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- From 2e359284497c361e3208501fc70d49b2c54dc4ef Mon Sep 17 00:00:00 2001
- From: Michael Jeanson <mjeanson@efficios.com>
- Date: Tue, 14 Sep 2021 10:41:08 -0400
- Subject: [PATCH] Always use '__thread' for Thread local storage except on MSVC
- Use the GCC extension '__thread' [1] for Thread local storage on all C
- and C++ compilers except MSVC.
- While C11 and C++11 respectively offer '_Thread_local' and
- 'thread_local' as potentialy faster implementations, they offer no
- guarantees of compatibility when used in a library interface which might
- be used by both C and C++ client code.
- [1] https://gcc.gnu.org/onlinedocs/gcc/Thread-Local.html
- Change-Id: If4fe8bcdbda24b21dedf382112bd5c5f836c00c8
- Signed-off-by: Michael Jeanson <mjeanson@efficios.com>
- Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
- [Retrieved from:
- https://github.com/urcu/userspace-rcu/commit/2e359284497c361e3208501fc70d49b2c54dc4ef]
- Signed-off-by: Fabrice Fontaine <fontaine.fabrice@gmail.com>
- ---
- include/urcu/tls-compat.h | 15 +++++++--------
- 1 file changed, 7 insertions(+), 8 deletions(-)
- diff --git a/include/urcu/tls-compat.h b/include/urcu/tls-compat.h
- index 25cf375a..a2c94ded 100644
- --- a/include/urcu/tls-compat.h
- +++ b/include/urcu/tls-compat.h
- @@ -35,15 +35,14 @@ extern "C" {
- #ifdef CONFIG_RCU_TLS
-
- /*
- - * Don't use C++ 'thread_local' on MacOs, the implementation is incompatible
- - * with C and will result in a link error when accessing an extern variable
- - * provided by the C library from C++ code.
- + * Default to '__thread' on all C and C++ compilers except MSVC. While C11 has
- + * '_Thread_local' and C++11 has 'thread_local', only '__thread' seems to have
- + * a compatible implementation when linking public extern symbols across
- + * language boundaries.
- + *
- + * For more details, see 'https://gcc.gnu.org/onlinedocs/gcc/Thread-Local.html'.
- */
- -#if defined (__cplusplus) && (__cplusplus >= 201103L) && !defined(__APPLE__)
- -# define URCU_TLS_STORAGE_CLASS thread_local
- -#elif defined (__STDC_VERSION__) && (__STDC_VERSION__ >= 201112L)
- -# define URCU_TLS_STORAGE_CLASS _Thread_local
- -#elif defined (_MSC_VER)
- +#if defined(_MSC_VER)
- # define URCU_TLS_STORAGE_CLASS __declspec(thread)
- #else
- # define URCU_TLS_STORAGE_CLASS __thread
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