libgcc/config/i386/gthr-win32.c

   1 /* Implementation of W32-specific threads compatibility routines for
   2    libgcc2.  */
   3
   4 /* Copyright (C) 1999-2015 Free Software Foundation, Inc.
   5    Contributed by Mumit Khan <khan@xraylith.wisc.edu>.
   6    Modified and moved to separate file by Danny Smith
   7    <dannysmith@users.sourceforge.net>.
   8
   9 This file is part of GCC.
  10
  11 GCC is free software; you can redistribute it and/or modify it under
  12 the terms of the GNU General Public License as published by the Free
  13 Software Foundation; either version 3, or (at your option) any later
  14 version.
  15
  16 GCC is distributed in the hope that it will be useful, but WITHOUT ANY
  17 WARRANTY; without even the implied warranty of MERCHANTABILITY or
  18 FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  19 for more details.
  20
  21 Under Section 7 of GPL version 3, you are granted additional
  22 permissions described in the GCC Runtime Library Exception, version
  23 3.1, as published by the Free Software Foundation.
  24
  25 You should have received a copy of the GNU General Public License and
  26 a copy of the GCC Runtime Library Exception along with this program;
  27 see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see
  28 <http://www.gnu.org/licenses/>.  */
  29
  30 #include <windows.h>
  31 #ifndef __GTHREAD_HIDE_WIN32API
  32 # define __GTHREAD_HIDE_WIN32API 1
  33 #endif
  34 #undef  __GTHREAD_I486_INLINE_LOCK_PRIMITIVES
  35 #define __GTHREAD_I486_INLINE_LOCK_PRIMITIVES
  36 #include "gthr-win32.h"
  37
  38 /* Windows32 threads specific definitions. The windows32 threading model
  39    does not map well into pthread-inspired gcc's threading model, and so
  40    there are caveats one needs to be aware of.
  41
  42    1. The destructor supplied to __gthread_key_create is ignored for
  43       generic x86-win32 ports. This will certainly cause memory leaks
  44       due to unreclaimed eh contexts (sizeof (eh_context) is at least
  45       24 bytes for x86 currently).
  46
  47       This memory leak may be significant for long-running applications
  48       that make heavy use of C++ EH.
  49
  50       However, Mingw runtime (version 0.3 or newer) provides a mechanism
  51       to emulate pthreads key dtors; the runtime provides a special DLL,
  52       linked in if -mthreads option is specified, that runs the dtors in
  53       the reverse order of registration when each thread exits. If
  54       -mthreads option is not given, a stub is linked in instead of the
  55       DLL, which results in memory leak. Other x86-win32 ports can use
  56       the same technique of course to avoid the leak.
  57
  58    2. The error codes returned are non-POSIX like, and cast into ints.
  59       This may cause incorrect error return due to truncation values on
  60       hw where sizeof (DWORD) > sizeof (int).
  61
  62    3. We are currently using a special mutex instead of the Critical
  63       Sections, since Win9x does not support TryEnterCriticalSection
  64       (while NT does).
  65
  66    The basic framework should work well enough. In the long term, GCC
  67    needs to use Structured Exception Handling on Windows32.  */
  68
  69 int
  70 __gthr_win32_once (__gthread_once_t *once, void (*func) (void))
  71 {
  72   if (once == NULL || func == NULL)
  73     return EINVAL;
  74
  75   if (! once->done)
  76     {
  77       if (InterlockedIncrement (&(once->started)) == 0)
  78         {
  79           (*func) ();
  80           once->done = TRUE;
  81         }
  82       else
  83         {
  84           /* Another thread is currently executing the code, so wait for it
  85              to finish; yield the CPU in the meantime.  If performance
  86              does become an issue, the solution is to use an Event that
  87              we wait on here (and set above), but that implies a place to
  88              create the event before this routine is called.  */
  89           while (! once->done)
  90             Sleep (0);
  91         }
  92     }
  93   return 0;
  94 }
  95
  96 /* Windows32 thread local keys don't support destructors; this leads to
  97    leaks, especially in threaded applications making extensive use of
  98    C++ EH. Mingw uses a thread-support DLL to work-around this problem.  */
  99
 100 int
 101 __gthr_win32_key_create (__gthread_key_t *key,
 102                          void (*dtor) (void *) __attribute__((unused)))
 103 {
 104   int status = 0;
 105   DWORD tls_index = TlsAlloc ();
 106   if (tls_index != 0xFFFFFFFF)
 107     {
 108       *key = tls_index;
 109 #ifdef MINGW32_SUPPORTS_MT_EH
 110       /* Mingw runtime will run the dtors in reverse order for each thread
 111          when the thread exits.  */
 112       status = __mingwthr_key_dtor (*key, dtor);
 113 #endif
 114     }
 115   else
 116     status = (int) GetLastError ();
 117   return status;
 118 }
 119
 120 int
 121 __gthr_win32_key_delete (__gthread_key_t key)
 122 {
 123   return (TlsFree (key) != 0) ? 0 : (int) GetLastError ();
 124 }
 125
 126 void *
 127 __gthr_win32_getspecific (__gthread_key_t key)
 128 {
 129   DWORD lasterror;
 130   void *ptr;
 131   lasterror = GetLastError();
 132   ptr = TlsGetValue(key);
 133   SetLastError( lasterror );
 134   return ptr;
 135 }
 136
 137 int
 138 __gthr_win32_setspecific (__gthread_key_t key, const void *ptr)
 139 {
 140   if (TlsSetValue (key, CONST_CAST2(void *, const void *, ptr)) != 0)
 141     return 0;
 142   else
 143     return GetLastError ();
 144 }
 145
 146 void
 147 __gthr_win32_mutex_init_function (__gthread_mutex_t *mutex)
 148 {
 149   mutex->counter = -1;
 150   mutex->sema = CreateSemaphoreW (NULL, 0, 65535, NULL);
 151 }
 152
 153 void
 154 __gthr_win32_mutex_destroy (__gthread_mutex_t *mutex)
 155 {
 156   CloseHandle ((HANDLE) mutex->sema);
 157 }
 158
 159 int
 160 __gthr_win32_mutex_lock (__gthread_mutex_t *mutex)
 161 {
 162   if (InterlockedIncrement (&mutex->counter) == 0 ||
 163       WaitForSingleObject (mutex->sema, INFINITE) == WAIT_OBJECT_0)
 164     return 0;
 165   else
 166     {
 167       /* WaitForSingleObject returns WAIT_FAILED, and we can only do
 168          some best-effort cleanup here.  */
 169       InterlockedDecrement (&mutex->counter);
 170       return 1;
 171     }
 172 }
 173
 174 int
 175 __gthr_win32_mutex_trylock (__gthread_mutex_t *mutex)
 176 {
 177   if (__GTHR_W32_InterlockedCompareExchange (&mutex->counter, 0, -1) < 0)
 178     return 0;
 179   else
 180     return 1;
 181 }
 182
 183 int
 184 __gthr_win32_mutex_unlock (__gthread_mutex_t *mutex)
 185 {
 186   if (InterlockedDecrement (&mutex->counter) >= 0)
 187     return ReleaseSemaphore (mutex->sema, 1, NULL) ? 0 : 1;
 188   else
 189     return 0;
 190 }
 191
 192 void
 193 __gthr_win32_recursive_mutex_init_function (__gthread_recursive_mutex_t *mutex)
 194 {
 195   mutex->counter = -1;
 196   mutex->depth = 0;
 197   mutex->owner = 0;
 198   mutex->sema = CreateSemaphoreW (NULL, 0, 65535, NULL);
 199 }
 200
 201 int
 202 __gthr_win32_recursive_mutex_lock (__gthread_recursive_mutex_t *mutex)
 203 {
 204   DWORD me = GetCurrentThreadId();
 205   if (InterlockedIncrement (&mutex->counter) == 0)
 206     {
 207       mutex->depth = 1;
 208       mutex->owner = me;
 209     }
 210   else if (mutex->owner == me)
 211     {
 212       InterlockedDecrement (&mutex->counter);
 213       ++(mutex->depth);
 214     }
 215   else if (WaitForSingleObject (mutex->sema, INFINITE) == WAIT_OBJECT_0)
 216     {
 217       mutex->depth = 1;
 218       mutex->owner = me;
 219     }
 220   else
 221     {
 222       /* WaitForSingleObject returns WAIT_FAILED, and we can only do
 223          some best-effort cleanup here.  */
 224       InterlockedDecrement (&mutex->counter);
 225       return 1;
 226     }
 227   return 0;
 228 }
 229
 230 int
 231 __gthr_win32_recursive_mutex_trylock (__gthread_recursive_mutex_t *mutex)
 232 {
 233   DWORD me = GetCurrentThreadId();
 234   if (__GTHR_W32_InterlockedCompareExchange (&mutex->counter, 0, -1) < 0)
 235     {
 236       mutex->depth = 1;
 237       mutex->owner = me;
 238     }
 239   else if (mutex->owner == me)
 240     ++(mutex->depth);
 241   else
 242     return 1;
 243
 244   return 0;
 245 }
 246
 247 int
 248 __gthr_win32_recursive_mutex_unlock (__gthread_recursive_mutex_t *mutex)
 249 {
 250   --(mutex->depth);
 251   if (mutex->depth == 0)
 252     {
 253       mutex->owner = 0;
 254
 255       if (InterlockedDecrement (&mutex->counter) >= 0)
 256         return ReleaseSemaphore (mutex->sema, 1, NULL) ? 0 : 1;
 257     }
 258
 259   return 0;
 260 }
 261
 262 int
 263 __gthr_win32_recursive_mutex_destroy (__gthread_recursive_mutex_t *mutex)
 264 {
 265   CloseHandle ((HANDLE) mutex->sema);
 266   return 0;
 267 }