IRGen: Start support for embedded existentials

Allow storing struct, enum, and tuple types in an any.

test/embedded/existential.swift

@@ -1,23 +1,78 @@
 // RUN: %target-swift-frontend -enable-experimental-feature EmbeddedExistentials -enable-experimental-feature Embedded -parse-as-library -wmo -emit-sil %s | %FileCheck %s
+// RUN: %target-run-simple-swift(-enable-experimental-feature EmbeddedExistentials -enable-experimental-feature Embedded -parse-as-library -wmo) | %FileCheck %s --check-prefix=OUTPUT
 
 // REQUIRES: swift_in_compiler
+// REQUIRES: executable_test
 // REQUIRES: optimized_stdlib
 // REQUIRES: swift_feature_Embedded
 // REQUIRES: swift_feature_EmbeddedExistentials
 
-class C {}
+class CP {
+}
+
+class C : CP {
+    func foo() { }
+}
+
+class GC<T> {
+    var x: T? = nil
+    func foo() {}
+    deinit {
+        print("deinit called")
+    }
+}
+
+struct StructWithClass {
+    var c = GC<Int>()
+}
+
+struct GenericStructWithClass<T> {
+    var c = GC<T>()
+    var d = GC<T>()
+}
+
+enum EnumWithClass {
+    case a
+    case c(GC<Int>)
+}
+
+enum GenericEnumWithClass<T> {
+    case a
+    case c(GC<T>)
+}
 
 // CHECK: sil @$e11existential4testyyF
 // CHECK: init_existential_addr
 // CHECK: } // end sil function '$e11existential4testyyF'
 
+// There are 8 class instances that are destroyed.
+
+// OUTPUT:  deinit called
+// OUTPUT:  deinit called
+// OUTPUT:  deinit called
+// OUTPUT:  deinit called
+
+// OUTPUT:  deinit called
+// OUTPUT:  deinit called
+// OUTPUT:  deinit called
+// OUTPUT:  deinit called
+
+// OUTPUT-NOT:  deinit called
+
 func test() {
-  let any: any Any = C()
+    let _: any Any = GC<Int>()
+    let _: any Any = 3
+    let _: any Any = StructWithClass()
+    let _: any Any = GenericStructWithClass<Int>()
+    let _: any Any = EnumWithClass.c(GC<Int>())
+    let _: any Any = GenericEnumWithClass.c(GC<Int>())
+    let _: any Any = (3, 4)
+    let _: any Any = (StructWithClass(), StructWithClass())
 }
 
 @main
 struct Main {
-  static func main() {
-    test()
-  }
+    static func main() {
+        test()
+    }
 }