[libcxx] r248313 - Add placeholder __libcpp_relaxed_store() for when atomic builtins are not available.

Dimitry Andric via cfe-commits cfe-commits at lists.llvm.org
Tue Sep 22 11:55:37 PDT 2015

Author: dim
Date: Tue Sep 22 13:55:37 2015
New Revision: 248313

URL: http://llvm.org/viewvc/llvm-project?rev=248313&view=rev
Add placeholder __libcpp_relaxed_store() for when atomic builtins are not available.

In rL241532, atomic_support.h was added, which provides handling of
atomic operations for libc++.  When atomic builtins are not available,
it emits a warning about being unsupported, but it still provides a
number of stubs for the required functions.

However, it misses a stub for `__libcpp_relaxed_store()`.  Add it, by
using the same implementation as for `__libcpp_atomic_store()`.

(Note that I encountered this on arm-freebsd, which still defaults to
armv4, and does not have the runtime libcalls to support atomic
builtins.  For now, I have simply disabled using them.)

Reviewers: mclow.lists, EricWF

Subscribers: theraven, cfe-commits, jroelofs, majnemer, aemerson

Differential Revision: http://reviews.llvm.org/D13051


Modified: libcxx/trunk/src/include/atomic_support.h
URL: http://llvm.org/viewvc/llvm-project/libcxx/trunk/src/include/atomic_support.h?rev=248313&r1=248312&r2=248313&view=diff
--- libcxx/trunk/src/include/atomic_support.h (original)
+++ libcxx/trunk/src/include/atomic_support.h Tue Sep 22 13:55:37 2015
@@ -103,6 +103,13 @@ void __libcpp_atomic_store(_ValueType* _
     *__dest = __val;
+template <class _ValueType, class _FromType>
+void __libcpp_relaxed_store(_ValueType* __dest, _FromType __val)
+    *__dest = __val;
 template <class _ValueType>
 _ValueType __libcpp_atomic_load(_ValueType const* __val,

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