diff options
Diffstat (limited to 'gcc-4.4.3/libstdc++-v3/libsupc++/guard.cc')
| -rw-r--r-- | gcc-4.4.3/libstdc++-v3/libsupc++/guard.cc | 416 |
1 files changed, 0 insertions, 416 deletions
diff --git a/gcc-4.4.3/libstdc++-v3/libsupc++/guard.cc b/gcc-4.4.3/libstdc++-v3/libsupc++/guard.cc deleted file mode 100644 index 37b0ffdd6..000000000 --- a/gcc-4.4.3/libstdc++-v3/libsupc++/guard.cc +++ /dev/null @@ -1,416 +0,0 @@ -// Copyright (C) 2002, 2004, 2006, 2008, 2009 Free Software Foundation, Inc. -// -// This file is part of GCC. -// -// GCC is free software; you can redistribute it and/or modify -// it under the terms of the GNU General Public License as published by -// the Free Software Foundation; either version 3, or (at your option) -// any later version. - -// GCC is distributed in the hope that it will be useful, -// but WITHOUT ANY WARRANTY; without even the implied warranty of -// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the -// GNU General Public License for more details. - -// Under Section 7 of GPL version 3, you are granted additional -// permissions described in the GCC Runtime Library Exception, version -// 3.1, as published by the Free Software Foundation. - -// You should have received a copy of the GNU General Public License and -// a copy of the GCC Runtime Library Exception along with this program; -// see the files COPYING3 and COPYING.RUNTIME respectively. If not, see -// <http://www.gnu.org/licenses/>. - -// Written by Mark Mitchell, CodeSourcery LLC, <mark@codesourcery.com> -// Thread support written by Jason Merrill, Red Hat Inc. <jason@redhat.com> - -#include <bits/c++config.h> -#include <cxxabi.h> -#include <exception> -#include <new> -#include <ext/atomicity.h> -#include <ext/concurrence.h> -#if defined(__GTHREADS) && defined(__GTHREAD_HAS_COND) \ - && defined(_GLIBCXX_ATOMIC_BUILTINS_4) && defined(_GLIBCXX_HAVE_LINUX_FUTEX) -# include <climits> -#if defined(__ANDROID__) -# include <sys/syscall.h> -# define SYS_futex __NR_futex -#else -# include <syscall.h> -#endif -# define _GLIBCXX_USE_FUTEX -# define _GLIBCXX_FUTEX_WAIT 0 -# define _GLIBCXX_FUTEX_WAKE 1 -#endif - -// The IA64/generic ABI uses the first byte of the guard variable. -// The ARM EABI uses the least significant bit. - -// Thread-safe static local initialization support. -#ifdef __GTHREADS -# ifndef _GLIBCXX_USE_FUTEX -namespace -{ - // A single mutex controlling all static initializations. - static __gnu_cxx::__recursive_mutex* static_mutex; - - typedef char fake_recursive_mutex[sizeof(__gnu_cxx::__recursive_mutex)] - __attribute__ ((aligned(__alignof__(__gnu_cxx::__recursive_mutex)))); - fake_recursive_mutex fake_mutex; - - static void init() - { static_mutex = new (&fake_mutex) __gnu_cxx::__recursive_mutex(); } - - __gnu_cxx::__recursive_mutex& - get_static_mutex() - { - static __gthread_once_t once = __GTHREAD_ONCE_INIT; - __gthread_once(&once, init); - return *static_mutex; - } - - // Simple wrapper for exception safety. - struct mutex_wrapper - { - bool unlock; - mutex_wrapper() : unlock(true) - { get_static_mutex().lock(); } - - ~mutex_wrapper() - { - if (unlock) - static_mutex->unlock(); - } - }; -} -# endif - -# if defined(__GTHREAD_HAS_COND) && !defined(_GLIBCXX_USE_FUTEX) -namespace -{ - // A single conditional variable controlling all static initializations. - static __gnu_cxx::__cond* static_cond; - - // using a fake type to avoid initializing a static class. - typedef char fake_cond_t[sizeof(__gnu_cxx::__cond)] - __attribute__ ((aligned(__alignof__(__gnu_cxx::__cond)))); - fake_cond_t fake_cond; - - static void init_static_cond() - { static_cond = new (&fake_cond) __gnu_cxx::__cond(); } - - __gnu_cxx::__cond& - get_static_cond() - { - static __gthread_once_t once = __GTHREAD_ONCE_INIT; - __gthread_once(&once, init_static_cond); - return *static_cond; - } -} -# endif - -# ifndef _GLIBCXX_GUARD_TEST_AND_ACQUIRE -inline bool -__test_and_acquire (__cxxabiv1::__guard *g) -{ - bool b = _GLIBCXX_GUARD_TEST (g); - _GLIBCXX_READ_MEM_BARRIER; - return b; -} -# define _GLIBCXX_GUARD_TEST_AND_ACQUIRE(G) __test_and_acquire (G) -# endif - -# ifndef _GLIBCXX_GUARD_SET_AND_RELEASE -inline void -__set_and_release (__cxxabiv1::__guard *g) -{ - _GLIBCXX_WRITE_MEM_BARRIER; - _GLIBCXX_GUARD_SET (g); -} -# define _GLIBCXX_GUARD_SET_AND_RELEASE(G) __set_and_release (G) -# endif - -#else /* !__GTHREADS */ - -# undef _GLIBCXX_GUARD_TEST_AND_ACQUIRE -# undef _GLIBCXX_GUARD_SET_AND_RELEASE -# define _GLIBCXX_GUARD_SET_AND_RELEASE(G) _GLIBCXX_GUARD_SET (G) - -#endif /* __GTHREADS */ - -namespace __gnu_cxx -{ - // 6.7[stmt.dcl]/4: If control re-enters the declaration (recursively) - // while the object is being initialized, the behavior is undefined. - - // Since we already have a library function to handle locking, we might - // as well check for this situation and throw an exception. - // We use the second byte of the guard variable to remember that we're - // in the middle of an initialization. - class recursive_init_error: public std::exception - { - public: - recursive_init_error() throw() { } - virtual ~recursive_init_error() throw (); - }; - - recursive_init_error::~recursive_init_error() throw() { } -} - -// -// Here are C++ run-time routines for guarded initiailization of static -// variables. There are 4 scenarios under which these routines are called: -// -// 1. Threads not supported (__GTHREADS not defined) -// 2. Threads are supported but not enabled at run-time. -// 3. Threads enabled at run-time but __gthreads_* are not fully POSIX. -// 4. Threads enabled at run-time and __gthreads_* support all POSIX threads -// primitives we need here. -// -// The old code supported scenarios 1-3 but was broken since it used a global -// mutex for all threads and had the mutex locked during the whole duration of -// initlization of a guarded static variable. The following created a dead-lock -// with the old code. -// -// Thread 1 acquires the global mutex. -// Thread 1 starts initializing static variable. -// Thread 1 creates thread 2 during initialization. -// Thread 2 attempts to acuqire mutex to initialize another variable. -// Thread 2 blocks since thread 1 is locking the mutex. -// Thread 1 waits for result from thread 2 and also blocks. A deadlock. -// -// The new code here can handle this situation and thus is more robust. Howere, -// we need to use the POSIX thread conditional variable, which is not supported -// in all platforms, notably older versions of Microsoft Windows. The gthr*.h -// headers define a symbol __GTHREAD_HAS_COND for platforms that support POSIX -// like conditional variables. For platforms that do not support conditional -// variables, we need to fall back to the old code. - -// If _GLIBCXX_USE_FUTEX, no global mutex or conditional variable is used, -// only atomic operations are used together with futex syscall. -// Valid values of the first integer in guard are: -// 0 No thread encountered the guarded init -// yet or it has been aborted. -// _GLIBCXX_GUARD_BIT The guarded static var has been successfully -// initialized. -// _GLIBCXX_GUARD_PENDING_BIT The guarded static var is being initialized -// and no other thread is waiting for its -// initialization. -// (_GLIBCXX_GUARD_PENDING_BIT The guarded static var is being initialized -// | _GLIBCXX_GUARD_WAITING_BIT) and some other threads are waiting until -// it is initialized. - -namespace __cxxabiv1 -{ -#ifdef _GLIBCXX_USE_FUTEX - namespace - { - static inline int __guard_test_bit (const int __byte, const int __val) - { - union { int __i; char __c[sizeof (int)]; } __u = { 0 }; - __u.__c[__byte] = __val; - return __u.__i; - } - } -#endif - - static inline int - init_in_progress_flag(__guard* g) - { return ((char *)g)[1]; } - - static inline void - set_init_in_progress_flag(__guard* g, int v) - { ((char *)g)[1] = v; } - - static inline void - throw_recursive_init_exception() - { -#ifdef __EXCEPTIONS - throw __gnu_cxx::recursive_init_error(); -#else - // Use __builtin_trap so we don't require abort(). - __builtin_trap(); -#endif - } - - // acuire() is a helper function used to acquire guard if thread support is - // not compiled in or is compiled in but not enabled at run-time. - static int - acquire(__guard *g) - { - // Quit if the object is already initialized. - if (_GLIBCXX_GUARD_TEST(g)) - return 0; - - if (init_in_progress_flag(g)) - throw_recursive_init_exception(); - - set_init_in_progress_flag(g, 1); - return 1; - } - - extern "C" - int __cxa_guard_acquire (__guard *g) - { -#ifdef __GTHREADS - // If the target can reorder loads, we need to insert a read memory - // barrier so that accesses to the guarded variable happen after the - // guard test. - if (_GLIBCXX_GUARD_TEST_AND_ACQUIRE (g)) - return 0; - -# ifdef _GLIBCXX_USE_FUTEX - // If __sync_* and futex syscall are supported, don't use any global - // mutex. - if (__gthread_active_p ()) - { - int *gi = (int *) (void *) g; - const int guard_bit = _GLIBCXX_GUARD_BIT; - const int pending_bit = _GLIBCXX_GUARD_PENDING_BIT; - const int waiting_bit = _GLIBCXX_GUARD_WAITING_BIT; - - while (1) - { - int old = __sync_val_compare_and_swap (gi, 0, pending_bit); - if (old == 0) - return 1; // This thread should do the initialization. - - if (old == guard_bit) - return 0; // Already initialized. - - if (old == pending_bit) - { - int newv = old | waiting_bit; - if (__sync_val_compare_and_swap (gi, old, newv) != old) - continue; - - old = newv; - } - - syscall (SYS_futex, gi, _GLIBCXX_FUTEX_WAIT, old, 0); - } - } -# else - if (__gthread_active_p ()) - { - mutex_wrapper mw; - - while (1) // When this loop is executing, mutex is locked. - { -# ifdef __GTHREAD_HAS_COND - // The static is already initialized. - if (_GLIBCXX_GUARD_TEST(g)) - return 0; // The mutex will be unlocked via wrapper - - if (init_in_progress_flag(g)) - { - // The guarded static is currently being initialized by - // another thread, so we release mutex and wait for the - // conditional variable. We will lock the mutex again after - // this. - get_static_cond().wait_recursive(&get_static_mutex()); - } - else - { - set_init_in_progress_flag(g, 1); - return 1; // The mutex will be unlocked via wrapper. - } -# else - // This provides compatibility with older systems not supporting - // POSIX like conditional variables. - if (acquire(g)) - { - mw.unlock = false; - return 1; // The mutex still locked. - } - return 0; // The mutex will be unlocked via wrapper. -# endif - } - } -# endif -#endif - - return acquire (g); - } - - extern "C" - void __cxa_guard_abort (__guard *g) - { -#ifdef _GLIBCXX_USE_FUTEX - // If __sync_* and futex syscall are supported, don't use any global - // mutex. - if (__gthread_active_p ()) - { - int *gi = (int *) (void *) g; - const int waiting_bit = _GLIBCXX_GUARD_WAITING_BIT; - int old = __sync_lock_test_and_set (gi, 0); - - if ((old & waiting_bit) != 0) - syscall (SYS_futex, gi, _GLIBCXX_FUTEX_WAKE, INT_MAX); - return; - } -#elif defined(__GTHREAD_HAS_COND) - if (__gthread_active_p()) - { - mutex_wrapper mw; - - set_init_in_progress_flag(g, 0); - - // If we abort, we still need to wake up all other threads waiting for - // the conditional variable. - get_static_cond().broadcast(); - return; - } -#endif - - set_init_in_progress_flag(g, 0); -#if defined(__GTHREADS) && !defined(__GTHREAD_HAS_COND) - // This provides compatibility with older systems not supporting POSIX like - // conditional variables. - if (__gthread_active_p ()) - static_mutex->unlock(); -#endif - } - - extern "C" - void __cxa_guard_release (__guard *g) - { -#ifdef _GLIBCXX_USE_FUTEX - // If __sync_* and futex syscall are supported, don't use any global - // mutex. - if (__gthread_active_p ()) - { - int *gi = (int *) (void *) g; - const int guard_bit = _GLIBCXX_GUARD_BIT; - const int waiting_bit = _GLIBCXX_GUARD_WAITING_BIT; - int old = __sync_lock_test_and_set (gi, guard_bit); - - if ((old & waiting_bit) != 0) - syscall (SYS_futex, gi, _GLIBCXX_FUTEX_WAKE, INT_MAX); - return; - } -#elif defined(__GTHREAD_HAS_COND) - if (__gthread_active_p()) - { - mutex_wrapper mw; - - set_init_in_progress_flag(g, 0); - _GLIBCXX_GUARD_SET_AND_RELEASE(g); - - get_static_cond().broadcast(); - return; - } -#endif - - set_init_in_progress_flag(g, 0); - _GLIBCXX_GUARD_SET_AND_RELEASE (g); - -#if defined(__GTHREADS) && !defined(__GTHREAD_HAS_COND) - // This provides compatibility with older systems not supporting POSIX like - // conditional variables. - if (__gthread_active_p()) - static_mutex->unlock(); -#endif - } -} |