[ObjC++] Make parameter passing and function return compatible with ObjC

    
ObjC and ObjC++ pass non-trivial structs in a way that is incompatible
with each other. For example:
    
typedef struct {
  id f0;
  __weak id f1;
} S;
    
// this code is compiled in c++.
extern "C" {
  void foo(S s);
}
    
void caller() {
  // the caller passes the parameter indirectly and destructs it.
  foo(S());
}
    
// this function is compiled in c.
// 'a' is passed directly and is destructed in the callee.
void foo(S a) {
}
    
This patch fixes the incompatibility by passing and returning structs
with __strong or weak fields using the C ABI in C++ mode. __strong and
__weak fields in a struct do not cause the struct to be destructed in
the caller and __strong fields do not cause the struct to be passed
indirectly.
    
Also, this patch fixes the microsoft ABI bug mentioned here:
    
https://reviews.llvm.org/D41039?id=128767#inline-364710
    
rdar://problem/38887866
    
Differential Revision: https://reviews.llvm.org/D44908


git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@328731 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 0 insertions, 3 deletions

diff --git a/test/CodeGenCXX/microsoft-abi-sret-and-byval.cpp b/test/CodeGenCXX/microsoft-abi-sret-and-byval.cpp
index f990c27426..36c9ca40db 100644
--- a/test/CodeGenCXX/microsoft-abi-sret-and-byval.cpp
+++ b/test/CodeGenCXX/microsoft-abi-sret-and-byval.cpp
@@ -172,12 +172,9 @@ void small_arg_with_dtor(SmallWithDtor s) {}
 void call_small_arg_with_dtor() {
   small_arg_with_dtor(SmallWithDtor());
 }
-// The temporary is copied, so it's destroyed in the caller as well as the
-// callee.
 // WIN64-LABEL: define dso_local void @"?call_small_arg_with_dtor@@YAXXZ"()
 // WIN64:   call %struct.SmallWithDtor* @"??0SmallWithDtor@@QEAA@XZ"
 // WIN64:   call void @"?small_arg_with_dtor@@YAXUSmallWithDtor@@@Z"(i32 %{{.*}})
-// WIN64:   call void @"??1SmallWithDtor@@QEAA@XZ"
 // WIN64:   ret void
 
 // Test that references aren't destroyed in the callee.