[gcc r12-74] aix: delete AIX pre-PowerPC version of atomicity.h

[David Edelsohn]

https://gcc.gnu.org/g:b5f79f4d3808294192ec7438718aa54cf8982128

commit r12-74-gb5f79f4d3808294192ec7438718aa54cf8982128
Author: David Edelsohn <dje.gcc@gmail.com>
Date:   Thu Apr 22 14:52:22 2021 -0400

    aix: delete AIX pre-PowerPC version of atomicity.h
    
    The AIX-specific version of atomicity.h that provides compatibility
    for the origina POWER architecture without atomic instructions no longer
    is referenced.  This patch deletes the file.
    
    libstdc++-v3/ChangeLog:
    
            * config/os/aix/atomicity.h: Delete.

Diff:
---
 libstdc++-v3/config/os/aix/atomicity.h | 56 ----------------------------------
 1 file changed, 56 deletions(-)

diff --git a/libstdc++-v3/config/os/aix/atomicity.h b/libstdc++-v3/config/os/aix/atomicity.h
deleted file mode 100644
index 13a51daa68b..00000000000
--- a/libstdc++-v3/config/os/aix/atomicity.h
+++ /dev/null
@@ -1,56 +0,0 @@
-// Low-level functions for atomic operations: AIX version  -*- C++ -*-
-
-// Copyright (C) 2000-2021 Free Software Foundation, Inc.
-//
-// This file is part of the GNU ISO C++ Library.  This library is free
-// software; you can redistribute it and/or modify it under the
-// terms of the GNU General Public License as published by the
-// Free Software Foundation; either version 3, or (at your option)
-// any later version.
-
-// This library is distributed in the hope that it will be useful,
-// but WITHOUT ANY WARRANTY; without even the implied warranty of
-// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
-// GNU General Public License for more details.
-
-// Under Section 7 of GPL version 3, you are granted additional
-// permissions described in the GCC Runtime Library Exception, version
-// 3.1, as published by the Free Software Foundation.
-
-// You should have received a copy of the GNU General Public License and
-// a copy of the GCC Runtime Library Exception along with this program;
-// see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see
-// <http://www.gnu.org/licenses/>.
-
-#include <ext/atomicity.h>
-
-/* We cannot use the cpu/powerpc/bits/atomicity.h inline assembly
-   definitions for these operations since they depend on operations
-   that are not available on the original POWER architecture.  AIX
-   still runs on the POWER architecture, so it would be incorrect to
-   assume the existence of these instructions.
-
-   The definition of _Atomic_word must match the type pointed to by
-   atomic_p in <sys/atomic_op.h>.  */
-
-extern "C"
-{
-#include <sys/atomic_op.h>
-}
-
-namespace __gnu_cxx _GLIBCXX_VISIBILITY(default)
-{
-_GLIBCXX_BEGIN_NAMESPACE_VERSION
-
-  _Atomic_word
-  __attribute__ ((__unused__))
-  __exchange_and_add (volatile _Atomic_word* __mem, int __val) throw ()
-  { return ::fetch_and_add(const_cast<atomic_p>(__mem), __val); }
-
-  void
-  __attribute__ ((__unused__))
-  __atomic_add (volatile _Atomic_word* __mem, int __val) throw ()
-  { (void) ::fetch_and_add(const_cast<atomic_p>(__mem), __val); }
-
-_GLIBCXX_END_NAMESPACE_VERSION
-} // namespace