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Move internal usages of alignof/__alignof to use _LIBCPP_ALIGNOF.

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Summary:
Starting in Clang 8.0 and GCC 8.0, `alignof` and `__alignof` return different values in same cases. Specifically `alignof` and `_Alignof` return the minimum alignment for a type, where as `__alignof` returns the preferred alignment. libc++ currently uses `__alignof` but means to use `alignof`. See  llvm.org/PR39713

This patch introduces the macro `_LIBCPP_ALIGNOF` so we can control which spelling gets used.

This patch does not introduce any ABI guard to provide the old behavior with newer compilers. However, if we decide that is needed, this patch makes it trivial to implement.

I think we should commit this change immediately, and decide what we want to do about the ABI afterwards. 

Reviewers: ldionne, EricWF

Reviewed By: EricWF

Subscribers: christof, libcxx-commits

Differential Revision: https://reviews.llvm.org/D54814

git-svn-id: https://llvm.org/svn/llvm-project/libcxx/trunk@347787 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Eric Fiselier
2018-11-28 18:16:02 +00:00
parent 581671fd26
commit 087f065cb0
10 changed files with 91 additions and 44 deletions
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6
include/experimental/coroutine
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@@ -214,7 +214,7 @@ public:
_LIBCPP_INLINE_VISIBILITY
_Promise& promise() const {
return *static_cast<_Promise*>(
__builtin_coro_promise(this->__handle_, __alignof(_Promise), false));
__builtin_coro_promise(this->__handle_, _LIBCPP_ALIGNOF(_Promise), false));
}
public:
@@ -254,7 +254,7 @@ public:
coroutine_handle __tmp;
__tmp.__handle_ = __builtin_coro_promise(
_VSTD::addressof(const_cast<_RawPromise&>(__promise)),
__alignof(_Promise), true);
_LIBCPP_ALIGNOF(_Promise), true);
return __tmp;
}
};
@@ -272,7 +272,7 @@ public:
_LIBCPP_INLINE_VISIBILITY
_Promise& promise() const {
return *static_cast<_Promise*>(
__builtin_coro_promise(this->__handle_, __alignof(_Promise), false));
__builtin_coro_promise(this->__handle_, _LIBCPP_ALIGNOF(_Promise), false));
}
_LIBCPP_CONSTEXPR explicit operator bool() const _NOEXCEPT { return true; }