[libc++][AIX] Fix trivial_abi return tests for unique_ptr/weak_ptr

[jsji]

Summary

The unique_ptr_ret and weak_ptr_ret tests are not expected to pass on
AIX. These tests check that unique_ptr and weak_ptr are returned by
value, but on AIX, all structs are always returned by reference.

3.9.6 Function Return Values
...

Note: Structures of any length and character strings longer than four
bytes are returned in a storage buffer allocated by the caller. The
address of this buffer is passed as a hidden first argument in GPR3,
which causes the first explicit argument word to be passed in GPR4. This
hidden argument is treated as a formal argument and corresponds to the
first word of the argument area.

[• Quuxplusone]

libcxx/test/libcxx/memory/trivial_abi/weak_ptr_ret.pass.cpp

54

This PR LGTM, but for what it's worth, I wonder whether defined(__arm__) might also be true on ARM64...

[jsji]

libcxx/test/libcxx/memory/trivial_abi/weak_ptr_ret.pass.cpp

54

Thanks. @Quuxplusone.

I am not familiar with arm, it looks like to me that at least clang does not define __arm__ for AArch64, it use __aarch64__ instead.

[daltenty]

LGTM, thanks!

[jsji]

Ping.. Can someone in libc++ group help to have a quick look? This only affect AIX test. Thank you so much!

[jsji]

Thank you so much Nikolas! @philnik

libcxx/test/libcxx/memory/trivial_abi/unique_ptr_ret.pass.cpp

 //===----------------------------------------------------------------------===//
 //
 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
 // See https://llvm.org/LICENSE.txt for license information.
 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
 //
 //===----------------------------------------------------------------------===//
 
-// XFAIL: LIBCXX-AIX-FIXME
-
 // <memory>
 
 // Test unique_ptr<T> with trivial_abi as return-type.
 
 // ADDITIONAL_COMPILE_FLAGS: -D_LIBCPP_ABI_ENABLE_UNIQUE_PTR_TRIVIAL_ABI
 
 // XFAIL: gcc
 
int main(int, char**) {
   auto ret = make_val(&local_addr);
   assert(local_addr != nullptr);
 
   // Without trivial_abi, &ret == local_addr because the return value
   // is allocated here in main's stackframe.
   //
   // With trivial_abi, local_addr is the address of a local variable in
   // make_val, and hence different from &ret.
-#if !defined(__i386__) && !defined(_WIN32)
+#if !defined(__i386__) && !defined(_WIN32) && !defined(_AIX)
   // On X86, structs are never returned in registers.
+  // On AIX, structs are never returned in registers.
   // Thus, unique_ptr will be passed indirectly even if it is trivial.
   // On Windows, structs with a destructor are always returned indirectly.
   assert((void*)&ret != local_addr);
 #endif
 
   return 0;
 }

libcxx/test/libcxx/memory/trivial_abi/weak_ptr_ret.pass.cpp

 //===----------------------------------------------------------------------===//
 //
 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
 // See https://llvm.org/LICENSE.txt for license information.
 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
 //
 //===----------------------------------------------------------------------===//
 
 // <memory>
 
 // Test weak_ptr<T> with trivial_abi as return-type.
 
 // ADDITIONAL_COMPILE_FLAGS: -D_LIBCPP_ABI_ENABLE_SHARED_PTR_TRIVIAL_ABI
 
 // XFAIL: gcc
-// XFAIL: LIBCXX-AIX-FIXME
 
 #include <memory>
 #include <cassert>
 
 __attribute__((noinline)) void call_something() { asm volatile(""); }
 
 struct Node {
   explicit Node() {}
int main(int, char**) {
   std::weak_ptr<Node> ret = make_val(sptr, &local_addr);
   assert(local_addr != nullptr);
 
   // Without trivial_abi, &ret == local_addr because the return value
   // is allocated here in main's stackframe.
   //
   // With trivial_abi, local_addr is the address of a local variable in
   // make_val, and hence different from &ret.
-#if !defined(__i386__) && !defined(__arm__) && !defined(_WIN32)
+#if !defined(__i386__) && !defined(__arm__) && !defined(_WIN32) && !defined(_AIX)
   // On X86, structs are never returned in registers.
+  // On AIX, structs are never returned in registers.
   // On ARM32, structs larger than 4 bytes cannot be returned in registers.
   // On Windows, structs with a destructor are always returned indirectly.
   // Thus, weak_ptr will be passed indirectly even if it is trivial.
   assert((void*)&ret != local_addr);
 #endif
   return 0;
 }