MSVC allows interpreting volatile loads and stores, when combined with
/volatile:iso, as having acquire/release semantics. MSVC also exposes a
define, _ISO_VOLATILE, which allows users to enquire if this feature is
enabled or disabled.
MSVC says this should be 202002L for /std:c++20, and of VS16.11
that's indeed the case (older versions warn that they don't
understand /std:c++20, and then cl.exe defaults to C++14 and
sets _MSVC_LANG to 201402 accordingly).
Differential Revision: https://reviews.llvm.org/D114867
Summary:
The patch adds correct value of _MSVC_LANG to match with MSVC++ VS2019 /std:c++latest mode.
Bugzilla - Bug 43965
https://bugs.llvm.org/show_bug.cgi?id=43965
The value for a MS specific macro differs from Microsoft starting with VS2019 in /std:c++latest mode.
-bash-4.2$ cat msvclang.cpp
_MSVC_LANG
-bash-4.2$ cl /std:c++latest -E msvclang.cpp
Microsoft (R) C/C++ Optimizing Compiler Version 19.20.27508.1 for x64
Copyright (C) Microsoft Corporation. All rights reserved.
/std:c++latest is provided as a preview of language features from the latest C++
working draft, and we're eager to hear about bugs and suggestions for improvements.
However, note that these features are provided as-is without support, and subject
to changes or removal as the working draft evolves. See
https://go.microsoft.com/fwlink/?linkid=2045807 for details.
msvclang.cpp
201705L
-bash-4.2$ clang-cl /std:c++latest -E msvclang.cpp
201704L
Reviewers: rnk
Reviewed By: rnk
Differential Revision: https://reviews.llvm.org/D70996
Use the new cx8 feature flag that was added to the backend to represent support for cmpxchg8b. Use this flag to set the MaxAtomicInlineWidth.
This also assumes all the cmpxchg instructions are enabled for CK_Generic which is what cc1 defaults to when nothing is specified.
Differential Revision: https://reviews.llvm.org/D59566
llvm-svn: 356709
David Majnemer