[libcxx-commits] [libcxx] [libcxxabi] [llvm] [libc++] Implement library support for MCF thread model (PR #116550)
LIU Hao via libcxx-commits
libcxx-commits at lists.llvm.org
Sun Nov 17 09:15:44 PST 2024
https://github.com/lhmouse created https://github.com/llvm/llvm-project/pull/116550
This commit allows building libcxx and libcxxabi with
cmake -DLIBCXX_HAS_MCF_THREAD_API=ON \
-DLIBCXXABI_HAS_MCF_THREAD_API=ON \
...
This commit adds a new macro, `_LIBCPP_HAS_THREAD_API_MCF`, to indicate that the libraries have been built with MCF thread model.
These functions, and member functions of these classes, are implemented directly in libmcfgthread. The list is exhaustive. If someone wants to implement more, such as `std::counting_semaphore` and `std::timed_mutex`, please let me know:
* `__cxa_guard_acquire()`
* `__cxa_guard_release()`
* `__cxa_guard_abort()`
* `std::mutex`
* `std::call_once()`
* `std::recursive_mutex`
* `std::condition_variable`
* `std::thread`
* `std::this_thread::get_id()`
* `std::this_thread::sleep_for()`
* `std::this_thread::yield()`
Reference: https://gcc.gnu.org/git/?p=gcc.git;a=commit;h=f036d759ecee538555fa8c6b11963e4033732463
Reference: https://github.com/lhmouse/mcfgthread/wiki/How-the-MCF-thread-model-works
>From 689470df2a7aed3efcc739f172a66e6893725d24 Mon Sep 17 00:00:00 2001
From: LIU Hao <lh_mouse at 126.com>
Date: Sun, 17 Nov 2024 23:56:57 +0800
Subject: [PATCH] [libc++] Implement library support for MCF thread model
This commit allows building libcxx and libcxxabi with
cmake -DLIBCXX_HAS_MCF_THREAD_API=ON \
-DLIBCXXABI_HAS_MCF_THREAD_API=ON \
...
This commit adds a new macro, `_LIBCPP_HAS_THREAD_API_MCF`, to indicate that
the libraries have been built with MCF thread model.
These functions, and member functions of these classes, are implemented
directly in libmcfgthread. The list is exhaustive. If someone wants to
implement more, such as `std::counting_semaphore` and `std::timed_mutex`,
please let me know:
* `__cxa_guard_acquire()`
* `__cxa_guard_release()`
* `__cxa_guard_abort()`
* `std::mutex`
* `std::call_once()`
* `std::recursive_mutex`
* `std::condition_variable`
* `std::thread`
* `std::this_thread::get_id()`
* `std::this_thread::sleep_for()`
* `std::this_thread::yield()`
Reference: https://gcc.gnu.org/git/?p=gcc.git;a=commit;h=f036d759ecee538555fa8c6b11963e4033732463
Reference: https://github.com/lhmouse/mcfgthread/wiki/How-the-MCF-thread-model-works
Signed-off-by: LIU Hao <lh_mouse at 126.com>
---
libcxx/CMakeLists.txt | 25 +++++++++-
.../docs/DesignDocs/ThreadingSupportAPI.rst | 4 ++
libcxx/include/__config | 6 ++-
libcxx/include/__config_site.in | 1 +
libcxx/include/__thread/support.h | 2 +
libcxx/src/CMakeLists.txt | 2 +-
libcxxabi/CMakeLists.txt | 28 +++++++++++
libcxxabi/src/CMakeLists.txt | 4 ++
libcxxabi/src/cxa_guard_impl.h | 48 ++++++++++++++++++-
libcxxabi/src/cxa_thread_atexit.cpp | 17 ++++---
.../gn/secondary/libcxx/include/BUILD.gn | 1 +
11 files changed, 127 insertions(+), 11 deletions(-)
diff --git a/libcxx/CMakeLists.txt b/libcxx/CMakeLists.txt
index abe12c2805a7cf..616b31dd79140e 100644
--- a/libcxx/CMakeLists.txt
+++ b/libcxx/CMakeLists.txt
@@ -295,6 +295,7 @@ endif()
option(LIBCXX_HAS_MUSL_LIBC "Build libc++ with support for the Musl C library" OFF)
option(LIBCXX_HAS_PTHREAD_API "Ignore auto-detection and force use of pthread API" OFF)
option(LIBCXX_HAS_WIN32_THREAD_API "Ignore auto-detection and force use of win32 thread API" OFF)
+option(LIBCXX_HAS_MCF_THREAD_API "Ignore auto-detection and force use of mcfgthread API" OFF)
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)
@@ -342,7 +343,10 @@ if(NOT LIBCXX_ENABLE_THREADS)
message(FATAL_ERROR "LIBCXX_HAS_WIN32_THREAD_API can only be set to ON"
" when LIBCXX_ENABLE_THREADS is also set to ON.")
endif()
-
+ if (LIBCXX_HAS_MCF_THREAD_API)
+ message(FATAL_ERROR "LIBCXX_HAS_MCF_THREAD_API can only be set to ON"
+ " when LIBCXX_ENABLE_THREADS is also set to ON.")
+ endif()
endif()
if (LIBCXX_HAS_EXTERNAL_THREAD_API)
@@ -356,6 +360,11 @@ if (LIBCXX_HAS_EXTERNAL_THREAD_API)
" and LIBCXX_HAS_WIN32_THREAD_API cannot be both"
" set to ON at the same time.")
endif()
+ if (LIBCXX_HAS_MCF_THREAD_API)
+ message(FATAL_ERROR "The options LIBCXX_HAS_EXTERNAL_THREAD_API"
+ " and LIBCXX_HAS_MCF_THREAD_API cannot be both"
+ " set to ON at the same time.")
+ endif()
endif()
if (LIBCXX_HAS_PTHREAD_API)
@@ -364,6 +373,19 @@ if (LIBCXX_HAS_PTHREAD_API)
" and LIBCXX_HAS_WIN32_THREAD_API cannot be both"
" set to ON at the same time.")
endif()
+ if (LIBCXX_HAS_MCF_THREAD_API)
+ message(FATAL_ERROR "The options LIBCXX_HAS_PTHREAD_API"
+ " and LIBCXX_HAS_MCF_THREAD_API cannot be both"
+ " set to ON at the same time.")
+ endif()
+endif()
+
+if (LIBCXX_HAS_WIN32_THREAD_API)
+ if (LIBCXX_HAS_MCF_THREAD_API)
+ message(FATAL_ERROR "The options LIBCXX_HAS_WIN32_THREAD_API"
+ " and LIBCXX_HAS_MCF_THREAD_API cannot be both"
+ " set to ON at the same time.")
+ endif()
endif()
if (NOT LIBCXX_ENABLE_RTTI AND LIBCXX_ENABLE_EXCEPTIONS)
@@ -754,6 +776,7 @@ endif()
config_define(${LIBCXX_HAS_PTHREAD_API} _LIBCPP_HAS_THREAD_API_PTHREAD)
config_define(${LIBCXX_HAS_EXTERNAL_THREAD_API} _LIBCPP_HAS_THREAD_API_EXTERNAL)
config_define(${LIBCXX_HAS_WIN32_THREAD_API} _LIBCPP_HAS_THREAD_API_WIN32)
+config_define(${LIBCXX_HAS_MCF_THREAD_API} _LIBCPP_HAS_THREAD_API_MCF)
config_define(${LIBCXX_HAS_MUSL_LIBC} _LIBCPP_HAS_MUSL_LIBC)
config_define_if(LIBCXX_NO_VCRUNTIME _LIBCPP_NO_VCRUNTIME)
config_define(${LIBCXX_ENABLE_FILESYSTEM} _LIBCPP_HAS_FILESYSTEM)
diff --git a/libcxx/docs/DesignDocs/ThreadingSupportAPI.rst b/libcxx/docs/DesignDocs/ThreadingSupportAPI.rst
index d103c49e25952f..a8cf749fbaff08 100644
--- a/libcxx/docs/DesignDocs/ThreadingSupportAPI.rst
+++ b/libcxx/docs/DesignDocs/ThreadingSupportAPI.rst
@@ -65,3 +65,7 @@ Threading Configuration Macros
**_LIBCPP_HAS_THREAD_API_WIN32**
This macro is defined when libc++ should use Win32 threads to implement the
internal threading API.
+
+**_LIBCPP_HAS_THREAD_API_MCF**
+ This macro is defined when libc++ should use the mcfgthread library to
+ implement the internal threading API.
diff --git a/libcxx/include/__config b/libcxx/include/__config
index 9db00cd0c9fb93..5bee6efdc0456d 100644
--- a/libcxx/include/__config
+++ b/libcxx/include/__config
@@ -809,6 +809,7 @@ typedef __char32_t char32_t;
# if _LIBCPP_HAS_THREADS && \
!_LIBCPP_HAS_THREAD_API_PTHREAD && \
!_LIBCPP_HAS_THREAD_API_WIN32 && \
+ !_LIBCPP_HAS_THREAD_API_MCF && \
!_LIBCPP_HAS_THREAD_API_EXTERNAL
# if defined(__FreeBSD__) || \
@@ -882,7 +883,7 @@ typedef __char32_t char32_t;
// clang-format off
# if (_LIBCPP_HAS_THREAD_API_PTHREAD && defined(__GLIBC__)) || \
(_LIBCPP_HAS_THREAD_API_C11 && defined(__Fuchsia__)) || \
- _LIBCPP_HAS_THREAD_API_WIN32
+ _LIBCPP_HAS_THREAD_API_WIN32 || _LIBCPP_HAS_THREAD_API_MCF
// clang-format on
# define _LIBCPP_HAS_TRIVIAL_MUTEX_DESTRUCTION 1
# else
@@ -897,7 +898,8 @@ typedef __char32_t char32_t;
//
// TODO(EricWF): This is potentially true for some pthread implementations
// as well.
-# if (_LIBCPP_HAS_THREAD_API_C11 && defined(__Fuchsia__)) || _LIBCPP_HAS_THREAD_API_WIN32
+# if (_LIBCPP_HAS_THREAD_API_C11 && defined(__Fuchsia__)) || \
+ _LIBCPP_HAS_THREAD_API_WIN32 || _LIBCPP_HAS_THREAD_API_MCF
# define _LIBCPP_HAS_TRIVIAL_CONDVAR_DESTRUCTION 1
# else
# define _LIBCPP_HAS_TRIVIAL_CONDVAR_DESTRUCTION 0
diff --git a/libcxx/include/__config_site.in b/libcxx/include/__config_site.in
index fc01aaf2d8746e..f5d2f0240c1003 100644
--- a/libcxx/include/__config_site.in
+++ b/libcxx/include/__config_site.in
@@ -20,6 +20,7 @@
#cmakedefine01 _LIBCPP_HAS_THREAD_API_PTHREAD
#cmakedefine01 _LIBCPP_HAS_THREAD_API_EXTERNAL
#cmakedefine01 _LIBCPP_HAS_THREAD_API_WIN32
+#cmakedefine01 _LIBCPP_HAS_THREAD_API_MCF
#define _LIBCPP_HAS_THREAD_API_C11 0 // FIXME: Is this guarding dead code?
#cmakedefine _LIBCPP_DISABLE_VISIBILITY_ANNOTATIONS
#cmakedefine01 _LIBCPP_HAS_VENDOR_AVAILABILITY_ANNOTATIONS
diff --git a/libcxx/include/__thread/support.h b/libcxx/include/__thread/support.h
index 50a18daf2b685a..6b2e6851b20139 100644
--- a/libcxx/include/__thread/support.h
+++ b/libcxx/include/__thread/support.h
@@ -114,6 +114,8 @@ _LIBCPP_END_NAMESPACE_STD
# include <__thread/support/c11.h>
# elif _LIBCPP_HAS_THREAD_API_WIN32
# include <__thread/support/windows.h>
+# elif defined(_LIBCPP_HAS_THREAD_API_MCF)
+# include <mcfgthread/libcxx.h>
# else
# error "No threading API was selected"
# endif
diff --git a/libcxx/src/CMakeLists.txt b/libcxx/src/CMakeLists.txt
index cce8b8976f73c0..fa8e30741f1113 100644
--- a/libcxx/src/CMakeLists.txt
+++ b/libcxx/src/CMakeLists.txt
@@ -105,7 +105,7 @@ if(WIN32)
support/win32/support.cpp
)
- if (NOT LIBCXX_HAS_PTHREAD_API)
+ if (LIBCXXABI_HAS_WIN32_THREAD_API)
list(APPEND LIBCXX_SOURCES
support/win32/thread_win32.cpp
)
diff --git a/libcxxabi/CMakeLists.txt b/libcxxabi/CMakeLists.txt
index da0e8b286cddc1..a876e4d74ae37e 100644
--- a/libcxxabi/CMakeLists.txt
+++ b/libcxxabi/CMakeLists.txt
@@ -56,6 +56,7 @@ option(LIBCXXABI_USE_COMPILER_RT "Use compiler-rt instead of libgcc" OFF)
option(LIBCXXABI_ENABLE_THREADS "Build with threads enabled" ON)
option(LIBCXXABI_HAS_PTHREAD_API "Ignore auto-detection and force use of pthread API" OFF)
option(LIBCXXABI_HAS_WIN32_THREAD_API "Ignore auto-detection and force use of win32 thread API" OFF)
+option(LIBCXXABI_HAS_MCF_THREAD_API "Ignore auto-detection and force use of mcfgthread API" OFF)
option(LIBCXXABI_HAS_EXTERNAL_THREAD_API
"Build libc++abi with an externalized threading API.
This option may only be set to ON when LIBCXXABI_ENABLE_THREADS=ON." OFF)
@@ -318,6 +319,11 @@ if (NOT LIBCXXABI_ENABLE_THREADS)
" be set to ON when LIBCXXABI_ENABLE_THREADS"
" is also set to ON.")
endif()
+ if (LIBCXXABI_HAS_MCF_THREAD_API)
+ message(FATAL_ERROR "LIBCXXABI_HAS_MCF_THREAD_API can only"
+ " be set to ON when LIBCXXABI_ENABLE_THREADS"
+ " is also set to ON.")
+ endif()
add_definitions(-D_LIBCXXABI_HAS_NO_THREADS)
endif()
@@ -332,6 +338,11 @@ if (LIBCXXABI_HAS_EXTERNAL_THREAD_API)
" and LIBCXXABI_HAS_WIN32_THREAD_API cannot be both"
" set to ON at the same time.")
endif()
+ if (LIBCXXABI_HAS_MCF_THREAD_API)
+ message(FATAL_ERROR "The options LIBCXXABI_HAS_EXTERNAL_THREAD_API"
+ " and LIBCXXABI_HAS_MCF_THREAD_API cannot be both"
+ " set to ON at the same time.")
+ endif()
endif()
if (LIBCXXABI_HAS_PTHREAD_API)
@@ -340,6 +351,19 @@ if (LIBCXXABI_HAS_PTHREAD_API)
"and LIBCXXABI_HAS_WIN32_THREAD_API cannot be both"
"set to ON at the same time.")
endif()
+ if (LIBCXXABI_HAS_MCF_THREAD_API)
+ message(FATAL_ERROR "The options LIBCXXABI_HAS_PTHREAD_API"
+ "and LIBCXXABI_HAS_MCF_THREAD_API cannot be both"
+ "set to ON at the same time.")
+ endif()
+endif()
+
+if (LIBCXXABI_HAS_WIN32_THREAD_API)
+ if (LIBCXXABI_HAS_MCF_THREAD_API)
+ message(FATAL_ERROR "The options LIBCXXABI_HAS_WIN32_THREAD_API"
+ "and LIBCXXABI_HAS_MCF_THREAD_API cannot be both"
+ "set to ON at the same time.")
+ endif()
endif()
if (LLVM_ENABLE_MODULES)
@@ -375,6 +399,10 @@ if (LIBCXXABI_HAS_EXTERNAL_THREAD_API)
add_definitions(-D_LIBCPP_HAS_THREAD_API_EXTERNAL)
endif()
+if (LIBCXXABI_HAS_MCF_THREAD_API)
+ add_definitions(-D_LIBCPP_HAS_THREAD_API_MCF)
+endif()
+
if (MSVC)
add_definitions(-D_CRT_SECURE_NO_WARNINGS)
endif()
diff --git a/libcxxabi/src/CMakeLists.txt b/libcxxabi/src/CMakeLists.txt
index 84fe2784bec5ca..17c5d5e335f709 100644
--- a/libcxxabi/src/CMakeLists.txt
+++ b/libcxxabi/src/CMakeLists.txt
@@ -90,6 +90,10 @@ if (ANDROID AND ANDROID_PLATFORM_LEVEL LESS 21)
list(APPEND LIBCXXABI_LIBRARIES android_support)
endif()
+if (LIBCXXABI_HAS_MCF_THREAD_API)
+ list(APPEND LIBCXXABI_LIBRARIES mcfgthread ntdll)
+endif()
+
# Setup flags.
if (CXX_SUPPORTS_NOSTDLIBXX_FLAG)
add_link_flags_if_supported(-nostdlib++)
diff --git a/libcxxabi/src/cxa_guard_impl.h b/libcxxabi/src/cxa_guard_impl.h
index 7b05bf32f3eda7..78d4fa5e1f20d7 100644
--- a/libcxxabi/src/cxa_guard_impl.h
+++ b/libcxxabi/src/cxa_guard_impl.h
@@ -68,6 +68,9 @@
# if defined(__ELF__) && defined(_LIBCXXABI_LINK_PTHREAD_LIB)
# pragma comment(lib, "pthread")
# endif
+# if _LIBCPP_HAS_THREAD_API_MCF
+# include <mcfgthread/cxa.h>
+# endif
#endif
#if defined(__clang__)
@@ -608,6 +611,39 @@ struct GuardObject {
}
};
+//===----------------------------------------------------------------------===//
+// GuardObject for MCF
+//===----------------------------------------------------------------------===//
+
+/// Forwards everything to libmcfgthread
+struct GuardObject_MCF {
+ GuardObject_MCF() = delete;
+ GuardObject_MCF(GuardObject_MCF const&) = delete;
+ GuardObject_MCF& operator=(GuardObject_MCF const&) = delete;
+
+private:
+ int64_t* guard_ptr;
+
+public:
+ explicit GuardObject_MCF(uint64_t* raw_guard_object)
+ : guard_ptr(reinterpret_cast<int64_t*>(raw_guard_object)) { }
+
+ /// Implements __cxa_guard_acquire.
+ AcquireResult cxa_guard_acquire() {
+ return static_cast<AcquireResult>(__MCF_cxa_guard_acquire(guard_ptr));
+ }
+
+ /// Implements __cxa_guard_release.
+ void cxa_guard_release() {
+ __MCF_cxa_guard_release(guard_ptr);
+ }
+
+ /// Implements __cxa_guard_abort.
+ void cxa_guard_abort() {
+ __MCF_cxa_guard_abort(guard_ptr);
+ }
+};
+
//===----------------------------------------------------------------------===//
// Convenience Classes
//===----------------------------------------------------------------------===//
@@ -628,6 +664,9 @@ template <void (*Wait)(int*, int) = PlatformFutexWait, void (*Wake)(int*) = Plat
uint32_t (*GetThreadIDArg)() = PlatformThreadID>
using FutexGuard = GuardObject<InitByteFutex<Wait, Wake, GetThreadIDArg>>;
+/// MCFGuard - Forwards everything to libmcfgthread
+using MCFGuard = GuardObject_MCF;
+
//===----------------------------------------------------------------------===//
//
//===----------------------------------------------------------------------===//
@@ -639,7 +678,7 @@ struct GlobalStatic {
template <class T>
_LIBCPP_CONSTINIT T GlobalStatic<T>::instance = {};
-enum class Implementation { NoThreads, GlobalMutex, Futex };
+enum class Implementation { NoThreads, GlobalMutex, Futex, MCF };
template <Implementation Impl>
struct SelectImplementation;
@@ -660,6 +699,11 @@ struct SelectImplementation<Implementation::Futex> {
using type = FutexGuard<PlatformFutexWait, PlatformFutexWake, PlatformThreadID>;
};
+template <>
+struct SelectImplementation<Implementation::MCF> {
+ using type = MCFGuard;
+};
+
// TODO(EricWF): We should prefer the futex implementation when available. But
// it should be done in a separate step from adding the implementation.
constexpr Implementation CurrentImplementation =
@@ -667,6 +711,8 @@ constexpr Implementation CurrentImplementation =
Implementation::NoThreads;
#elif defined(_LIBCXXABI_USE_FUTEX)
Implementation::Futex;
+#elif defined(_LIBCPP_HAS_THREAD_API_MCF)
+ Implementation::MCF;
#else
Implementation::GlobalMutex;
#endif
diff --git a/libcxxabi/src/cxa_thread_atexit.cpp b/libcxxabi/src/cxa_thread_atexit.cpp
index 8546cfe48c3976..445eeb41aa6996 100644
--- a/libcxxabi/src/cxa_thread_atexit.cpp
+++ b/libcxxabi/src/cxa_thread_atexit.cpp
@@ -10,9 +10,12 @@
#include "cxxabi.h"
#include <__thread/support.h>
#ifndef _LIBCXXABI_HAS_NO_THREADS
-#if defined(__ELF__) && defined(_LIBCXXABI_LINK_PTHREAD_LIB)
-#pragma comment(lib, "pthread")
-#endif
+# if defined(__ELF__) && defined(_LIBCXXABI_LINK_PTHREAD_LIB)
+# pragma comment(lib, "pthread")
+# endif
+# if _LIBCPP_HAS_THREAD_API_MCF
+# include <mcfgthread/cxa.h>
+# endif
#endif
#include <stdlib.h>
@@ -22,14 +25,14 @@ namespace __cxxabiv1 {
using Dtor = void(*)(void*);
extern "C"
-#ifndef HAVE___CXA_THREAD_ATEXIT_IMPL
+#if !defined(HAVE___CXA_THREAD_ATEXIT_IMPL)
// A weak symbol is used to detect this function's presence in the C library
// at runtime, even if libc++ is built against an older libc
_LIBCXXABI_WEAK
#endif
int __cxa_thread_atexit_impl(Dtor, void*, void*);
-#ifndef HAVE___CXA_THREAD_ATEXIT_IMPL
+#if !(_LIBCPP_HAS_THREAD_API_MCF || defined(HAVE___CXA_THREAD_ATEXIT_IMPL))
namespace {
// This implementation is used if the C library does not provide
@@ -109,7 +112,9 @@ namespace {
extern "C" {
_LIBCXXABI_FUNC_VIS int __cxa_thread_atexit(Dtor dtor, void* obj, void* dso_symbol) throw() {
-#ifdef HAVE___CXA_THREAD_ATEXIT_IMPL
+#if _LIBCPP_HAS_THREAD_API_MCF
+ return __MCF_cxa_thread_atexit(dtor, obj, dso_symbol);
+#elif defined(HAVE___CXA_THREAD_ATEXIT_IMPL)
return __cxa_thread_atexit_impl(dtor, obj, dso_symbol);
#else
if (__cxa_thread_atexit_impl) {
diff --git a/llvm/utils/gn/secondary/libcxx/include/BUILD.gn b/llvm/utils/gn/secondary/libcxx/include/BUILD.gn
index 229a056c8afefd..8ab51e22711409 100644
--- a/llvm/utils/gn/secondary/libcxx/include/BUILD.gn
+++ b/llvm/utils/gn/secondary/libcxx/include/BUILD.gn
@@ -26,6 +26,7 @@ if (current_toolchain == default_toolchain) {
"_LIBCPP_HAS_THREAD_API_PTHREAD=",
"_LIBCPP_HAS_THREAD_API_EXTERNAL=",
"_LIBCPP_HAS_THREAD_API_WIN32=",
+ "_LIBCPP_HAS_THREAD_API_MCF=",
"_LIBCPP_DISABLE_VISIBILITY_ANNOTATIONS=",
"_LIBCPP_HAS_VENDOR_AVAILABILITY_ANNOTATIONS=",
"_LIBCPP_NO_VCRUNTIME=",
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