw layout type. This address is
+/// only valid during a borrow access of the raw layout type or until the value
+/// is either moved or consumed.
+BUILTIN_SIL_OPERATION(AddressOfRawLayout, "addressOfRawLayout", Special)
+
 /// Builtins for instrumentation added by sanitizers during SILGen.
 #ifndef BUILTIN_SANITIZER_OPERATION
 #define BUILTIN_SANITIZER_OPERATION(Id, Name, Attrs) BUILTIN(Id, Name, Attrs)

include/swift/Basic/Features.def

@@ -170,6 +170,7 @@ LANGUAGE_FEATURE(ExpressionMacroDefaultArguments, 422, "Expression macro as call
 LANGUAGE_FEATURE(BuiltinStoreRaw, 0, "Builtin.storeRaw")
 LANGUAGE_FEATURE(BuiltinCreateTask, 0, "Builtin.createTask and Builtin.createDiscardingTask")
 SUPPRESSIBLE_LANGUAGE_FEATURE(AssociatedTypeImplements, 0, "@_implements on associated types")
+LANGUAGE_FEATURE(BuiltinAddressOfRawLayout, 0, "Builtin.addressOfRawLayout")
 
 // Swift 6
 UPCOMING_FEATURE(ConciseMagicFile, 274, 6)

lib/AST/Builtins.cpp

@@ -2118,6 +2118,15 @@ static ValueDecl *getInjectEnumTag(ASTContext &ctx, Identifier id) {
   return builder.build(id);
 }
 
+static ValueDecl *getAddressOfRawLayout(ASTContext &ctx, Identifier id) {
+  BuiltinFunctionBuilder builder(ctx, /* genericParamCount */ 1);
+
+  builder.addParameter(makeGenericParam(), ParamSpecifier::Borrowing);
+  builder.setResult(makeConcrete(ctx.TheRawPointerType));
+
+  return builder.build(id);
+}
+
 /// An array of the overloaded builtin kinds.
 static const OverloadedBuiltinKind OverloadedBuiltinKinds[] = {
   OverloadedBuiltinKind::None,
@@ -3191,6 +3200,9 @@ ValueDecl *swift::getBuiltinValueDecl(ASTContext &Context, Identifier Id) {
 
   case BuiltinValueKind::DistributedActorAsAnyActor:
     return getDistributedActorAsAnyActor(Context, Id);
+
+  case BuiltinValueKind::AddressOfRawLayout:
+    return getAddressOfRawLayout(Context, Id);
   }
 
   llvm_unreachable("bad builtin value!");

lib/AST/FeatureSet.cpp

@@ -359,6 +359,7 @@ static bool usesFeatureExpressionMacroDefaultArguments(Decl *decl) {
 }
 
 UNINTERESTING_FEATURE(BuiltinStoreRaw)
+UNINTERESTING_FEATURE(BuiltinAddressOfRawLayout)
 
 // ----------------------------------------------------------------------------
 // MARK: - Upcoming Features

lib/SILGen/SILGenBuiltin.cpp

@@ -2012,6 +2012,21 @@ static ManagedValue emitBuiltinDistributedActorAsAnyActor(
   return SGF.emitDistributedActorAsAnyActor(loc, subs, args[0]);
 }
 
+static ManagedValue emitBuiltinAddressOfRawLayout(SILGenFunction &SGF,
+                                                  SILLocation loc,
+                                                  SubstitutionMap subs,
+                                                  ArrayRef<ManagedValue> args,
+                                                  SGFContext C) {
+  auto &ctx = SGF.getASTContext();
+
+  auto bi = SGF.B.createBuiltin(
+    loc, ctx.getIdentifier(getBuiltinName(BuiltinValueKind::AddressOfRawLayout)),
+    SILType::getRawPointerType(ctx), subs,
+    { args[0].getValue() });
+
+  return ManagedValue::forObjectRValueWithoutOwnership(bi);
+}
+
 std::optional<SpecializedEmitter>
 SpecializedEmitter::forDecl(SILGenModule &SGM, SILDeclRef function) {
   // Only consider standalone declarations in the Builtin module.