[test] Add IRGen test for .cxx_destruct method signature

Author: fay59

test/IRGen/objc_methods.swift

@@ -25,16 +25,24 @@ class Foo: Fooable {
   @IBAction func garply(_: AnyObject?) {}
   @objc func block(_: (Int) -> Int) {}
   @objc func block2(_: (Int,Int) -> Int) {}
-
+  
   @objc func takesString(_ x: String) -> String { return x }
   @objc func takesArray(_ x: [AnyObject]) -> [AnyObject] { return x }
   @objc func takesDict(_ x: [NSObject: AnyObject]) -> [NSObject: AnyObject] { return x }
   @objc func takesSet(_ x: Set<NSObject>) -> Set<NSObject> { return x }
-
+  
   @objc func fail() throws {}
 }
 
-// CHECK: [[BAZ_SIGNATURE:@.*]] = private unnamed_addr constant [8 x i8] c"v16@0:8\00"
+class ObjcDestructible: NSObject {
+  var object: NSObject
+  
+  init(object: NSObject) {
+    self.object = object
+  }
+}
+
+// CHECK: [[IMPLICIT_PARAMS_SIGNATURE:@.*]] = private unnamed_addr constant [8 x i8] c"v16@0:8\00"
 // CHECK: [[GARPLY_SIGNATURE:@.*]] = private unnamed_addr constant [11 x i8] c"v24@0:8@16\00"
 // CHECK: [[BLOCK_SIGNATURE_TRAD:@.*]] = private unnamed_addr constant [12 x i8] c"v24@0:8@?16\00"
 // CHECK-macosx: [[FAIL_SIGNATURE:@.*]] = private unnamed_addr constant [12 x i8] c"c24@0:8^@16\00"
@@ -45,7 +53,7 @@ class Foo: Fooable {
 // CHECK:   i32 9,
 // CHECK:   [9 x { i8*, i8*, i8* }] [{
 // CHECK:     i8* getelementptr inbounds ([4 x i8], [4 x i8]* @"\01L_selector_data(baz)", i64 0, i64 0),
-// CHECK:     i8* getelementptr inbounds ([8 x i8], [8 x i8]* [[BAZ_SIGNATURE]], i64 0, i64 0),
+// CHECK:     i8* getelementptr inbounds ([8 x i8], [8 x i8]* [[IMPLICIT_PARAMS_SIGNATURE]], i64 0, i64 0),
 // CHECK:     i8* bitcast (void (i8*, i8*)* @"$S12objc_methods3FooC3bazyyFTo" to i8*)
 // CHECK:   }, {
 // CHECK:     i8* getelementptr inbounds ([8 x i8], [8 x i8]* @"\01L_selector_data(garply:)", i64 0, i64 0),
@@ -66,6 +74,15 @@ class Foo: Fooable {
 // CHECK-ios:     i8* bitcast (i1 (i8*, i8*, %4**)* @"$S12objc_methods3FooC4failyyKFTo" to i8*)
 // CHECK:   }]
 // CHECK: }, section "__DATA, __objc_const", align 8
+// CHECK: @_INSTANCE_METHODS__TtC12objc_methods16ObjcDestructible = private constant { {{.*}}] } {
+// CHECK:   i32 24,
+// CHECK:   i32 2,
+// CHECK:   [2 x { i8*, i8*, i8* }] [{
+// CHECK:     i8* getelementptr inbounds ([14 x i8], [14 x i8]* @"\01L_selector_data(.cxx_destruct)", i64 0, i64 0),
+// CHECK:     i8* getelementptr inbounds ([8 x i8], [8 x i8]* [[IMPLICIT_PARAMS_SIGNATURE]], i64 0, i64 0),
+// CHECK:     i8* bitcast (void (%6*, i8*)* @"$S12objc_methods16ObjcDestructibleCfETo" to i8*) }]
+// CHECK:   }]
+// CHECK: }, section "__DATA, __objc_const", align 8
 // CHECK: [[BLOCK_SIGNATURE_EXT_1:@.*]] = private unnamed_addr constant [18 x i8] c"v24@0:8@?<q@?q>16\00"
 // CHECK: [[BLOCK_SIGNATURE_EXT_2:@.*]] = private unnamed_addr constant [19 x i8] c"v24@0:8@?<q@?qq>16\00"
 // CHECK: [[STRING_SIGNATURE_EXT:@.*]] = private unnamed_addr constant [31 x i8] c"@\22NSString\2224@0:8@\22NSString\2216\00"