[libcxx] r291275 - [libc++] Cleanup and document <__threading_support>
Eric Fiselier via cfe-commits
cfe-commits at lists.llvm.org
Fri Jan 6 12:05:40 PST 2017
Author: ericwf
Date: Fri Jan 6 14:05:40 2017
New Revision: 291275
URL: http://llvm.org/viewvc/llvm-project?rev=291275&view=rev
Log:
[libc++] Cleanup and document <__threading_support>
Summary:
This patch attempts to clean up the macro configuration mess in `<__threading_support>`, specifically the mess involving external threading variants. Additionally this patch adds design documentation for `<__threading_support>` and the configuration macros it uses.
The primary change in this patch is separating the idea of an "external API" provided by `<__external_threading>` and the idea of having an external threading library. Now `_LIBCPP_HAS_THREAD_API_EXTERNAL` means that libc++ should use `<__external_threading>` and that the header is expected to exist. Additionally the new macro `_LIBCPP_HAS_THREAD_LIBRARY_EXTERNAL` is now used to configure for using an "external library" with the default threading API.
Reviewers: compnerd, rmaprath
Subscribers: smeenai, cfe-commits, mgorny
Differential Revision: https://reviews.llvm.org/D28316
Added:
libcxx/trunk/docs/DesignDocs/ThreadingSupportAPI.rst
Modified:
libcxx/trunk/CMakeLists.txt
libcxx/trunk/docs/index.rst
libcxx/trunk/include/__config
libcxx/trunk/include/__config_site.in
libcxx/trunk/include/__threading_support
libcxx/trunk/lib/CMakeLists.txt
libcxx/trunk/test/CMakeLists.txt
libcxx/trunk/test/lit.site.cfg.in
libcxx/trunk/test/support/external_threads.cpp
Modified: libcxx/trunk/CMakeLists.txt
URL: http://llvm.org/viewvc/llvm-project/libcxx/trunk/CMakeLists.txt?rev=291275&r1=291274&r2=291275&view=diff
==============================================================================
--- libcxx/trunk/CMakeLists.txt (original)
+++ libcxx/trunk/CMakeLists.txt Fri Jan 6 14:05:40 2017
@@ -169,6 +169,9 @@ option(LIBCXX_HAS_PTHREAD_API "Ignore au
option(LIBCXX_HAS_EXTERNAL_THREAD_API
"Build libc++ with an externalized threading API.
This option may only be set to ON when LIBCXX_ENABLE_THREADS=ON." OFF)
+option(LIBCXX_BUILD_EXTERNAL_THREAD_LIBRARY
+ "Build libc++ with an externalized threading library.
+ This option may only be set to ON when LIBCXX_ENABLE_THREADS=ON" OFF)
# Misc options ----------------------------------------------------------------
# FIXME: Turn -pedantic back ON. It is currently off because it warns
@@ -230,6 +233,17 @@ if(NOT LIBCXX_ENABLE_THREADS)
message(FATAL_ERROR "LIBCXX_HAS_EXTERNAL_THREAD_API can only be set to ON"
" when LIBCXX_ENABLE_THREADS is also set to ON.")
endif()
+ if (LIBCXX_BUILD_EXTERNAL_THREAD_LIBRARY)
+ message(FATAL_ERROR "LIBCXX_BUILD_EXTERNAL_THREAD_LIBRARY can only be set "
+ "to ON when LIBCXX_ENABLE_THREADS is also set to ON.")
+ endif()
+
+endif()
+
+if (LIBCXX_BUILD_EXTERNAL_THREAD_LIBRARY AND LIBCXX_HAS_EXTERNAL_THREAD_API)
+ message(FATAL_ERROR "The options LIBCXX_BUILD_EXTERNAL_THREAD_LIBRARY and "
+ "LIBCXX_HAS_EXTERNAL_THREAD_API cannot both be ON at "
+ "the same time")
endif()
if(LIBCXX_HAS_PTHREAD_API AND LIBCXX_HAS_EXTERNAL_THREAD_API)
@@ -520,6 +534,7 @@ config_define_if_not(LIBCXX_ENABLE_THREA
config_define_if(LIBCXX_HAS_PTHREAD_API _LIBCPP_HAS_THREAD_API_PTHREAD)
config_define_if(LIBCXX_HAS_EXTERNAL_THREAD_API _LIBCPP_HAS_THREAD_API_EXTERNAL)
+config_define_if(LIBCXX_BUILD_EXTERNAL_THREAD_LIBRARY _LIBCPP_HAS_THREAD_LIBRARY_EXTERNAL)
config_define_if(LIBCXX_HAS_MUSL_LIBC _LIBCPP_HAS_MUSL_LIBC)
# By default libc++ on Windows expects to use a shared library, which requires
Added: libcxx/trunk/docs/DesignDocs/ThreadingSupportAPI.rst
URL: http://llvm.org/viewvc/llvm-project/libcxx/trunk/docs/DesignDocs/ThreadingSupportAPI.rst?rev=291275&view=auto
==============================================================================
--- libcxx/trunk/docs/DesignDocs/ThreadingSupportAPI.rst (added)
+++ libcxx/trunk/docs/DesignDocs/ThreadingSupportAPI.rst Fri Jan 6 14:05:40 2017
@@ -0,0 +1,70 @@
+=====================
+Threading Support API
+=====================
+
+.. contents::
+ :local:
+
+Overview
+========
+
+Libc++ supports using multiple different threading models and configurations
+to implement the threading parts of libc++, including ``<thread>`` and ``<mutex>``.
+These different models provide entirely different interfaces from each
+other. To address this libc++ wraps the underlying threading API in a new and
+consistent API, which it uses internally to implement threading primitives.
+
+The ``<__threading_support>`` header is where libc++ defines its internal
+threading interface. It contains forward declarations of the internal threading
+interface as well as definitions for the interface.
+
+External Threading API and the ``<__external_threading>`` header
+================================================================
+
+In order to support vendors with custom threading API's libc++ allows the
+entire internal threading interface to be provided by an external,
+vendor provided, header.
+
+When ``_LIBCPP_HAS_THREAD_API_EXTERNAL`` is defined the ``<__threading_support>``
+header simply forwards to the ``<__external_threading>`` header (which must exist).
+It is expected that the ``<__external_threading>`` header provide the exact
+interface normally provided by ``<__threading_support>``.
+
+External Threading Library
+==========================
+
+Normally ``<__threading_support>`` provides inline definitions to each internal
+threading API function it declares. However libc++ also supports using an
+external library to provide the definitions.
+
+When ``_LIBCPP_HAS_THREAD_LIBRARY_EXTERNAL`` libc++ does not provide inline
+definitions for the internal API, instead assuming the definitions will be
+provided by an external library.
+
+Threading Configuration Macros
+==============================
+
+**_LIBCPP_HAS_NO_THREADS**
+ This macro is defined when libc++ is built without threading support. It
+ should not be manually defined by the user.
+
+**_LIBCPP_HAS_THREAD_API_EXTERNAL**
+ This macro is defined when libc++ should use the ``<__external_threading>``
+ header to provide the internal threading API. This macro overrides
+ ``_LIBCPP_HAS_THREAD_API_PTHREAD``.
+
+**_LIBCPP_HAS_THREAD_API_PTHREAD**
+ This macro is defined when libc++ should use POSIX threads to implement the
+ internal threading API.
+
+**_LIBCPP_HAS_THREAD_LIBRARY_EXTERNAL**
+ This macro is defined when libc++ expects the definitions of the internal
+ threading API to be provided by an external library. When defined
+ ``<__threading_support>`` will only provide the forward declarations and
+ typedefs for the internal threading API.
+
+**_LIBCPP_BUILDING_THREAD_LIBRARY_EXTERNAL**
+ This macro is used to build an external threading library using the
+ ``<__threading_support>``. Specifically it exposes the threading API
+ definitions in ``<__threading_support>`` as non-inline definitions meant to
+ be compiled into a library.
Modified: libcxx/trunk/docs/index.rst
URL: http://llvm.org/viewvc/llvm-project/libcxx/trunk/docs/index.rst?rev=291275&r1=291274&r2=291275&view=diff
==============================================================================
--- libcxx/trunk/docs/index.rst (original)
+++ libcxx/trunk/docs/index.rst Fri Jan 6 14:05:40 2017
@@ -131,7 +131,7 @@ Design Documents
DesignDocs/CapturingConfigInfo
DesignDocs/ABIVersioning
DesignDocs/VisibilityMacros
-
+ DesignDocs/ThreadingSupportAPI
* `<atomic> design <http://libcxx.llvm.org/atomic_design.html>`_
* `<type_traits> design <http://libcxx.llvm.org/type_traits_design.html>`_
Modified: libcxx/trunk/include/__config
URL: http://llvm.org/viewvc/llvm-project/libcxx/trunk/include/__config?rev=291275&r1=291274&r2=291275&view=diff
==============================================================================
--- libcxx/trunk/include/__config (original)
+++ libcxx/trunk/include/__config Fri Jan 6 14:05:40 2017
@@ -891,9 +891,7 @@ _LIBCPP_FUNC_VIS extern "C" void __sanit
#endif
// Thread API
-#if !defined(_LIBCPP_HAS_NO_THREADS) && \
- !defined(_LIBCPP_HAS_THREAD_API_PTHREAD) && \
- !defined(_LIBCPP_HAS_THREAD_API_EXTERNAL)
+#if !defined(_LIBCPP_HAS_NO_THREADS)
# if defined(__FreeBSD__) || \
defined(__Fuchsia__) || \
defined(__NetBSD__) || \
@@ -901,7 +899,9 @@ _LIBCPP_FUNC_VIS extern "C" void __sanit
defined(__APPLE__) || \
defined(__CloudABI__) || \
defined(__sun__)
-# define _LIBCPP_HAS_THREAD_API_PTHREAD
+# ifndef _LIBCPP_HAS_THREAD_API_PTHREAD
+# define _LIBCPP_HAS_THREAD_API_PTHREAD
+# endif
# else
# error "No thread API"
# endif // _LIBCPP_HAS_THREAD_API
Modified: libcxx/trunk/include/__config_site.in
URL: http://llvm.org/viewvc/llvm-project/libcxx/trunk/include/__config_site.in?rev=291275&r1=291274&r2=291275&view=diff
==============================================================================
--- libcxx/trunk/include/__config_site.in (original)
+++ libcxx/trunk/include/__config_site.in Fri Jan 6 14:05:40 2017
@@ -21,6 +21,7 @@
#cmakedefine _LIBCPP_HAS_MUSL_LIBC
#cmakedefine _LIBCPP_HAS_THREAD_API_PTHREAD
#cmakedefine _LIBCPP_HAS_THREAD_API_EXTERNAL
+#cmakedefine _LIBCPP_HAS_THREAD_LIBRARY_EXTERNAL
#cmakedefine _LIBCPP_DISABLE_VISIBILITY_ANNOTATIONS
#endif // _LIBCPP_CONFIG_SITE
Modified: libcxx/trunk/include/__threading_support
URL: http://llvm.org/viewvc/llvm-project/libcxx/trunk/include/__threading_support?rev=291275&r1=291274&r2=291275&view=diff
==============================================================================
--- libcxx/trunk/include/__threading_support (original)
+++ libcxx/trunk/include/__threading_support Fri Jan 6 14:05:40 2017
@@ -17,39 +17,17 @@
#pragma GCC system_header
#endif
-#ifndef _LIBCPP_HAS_NO_THREADS
-
-#ifndef __libcpp_has_include
- #ifndef __has_include
- #define __libcpp_has_include(x) 0
- #else
- #define __libcpp_has_include(x) __has_include(x)
- #endif
-#endif
-
-#if defined(_LIBCPP_HAS_THREAD_API_EXTERNAL) && \
- !__libcpp_has_include(<__external_threading>)
-// If the <__external_threading> header is absent, build libc++ against a
-// pthread-oriented thread api but leave out its implementation. This setup
-// allows building+testing of an externally-threaded library variant (on any
-// platform that supports pthreads). Here, an 'externally-threaded' library
-// variant is one where the implementation of the libc++ thread api is provided
-// as a separate library.
-#define _LIBCPP_HAS_THREAD_API_EXTERNAL_PTHREAD
-#endif
-
-#if defined(_LIBCPP_HAS_THREAD_API_EXTERNAL) && \
- __libcpp_has_include(<__external_threading>)
-#include <__external_threading>
-#else
+#if defined(_LIBCPP_HAS_THREAD_API_EXTERNAL)
+# include <__external_threading>
+#elif !defined(_LIBCPP_HAS_NO_THREADS)
-#if defined(_LIBCPP_HAS_THREAD_API_PTHREAD) || \
- defined(_LIBCPP_HAS_THREAD_API_EXTERNAL_PTHREAD)
-#include <pthread.h>
-#include <sched.h>
+#if defined(_LIBCPP_HAS_THREAD_API_PTHREAD)
+# include <pthread.h>
+# include <sched.h>
#endif
-#if defined(_LIBCPP_HAS_THREAD_API_EXTERNAL)
+#if defined(_LIBCPP_HAS_THREAD_LIBRARY_EXTERNAL) || \
+ defined(_LIBCPP_BUILDING_THREAD_LIBRARY_EXTERNAL)
#define _LIBCPP_THREAD_ABI_VISIBILITY _LIBCPP_FUNC_VIS
#else
#define _LIBCPP_THREAD_ABI_VISIBILITY inline _LIBCPP_INLINE_VISIBILITY
@@ -57,8 +35,7 @@
_LIBCPP_BEGIN_NAMESPACE_STD
-#if defined(_LIBCPP_HAS_THREAD_API_PTHREAD) || \
- defined(_LIBCPP_HAS_THREAD_API_EXTERNAL_PTHREAD)
+#if defined(_LIBCPP_HAS_THREAD_API_PTHREAD)
// Mutex
typedef pthread_mutex_t __libcpp_mutex_t;
#define _LIBCPP_MUTEX_INITIALIZER PTHREAD_MUTEX_INITIALIZER
@@ -175,8 +152,10 @@ void *__libcpp_tls_get(__libcpp_tls_key
_LIBCPP_THREAD_ABI_VISIBILITY
int __libcpp_tls_set(__libcpp_tls_key __key, void *__p);
-#if defined(_LIBCPP_HAS_THREAD_API_PTHREAD) || \
- defined(_LIBCPP_BUILDING_THREAD_API_EXTERNAL_PTHREAD)
+#if !defined(_LIBCPP_HAS_THREAD_LIBRARY_EXTERNAL) || \
+ defined(_LIBCPP_BUILDING_THREAD_LIBRARY_EXTERNAL)
+
+#if defined(_LIBCPP_HAS_THREAD_API_PTHREAD)
int __libcpp_recursive_mutex_init(__libcpp_recursive_mutex_t *__m)
{
@@ -344,10 +323,10 @@ int __libcpp_tls_set(__libcpp_tls_key __
#endif // _LIBCPP_HAS_THREAD_API_PTHREAD
-_LIBCPP_END_NAMESPACE_STD
+#endif // !_LIBCPP_HAS_THREAD_LIBRARY_EXTERNAL || _LIBCPP_BUILDING_THREAD_LIBRARY_EXTERNAL
-#endif // !_LIBCPP_HAS_THREAD_API_EXTERNAL || !__libcpp_has_include(<__external_threading>)
+_LIBCPP_END_NAMESPACE_STD
-#endif // _LIBCPP_HAS_NO_THREADS
+#endif // !_LIBCPP_HAS_NO_THREADS
#endif // _LIBCPP_THREADING_SUPPORT
Modified: libcxx/trunk/lib/CMakeLists.txt
URL: http://llvm.org/viewvc/llvm-project/libcxx/trunk/lib/CMakeLists.txt?rev=291275&r1=291274&r2=291275&view=diff
==============================================================================
--- libcxx/trunk/lib/CMakeLists.txt (original)
+++ libcxx/trunk/lib/CMakeLists.txt Fri Jan 6 14:05:40 2017
@@ -275,7 +275,7 @@ if (LIBCXX_ENABLE_EXPERIMENTAL_LIBRARY)
)
endif()
-if (LIBCXX_HAS_EXTERNAL_THREAD_API)
+if (LIBCXX_BUILD_EXTERNAL_THREAD_LIBRARY)
file(GLOB LIBCXX_EXTERNAL_THREADING_SUPPORT_SOURCES ../test/support/external_threads.cpp)
if (LIBCXX_ENABLE_SHARED)
Modified: libcxx/trunk/test/CMakeLists.txt
URL: http://llvm.org/viewvc/llvm-project/libcxx/trunk/test/CMakeLists.txt?rev=291275&r1=291274&r2=291275&view=diff
==============================================================================
--- libcxx/trunk/test/CMakeLists.txt (original)
+++ libcxx/trunk/test/CMakeLists.txt Fri Jan 6 14:05:40 2017
@@ -34,7 +34,7 @@ pythonize_bool(LIBCXXABI_ENABLE_SHARED)
pythonize_bool(LIBCXXABI_USE_LLVM_UNWINDER)
pythonize_bool(LIBCXX_HAS_ATOMIC_LIB)
pythonize_bool(LIBCXX_HAVE_CXX_ATOMICS_WITH_LIB)
-pythonize_bool(LIBCXX_HAS_EXTERNAL_THREAD_API)
+pythonize_bool(LIBCXX_BUILD_EXTERNAL_THREAD_LIBRARY)
# By default, for non-standalone builds, libcxx and libcxxabi share a library
# directory.
Modified: libcxx/trunk/test/lit.site.cfg.in
URL: http://llvm.org/viewvc/llvm-project/libcxx/trunk/test/lit.site.cfg.in?rev=291275&r1=291274&r2=291275&view=diff
==============================================================================
--- libcxx/trunk/test/lit.site.cfg.in (original)
+++ libcxx/trunk/test/lit.site.cfg.in Fri Jan 6 14:05:40 2017
@@ -28,7 +28,7 @@ config.has_libatomic = "@LIBC
config.use_libatomic = "@LIBCXX_HAVE_CXX_ATOMICS_WITH_LIB@"
config.libcxxabi_shared = "@LIBCXXABI_ENABLE_SHARED@"
-config.cxx_ext_threads = "@LIBCXX_HAS_EXTERNAL_THREAD_API@"
+config.cxx_ext_threads = "@LIBCXX_BUILD_EXTERNAL_THREAD_LIBRARY@"
# Let the main config do the real work.
config.loaded_site_config = True
Modified: libcxx/trunk/test/support/external_threads.cpp
URL: http://llvm.org/viewvc/llvm-project/libcxx/trunk/test/support/external_threads.cpp?rev=291275&r1=291274&r2=291275&view=diff
==============================================================================
--- libcxx/trunk/test/support/external_threads.cpp (original)
+++ libcxx/trunk/test/support/external_threads.cpp Fri Jan 6 14:05:40 2017
@@ -6,5 +6,5 @@
// Source Licenses. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
-#define _LIBCPP_BUILDING_THREAD_API_EXTERNAL_PTHREAD
+#define _LIBCPP_BUILDING_THREAD_LIBRARY_EXTERNAL
#include <__threading_support>
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