IRGen: Clang type lowering for subclass existentials

It looks like this is really only used in one place, the
"extended encoding" for @objc protocol metadata.

If it wasn't for that, we could just lower all class and
existential types as 'id'.

Author: slavapestov

lib/IRGen/GenClangType.cpp

@@ -599,27 +599,39 @@ clang::CanQualType GenClangType::visitSILBlockStorageType(CanSILBlockStorageType
 
 clang::CanQualType GenClangType::visitProtocolCompositionType(
   CanProtocolCompositionType type) {
+  auto &clangCtx = getClangASTContext();
+
   // FIXME. Eventually, this will have its own helper routine.
   SmallVector<const clang::ObjCProtocolDecl *, 4> Protocols;
   auto layout = type.getExistentialLayout();
-  assert(layout.requiresClass && "Cannot represent opaque existential in Clang");
-  assert(!layout.superclass && "Subclass existentials not supported here yet");
+  assert(layout.isObjC() && "Cannot represent opaque existential in Clang");
+
+  auto superclassTy = clangCtx.ObjCBuiltinIdTy;
+  if (layout.superclass) {
+    superclassTy = clangCtx.getCanonicalType(
+      cast<clang::ObjCObjectPointerType>(
+        Converter.convert(IGM, CanType(layout.superclass)))
+        ->getPointeeType());
+  }
+
   for (Type t : layout.getProtocols()) {
     auto opt = cast<clang::ObjCObjectPointerType>(
       Converter.convert(IGM, CanType(t)));
     for (auto p : opt->quals())
       Protocols.push_back(p);
   }
 
-  auto &clangCtx = getClangASTContext();
   if (Protocols.empty())
-    return getClangIdType(clangCtx);
+    return superclassTy;
+
   // id<protocol-list>
-  clang::ObjCProtocolDecl **ProtoQuals = new(clangCtx) clang::ObjCProtocolDecl*[Protocols.size()];
-  memcpy(ProtoQuals, Protocols.data(), sizeof(clang::ObjCProtocolDecl*)*Protocols.size());
-  auto clangType = clangCtx.getObjCObjectType(clangCtx.ObjCBuiltinIdTy,
-                     ProtoQuals,
-                     Protocols.size());
+  clang::ObjCProtocolDecl **ProtoQuals =
+    new(clangCtx) clang::ObjCProtocolDecl*[Protocols.size()];
+  memcpy(ProtoQuals, Protocols.data(),
+         sizeof(clang::ObjCProtocolDecl*)*Protocols.size());
+  auto clangType = clangCtx.getObjCObjectType(superclassTy,
+                                              ProtoQuals,
+                                              Protocols.size());
   auto ptrTy = clangCtx.getObjCObjectPointerType(clangType);
   return clangCtx.getCanonicalType(ptrTy);
 }

test/IRGen/objc_type_encoding.swift

@@ -1,6 +1,6 @@
 // RUN: rm -rf %t && mkdir -p %t
 // RUN: %build-irgen-test-overlays
-// RUN: %target-swift-frontend(mock-sdk: -sdk %S/Inputs -I %t) %s -emit-ir -disable-objc-attr-requires-foundation-module | %FileCheck %s -check-prefix=CHECK-%target-os
+// RUN: %target-swift-frontend(mock-sdk: -sdk %S/Inputs -I %t) %s -emit-ir -disable-objc-attr-requires-foundation-module -enable-experimental-subclass-existentials | %FileCheck %s -check-prefix=CHECK-%target-os
 
 // REQUIRES: CPU=x86_64
 // REQUIRES: objc_interop
@@ -163,17 +163,21 @@ import gizmo
 	func myMethod2(_ arg : NSRuncing & NSFunging)
   func readWithAuthorization(_ authData : Gizmo, reply : (NSView, NSSpoon) -> Void)
   func doSomething(_ context: MyCustomObject)
+  func subclassComposition(_: MyCustomObject & NSRuncing & NSFunging)
 }
 
 // CHECK-macosx: [[ENC1:@.*]] = private unnamed_addr constant [35 x i8] c"v24@0:8@\22<NSFunging><NSRuncing>\2216\00"
 // CHECK-macosx: [[ENC2:@.*]] = private unnamed_addr constant [46 x i8] c"v32@0:8@\22Gizmo\2216@?<v@?@\22NSView\22@\22NSSpoon\22>24\00"
 // CHECK-macosx: [[ENC3:@.*]] = private unnamed_addr constant [53 x i8] c"v24@0:8@\22_TtC18objc_type_encoding14MyCustomObject\2216\00"
-// CHECK-macosx: @_PROTOCOL_METHOD_TYPES__TtP18objc_type_encoding10MyProtocol_ = private constant [3 x i8*] [i8* getelementptr inbounds ([35 x i8], [35 x i8]* [[ENC1]], i64 0, i64 0), i8* getelementptr inbounds ([46 x i8], [46 x i8]* [[ENC2]], i64 0, i64 0), i8* getelementptr inbounds ([53 x i8], [53 x i8]* [[ENC3]], i64 0, i64 0)]
+// CHECK-macosx: [[ENC4:@.*]] = private unnamed_addr constant [75 x i8] c"v24@0:8@\22_TtC18objc_type_encoding14MyCustomObject<NSFunging><NSRuncing>\2216\00"
+// CHECK-macosx: @_PROTOCOL_METHOD_TYPES__TtP18objc_type_encoding10MyProtocol_ = private constant [4 x i8*] [i8* getelementptr inbounds ([35 x i8], [35 x i8]* [[ENC1]], i64 0, i64 0), i8* getelementptr inbounds ([46 x i8], [46 x i8]* [[ENC2]], i64 0, i64 0), i8* getelementptr inbounds ([53 x i8], [53 x i8]* [[ENC3]], i64 0, i64 0), i8* getelementptr inbounds ([75 x i8], [75 x i8]* [[ENC4]], i64 0, i64 0)]
 // CHECK-ios: [[ENC1:@.*]] = private unnamed_addr constant [35 x i8] c"v24@0:8@\22<NSFunging><NSRuncing>\2216\00"
 // CHECK-ios: [[ENC2:@.*]] = private unnamed_addr constant [46 x i8] c"v32@0:8@\22Gizmo\2216@?<v@?@\22NSView\22@\22NSSpoon\22>24\00"
 // CHECK-ios: [[ENC3:@.*]] = private unnamed_addr constant [53 x i8] c"v24@0:8@\22_TtC18objc_type_encoding14MyCustomObject\2216\00"
-// CHECK-ios: @_PROTOCOL_METHOD_TYPES__TtP18objc_type_encoding10MyProtocol_ = private constant [3 x i8*] [i8* getelementptr inbounds ([35 x i8], [35 x i8]* [[ENC1]], i64 0, i64 0), i8* getelementptr inbounds ([46 x i8], [46 x i8]* [[ENC2]], i64 0, i64 0), i8* getelementptr inbounds ([53 x i8], [53 x i8]* [[ENC3]], i64 0, i64 0)]
+// CHECK-ios: [[ENC4:@.*]] = private unnamed_addr constant [75 x i8] c"v24@0:8@\22_TtC18objc_type_encoding14MyCustomObject<NSFunging><NSRuncing>\2216\00"
+// CHECK-ios: @_PROTOCOL_METHOD_TYPES__TtP18objc_type_encoding10MyProtocol_ = private constant [4 x i8*] [i8* getelementptr inbounds ([35 x i8], [35 x i8]* [[ENC1]], i64 0, i64 0), i8* getelementptr inbounds ([46 x i8], [46 x i8]* [[ENC2]], i64 0, i64 0), i8* getelementptr inbounds ([53 x i8], [53 x i8]* [[ENC3]], i64 0, i64 0), i8* getelementptr inbounds ([75 x i8], [75 x i8]* [[ENC4]], i64 0, i64 0)]
 // CHECK-tvos: [[ENC1:@.*]] = private unnamed_addr constant [35 x i8] c"v24@0:8@\22<NSFunging><NSRuncing>\2216\00"
 // CHECK-tvos: [[ENC2:@.*]] = private unnamed_addr constant [46 x i8] c"v32@0:8@\22Gizmo\2216@?<v@?@\22NSView\22@\22NSSpoon\22>24\00"
 // CHECK-tvos: [[ENC3:@.*]] = private unnamed_addr constant [53 x i8] c"v24@0:8@\22_TtC18objc_type_encoding14MyCustomObject\2216\00"
-// CHECK-tvos: @_PROTOCOL_METHOD_TYPES__TtP18objc_type_encoding10MyProtocol_ = private constant [3 x i8*] [i8* getelementptr inbounds ([35 x i8], [35 x i8]* [[ENC1]], i64 0, i64 0), i8* getelementptr inbounds ([46 x i8], [46 x i8]* [[ENC2]], i64 0, i64 0), i8* getelementptr inbounds ([53 x i8], [53 x i8]* [[ENC3]], i64 0, i64 0)]
+// CHECK-tvos: [[ENC4:@.*]] = private unnamed_addr constant [75 x i8] c"v24@0:8@\22_TtC18objc_type_encoding14MyCustomObject<NSFunging><NSRuncing>\2216\00"
+// CHECK-tvos: @_PROTOCOL_METHOD_TYPES__TtP18objc_type_encoding10MyProtocol_ = private constant [4 x i8*] [i8* getelementptr inbounds ([35 x i8], [35 x i8]* [[ENC1]], i64 0, i64 0), i8* getelementptr inbounds ([46 x i8], [46 x i8]* [[ENC2]], i64 0, i64 0), i8* getelementptr inbounds ([53 x i8], [53 x i8]* [[ENC3]], i64 0, i64 0), i8* getelementptr inbounds ([75 x i8], [75 x i8]* [[ENC4]], i64 0, i64 0)]