Add ObjCXX unit test for stret on WoA64

Author: hmelder

clang/test/CodeGenObjCXX/msabi-stret-arm64.mm

@@ -0,0 +1,77 @@
+// RUN: %clang_cc1 -triple aarch64-pc-windows-msvc -fobjc-runtime=gnustep-2.2 -fobjc-dispatch-method=non-legacy -emit-llvm -o - %s | FileCheck %s
+
+// Pass and return for type size <= 8 bytes.
+struct S1 {
+  int a[2];
+};
+
+// Pass and return hfa <= 8 bytes
+struct F1 {
+  float a[2];
+};
+
+// Pass and return for type size > 16 bytes.
+struct S2 {
+  int a[5];
+};
+
+// Pass and return aggregate (of size < 16 bytes) with non-trivial destructor.
+// Sret and inreg: Returned in x0
+struct S3 {
+  int a[3];
+  ~S3();
+};
+S3::~S3() {
+}
+
+
+@interface MsgTest { id isa; } @end
+@implementation MsgTest 
+- (S1) smallS1 {
+  S1 x;
+  x.a[0] = 0;
+  x.a[1] = 1;
+  return x;
+
+}
+- (F1) smallF1 {
+  F1 x;
+  x.a[0] = 0.2f;
+  x.a[1] = 0.5f;
+  return x;
+}
+- (S2) stretS2 {
+  S2 x;
+  for (int i = 0; i < 5; i++) {
+    x.a[i] = i;
+  }
+  return x;
+}
+- (S3) stretInRegS3 {
+  S3 x;
+  for (int i = 0; i < 3; i++) {
+    x.a[i] = i;
+  }
+  return x;
+}
++ (S3) msgTestStretInRegS3 {
+  S3 x;
+  for (int i = 0; i < 3; i++) {
+    x.a[i] = i;
+  }
+  return x;
+}
+@end
+
+void test0(MsgTest *t) {
+    // CHECK: call {{.*}} @objc_msgSend
+    S1 ret = [t smallS1];
+    // CHECK: call {{.*}} @objc_msgSend
+    F1 ret2 = [t smallF1];
+    // CHECK: call {{.*}} @objc_msgSend_stret
+    S2 ret3 = [t stretS2];
+    // CHECK: call {{.*}} @objc_msgSend_stret2_np
+    S3 ret4 = [t stretInRegS3];
+    // CHECK: call {{.*}} @objc_msgSend_stret2_np
+    S3 ret5 = [MsgTest msgTestStretInRegS3];
+}